lnu.sePublikasjoner
Endre søk
Begrens søket
2122232425 1151 - 1200 of 1215
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1151.
    Wille, Michelle
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Avril, Alexis
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). CIRAD, F-34398 Montpellier, France.
    Tolf, Conny
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Schager, Anna
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Larsson, Sara
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Borg, Olivia
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Olsen, Björn
    Uppsala Univ.
    Waldenström, Jonas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Temporal dynamics, diversity, and interplay in three components of the virodiversity of a Mallard population: Influenza A virus, avian paramyxovirus and avian coronavirus2015Inngår i: Infection, Genetics and Evolution, ISSN 1567-1348, E-ISSN 1567-7257, Vol. 29, s. 129-137Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multiple infections, or simultaneous infection of a host with multiple parasites, are the rule rather than the exception. Interactions between co-occurring pathogens in a population may be mutualistic, competitive or facilitative. For some pathogen combinations, these interrelated effects will have epidemiological consequences; however this is as yet poorly incorporated into practical disease ecology. For example, screening of Mallards for influenza A viruses (IAV) have repeatedly revealed high prevalence and large subtype diversity in the Northern Hemisphere. Other studies have identified avian paramyxovirus type 1 (APMV-1) and coronaviruses (CoVs) in Mallards, but without making inferences on the larger viral assemblage. In this study we followed 144 wild Mallards across an autumn season in a natural stopover site and constructed infection histories of IAV, APMV-1 and CoV. There was a high prevalence of IAV, comprising of 27 subtype combinations, while APMV-1 had a comparatively low prevalence (with a peak of 2%) and limited strain variation, similar to previous findings. Avian CoVs were common, with prevalence up to 12%, and sequence analysis identified different putative genetic lineages. An investigation of the dynamics of co-infections revealed a synergistic effect between CoV and IAV, whereby Coy prevalence was higher given that the birds were co-infected with IAV. There were no interactive effects between IAV and APMV-1. Disease dynamics are the result of an interplay between parasites, host immune responses, and resources; and is imperative that we begin to include all factors to better understand infectious disease risk. (C) 2014 Elsevier B.V. All rights reserved.

  • 1152.
    Wille, Michelle
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Peter Doherty Inst Infect & Immun, Australia.
    Latorre-Margalef, Neus
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Lund University.
    Tolf, Conny
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Halpin, Rebecca
    J Craig Venter Inst, USA.
    Wentworth, David
    J Craig Venter Inst, USA.
    Fouchier, Ron A. M.
    Erasmus MC, Netherlands.
    Raghwani, Jayna
    Univ Oxford, UK.
    Pybus, Oliver G.
    Univ Oxford, UK.
    Olsen, Bjorn
    Uppsala University.
    Waldenström, Jonas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Where do all the subtypes go?: Temporal dynamics of H8-H12 influenza A viruses in waterfowl2018Inngår i: Virus Evolution, E-ISSN 2057-1577, Vol. 4, nr 2, artikkel-id vey025Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Influenza A virus (IAV) is ubiquitous in waterfowl. In the northern hemisphere IAV prevalence is highest during the autumn and coincides with a peak in viral subtype diversity. Although haemagglutinin subtypes H1-H12 are associated with waterfowl hosts, subtypes H8-H12 are detected very infrequently. To better understand the role of waterfowl in the maintenance of these rare subtypes, we sequenced H8-H12 viruses isolated from Mallards (Anas platyrhynchos) from 2002 to 2009. These rare viruses exhibited varying ecological and phylodynamic features. The Eurasian clades of H8 and H12 phylogenies were dominated by waterfowl sequences; mostly viruses sequenced in this study. H11, once believed to be a subtype that infected charadriiformes (shorebirds), exhibited patterns more typical of common virus subtypes. Finally, subtypes H9 and H10, which have maintained lineages in poultry, showed markedly different patterns: H10 was associated with all possible NA subtypes and this drove HA lineage diversity within years. Rare viruses belonging to subtypes H8-H12 were highly reassorted, indicating that these rare subtypes are part of the broader IAV pool. Our results suggest that waterfowl play a role in the maintenance of these rare subtypes, but we recommend additional sampling of non-traditional hosts to better understand the reservoirs of these rare viruses.

  • 1153.
    Wille, Michelle
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Uppsala University.
    Latorre-Margalef, Neus
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). University of Georgia, USA.
    Tolf, Conny
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Stallknecht, D. E.
    University of Georgia, USA.
    Waldenström, Jonas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    No evidence for homosubtypic immunity of influenza H3 in Mallards following vaccination in a natural experimental system2017Inngår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 26, nr 5, s. 1420-1431Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Mallard (Anas platyrhynchos) is an important reservoir species for influenza A viruses (IAV), and in this host, prevalence and virus diversity are high. Studies have demonstrated the presence of homosubtypic immunity, where individuals are unlikely to be reinfected with the same subtype within an autumn season. Further, evidence for heterosubtypic immunity exists, whereby immune responses specific for one subtype offer partial or complete protection against related HA subtypes. We utilized a natural experimental system to determine whether homo- or heterospecific immunity could be induced following experimental vaccination. Thirty Mallards were vaccinated with an inactivated H3, H6 or a sham vaccine and after seroconversion were exposed to naturally infected wild conspecifics. All ducks were infected within 2days and had both primary and secondary infections. Overall, there was no observable difference between groups; all individuals were infected with H3 and H10 IAV. At the cessation of the experiment, most individuals had anti-NP antibodies and neutralizing antibodies against H10. Not all individuals had H3 neutralizing antibodies. The isolated H3 IAVs revealed genetic dissimilarity to the H3 vaccine strain, specifically substitutions in the vicinity of the receptor-binding site. There was no evidence of vaccine-induced homosubtypic immunity to H3, a likely result of both a poor H3 immune response in the ducks and H3 immune escape. Likewise, there was no observed heterosubtypic protection related to H6 vaccination. This study highlights the need for experimental approaches to assess how exposure to pathogens and resulting immune processes translates to individual and population disease dynamics.

  • 1154.
    Wille, Michelle
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Latorre-Margalef, Neus
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Tolf, Conny
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Stallknecht, D.
    Waldenström, Jonas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Putative escape and poor humoral response to inactivatedvaccine in Mallards results in no homo- or heterosubtypic immunity againstH3 influenza A in a natural-experimental system.Manuskript (preprint) (Annet vitenskapelig)
  • 1155.
    Wille, Michelle
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Uppsala University.
    Muradrasoli, Shaman
    Uppsala University;Swedish University of Agricultural Sciences.
    Nilsson, Anna
    Uppsala University.
    Jarhult, Josef D.
    Uppsala University.
    High Prevalence and Putative Lineage Maintenance of Avian Coronaviruses in Scandinavian Waterfowl2016Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 3, artikkel-id e0150198Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Coronaviruses (CoVs) are found in a wide variety of wild and domestic animals, and constitute a risk for zoonotic and emerging infectious disease. In poultry, the genetic diversity, evolution, distribution and taxonomy of some coronaviruses have been well described, but little is known about the features of CoVs in wild birds. In this study we screened 764 samples from 22 avian species of the orders Anseriformes and Charadriiformes in Sweden collected in 2006/2007 for CoV, with an overall CoV prevalence of 18.7%, which is higher than many other wild bird surveys. The highest prevalence was found in the diving duck-smainly Greater Scaup (Aythya marila; 51.5%)-and the dabbling duck Mallard (Anas platyrhynchos; 19.2%). Sequences from two of the Greater Scaup CoV fell into an infrequently detected lineage, shared only with a Tufted Duck (Aythya fuligula) CoV. Coronavirus sequences from Mallards in this study were highly similar to CoV sequences from the sample species and location in 2011, suggesting long-term maintenance in this population. A single Black-headed Gull represented the only positive sample from the order Charadriiformes. Globally, Anas species represent the largest fraction of avian CoV sequences, and there seems to be no host species, geographical or temporal structure. To better understand the eitiology, epidemiology and ecology of these viruses more systematic surveillance of wild birds and subsequent sequencing of detected CoV is imperative.

  • 1156.
    Wille, Michelle
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Tolf, Conny
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Avril, Alexis
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). CIRAD, Campusinternational de Baillarguet, Montpellier 34398, France.
    Latorre-Margalef, Neus
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Wallerström, Sofie
    Karolinska institutet.
    Olsen, Björn
    Uppsala universitet.
    Waldenström, Jonas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Frequency and patterns of reassortment in natural influenza A virus infection in a reservoir host2013Inngår i: Virology, ISSN 0042-6822, E-ISSN 1096-0341, Vol. 443, nr 15, s. 150-160Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Influenza A viruses (IAV) can dramatically alter both genotype and phenotype at a rapid rate as a product of co-infection and reassortment Avian IAV exhibit high levels of phylogenetic incongruence, suggesting high levels of reassortment in the virus reservoir. Using a natural-experimental system, we reconstructed relationships amongst 92 viruses across 15 subtypes from 10 Mallards in an autumn season. Phylogenetic analyses estimated that 56% of the isolated viruses were reassorted. Network analysis demonstrated different patterns of reassortment and limited exchange of segments between primary and secondary infections. No clear patterns of linkage between segments were found, and patterns within a season were likely the consequence of continued introduction ofnew constellations, high viral load and diversity in the wild bird reservoir, and co-infections. This is the first IAV study to implement multiple tools available for elucidating factors governing reassortment patterns in naturally infected Mallards.

    Fulltekst (pdf)
    fulltext
  • 1157.
    Wille, Michelle
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Tolf, Conny
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Latorre-Margalef, Neus
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Fouchier, R. A. M.
    Halpin, R. A.
    Wentworth, D. E.
    Ragwani, J.
    Pybus, O.
    Olsen, Björn
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Waldenström, Jonas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Limited diffusion of genome constellations and pervasive reassortment arefeatures of long-term circulation of H4N6 influenza A in European waterfowlManuskript (preprint) (Annet vitenskapelig)
  • 1158.
    Wille, Michelle
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    van Run, Peter
    Erasmus Medical Centre, The Netherlands.
    Waldenström, Jonas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Kuiken, Thijs
    Erasmus Medical Centre, The Netherlands.
    Infected or not: are PCR-positive oropharyngeal swabs indicative of low pathogenic influenza A virus infection in the respiratory tract of Mallard Anas platyrhynchos?2014Inngår i: Veterinary research (Print), ISSN 0928-4249, E-ISSN 1297-9716, Vol. 45, s. Article ID: 53-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Detection of influenza virus in oropharyngeal swabs collected during wild bird surveillance is assumed to representrespiratory infection, although intestine is the main site of infection. We tested this assumption by histologicalexamination of the respiratory tract of wild Mallards with virus-positive oropharyngeal swabs. Thirty-two of 125Mallards tested had viral-RNA positive oropharyngeal swabs. The respiratory tracts of four Mallards with the mostvirus were examined in detail by immunohistochemistry. None had detectable virus antigen in the respiratory tract,suggesting it was not infected. An alternative explanation is that the oropharynx was contaminated with virusthrough feeding in surface water or through preening.

    Fulltekst (pdf)
    Wille_2014_VetRes_IHC
  • 1159.
    Williams, C. M.
    et al.
    Univ Georgia, USA.
    Dupont, A. M.
    Univ Georgia, USA.
    Loevenich, J.
    Univ Georgia, USA.
    Post, A. F.
    URI, USA.
    Dinasquet, Julie
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Univ Copenhagen, Denmark.
    Yager, P. L.
    Univ Georgia, USA.
    Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica2016Inngår i: Elementa: Science of the Anthropocene, E-ISSN 2325-1026, Vol. 4, s. 1-18, artikkel-id 000102Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Heterotrophic bacteria play a key role in marine carbon cycling, and understanding their activities in polar systems is important for considering climate change impacts there. One goal of the ASPIRE project was to examine the relationship between the phytoplankton bloom and bacterial heterotrophy in the Amundsen Sea Polynya (ASP). Bacterial abundance, production (BP), respiration, growth efficiency, and extracellular enzyme activity (EEA) were compared to nutrient and organic matter inventories, chlorophyll a (Chl a), viral and microzooplankton abundance, and net primary production (NPP). Bacterial production and respiration clearly responded (0.04-4.0 and 10-53 mu g C L-1 d(-1), respectively) to the buildup of a massive Phaeocystis antarctica bloom (Chl a: 0.2-22 mu g L-1), with highest rates observed in the central polynya where Chl a and particulate organic carbon (POC) were greatest. The highest BP rates exceeded those reported for the Ross Sea or any other Antarctic coastal system, yet the BP: NPP ratio (2.1-9.4%) was relatively low. Bacterial respiration was also high, and growth efficiency (2-27%; median = 10%) was similar to oligotrophic systems. Thus, the integrated bacterial carbon demand (0.8-2.8 g C m(-2) d(-1)) was a high fraction (25-128%; median = 43%) of NPP during bloom development. During peak bloom, activity was particle-associated: BP and EEA correlated well with POC, and size fractionation experiments showed that the larger size fraction (> 3 mu m) accounted for a majority (similar to 75%) of the BP. The community was psychrophilic, with a 5x reduction in BP when warmed to 20 degrees C. In deeper waters, respiration remained relatively high, likely fueled by the significant downward particle flux in the region. A highly active, particle-associated, heterotrophic microbial community clearly responded to the extraordinary phytoplankton bloom in the ASP, likely limiting biological pump efficiency during the early season.

  • 1160.
    Williams, Richard A. J.
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Univ Kansas, USA.;Univ Complutense Madrid, Spain.
    Owens, Hannah L.
    Univ Kansas, USA;Univ Florida, USA.
    Clamp, John
    North Carolina Cent Univ, USA.
    Peterson, A. Townsend
    Univ Kansas, USA.
    Warren, Alan
    Nat Hist Museum, UK.
    Martin-Cereceda, Mercedes
    Univ Complutense Madrid, Spain.
    Endemicity and climatic niche differentiation in three marine ciliated protists2018Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 63, nr 6, s. 2727-2736Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The biogeographic pattern of single-celled eukaryotes (protists), including ciliates, is poorly understood. Most marine species are believed to have a relatively high dispersal potential, such that both globally distributed and geographically isolated taxa exist. Primary occurrence data for three large, easily identified ciliate species, Parafavella gigantea, Schmidingerella serrata, and Zoothamnium pelagicum, and environmental data drawn from the National Oceanic and Atmospheric Administration's World Ocean Atlas were used to estimate each species' spatial and environmental distributions using Maxent v3.3.3k. The predictive power of the models was tested with a series of spatial stratification studies, which were evaluated using partial receiver operating characteristic (ROC) statistics. Differences between niches occupied by each taxon were evaluated using background similarity tests. All predictions showed significant ability to anticipate test points. The null hypotheses of niche similarity were rejected in all background similarity tests comparing the niches among the three species. This article provides the first quantitative assessment of environmental conditions associated with three species of ciliates and a first estimate of their spatial distributions in the North Atlantic, which can serve as a benchmark against which to document distributional shifts. These species follow consistent, predictable patterns related to climate and environmental biochemistry; the importance of climatic conditions as regards protist distributions is noteworthy considering the effects of global climate change.

  • 1161.
    Williams, Richard A. J.
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Tolf, Conny
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Waldenström, Jonas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Molecular identification of papillomavirus in ducks2018Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, artikkel-id 9096Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Papillomaviruses infect many vertebrates, including birds. Persistent infections by some strains can cause malignant proliferation of cells (i.e. cancer), though more typically infections cause benign tumours, or may be completely subclinical. Sometimes extensive, persistent tumours are recorded-notably in chaffinches and humans. In 2016, a novel papillomavirus genotype was characterized from a duck faecal microbiome, in Bhopal, India; the sixth papillomavirus genotype from birds. Prompted by this finding, we screened 160 cloacal swabs and 968 faecal samples collected from 299 ducks sampled at Ottenby Bird Observatory, Sweden in 2015, using a newly designed real-time PCR. Twenty one samples (1.9%) from six individuals (2%) were positive. Eighteen sequences were identical to the published genotype, duck papillomavirus 1. One additional novel genotype was recovered from three samples. Both genotypes were recovered from a wild strain domestic mallard that was infected for more than 60 days with each genotype. All positive individuals were adult (P = 0.004). Significantly more positive samples were detected from swabs than faecal samples (P < 0.0001). Sample type data suggests transmission may be via direct contact, and only infrequently, via the oral-faecal route. Infection in only adult birds supports the hypothesis that this virus is sexually transmitted, though more work is required to verify this.

  • 1162.
    Williamson, Craig E.
    et al.
    Miami University, USA.
    Neale, Patrick J.
    Smithsonian Environmental Research Center, USA.
    Hylander, Samuel
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Rose, Kevin C.
    Rensselaer Polytechnic Institute, USA.
    Figueroa, Félix L.
    University of Malaga, Spain.
    Robinson, Sharon A.
    University of Wollongong, Australia.
    Häder, Donat-P.
    Friedrich-Alexander Universität, Germany.
    Wängberg, Sten-Åke
    University of Gothenburg, Sweden.
    Worrest, Robert C.
    Columbia University, USA.
    The interactive effects of stratospheric ozone depletion, UV radiation, and climate change on aquatic ecosystems2019Inngår i: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 18, nr 3, s. 717-746Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This assessment summarises the current state of knowledge on the interactive effects of ozone depletion and climate change on aquatic ecosystems, focusing on how these affect exposures to UV radiation in both inland and oceanic waters. The ways in which stratospheric ozone depletion is directly altering climate in the southern hemisphere and the consequent extensive effects on aquatic ecosystems are also addressed. The primary objective is to synthesise novel findings over the past four years in the context of the existing understanding of ecosystem response to UV radiation and the interactive effects of climate change. If it were not for the Montreal Protocol, stratospheric ozone depletion would have led to high levels of exposure to solar UV radiation with much stronger negative effects on all trophic levels in aquatic ecosystems than currently experienced in both inland and oceanic waters. This “world avoided” scenario that has curtailed ozone depletion, means that climate change and other environmental variables will play the primary role in regulating the exposure of aquatic organisms to solar UV radiation. Reductions in the thickness and duration of snow and ice cover are increasing the levels of exposure of aquatic organisms to UV radiation. Climate change was also expected to increase exposure by causing shallow mixed layers, but new data show deepening in some regions and shoaling in others. In contrast, climate-change related increases in heavy precipitation and melting of glaciers and permafrost are increasing the concentration and colour of UV-absorbing dissolved organic matter (DOM) and particulates. This is leading to the “browning” of many inland and coastal waters, with consequent loss of the valuable ecosystem service in which solar UV radiation disinfects surface waters of parasites and pathogens. Many organisms can reduce damage due to exposure to UV radiation through behavioural avoidance, photoprotection, and photoenzymatic repair, but meta-analyses continue to confirm negative effects of UV radiation across all trophic levels. Modeling studies estimating photoinhibition of primary production in parts of the Pacific Ocean have demonstrated that the UV radiation component of sunlight leads to a 20% decrease in estimates of primary productivity. Exposure to UV radiation can also lead to positive effects on some organisms by damaging less UV-tolerant predators, competitors, and pathogens. UV radiation also contributes to the formation of microplastic pollutants and interacts with artificial sunscreens and other pollutants with adverse effects on aquatic ecosystems. Exposure to UV-B radiation can decrease the toxicity of some pollutants such as methyl mercury (due to its role in demethylation) but increase the toxicity of other pollutants such as some pesticides and polycyclic aromatic hydrocarbons. Feeding on microplastics by zooplankton can lead to bioaccumulation in fish. Microplastics are found in up to 20% of fish marketed for human consumption, potentially threatening food security. Depletion of stratospheric ozone has altered climate in the southern hemisphere in ways that have increased oceanic productivity and consequently the growth, survival and reproduction of many sea birds and mammals. In contrast, warmer sea surface temperatures related to these climate shifts are also correlated with declines in both kelp beds in Tasmania and corals in Brazil. This assessment demonstrates that knowledge of the interactive effects of ozone depletion, UV radiation, and climate change factors on aquatic ecosystems has advanced considerably over the past four years and confirms the importance of considering synergies between environmental factors.

  • 1163.
    Winberg, Rebecca
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Effekter av psykofarmaka på planktonsamhällen - Experimentell pilotstudie.2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Till följd av samhällets konsumtion av psykofarmaka, återfinns rester av preparaten i utgående avloppsvatten som oförändrade eller i form av metaboliter. Avloppsvattnet utgör därför en betyd-ande källa till att vår akvatiska miljö exponeras för psykofarmaka, vars verkningsmekanismer på-verkar akvatiska organismsamhällens struktur och funktion. Det är således betydelsefullt att skapa experimentellt underlag om hur primärproducerande akvatiska system reagerar på exponering för vanligt utskriven psykofarmaka. Denna studie syftar till att undersöka eventuella effekter till följd av exponering för utvald psykofarmaka; fluoxetin och oxazepam, i planktonsamhällen från en sötvattenrecipient. Under sju dagars testperiod exponerades identifierade organismer; Mesocyclops leuckarti, Chlorella vulgaris, Monoraphidium mirabile, Monoraphidium contortum, Monoraphidium griffithii och Glaucoma scintillans, mot fluoxetin; 500 och 50 μg/l samt oxazepam; 1700 och 170 μg/l. C. vulgaris och G. scintillans visade sig vara mer känsliga mot höga halter fluoxetin än andra identifierade arter. C. vulgaris och G. scintillans minskade med 70 respektive 100 %  till följd av 500 ug/l fluoxetin. Exponeringshalten är emellertid högre än uppmätt maxvärde i utgående avloppsvatten, och bedöms därför inte utgöra akut risk för planktonsamhällen i recipienter vars förhållanden är jämförbara med denna undersökning.

    Fulltekst (pdf)
    fulltext
  • 1164.
    Wolanski, E
    et al.
    Australian Institute of Marine Science, Australia.
    Newton, A
    Universidade do Algarve, Portugal.
    Rabalais, N
    Louisiana Universities Marine Consortium, USA.
    Legrand, Catherine
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Coastal Zone Management2013Inngår i: Reference Module in Earth Systems and Environmental Sciences / [ed] Scott A. Elias (editor in chief), Oxford: Elsevier, 2013Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    This article presents a scientific overview of the processes and the impact of environmental degradation of coastal waters due to human activities on the adjoining land. The direct effects range from eutrophication and harmful algal blooms, to hypoxia and anoxia. The indirect effects are more subtle and can also lead to the collapse of the ecosystem as in the case of coral reefs or seagrass meadows. Engineering solutions alone are not available to prevent this degradation that can only be reversed, or prevented, using a basin-wide ecohydrology approach.

  • 1165.
    Wu, Xiaofen
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Structure and function of microbial communities in acid sulfate soil and the terrestrial deep biosphere2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis describes the use of different DNA sequencing technologies to investigate the structure and function of microbial communities in two extreme environments, boreal acid sulfate soil and the terrestrial deep biosphere.

    The first of the two investigated environments was soils containing un-oxidized metal sulfides that are termed ‘potential acid sulfate soil’ (PASS) materials. If these materials are exposed to atmospheric oxygen by either natural phenomena (e.g., land uplift) or human activities (e.g., drainage) then the metal sulfides become oxidized and the PASS becomes acidic and is defined as an ‘acid sulfate soil’ (ASS). The resulting acid and metal release from metal sulfide oxidation can lead to severe environmental damage. Although acidophilic microorganisms capable of catalyzing acid and metal release have been identified from many sulfide mineral containing environments, the microbial community of boreal PASSs/ASSs remains unclear. This study investigated the physicochemical and microbial characteristics of PASSs and ASSs from the Risöfladan experimental field in Vasa, Finland. Sanger sequencing of 16S rRNA gene sequences of microorganisms present in the PASSs and ASSs were mostly assigned to acidophilic species and environmental clones previously identified from acid- and metal-contaminated environments. Enrichment cultures inoculated from the ASS demonstrated that the acidophilic microorganisms were responsible for catalyzing acid and metal release from PASSs/ASSs. Lastly, the study investigated how to mitigate metal sulfide oxidation and the concomitant formation of sulfuric acid by treating ASSs in situ with CaCO3 or Ca(OH)2 suspensions. The DNA sequencing still identified acidophilic microorganisms after the chemical treatments. However, the increased pH during and after treatment suggested that the activity of the acidophiles might be inhibited. This study was the first to identify the microbial community present in boreal PASSs/ASSs and suggested that treatment with basic compounds may inhibit microbial catalysis of metal sulfide dissolution.

    The second studied environment was the deep, dark terrestrial subsurface that is suggested to be both extremely stable and highly oligotrophic. Despite the scarcity of carbon and energy sources, the deep biosphere is estimated to constitute up to 20% of the total biomass on earth and thus, represents the largest microbial ecosystem. However, due to the difficulties of accessing this environment and our inability to cultivate the indigenous microbial populations, details of the diversity and metabolism of these communities remain largely unexplored. This study was carried out at Äspö Hard Rock Laboratory, Sweden and utilized second-generation sequencing to identify the taxonomic composition and genetic potential of planktonic and biofilm populations. Community DNA sequencing of planktonic cells from three water types at varied age and depth (‘modern marine’, ‘undefined mixed’, and ‘old saline’) showed the existence of ultra-small cells capable of passing through a 0.22 μm filter that were phylogenetically distinct communities from the >0.22 μm fraction. The reduced cell size and/or genome size suggested a potential adaptation to the oligotrophic environment in the terrestrial deep biosphere. The identified planktonic communities were dominated by Proteobacteria, Candidate divisions, unclassified archaea, and unclassified bacteria. Functional analysis of the assembled genomes showed that the planktonic population from the shallow modern marine water demonstrated a predominantly anaerobic and heterotrophic lifestyle. In contrast, the deeper, old saline water was more closely aligned with the hypothesis of a hydrogen-driven deep biosphere. Metagenomic analysis of subsurface biofilms from ‘modern marine’ and ‘old saline’ water types suggested only a subset of populations were involved in initial biofilm formation. The identified biofilm populations from both water types were distinct from the planktonic community and were suggested to be dominated by hydrogen fed, chemolithoautotrophic and diazotrophic populations.

    Fulltekst (pdf)
    Xiaofen Wu, Doctoral Thesis (Kappa)
    Download (jpg)
    Front page
  • 1166.
    Wu, Xiaofen
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Holmfeldt, Karin
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Hubalek, Valerie
    Uppsala University.
    Lundin, Daniel
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Bertilsson, Stefan
    Uppsala University.
    Dopson, Mark
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Microbial metagenomes from three aquifers in the Fennoscandian shield terrestrial deep biosphere reveal metabolic partitioning among populations2016Inngår i: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 10, nr 5, s. 1192-1203Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microorganisms in the terrestrial deep biosphere host up to 20% of the earth's biomass and are suggested to be sustained by the gases hydrogen and carbon dioxide. A metagenome analysis of three deep subsurface water types of contrasting age (from <20 to several thousand years) and depth (171 to 448 m) revealed phylogenetically distinct microbial community subsets that either passed or were retained by a 0.22 μm filter. Such cells of <0.22 μm would have been overlooked in previous studies relying on membrane capture. Metagenomes from the three water types were used for reconstruction of 69 distinct microbial genomes, each with >86% coverage. The populations were dominated by Proteobacteria, Candidate divisions, unclassified archaea and unclassified bacteria. The estimated genome sizes of the <0.22 μm populations were generally smaller than their phylogenetically closest relatives, suggesting that small dimensions along with a reduced genome size may be adaptations to oligotrophy. Shallow 'modern marine' water showed community members with a predominantly heterotrophic lifestyle. In contrast, the deeper, 'old saline' water adhered more closely to the current paradigm of a hydrogen-driven deep biosphere. The data were finally used to create a combined metabolic model of the deep terrestrial biosphere microbial community.

  • 1167.
    Wu, Xiaofen
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Pedersen, Karsten
    Microbial Analytics Sweden.
    Edlund, Johanna
    Eriksson, Lena
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Andersson, Anders
    Bertilsson, Stefan
    Dopson, Mark
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Hydrogen fed chemolithoautotrophic and diazotrophic populations initiate biofilm formation in oligotrophic, deep terrestrial subsurface watersManuskript (preprint) (Annet vitenskapelig)
  • 1168.
    Wu, Xiaofen
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Pedersen, Karsten
    Micans - Microbial Analytics Sweden AB.
    Edlund, Johanna
    Micans - Microbial Analytics Sweden AB.
    Eriksson, Lena
    Micans - Microbial Analytics Sweden AB.
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Andersson, Anders F.
    KTH Royal Institute of Technology.
    Bertilsson, Stefan
    Uppsala University.
    Dopson, Mark
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Potential for hydrogen-oxidizing chemolithoautotrophic and diazotrophic populations to initiate biofilm formation in oligotrophic, deep terrestrial subsurface waters2017Inngår i: Microbiome, ISSN 0026-2633, E-ISSN 2049-2618, Vol. 5, artikkel-id 37Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Deep terrestrial biosphere waters are separated from the light-driven surface by the time required to percolate to the subsurface. Despite biofilms being the dominant form of microbial life in many natural environments, they have received little attention in the oligotrophic and anaerobic waters found in deep bedrock fractures. This study is the first to use community DNA sequencing to describe biofilm formation under in situ conditions in the deep terrestrial biosphere. Results: In this study, flow cells were attached to boreholes containing either "modern marine" or "old saline" waters of different origin and degree of isolation from the light-driven surface of the earth. Using 16S rRNA gene sequencing, we showed that planktonic and attached populations were dissimilar while gene frequencies in the metagenomes suggested that hydrogen-fed, carbon dioxide-and nitrogen-fixing populations were responsible for biofilm formation across the two aquifers. Metagenome analyses further suggested that only a subset of the populations were able to attach and produce an extracellular polysaccharide matrix. Initial biofilm formation is thus likely to be mediated by a few bacterial populations which were similar to Epsilonproteobacteria, Deltaproteobacteria, Betaproteobacteria, Verrucomicrobia, and unclassified bacteria. Conclusions: Populations potentially capable of attaching to a surface and to produce extracellular polysaccharide matrix for attachment were identified in the terrestrial deep biosphere. Our results suggest that the biofilm populations were taxonomically distinct from the planktonic community and were enriched in populations with a chemolithoautotrophic and diazotrophic metabolism coupling hydrogen oxidation to energy conservation under oligotrophic conditions.

  • 1169.
    Wu, Xiaofen
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Sten, Pekka
    Vaasa University of Applied Sciences, Finland.
    Engblom, Sten
    Novia University of Applied Sciences, Finland.
    Nowak, Pawel
    Polish Academy of Sciences, Poland.
    Österholm, Peter
    Åbo Akademi University, Finland.
    Dopson, Mark
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Impact of mitigation strategies on acid sulfate soil chemistry and microbial community2015Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 526, s. 215-221Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Potential acid sulfate soils contain reduced iron sulfides that if oxidized, can cause significant environmental damage by releasing large amounts of acid and metals. This study examines metal and acid release as well as the microbial community capable of catalyzing metal sulfide oxidation after treating acid sulfate soil with calcium carbonate (CaCO3) or calcium hydroxide (Ca(OH)2). Leaching tests of acid sulfate soil samples were carried out in the laboratory. The pH of the leachate during the initial flushing with water lay between 3.8 and 4.4 suggesting that the jarosite/schwertmannite equilibrium controls the solution chemistry. However, the pH increased to circa 6 after treatment with CaCO3 suspension and circa 12 after introducing Ca(OH)2 solution. 16S rRNA gene sequences amplified from community DNA extracted from the untreated and both CaCO3and Ca(OH)2 treated acid sulfate soils were most similar to bacteria (69.1% to 85.7%) and archaea (95.4% to 100%) previously identified from acid and metal contaminated environments. These species included a Thiomonas cuprina-like and an Acidocella-like bacteria as well as a Ferroplasma acidiphilum-like archeon. Although the CaCO3 and Ca(OH)2 treatments did not decrease the proportion of microorganisms capable of accelerating acid and metal release, the chemical effects of the treatments suggested their reduced activity.

  • 1170.
    Wu, Xiaofen
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Wong, Zhen Lim
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Sten, Pekka
    Engblom, Sten
    Osterholm, Peter
    Dopson, Mark
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Microbial community potentially responsible for acid and metal release from an Ostrobothnian acid sulfate soil2013Inngår i: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 84, nr 3, s. 555-563Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Soils containing an approximately equal mixture of metastable iron sulfides and pyrite occur in the boreal Ostrobothnian coastal region of Finland, termed 'potential acid sulfate soil materials'. If the iron sulfides are exposed to air, oxidation reactions result in acid and metal release to the environment that can cause severe damage. Despite that acidophilic microorganisms catalyze acid and metal release from sulfide minerals, the microbiology of acid sulfate soil (ASS) materials has been neglected. The molecular phylogeny of a depth profile through the plough and oxidized ASS layers identified several known acidophilic microorganisms and environmental clones previously identified from acid- and metal-contaminated environments. In addition, several of the 16S rRNA gene sequences were more similar to sequences previously identified from cold environments. Leaching of the metastable iron sulfides and pyrite with an ASS microbial enrichment culture incubated at low pH accelerated metal release, suggesting microorganisms capable of catalyzing metal sulfide oxidation were present. The 16S rRNA gene analysis showed the presence of species similar to Acidocella sp. and other clones identified from acid mine environments. These data support that acid and metal release from ASSs was catalyzed by indigenous microorganisms adapted to low pH.

  • 1171.
    Wällstedt, Elin
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Development and preliminary evaluation of novel materials for selective detection of oseltamivir in waste water2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This project aims to investigate whether it is possible to detect consentrations down to 0,3 µg/L of oseltamirir in waste water by Quartz Crystal Microbalance. The risks linked to this contaminant could be not only environmental, scientists have found that infuence recistence can propagate due to contaminats of this kind. Cases similar to the bird- and swine-flu could occure if the drug spreads through animals and mutate.

     

    Four systems of different character was synthesised. As a result it was found that MAA functional monomer systems probably was interfering with charges within it’s own nanowires.

    Reference systems could not detect 0,01 mg/mL and HEMA polymer surfaces was the only reliable system, pH of 5,1. Lowest limit of detection (LOD) was found in Molecular Imprinted Polymer nanowires (MIP Nw) at 0,01 mg/mL and could be scaled down to 0,1 mg/L with increased loop size (injection at 10x that of 0,01 mg/mL at about 500 µL and a halved flow rate.)

     

    An alternative could be nano structuring such as ”polystyrene balls” that possibly could be able to achieve surfaces with even more binding sites needed to detect the lowest limit at 0,3 µg/L. 

    Fulltekst (pdf)
    fulltext
  • 1172.
    Xia, Shaopan
    et al.
    Tianjin University, China.
    Song, Zhaoliang
    Tianjin University, China.
    Van Zwieten, Lukas
    NSW Department of Primary Industries, Australia.
    Guo, Laodong
    University of Wisconsin-Milwaukee, USA.
    Yu, Changxun
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Hartley, Iain P.
    University of Exeter, UK.
    Wang, Hailong
    Foshan University, China;Zhejiang A&F University, China.
    Silicon accumulation controls carbon cycle in wetlands through modifying nutrients stoichiometry and lignin synthesis of Phragmites australis2020Inngår i: Environmental and Experimental Botany, ISSN 0098-8472, E-ISSN 1873-7307, Vol. 175, s. 1-11, artikkel-id 104058Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Silicon (Si) is one of the most abundant elements in the Earth’s crust but its role in governing the biogeochemicalcycling of other elements remains poor understood. There is a paucity of information on the role of Si in wetlandplants, and how this may alter wetland C production and storage. Therefore, this study investigated Si distribution,nutrient stoichiometry and lignin abundance in Phragmites australis from a wetland system in China tobetter understand the biogeochemical cycling and C storage. Our data show that Si content (ranging between0.202% to 6.614%) of Phragmites australis is negatively correlated with C concentration (38.150%–47.220%).Furthermore, Si content was negatively antagonistically related to the concentration of lignin-derived phenols inthe stem (66.763–120.670 mg g-1 C) and sheath (65.400–114.118 mg g-1 C), but only a weak relationship wasobserved in the leaf tissue (36.439–55.905 mg g-1 C), which is relevant to the photosynthesis or stabilizationfunction of the plant tissues. These results support the notion that biogenic Si (BSi) can substitute lignin as astructural component, due to their similar eco-physiological functions, reduces costs associated with ligninbiosynthesis. The accumulation of BSi increased total biomass C storage and nutrient accumulation due togreater productivity of Phragmites australis. On the other hand, BSi regulated litter composition and quality (e.g.,nutrient stoichiometry and lignin) that provide a possibility for the factors affecting litter decomposition. Thuscompeting processes (i.e., biomass quantity vs quality) can be influenced by Si cycling in wetlands.

  • 1173.
    Xu, Jingzhe
    et al.
    Hunan Normal University, Peoples Republic of China.
    Peng, Bo
    Hunan Normal University, Peoples Republic of China.
    Yu, Changxun
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Hunan Normal University, Peoples Republic of China.
    Yang, Guang
    Hunan Normal University, Peoples Republic of China.
    Tang, Xiaoyan
    Hunan Normal University, Peoples Republic of China.
    Tan, Changyin
    Hunan Normal University, Peoples Republic of China.
    Xie, Shurong
    East China Institute of Science and Technology, Peoples Republic of China.
    Tu, Xianglin
    Chinese Academy of Sciences, Peoples Republic of China.
    Bao, Zhicheng
    Hunan Normal University, Peoples Republic of China.
    Quan, Meijie
    Hunan Normal University, Peoples Republic of China.
    Xiao, Min
    Hunan Normal University, Peoples Republic of China.
    Geochemistry of soils derived from black shales in the Ganziping mine area, western Hunan, China2013Inngår i: Environmental Earth Sciences, ISSN 1866-6280, Vol. 70, nr 1, s. 175-190Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The geochemistry of major and trace elements (including heavy metals and rare earth elements) of the fresh and weathered black shales, and the soils derived from black shales in the Ganziping mine area in western Hunan province (China) were studied using the following techniques: X-ray fluorescence (XRF), inductively coupled plasma mass spectrometer (ICP-MS) and X-ray diffraction (XRD). The results show that the black-shale soils are significantly enriched with Al2O3 and Fe2O3, and depleted of mobile elements CaO, Na2O and K2O. The soils are also highly enriched with heavy metals U, V, Ni, Ba, Cu, Zn and Pb, that may cause potential heavy-metal contamination of the soils. Composition of the soils is homogeneous compared to the weathered black shales, for which the concentrations of major elements except CaO and Na2O, and trace elements except heavy metals (U, V, Ni, Ba, Cu, Zn and Pb) as well as the mobile Sr, show lower variations than in the weathered black shales. Ratios of Zr/Hf, Ta/Nb, Y/Ho, Nd/Sm, and Ti/(Ti + Zr), of the soils are also less variable, with values constantly similar to that of the fresh and weathered black shales correspondingly. Thus, components of the soils are believed to be contributed from the parent black shales through weathering and pedogenesis. It is concluded that the soils were formed by at least two stages of geochemical processes: the early stage of chemical differentiation and the later stage of chemical homogenization. The chemical differentiation that was taken during black-shale weathering might have caused the depletion of CaO and Na2O, and the enrichment of Al2O3 and Fe2O3; while the chemical homogenization that was taken during pedogenesis led to the depletion of SiO2 and K2O, and to the further enrichment of Al2O3 and Fe2O3. The heavy-metal enrichment (contamination) of the soils was then genetically related to the enrichment of Al2O3 and Fe2O3 in the soils.

  • 1174.
    Xu, Qinghai
    et al.
    Hebei Normal University, China.
    Zhang, Shengrui
    Chinese Academy of Sciences, China.
    Gaillard, Marie-José
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Li, Manyue
    Hebei Normal University, China.
    Cao, Xianyong
    Hebei Normal University, China ; Alfred Wegener Institute, Germany.
    Tian, Fang
    Hebei Normal University, China ; Alfred Wegener Institute, Germany.
    Li, Furong
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Studies of modern pollen assemblages for pollen dispersal- deposition- preservation process understanding and for pollen-based reconstructions of past vegetation, climate, and human impact: A review based on case studies in China2016Inngår i: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 149, s. 151-166Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fossil pollen, as a direct proxy record of past vegetation, and indirect proxy record of past climate, plays an essential role in revealing and reconstructing past vegetation and climate. However, relationships between pollen, vegetation and climate are not linear, hence quantitative reconstructions of past vegetation and climate based on pollen records are not straightforward, and results may be highly contradictory and difficult to interpret. One of the main causes of discrepancies between results has been the lack of comprehensive and systematical studies on modern pollen dispersal and deposition processes, particularly on the quantification of these processes. Based on empirical studies performed in China over the last 30 years, this paper provides the state-of-the-art of the understanding of pollen dispersal and deposition processes in China and the remaining questions to be investigated. We show that major progress has been achieved in the study of modern pollen dispersal and deposition processes, and in the application of models of the pollen-vegetation-climate relationships for quantitative reconstruction of past vegetation and climate. However, several issues are not entirely solved or understood yet, such as how to quantify the reworking and re-deposition of pollen grains in quaternary alluvial sediments, the influence of pollen preservation on pollen assemblages, and human impact on vegetation. Even so, the progress made during the last decades makes it possible to achieve significantly more precise and informative reconstructions of past vegetation, land-use and climate in China than was possible earlier.

  • 1175.
    Yager, P. L.
    et al.
    Univ Georgia, USA.
    Sherrell, R. M.
    Rutgers State Univ, USA.
    Stammerjohn, S. E.
    Univ Colorado, USA.
    Ducklow, H. W.
    Columbia Univ, USA.
    Schofield, O. M. E.
    Rutgers State Univ, USA.
    Ingall, E. D.
    Georgia Inst Technol, USA.
    Wilson, S. E.
    Bangor Univ, UK.
    Lowry, K. E.
    Stanford Univ, USA.
    Williams, C. M.
    Univ Georgia, USA.
    Riemann, Lasse
    Univ Copenhagen, Denmark.
    Bertilsson, S.
    Uppsala University.
    Alderkamp, A-C
    Stanford Univ, USA.
    Dinasquet, Julie
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Univ Copenhagen, Denmark.
    Logares, R.
    CSIC, Spain.
    Richert, I.
    Uppsala University.
    Sipler, R. E.
    Coll William & Mary, USA.
    Melara, A. J.
    Univ Georgia, USA.
    Mu, L.
    Univ Georgia, USA.
    Newstead, R. G.
    Bangor Univ, UK.
    Post, A. F.
    Florida Atlantic Univ, USA.
    Swalethorp, R.
    Tech Univ Denmark, Denmark;University of Gothenburg.
    van Dijken, G. L.
    Stanford Univ, USA.
    A carbon budget for the Amundsen Sea Polynya, Antarctica: Estimating net community production and export in a highly productive polar ecosystem2016Inngår i: Elementa: Science of the Anthropocene, E-ISSN 2325-1026, Vol. 4, artikkel-id 000140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polynyas, or recurring areas of seasonally open water surrounded by sea ice, are foci for energy and material transfer between the atmosphere and the polar ocean. They are also climate sensitive, with both sea ice extent and glacial melt influencing their productivity. The Amundsen Sea Polynya (ASP) is the greenest polynya in the Southern Ocean, with summertime chlorophyll a concentrations exceeding 20 mu g L-1. During the Amundsen Sea Polynya International Research Expedition (ASPIRE) in austral summer 2010-11, we aimed to determine the fate of this high algal productivity. We collected water column profiles for total dissolved inorganic carbon (DIC) and nutrients, particulate and dissolved organic matter, chlorophyll a, mesozoo-plankton, and microbial biomass to make a carbon budget for this ecosystem. We also measured primary and secondary production, community respiration rates, vertical particle flux and fecal pellet production and grazing. With observations arranged along a gradient of increasing integrated dissolved inorganic nitrogen drawdown (Delta DIN; 0.027-0.74 mol N m(-2)), changes in DIC in the upper water column (ranging from 0.2 to 4.7 mol C m(-2)) and gas exchange (0-1.7 mol C m(-2)) were combined to estimate early season net community production (sNCP; 0.2-5.9 mol C m(-2)) and then compared to organic matter inventories to estimate export. From a phytoplankton bloom dominated by Phaeocystis antarctica, a high fraction (up to similar to 60%) of sNCP was exported to sub-euphotic depths. Microbial respiration remineralized much of this export in the mid waters. Comparisons to short-term (2-3 days) drifting traps and a year-long moored sediment trap capturing the downward flux confirmed that a relatively high fraction (3-6%) of the export from similar to 100 m made it through the mid waters to depth. We discuss the climate-sensitive nature of these carbon fluxes, in light of the changing sea ice cover and melting ice sheets in the region.

  • 1176.
    Yang, Shilei
    et al.
    Tianjin University, Peoples Republic of China.
    Hao, Qian
    Tianjin University, Peoples Republic of China.
    Liu, Hongyan
    Peking University, Peoples Republic of China.
    Xiaodong, Zhang
    Tianjin University, Peoples Republic of China.
    Yu, Changxun
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Yang, Xiaomin
    Tianjin University, Peoples Republic of China.
    Xia, Shaopan
    Tianjin University, Peoples Republic of China.
    Yang, Weihua
    Tianjin University, Peoples Republic of China.
    Li, Jianwu
    Zhejiang Agricultural and Forestry University, Peoples Republic of China.
    Song, Zhaoliang
    Tianjin University, Peoples Republic of China.
    Impact of grassland degradation on the distribution and bioavailability of soil silicon: Implications for the Si cycle in grasslands2019Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 657, s. 811-818Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Grassland ecosystems play an important role in the global terrestrial silicon (Si) cycle, and Si is a beneficial elementand structural constituent for the growth of grasses. In previous decades, grasslands have been degradedto different degrees because of the drying climate and intense human disturbance. However, the impact of grasslanddegradation on the distribution and bioavailability of soil Si is largely unknown. Here, we investigated vegetationand soil conditions of 30 sites to characterize different degrees of degradation for grasslands in the agropastoralecotone of northern China. We then explored the impact of grassland degradation on the distributionand bioavailability of soil Si, including total Si and four forms of noncrystalline Si in three horizons (0–10,10–20 and 20–40 cm) of different soil profiles. The concentrations of noncrystalline Si in soil profiles significantlydecreased with increasing degrees of degradation, being 7.35 ± 0.88 mg g−1, 5.36 ± 0.39 mg g−1, 3.81 ±0.37 mg g−1 and 3.60±0.26 mg g−1 in non-degraded, lightly degraded, moderately degraded and seriously degradedgrasslands, respectively. Moreover, the storage of noncrystalline Si decreased from higher than 40 t ha−1to lower than 23 t ha−1. The corresponding bioavailability of soil Si also generally decreased with grassland degradation.These processes may not only affect the Si pools and fluxes in soils but also influence the Si uptake in 

    plants. We suggest that grassland degradation can significantly affect the global grassland Si cycle. Grasslandmanagement methods such as fertilizing and avoiding overgrazing can potentially double the content and storageof noncrystalline Si in soils, thereby enhancing the soil Si bioavailability by N17%.

  • 1177.
    Yang, Xiaomin
    et al.
    Tianjin University, China.
    Song, Zhaoliang
    Tianjin University, China.
    Yu, Changxun
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Ding, Fan
    Shenyang Agricultural University, China.
    Quantification of different silicon fractions in broadleaf and conifer forests of northern China and consequent implications for biogeochemical Si cycling2020Inngår i: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 361, s. 1-10, artikkel-id 114036Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The terrestrial biogeochemical silicon (Si) cycle significantly contributes to maintaining the functions and sustainability of terrestrial ecosystems. Over the short term, the biogeochemical Si cycle can be strongly influenced by dissolved Si, organic bound Si, Si adsorbed to pedogenic oxides/hydroxides, and biogenic and pedogenic amorphous Si. However, quantitative studies about these relatively soluble Si fractions are rare. In this study, we quantified different Si fractions in the 0–10 cm, 10–20 cm, 20–30 cm, 30–40 cm and 40–50 cm soil layers of broadleaf forests (Betula forest and Quercus forest) and conifer forests (Larix forest and Pinus forest) in northern China using a sequential chemical extraction scheme optimized for these Si fractions. The results showed that the total Si (Sit) in the soil layers consisted of 97.7–98.5% crystalline Si (Sicry) and 1.5–2.3% non-crystalline Si (Sinoncry) fractions. Within the Sinoncry fraction, the proportions of dissolved Si (Sidis), organic matter bound Si (Siorg), pedogenic oxides/hydroxides chemisorbed Si (Sisorb), and amorphous Si (Siamor) were 3.4–6.7%, 5.5–8.9%, 6.3–8.5%, and 77.7–84.8%, respectively. Although the Sidis fraction was the least abundant component, it is at the center of the interconversion processes among the different Sinoncry fractions. The Siamor fraction was the largest component of Sinoncry and was composed of 37.7–71.9% biogenic amorphous Si (Sibio-amor) and 28.1–62.3% pedogenic amorphous Si (Siped-amor). Our study indicated that i) Siped-amor fraction is more easily influenced by soil pH comparing to Sibio-amor fraction; ii) the Sibio-amor fraction contributes more to the biogeochemical Si cycle in broadleaf forests, whereas the Siped-amorfraction contributes more in conifer forests; and iii) soil pH, soil organic matter, and plant community differences can influence the vertical distribution of the different Sinoncry fractions and thus affect the multiple transformation processes among these Si fractions in studied forests.

  • 1178.
    Yildirim, Yeserin
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Massey Univ, New Zealand.
    Anderson, Marti J.
    Massey Univ, New Zealand.
    Hansson, Bengt
    Lund University.
    Patel, Selina
    Univ Auckland, New Zealand.
    Millar, Craig D.
    Univ Auckland, New Zealand.
    Rainey, Paul B.
    Massey Univ, New Zealand;Max Planck Inst Evolutionary Biol, Germany;PSL Res Univ, France.
    Genetic structure of the grey side-gilled sea slug (Pleurobranchaea maculata) in coastal waters of New Zealand2018Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, nr 8, artikkel-id e0202197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pleurobranchaea maculata is a rarely studied species of the Heterobranchia found throughout the south and western Pacific-and recently recorded in Argentina-whose population genetic structure is unknown. Interest in the species was sparked in New Zealand following a series of dog deaths caused by ingestions of slugs containing high levels of the neurotoxin tetrodotoxin. Here we describe the genetic structure and demographic history of P. maculata populations from five principle locations in New Zealand based on extensive analyses of 12 microsatellite loci and the COI and CytB regions of mitochondrial DNA (mtDNA). Microsatellite data showed significant differentiation between northern and southern populations with population structure being associated with previously described regional variations in tetrodotoxin concentrations. However, mtDNA sequence data did not support such structure, revealing a star-shaped haplotype network with estimates of expansion time suggesting a population expansion in the Pleistocene era. Inclusion of publicly available mtDNA sequence sea slugs from Argentina did not alter the star-shaped network. We interpret our data as indicative of a single founding population that fragmented following geographical changes that brought about the present day north-south divide in New Zealand waters. Lack of evidence of cryptic species supports data indicating that differences in toxicity of individuals among regions are a consequence of differences in diet.

  • 1179.
    Yildirim, Yeserin
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Tinnert, Jon
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Forsman, Anders
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Contrasting patterns of neutral and functional genetic diversity in stable and disturbed environments2018Inngår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 8, nr 23, s. 12073-12089Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Genetic structure among and diversity within natural populations is influenced by acombination of ecological and evolutionary processes. These processes can differentlyinfluence neutral and functional genetic diversity and also vary according toenvironmental settings. To investigate the roles of interacting processes as drivers ofpopulation‐level genetic diversity in the wild, we compared neutral and functionalstructure and diversity between 20 Tetrix undulata pygmy grasshopper populations indisturbed and stable habitats. Genetic differentiation was evident among the differentpopulations, but there was no genetic separation between stable and disturbedenvironments. The incidence of long‐winged phenotypes was higher in disturbedhabitats, indicating that these populations were recently established by flight‐capablecolonizers. Color morph diversity and dispersion of outlier genetic diversity, estimatedusing AFLP markers, were higher in disturbed than in stable environments,likely reflecting that color polymorphism and variation in other functionally importanttraits increase establishment success. Neutral genetic diversity estimated usingAFLP markers was lower in disturbed habitats, indicating stronger eroding effects onneutral diversity of genetic drift associated with founding events in disturbed comparedto stable habitats. Functional diversity and neutral diversity were negativelycorrelated across populations, highlighting the utility of outlier loci in genetics studiesand reinforcing that estimates of genetic diversity based on neutral markers donot infer evolutionary potential and the ability of populations and species to copewith environmental change.

  • 1180.
    Yin, Shenglai
    et al.
    Wageningen Univ & Res, Netherlands.
    Kleijn, David
    Wageningen Univ & Res, Netherlands.
    Muskens, Gerard J. D. M.
    Wageningen Univ & Res, Netherlands.
    Fouchier, Ron A. M.
    Erasmus MC, Netherlands.
    Verhagen, Josanne H.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Glazov, Petr M.
    Russian Acad Sci, Russia.
    Si, Yali
    Wageningen Univ & Res, Netherlands;Tsinghua Univ, Peoples Republic of China.
    Prins, Herbert H. T.
    Wageningen Univ & Res, Netherlands.
    de Boer, Willem Frederik
    Wageningen Univ & Res, Netherlands.
    No evidence that migratory geese disperse avian influenza viruses from breeding to wintering ground2017Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, nr 5, artikkel-id e0177790Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low pathogenic avian influenza virus can mutate to a highly pathogenic strain that causes severe clinical signs in birds and humans. Migratory waterfowl, especially ducks, are considered the main hosts of low pathogenic avian influenza virus, but the role of geese in dispersing the virus over long-distances is still unclear. We collected throat and cloaca samples from three goose species, Bean goose (Anser fabalis), Barnacle goose (Branta leucopsis) and Greater white-fronted goose (Anser albifrons), from their breeding grounds, spring stopover sites, and wintering grounds. We tested if the geese were infected with low pathogenic avian influenza virus outside of their wintering grounds, and analysed the spatial and temporal patterns of infection prevalence on their wintering grounds. Our results show that geese were not infected before their arrival on wintering grounds. Barnacle geese and Greater white-fronted geese had low prevalence of infection just after their arrival on wintering grounds in the Netherlands, but the prevalence increased in successive months, and peaked after December. This suggests that migratory geese are exposed to the virus after their arrival on wintering grounds, indicating that migratory geese might not disperse low pathogenic avian influenza virus during autumn migration.

  • 1181.
    Yu, Changxun
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Berger, Tobias
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). The Swedish Anglers Association, Sweden.
    Drake, Henrik
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Song, Zhaoliang
    Tianjin University, Peoples Republic of China.
    Peltola, Pasi
    Boliden Rönnskär, Sweden.
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Geochemical controls on dispersion of U and Th in Quaternary deposits, stream water, and aquatic plants in an area with a granite pluton2019Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 663, s. 16-28Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The weathering of U and/or Th rich granite plutons, which occurs worldwide, may serve as a potentially important, but as yet poorly defined source for U and Th in (sub-)surface environments. Here, we assessed the impact of an outcrop of such granite (5 km in diameter) and its erosional products on the distribution of U and Th in four nemo-boreal catchments. The results showed that (i) the pluton was enriched in both U and Th; and (ii) secondary U and Th phases were accumulated by peat/gyttja and in other Quaternary deposits with high contents of organic matter. Movement of the ice sheet during the latest glaciation led to dispersal of U- and Th-rich materials eroded from the pluton, resulting in a progressive increase in dissolved U and Th concentrations, as well as U concentrations in aquatic plants with increasing proximity to the pluton. The accumulation of U in the aquatic plants growing upon the pluton (100–365 mg kg−1, dry ash weight) shows that this rock represents a long-term risk for adjacent ecosystems. Dissolved pools of U and Th were correlated with those of dissolved organic matter (DOM) and were predicted to largely occur as organic complexes. This demonstrates the importance of DOM in the transport of U and Th in the catchments. Large fractions of Ca2UO2(CO3)30(aq) were modeled to occur in the stream with highest pH and alkalinity and thus, explain the strongly elevated U concentrations and fluxes in this particular stream. In future climate scenarios, boreal catchments will experience intensified runoff and warmer temperature that favor the production of hydrologically accessible DOM and alkalinity. Therefore, the results obtained from this study have implications for predicting the distribution and transport of Th and U in boreal catchments, especially those associated with U and/or Th rich granite plutons.

  • 1182.
    Yu, Changxun
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Boily, Jean-François
    Umeå University.
    Shchukarev, Andrey
    Umeå University.
    Drake, Henrik
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Song, Zhaoliang
    Tianjin University.
    Hogmalm, K. Johan
    University of Gothenburg.
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    A cryogenic XPS study of Ce fixation on nanosized manganite and vernadite: Interfacial reactions and effects of fulvic acid complexation2018Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 483, s. 304-311Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigated interfacial reactions between aqueous Ce(III) and two synthetic nanosized Mn (hydr-) oxides (manganite: γ-MnOOH, and vernadite: δ-MnO2) in the absence and presence of Nordic Lake fulvic acid (NLFA) at circumneutral pH by batch experiments and cryogenic X-ray photoelectron spectroscopy (XPS). The surfaces of manganite and vernadite were negatively charged (XPS-derived loadings of (Na+K)/Cl > 1) and loaded with 0.42–4.33 Ce ions nm−2. Manganite stabilized Ce-oxidation states almost identical to those for vernadite (approximately 75% Ce(IV) and 25% Ce(III)), providing the first experimental evidence that also a Mn (III) phase (manganite) can act as an important scavenger for Ce(IV) and thus, contribute to the decoupling of Ce from its neighboring rare earth elements and the development of Ce anomaly. In contrast, when exposed to Ce (III)-NLFA complexes, the oxidation of Ce by these two Mn (hydr-)oxides was strongly suppressed, suggesting that the formation of Ce(III) complexes with fulvic acid can stabilize Ce(III) even in the presence of oxidative Mn oxide surfaces. The experiments also showed that Ce(III) complexed with excess NLFA was nearly completely removed, pointing to a strong preferential sorption of Ce(III)-complexed NLFA over free NLFA. This finding suggests that the Ce(III)-NLFA complexes were most likely sorbed by their cation side, i.e. Ce(III) bridging between oxide groups on the Mn (hydr-)oxides and negatively-charged functional groups in NLFA. Hence, Ce(III) was in direct contact with the oxidative manganite and vernadite but despite that not oxidized. An implication is that in organic-rich environments there may be an absence of Ce(IV) and Ce anomaly despite otherwise favorable conditions for Ce(III) oxidation.

  • 1183.
    Yu, Changxun
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Drake, Henrik
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Dideriksen, Knud
    University of Copenhagen, Denmark.
    Frandsen, Cathrine
    Technical University of Denmark, Denmark.
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Iron speciation and valence in the upper 1 km of fractured crystalline bedrock on the Baltic shield2017Inngår i: Goldschmidt2017 Abstracts, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The widespread networks of open water-conducting fractures in crystalline bedrock are covered by a variety of Fe-bearing minerals. Quantitative information on Fe mineralogy and valence of these minerals is of great importance not only in constraining the biogeochemical cycle of Fe and other related elements in this largely unexplored space, but also in evaluating the mineralogical capacity to reduce oxygen which is one of the key issues in the risk assessment of nuclear waste repositories. 

    Here, we studied Fe mineralogy and valence in fracture coatings, fresh rocks and altered rocks in the upper 1 km of fractured crystalline bedrock at two sites (Laxemar and Forsmark areas, Sweden) on the Baltic shield. Fe3+/∑Fe ratios in these materials were quantified based on the centroid position of the pre-edge feature on Fe XANES spectra, while the speciation of Fe was predicted by reconstructing the sample EXFAS spectra using a linear combination of a large dataset of reference spectra collected previously[1] and in this study. The results were compared with Mössbauer spectra. The fresh and altered rocks showed no systematic difference in Fe3+/∑Fe ratio, indicating that past hydrothermal activities (red-staining on fracture wall-rock) did not lead to a reduction in reducing capacity within the fracture networks. The fracture coatings from the Forsmark area are of clear hydrothermal character (as indicated by an abundance of hematite, hornblende and muscovite) and have not experienced the same degree of low-T oxidative weathering as the samples from the Laxemar area having frequent and abundant illite and ferrihydrite. However, Fe3+/∑Fe ratios of the fracture coatings from the two areas showed similar features, including no depth trend and a similar variability from 0.24-0.85 and 0.12-0.71 which are overall larger than the fresh and altered rocks. This suggests that regional geological events can have a significant impact on the speciation of Fe, but not Fe valence.

    Fulltekst (pdf)
    fulltext
  • 1184.
    Yu, Changxun
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Drake, Henrik
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Dideriksen, Knud
    University of Copenhagen, Denmark.
    Tillberg, Mikael
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Song, Zhaoliang
    Tianjin University, China.
    Mørup, Steen
    Technical University of Denmark, Denmark.
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    A Combined X-ray Absorption and Mössbauer Spectroscopy Study on Fe Valence and Secondary Mineralogy in Granitoid Fracture Networks: Implications for Geological Disposal of Spent Nuclear Fuels2020Inngår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 54, nr 5, s. 2832-2842Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Underground repository in crystalline bedrock is a widely accepted solution for long-term disposal of spent nuclear fuels. During future deglaciations, meltwater will intrude via bedrock fractures to the depths of future repositories where O2 left in the meltwater could corrode metal canisters and enhance the migration of redox-sensitive radionuclides. Since glacial meltwater is poor in reduced phases, the quantity and (bio)accessibility of minerogenic Fe(II) in bedrock fractures determine to what extent O2 in future meltwater can be consumed. Here, we determined Fe valence and mineralogy in secondary mineral assemblages sampled throughout the upper kilometer of fractured crystalline bedrock at two sites on the Baltic Shield, using X-ray absorption and Mössbauer spectroscopic techniques that were found to deliver matching results. The data point to extensive O2-consuming capacity of the bedrock fractures, because Fe(II)-rich phyllosilicates were abundant and secondary pyrite was dispersed deep into the bedrock with no overall increase in Fe(II) concentrations and Fe(II)/Fe(III) proportions with depth. The results imply that repeated Pleistocene deglaciations did not cause a measurable decrease in the Fe(II) pool. In surficial fractures, largely opened during glacial unloading, ferrihydrite and illite have formed abundantly via oxidative transformation of Fe(II)-rich phyllosilicates and recently exposed primary biotite/hornblende.

  • 1185.
    Yu, Changxun
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Drake, Henrik
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Lopez-Fernandez, Margarita
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Whitehouse, Martin
    Swedish Museum of Natural History, Sweden.
    Dopson, Mark
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Micro-scale isotopic variability of low-temperature pyrite in fractured crystalline bedrock ― A large Fe isotope fractionation between Fe(II)aq/pyrite and absence of Fe-S isotope co-variation2019Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 522, s. 192-207Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study assessed Fe-isotope ratio (56Fe/54Fe, expressed as δ56Fe relative to the IRMM-014 standard) variability and controls in pyrite that has among the largest reported S-isotope variability (maximum δ34S: 140‰). The pyrite occurs as fine-grained secondary crystals in fractures throughout the upper kilometer of granitoids of the Baltic Shield, and was analyzed here for δ56Fe by in situ secondary ion mass spectrometry (SIMS). Part of these pyrite crystals were picked from borehole instrumentation at depths of >400 m below sea level (m.b.s.l.), and thus are modern (known to have formed within 17 years) and can be compared with the δ56Fe of the source dissolved ferrous iron. The δ56Fe values of the modern pyrite crystals (−1.81‰ to +2.29‰) varied to a much greater extent than those of the groundwaters from which they formed (−0.48‰ to +0.13‰), providing strong field evidence for a large Fe isotope fractionation during the conversion of Fe(II)aq to FeS and ultimately to pyrite. Enrichment of 56Fe in pyrite relative to the groundwater was explained by equilibrium Fe(II)aq-FeS isotope fractionation, whereas depletion of 56Fe in pyrite relative to the groundwater was mainly the result of sulfidization of magnetite and kinetic isotopic fractionation during partial transformation of microsized FeS to pyrite. In many pyrite crystals, there is an increase in δ34S from crystal center to rim reflecting Rayleigh distillation processes (reservoir effects) caused by the development of closed-system conditions in the micro-environment near the growing crystals. A corresponding center-to-rim feature was not observed for the δ56Fe values. It is therefore unlikely that the groundwater near the growing pyrite crystals became progressively enriched in the heavy Fe isotope, in contrast to what has been found for the sulfur in sulfate. Other pyrite crystals formed following bacterial sulfate reduction in the time period of mid-Mesozoicum to Quaternary, had an almost identical Fe-isotope variability (total range: −1.50‰ to +2.76‰), frequency-distribution pattern, and relationship with δ34S as the recent pyrite formed on the borehole instrumentation. These features suggest that fundamental processes are operating and governing the Fe-isotope composition of pyrite crystals formed in fractured crystalline bedrock over large time scales.

  • 1186.
    Yu, Changxun
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Drake, Henrik
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Mathurin, Frédéric A.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Cerium sequestration and accumulation in fractured crystalline bedrock: The role of Mn-Fe (hydr-)oxides and clay minerals2017Inngår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 199, s. 370-389Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study focuses on the mechanisms of Ce sequestration and accumulation in the fracture network of the upper kilometer of the granitoid bedrock of the Baltic Shield in southeast Sweden (Laxemar area, Sweden). The material includes 81 specimens of bulk secondary mineral precipitates ("fracture coatings") collected on fracture walls identified in 17 drill cores, and 66 groundwater samples collected from 21 deep boreholes with equipment designed for retrieval of representative groundwater at controlled depths. The concentrations of Ce in the fracture coatings, although varying considerably (10-90th percentiles: 67-438 mg kg(-1)), were frequently higher than those of the wall rock (10-90th percentiles: 70-118 mg kg(-1)). Linear combination fitting analysis of Ce L-III-edge X-ray absorption near-edge structure (XANES) spectra, obtained for 19 fracture coatings with relatively high Ce concentrations (>= 145 mg kg(-1)) and a wide range of Ce-anomaly values, revealed that Ce(IV) occurs frequently in the upper 10 m of the fracture network (Ce(IV)/Ce-total = 0.06-1.00 in 8 out of 11 specimens) and is mainly associated with Mn oxides (modeled as Ce oxidatively scavenged by birnessite). These features are in line with the strong oxidative and sorptive capacities of Mn oxide as demonstrated by previous studies, and abundant todorokite and birnessite-like Mn oxides identified in 3 out of 4 specimens analyzed by Mn K-edge X-ray absorption spectroscopy (XAS) in the upper parts of the fracture network (down to 5 m). For a specimen with very high Ce concentration (1430 mg kg(-1)) and NASC-normalized Ce anomaly (3.63), the analysis of Ce XANES and Mn XAS data revealed (i) a predominance of Ce oxide in addition to Ce scavenged by Mn oxide; and (ii) a large fraction of poorly-crystalline hexagonal birnessite and aqueous Mn2+, suggesting a recent or on-going oxidation of Mn2+ in this fracture. In addition, the Ce oxide precipitates on this fracture observed by in situ SEM-EDS contained considerable amounts of Mn. These spectroscopic and microscopic features led us to suggest that the remarkable accumulation of Ce(IV) in this fracture is a result of repeated formation and dissolution of Mn oxides, that is, formation of Mn oxide followed by oxidative scavenging of Ce as Ce oxide nanoparticles, which largely remained during the subsequent reductive dissolution of the Mn oxides. In addition, the XANES data indicate that goethite has the capability to oxidize Ce at near-neutral pH under our experimental conditions (goethite reacted with 0.001M Ce for 48 h in a glove box with O-2 < 1 ppm). This previously unrecognized Ce oxidation pathway also seems to contribute to a minor extent to the oxidative scavenging of Ce in the fracture network. Trivalent Ce in the fracture coatings, in particular below 2.5 m, is mainly sorbed as inner-sphere complexes on clay minerals. Taking into account the facts that Ce in the present groundwater is scarce and modeled to be largely complexed with humic substance, it is argued that the inner-sphere complexes were mainly formed from past (Paleozoic) hydrothermal fluids. (C) 2016 Elsevier Ltd. All rights reserved.

  • 1187.
    Yu, Changxun
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Drake, Henrik
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Mathurin, Frédéric A.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Cerium Sequestration in Fractures in the Upper Kilometer of Granitoids, SE, Sweden2013Inngår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, nr 5, s. 2568-2568Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study seeks to define geochemical processes governing the accumulation and sequestration of Ce in granitoidic fractures down to >700 m depth, revealing past intrusions of oxygenated waters. The fracture coatings (secondary mineral precipitates in open fractures) gathered from the study area (Laxemar, SE Sweden) are characterized by high levels of Ce (Fig. 1b) compared to host rock cocentration (average: 86 ppm, n=65) and show a striking feature of distinct positive Ce anomalies (CeWN*=1.21-3.95, n=8) in the uppermost 20 m of the bedrock (Fig. 1a). Cerium and Mn X-ray absorption spectroscopy (XAS) of selected fracture coatings, together with existing data (e.g. fracture mineralogy and groundwater chemistry), indicate that: (1) Ce(IV) occurs down to c.a. 70 m depth and is exclusively associated with Mn oxides which occur as todorokite and triclinic birnessite as suggested by Mn EXAFS spectra; (2) Since Mn is largely speciated as Mn2+ in the present bedrock groundwaters, the Ce(IV)-bearing Mn oxides most probably resulted from oxidative weathering of wall rock and fracture coating minerals when oxygenated waters intruded into the bedrock (down to several hundred meters depth) during deglacation events (>13000 BP); (3) Unlike other samples, clear XAS features of a poorly-crystalline hexagonalbirnessite-like phase and larger proportion of aqueous Mn2+ were observed in the sample with strikingly positive Ce anomaly (CeWN* = 3.95) (Fig. 1b) at the depth of 0.87 m, suggesting an ongoing dynamic accumulatinon of Ce(IV), i.e. dissolution and reprecipiation of Mn oxides while Ce(IV)- enriched residue largely remained.

    Fulltekst (pdf)
    fulltext
  • 1188.
    Yu, Changxun
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Lavergren, Ulf
    County Administrative Board of Gotland, Sweden.
    Peltola, Pasi
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Drake, Henrik
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Bergbäck, Bo
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Retention and transport of arsenic, uranium and nickel in a black shale setting revealed by a long-term humidity cell test and sequential chemica extractions2014Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 363, s. 134-144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dispersion of acidic solutions with high levels of metals/metalloids, as a result of oxidative weathering of pyritic geomaterials, is a major environmental problem in areas where these materials are widely distributed and/or were historically mined. In this study, four types of materials encountered in an old black-shale mining area (unweathered black shale, weathered black shale, burnt black shale, and lime-mixed burnt black shale) were subjected to a long-term (up to 137 weeks) humidity cell test (HCT) combined with sequential chemical extractions (SCE), with the aim of examining geochemical controls on the release of Ni, U and As in this kind of pyritic settings. By combining the results of HCT and SCE as well as previously collected groundwater data, it is clearly shown that the degree of pyrite oxidation is the only major factor controlling the release of Ni, resulting in its highly elevated concentrations in acidic groundwaters. Although U followed a similar leaching pattern as observed for Ni and occurred abundantly in acidic groundwaters, a major decrease in the chemical fraction targeting exchangeable and carbonate phases, and a correlation of U concentrations with redox potential in groundwaters collectively suggest that the release of U was largely controlled by the solubilization of sorbed/carbonate U phases by oxidation to the highly soluble form (UO22+). As compared to the HCT, the SCE procedures used in this study delivered equally good estimates of Ni, U and S cumulatively leached, suggesting the strength of the SCE in terms of quantification of these elements during the weathering of pyritic geomaterials. Arsenic X-ray absorption near-edge structure spectroscopy shows that during the HCT (oxidation and leaching) of unweathered black shale, As was oxidized from its reduced form (having the oxidation state of -1 and most probably occurs as arsenian pyrite) to As(+5). Compared to the two cationic metals, As was released to a very limited extent and was not detectable in the leachates having pH between 6 and 3. This is because As was speciated exclusively as negatively-charged oxyanions in these leachates as predicted by MINTEQ modeling, thus was effectively attenuated by concurrently formed iron minerals. These minerals include mainly schwertmannite and K-jarosite as observed by SEM-EDS and also predicted by MINTEQ modeling. Elevated levels of As exclusively occurred in the groundwaters from one tube strongly impacted by seawater intrusion. This was regarded as a reflection of loosely-sorbed As oxyanions reliberated through ion exchange with seawater chloride. In this context, sea-level rise on a global scale as a potential driver for arsenic remobilization in low-lying coastal areas deserves further attention.

  • 1189.
    Yu, Changxun
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Peltola, Pasi
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Nystrand, Miriam I.
    Åbo Akad Univ, Finland.
    Virtasalo, Joonas J.
    Geol Survey Finland GTK, Finland.
    Österholm, Peter
    Åbo Akad Univ, Finland.
    Ojala, Antti E. K.
    Geol Survey Finland GTK, Finland.
    Högmalm, Johan K.
    University of Gothenburg.
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Arsenic removal from contaminated brackish sea water by sorption onto Al hydroxides and Fe phases mobilized by land-use2016Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 542, s. 923-934Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study examines the spatial and temporal distribution patterns of arsenic (As) in solid and aqueous materials along the mixing zone of an estuary, located in the south-eastern part of the Bothnian Bay and fed by a creek running through an acid sulfate (AS) soil landscape. The concentrations of As in solution form (<1 kDa) increase steadily from the creek mouth to the outer estuary, suggesting that inflowing seawater, rather than AS soil, is the major As source in the estuary. In sediments at the outer estuary, As was accumulated and diagenetically cycled in the surficial layers, as throughout much of the Bothnian Bay. In contrast, in sediments in the inner estuary, As concentrations and accumulation rates showed systematical peaks at greater depths. These peaks were overall consistent with the temporal trend of past As discharges from the Ronnskar smelter and the accompanied As concentrations in past sea-water of the Bothnian Bay, pointing to a connection between the historical smelter activities and the sediment-bound As in the inner estuary. However, the concentrations and accumulation rates of As peaked at depths where the smelter activities had already declined, but a large increase in the deposition of Al hydroxides and Fe phases occurred in response to intensified land-use in the mid 1960's and early 1970's. This correspondence suggests that, apart from the inflowing As-contaminated seawater, capture by Al hydroxides, Fe hydroxides and Fe-organic complexes is another important factor for As deposition in the inner estuary. After accumulating in the sediment, the solid-phase As was partly remobilized, as reflected by increased pore-water As concentrations, a process favored by As(V) reduction and high concentrations of dissolved organic matter. (C) 2015 Elsevier B.V. All rights reserved.

  • 1190.
    Yu, Changxun
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Virtasalo, Joonas J.
    Geol Survey Finland GTK, Finland.
    Karlsson, Torbjörn
    Umea Univ.
    Peltola, Pasi
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Osterholm, Peter
    Åbo Akad Univ, Finland.
    Burton, Edward D.
    So Cross Univ, Australia.
    Arppe, Laura
    Univ Helsinki, Finland.
    Hogmalm, Johan K.
    Univ Gothenburg.
    Ojala, Antti E. K.
    Geol Survey Finland GTK, Finland..
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Iron behavior in a northern estuary: Large pools of non-sulfidized Fe(II) associated with organic matter2015Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 413, s. 73-85Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The estuaries of the Northern Baltic Sea (Gulf of Bothnia) receive an abundance of diagenetically reactive catchment-derived Fe, which is to a large degree complexed with organicmatter or present as Fe (hydr-) oxides. However, our understanding of sedimentary Fe diagenesis in these estuaries is limited. To address this limitation, the present study examines Fe geochemistry in a 3.5-m-thick estuarine benthic mud layer and three samples of suspended particulate matter of a catchment on the eastern Gulf of Bothnia. The age-depth model of the mud, constructed on the basis of sedimentary features as well as Cs-137 and aquatic plant C-14 determinations, revealed a high average rate of sedimentation (5 cm . yr(-1)) for the upper mud unit (0-182.5 cm, corresponding to 1973-2011), in response to intensive land-use (ditching) in the catchment since the 1960s and 1970s. The intensive land-use has resulted in a strong increase in the Fe accumulation rates, but has not caused a recognizable impact on the diagenetic processes of Fe including features such as degree of sulfidization and solid-phase partitioning. Iron X-ray absorption spectroscopy (XAS) indicated that in the suspended particulate matter, large proportions (47-58%) of Fe occur as Fe(III)-organic complexes and 2-line ferrihydrite. In the mud, the former is completely reduced, and reactive Fe (defined via extraction with 1 MHCl) was high throughout (52-68%, median = 61%) and strongly dominated by Fe(II). This reactive Fe(II) pool was sulfidized to only a limited extent (degree of reactive sulfidization = 11-26%, median = 17%). This phenomenon is attributed to the brackish-water conditions (i.e. low in sulfate) and the abundant input of reactive Fe(III) from the catchment, leading to a surplus of dissolved Fe2+ over dissolved sulfide in the sediment. The low availability of dissolved sulfide, in combination with the high average sedimentation rate, limits the formation of intermediate reduced sulfur compounds at the water-sediment interface, thereby retarding the conversion of FeS into pyrite (ratios of pyrite-S to AVS = 0.17-1.73, median = 0.37; degree of pyritization = 1-17%, median = 3%). Iron XAS, in combination with wavelet transform analysis, of representative sediment segments from the upper and lower mud units suggests that the non-sulfidized Fe(II) pool is dominantly complexed by organic matter, with the remaining Fe(II) occurring as mackinawite. This has implications for the understanding of early Fe diagenesis in settings with a high input of organic matter and relatively low supply of sulfate. (C) 2015 Elsevier B.V. All rights reserved.

  • 1191.
    Yu, Changxun
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Virtasalo, Joonas J.
    Geol Survey Finland GTK, Finland.
    Österholm, Peter
    Åbo Akad Univ, Finland.
    Burton, Edward D.
    Southern Cross Univ, Australia.
    Peltola, Pasi
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Ojala, Antti E. K.
    Geol Survey Finland GTK, Finland.
    Högmalm, Johan K.
    University of Gothenburg.
    Åström, Mats E.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Manganese accumulation and solid-phase speciation in a 3.5 m thick mud sequence from the estuary of an acidic and Mn-rich creek, northern Baltic Sea2016Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 437, s. 56-66Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In sediments, manganese (Mn) is typically enriched in the form of authigenic Mn hydroxides at the water-sediment interface where intensive redox cycling of Mn occurs. Here we show, based on existing hydrochemical and geochemical (sediment core) data and new detailed chemical and mineralogical characterization of a 3.5 m long sediment core from a Boreal estuary, that the behavior of Mn can be profoundly different and more complex in estuarine settings receiving an abundance of terrestrial Mn. The most notable feature in the 3.5 m long sediment core is two depth intervals (60-155 cm and 181-230 cm) where there are strong fine-scale variations in Mn concentrations with peaks episodically reaching up to 10-25 g kg(-1) and 6.7-12 g kg(-1), respectively. X-ray absorption spectroscopy and sequential chemical extraction show that Mn occurs mainly as authigenic rhodochrosite at these two depth intervals and is mainly surface-sorbed in other sections with relatively low and stable Mn concentrations. The data suggests that the strong fine-scale variations in Mn concentrations are a reflection of the extent of formation and settling of Mn hydroxides, the precursors of the authigenic rhodochrosite (and also of the surface-sorbed Mn), rather than Mn input to the estuary or redox-related Mn translocation within the sediment. There was agreement between the results of linear combination fitting of extended X-ray absorption fine structure data and a 7-step sequential chemical extraction (SCE) in terms of quantification of surface-sorbed Mn species, whereas the SCE experiment failed to fractionate a majority of rhodochrosite into SCE step-2 (1M NH4-acetate at pH 6), which is frequently employed to dissolve carbonate. We ascribe this discrepancy to only partial dissolution of rhodochrosite in the weakly acidic (pH = 6) NH4-acetate leach. (C) 2016 Elsevier B.V. All rights reserved.

  • 1192.
    Zalizar, Lili
    et al.
    University of Muhammadiyah Malang, Indonesia.
    Pancapalaga, Wehandaka
    University of Muhammadiyah Malang, Indonesia.
    Indratmi, Dian
    University of Muhammadiyah Malang, Indonesia.
    Jani, Yahya
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Patterns in anthelmintic administration for laying hens in Blitar and Kediri district - Indonesia and the opportunities of drug resistance: anthelmintic administration for laying hens and drug resistance2018Inngår i: Proceedings of the Pakistan Academy of Sciences: B. Life and Environmental Sciences, ISSN 2518-4261, Vol. 55, nr 4, s. 65-69Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to determine the management of anthelmintic administration and the possibility of drug resistance in laying hens in Blitar and Kediri districts in Indonesia. This study consisted of two stages: first surveying 48 farmers in Blitar and 81 farmers in Kediri to find out how anthelmintic administration management included the frequency of anthelmintic administration for laying hens, types of anthelmintic, the habit of farmers using sustainably the same (> 3 yr) type of anthelmintic, determination of dosage, and use of herbal medicines in controlling worm disease. In the second stage, examine worm eggs at laying hens farms treated with worm medicine at intervals of 2 wk to 4 wk. The results showed that the majority of laying hens provide anthelmintic every 2 mo to 3 mo. In Blitar, the number of farmers who used the same worm medicine in more than 3 yr was 83.33 %. While in Kediri the number reached 97.53 %. The number of farmers who determined anthelmintic doses based on chicken body weight was 95.84 % (Blitar) and 90.12 % (Kediri). The administration of the same type of anthelmintic for more than three consecutive years and the calculation of anthelmintic doses based on the average body weight is thought to have an influence on the occurrence of drug resistance. It is seen that even though chickens were treated with anthelmintic for only 2 wk to 4 wk, worm eggs were found in fecal examination. © Pakistan Academy of Sciences.

  • 1193.
    Zehr, Jonathan P.
    et al.
    University of California, USA.
    Shilova, Irina N.
    University of California, USA.
    Farnelid, Hanna
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). University of California, USA.
    Muñoz-Marín, Maria del Carmen
    University of California, USA;University of Córdoba, Spain.
    Turk-Kubo, Kendra A.
    University of California, USA.
    Unusual marine unicellular symbiosis with the nitrogen-fixing cyanobacterium UCYN-A2017Inngår i: Nature Microbiology, E-ISSN 2058-5276, Vol. 2, nr 1, s. 1-10, artikkel-id 16214Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nitrogen fixation — the reduction of dinitrogen (N2) gas to biologically available nitrogen (N) — is an important source of N for terrestrial and aquatic ecosystems. In terrestrial environments, N2-fixing symbioses involve multicellular plants, but in the marine environment these symbioses occur with unicellular planktonic algae. An unusual symbiosis between an uncultivated unicellular cyanobacterium (UCYN-A) and a haptophyte picoplankton alga was recently discovered in oligotrophic oceans. UCYN-A has a highly reduced genome, and exchanges fixed N for fixed carbon with its host. This symbiosis bears some resemblance to symbioses found in freshwater ecosystems. UCYN-A shares many core genes with the ‘spheroid bodies’ of Epithemia turgida and the endosymbionts of the amoeba Paulinella chromatophora. UCYN-A is widely distributed, and has diversified into a number of sublineages that could be ecotypes. Many questions remain regarding the physical and genetic mechanisms of the association, but UCYN-A is an intriguing model for contemplating the evolution of N2-fixing organelles.

  • 1194. Zhang, Chaosheng
    et al.
    Selinus, Olle
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Hursthouse, Andrew S.
    Xia, Xinghui
    Ding, Shiming
    Preface: selected papers from SESEH 2012 Sino-European Symposium on Environment and Health2013Inngår i: Environmental Geochemistry and Health, ISSN 0269-4042, E-ISSN 1573-2983, Vol. 35, nr 5, s. 551-552Artikkel i tidsskrift (Annet vitenskapelig)
  • 1195.
    Zhang, Hao
    et al.
    Chinese Univ Hong Kong, Peoples Republic of China.
    Yoshizawa, Susumu
    Univ Tokyo, Japan.
    Sun, Ying
    Chinese Univ Hong Kong, Peoples Republic of China.
    Huang, Yongjie
    Chinese Univ Hong Kong, Peoples Republic of China.
    Chu, Xiao
    Chinese Univ Hong Kong, Peoples Republic of China.
    Gonzalez, Jose M.
    Univ La Laguna, Spain.
    Pinhassi, Jarone
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Luo, Haiwei
    Chinese Univ Hong Kong, Peoples Republic of China.
    Repeated evolutionary transitions of flavobacteria from marine to non-marine habitats2019Inngår i: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 21, nr 2, s. 648-666Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The taxonomy of marine and non-marine organisms rarely overlap, but the mechanisms underlying this distinction are often unknown. Here, we predicted three major ocean-to-land transitions in the evolutionary history of Flavobacteriaceae, a family known for polysaccharide and peptide degradation. These unidirectional transitions were associated with repeated losses of marine signature genes and repeated gains of non-marine adaptive genes. This included various Na+-dependent transporters, osmolyte transporters and glycoside hydrolases (GH) for sulfated polysaccharide utilization in marine descendants, and in non-marine descendants genes for utilizing the land plant material pectin and genes facilitating terrestrial host interactions. The K+ scavenging ATPase was repeatedly gained whereas the corresponding low-affinity transporter repeatedly lost upon transitions, reflecting K+ ions are less available to non-marine bacteria. Strikingly, the central metabolism Na+-translocating NADH: quinone dehydrogenase gene was repeatedly gained in marine descendants, whereas the H+-translocating counterpart was repeatedly gained in non-marine lineages. Furthermore, GH genes were depleted in isolates colonizing animal hosts but abundant in bacteria inhabiting other non-marine niches; thus relative abundances of GH versus peptidase genes among Flavobacteriaceae lineages were inconsistent with the marine versus non-marine dichotomy. We suggest that phylogenomic analyses can cast novel light on mechanisms explaining the distribution and ecology of key microbiome components.

  • 1196.
    Zhang, Shengrui
    et al.
    Hebei Normal University, China.
    Xu, Qinghai
    Hebei Normal University, China.
    Gaillard, Marie-José
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Cao, Xianyong
    Hebei Normal University, China ; Research Unit Potsdam, Germany ; University of Potsdam, Germany.
    Li, Jianyong
    University of Helsinki, Finland.
    Zhang, Liyan
    Shijiazhuang University of Economics, China.
    Li, Yuecong
    Hebei Normal University, China.
    Tian, Fang
    Research Unit Potsdam, Germany ; University of Potsdam, Germany.
    Zhou, Liping
    Peking University, China.
    Lin, Fengyou
    Chinese Academy of Sciences, China.
    Yang, Xiaolan
    Hebei Institute of Geography Science, China.
    Characteristic pollen source area and vertical pollen dispersal and deposition in a mixed coniferous and deciduous broad-leaved woodland in the Changbai mountains, northeast China.2016Inngår i: Vegetation History and Archaeobotany, ISSN 0939-6314, E-ISSN 1617-6278, Vol. 25, nr 1, s. 29-43Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pollen influx (number of pollen grains cm−2 year−1) can objectively reflect the dispersal and deposition features of pollen within a certain time and space, and is often used as a basis for the quantitative reconstruction of palaeovegetation; however, little is known about the features and mechanisms of vertical dispersal of pollen. Here we present the results from a 5 year (2006–2010) monitoring program using pollen traps placed at different heights from ground level up to 60 m and surface soil samples in a mixed coniferous and deciduous broad-leaved woodland in the Changbai mountains, northeastern China. The pollen percentages and pollen influx from the traps have very similar characteristics to the highest values for Betula,FraxinusQuercus and Pinus, among the tree taxa and Artemisia, Chenopodiaceae and Asteraceae among the herb taxa. Pollen influx values vary significantly with height and show major differences between three distinct layers, above-canopy (≥32 m), within the trunk layer (8 ≤ 32 m) and on the ground (0 m). These differences in pollen influx are explained by differences in (i) the air flows in each of these layers and (ii) the fall speed of pollen of the various taxa. We found that the pollen recorded on the ground surface is a good representation of the major part of the pollen transported in the trunk space of the woodland. Comparison of the pollen influx values with the theoretical, calculated “characteristic pollen source area” (CPSA) of 12 selected taxa indicates that the pollen deposited on the ground surface of the woodland is a fair representation with 85–90 % of the total pollen deposited at a wind speed of 2.4 m s−1 coming from within ca. 1–5 km for Pinus and Quercus, ca. 5–10 km for UlmusTilia, Oleaceae and Betula, ca. 20–40 km for Fraxinus, Poaceae, Chenopodiaceae, Populus andSalix, and ca. 30–60 km for Artemisia; it is also a good representation with 90–98 % of the total pollen deposited coming from within 60 km at a wind speed of 2.4 m s−1, or 100 km at a wind speed: 6 m s−1, for the 12 selected taxa used in the CPSA calculation. Furthermore, comparison with the vegetation map of the area around the sampling site shows that the pollen deposited on the ground represents all plant communities which grow in the study area within 70 km radius of the sampling site. In this study, the pollen percentages obtained from the soil surface samples are significantly biased towards pollen taxa with good preservation due to thick and robust pollen walls. Therefore, if mosses are available instead, soil samples should be avoided for pollen studies, in particular for the study of pollen-vegetation relationships, the estimation of pollen productivities and quantitative reconstruction of past vegetation. The results also indicate that the existing model of pollen dispersal and deposition, Prentice’s model, provides a fair description of the actual pollen dispersal and deposition in this kind of woodland, which suggests that the application of the landscape reconstruction algorithm would be relevant for reconstruction of this type of woodland in the past.

  • 1197.
    Zhang, Xiaodong
    et al.
    Tianjin University, China.
    Song, Zhaoliang
    Tianjin University, China.
    Hao, Qian
    Tianjin University, China.
    Yu, Changxun
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Liu, Hongyan
    Peking University, China.
    Chen, Chunmei
    Tianjin University, China.
    Müller, Karin
    Ruakura Research Centre, New Zealand.
    Wang, Hailong
    Foshan University, China;Zhejiang A & F University, China.
    Storage of soil phytoliths and phytolith-occluded carbon along aprecipitation gradient in grasslands of northern China2020Inngår i: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 364, s. 1-9, artikkel-id 114200Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Climatic factors including mean annual precipitation (MAP) significantly influence the carbon (C) cycle interrestrial ecosystems and Earth overall. Phytolith-occluded carbon (PhytOC) is an important C sequestrationmechanism and as such plays a vital role in global long-term C sequestration. Understanding the spatialvariability in the storage of soil phytoliths and PhytOC and its relationship with climate is critical for evaluatingthe impact of global climate change on terrestrial ecosystem functions. However, little is known about theresponses of soil phytoliths and PhytOC to MAP in grassland ecosystems. This study sampled soil from 24natural, semi-arid steppe sites along a 2,500 km transect with a precipitation gradient of 243–481 mm yr−1 innorthern China. We investigated the influence of precipitation on the spatial distributions of soil phytoliths andPhytOC storage. Storage of soil phytoliths in bulk soil (0–100 cm depth) ranged from 21.3 ± 0.4 to88.4 ± 20.3 t ha−1 along the precipitation gradient. Amounts of soil phytoliths and PhytOC storage weresignificantly and positively correlated with MAP. Multiple regression analysis revealed that phytolith storage inbulk soil was best predicted by MAP (R = 0.5) and soil organic carbon (SOC, R = 0.4), with these two variablesaccounting for about 58% of the total variation observed. Considering the forecasted increase in MAP in theInner Mongolian steppe due to climate change, and the strong influence of MAP on the annual net primaryproductivity (ANPP) and related soil PhytOC input from litter decomposition in this region, we expect thatecosystem primary productivity will increase from deserts to meadow steppe and thereby promote soil PhytOCstorage. These findings have important implications for understanding the dynamics of soil phytoliths, andpredicting the impacts of global climate change on ecosystem functions and management practices in the EastAsian steppe ecosystems.

  • 1198.
    Zhao, Yan
    et al.
    Chinese Acad Sci, Peoples Republic of China.
    Tang, Yu
    Lanzhou Univ, Peoples Republic of China.
    Yu, Zicheng
    Lehigh Univ, USA.
    Li, Huan
    Lanzhou Univ, Peoples Republic of China.
    Yang, Bao
    Chinese Acad Sci, Peoples Republic of China.
    Zhao, Wenwei
    Lanzhou Univ, Peoples Republic of China;Univ Cologne, Germany.
    Li, Furong
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Lanzhou Univ, Peoples Republic of China.
    Li, Quan
    Chinese Acad Sci, Peoples Republic of China.
    Holocene peatland initiation, lateral expansion, and carbon dynamics in the Zoige Basin of the eastern Tibetan Plateau2014Inngår i: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 24, nr 9, s. 1137-1145Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Zoige Basin on the eastern Tibetan Plateau has the largest area of highland peatlands in China. However, the development history of these peatlands is still poorly understood. Understanding how these carbon-rich ecosystems responded to change in the Asian summer monsoons during the Holocene will provide insight into the peatland carbon accumulation processes under different climate boundary conditions. Here, we document the timing of initiation and expansion histories of these peatlands using 59 new basal peat ages across the Zoige Basin, with 29 ages for initiation analysis and 30 additional ages for lateral expansion analysis. Also, we synthesized basal ages from 26 sites and carbon accumulation records at four sites from previous studies in this region. The results show that the peatland initiation is widespread at 11.5-10 and 7-6 kyr (1 kyr = 1000 cal. yr BP) and the minimum initiation periods occurred after 5 kyr. Our multiple basal ages along eight transects show that slopes are a dominant control on peatland lateral expansion rates, with very slow and less variable rates at slopes >0.4 degrees. Furthermore, we found a significant relationship between peatland basal ages and peat depths from 85 sites, suggesting relatively uniform peat properties. Carbon accumulation rates from detailed downcore analysis at four sites and on the basis of peat depth-basal age relationship show similar patterns with a peak carbon accumulation at 10-8 kyr. On the basis of estimated mean values of bulk density and carbon content from the region, the Holocene average C accumulation for the Zoige Basin is 31.1 g C/m(2)/yr. The widespread peatland initiation and rapid accumulation in the early Holocene were likely in response to higher temperature and stronger summer monsoon intensity, while the slowdown of peatland development during the late Holocene might have been caused by climate cooling and drying.

  • 1199.
    Zheng, Hennisa
    et al.
    Univ Gadjah Mada, Indonesia.
    Risa, Novia
    Univ Gadjah Mada, Indonesia.
    Juliany,
    Univ Gadjah Mada, Indonesia.
    Kelvin, Shawn
    Univ Gadjah Mada, Indonesia.
    Kalati, Tyas Delilla
    Univ Gadjah Mada, Indonesia.
    Lukitaningsih, Raden Rara Endang
    Univ Gadjah Mada, Indonesia.
    Burlakovs, Juris
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Sembur Karo: Karo's Traditional Medicine as Burns Injury Alternative Treatment with Rattus norvegicus as Model2017Inngår i: 4th International Conference on Biological Science (2015) / [ed] Nuringtyas, TR Setyobudi, RH Burlakovs, J Mel, M Adinurani, PG VincevicaGaile, Z, 2017, s. 111-117Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Burns injury can be caused by flame, heat, chemical and electricity and it remains as one of the most serious problems in the medical world. Burns injury can be treated with traditional medicine. One of them is Sembur Karo. The objective of this research was to investigate the Sembur Karo potency for burns injury treatment. Sembur Karo obtained from North Sumatera was identified its plant composition and analyzed for bioactive compounds; flavonoid, steroid, and tannin. Twenty five rats (Rattus norvegicus) were used. The rats were divided into five groups of five. The first group used as a control without treatment, the second group are sprayed with Sembur Karo, while the third and the fourth groups were applied with Sembur Karo added with water and human saliva respectively. The last group were treated with Bioplacentone. All treatments were done once a day for 3 wk. Each week, one rat from all group were sacrificed with skins were taken for histology specimen. From this research, it was concluded that bioactive compounds in Sembur Karo were isoquersetin, sterol, and condensed tannin. The skin histology showed that the group which sprayed with Sembur Karo had the most effective effect among all groups.

  • 1200.
    Zuniga, Silvia
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Bat species richness and activity in forest habitats close to lakes versus far from lakes,  in Sweden2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The long-term effects of large-scale changes in forestry, agriculture and other land use on habitats and the large-scale expansion of wind farming  affects bats foraging environments. In order to predict consequences of exploitations on local bat species and populations, good surveys are important. To get good background information for an Environmental Impact Assessment (EIA) it  is crucial to rapidly assess which areas are most important for bats. The aim of this work was to measure the importance of the two types of forest environment for bats foraging : forest areas located close to or far from the lakes. Bat activity and species diversity was measured with automatic ultrasound recorders in 211  nights of fieldwork at 155 locations in 23 areas in different parts of Sweden during June, July and the first two weeks of August 2011 and 2012. A total of 11 species were recorded in forest far from lakes and 8 species in forest close to lakes. Eptesicus nilssonii , Myotis sp. and Pipistrellus pygmaeus were the most common taxa in both habitat types. Activity levels were higher in the vicinity of lakes compared to forests far away from lakes. Species diversity calculated on base on Chao 2 was similar for both types of habitats . The results suggest that the forests close to lakes are the most important habitats to surveys for bats in Sweden and that inventory efforts should be primarily invested in them.

    Fulltekst (pdf)
    fulltext
2122232425 1151 - 1200 of 1215
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf