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Christel, S., Yu, C., Wu, X., Josefsson, S., Lillhonga, T., Högfors-Rönnholm, E., . . . Dopson, M. (2019). Comparison of Boreal Acid Sulfate Soil Microbial Communities in Oxidative and Reductive Environments [Letter to the editor]. Research in Microbiology
Open this publication in new window or tab >>Comparison of Boreal Acid Sulfate Soil Microbial Communities in Oxidative and Reductive Environments
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2019 (English)In: Research in Microbiology, ISSN 0923-2508, E-ISSN 1769-7123Article in journal, Letter (Refereed) In press
Abstract [en]

Due to land uplift after the last ice age, previously stable Baltic Sea sulfidic sediments are becoming dry land. When these sediments are drained, the sulfide minerals are exposed to air and can release large amounts of metals and acid into the environment. This can cause severe ecological damage such as fish kills in rivers feeding the northern Baltic Sea. In this study, five sites were investigated for the occurrence of acid sulfate soils and their geochemistry and microbiology was identified. The pH and soil chemistry identified three of the areas as having classical acid sulfate soil characteristics and culture independent identification of 16S rRNA genes identified populations related to acidophilic bacteria capable of catalyzing sulfidic mineral dissolution, including species likely adapted to low temperature. These results were compared to an acid sulfate soil area that had been flooded for ten years and showed that the previously oxidized sulfidic materials had an increased pH compared to the unremediated oxidizied layers. In addition, the microbiology of the flooded soil had changed such that alkalinity producing ferric and sulfate reducing reactions had likely occurred. This suggested that flooding of acid sulfate soils mitigates their environmental impact.

Keywords
sulfide mineral; metal; sulfur; 16S rRNA gene; mitigation; wetland
National Category
Microbiology Earth and Related Environmental Sciences
Research subject
Natural Science, Environmental Science
Identifiers
urn:nbn:se:lnu:diva-77664 (URN)10.1016/j.resmic.2019.06.002 (DOI)
Available from: 2018-09-10 Created: 2018-09-10 Last updated: 2019-07-04
Tillberg, M., Maskenskaya, O. M., Drake, H., Hogmalm, J. K., Broman, C., Fallick, A. E. & Åström, M. E. (2019). Fractionation of Rare Earth Elements in Greisen and Hydrothermal Veins Related to A-Type Magmatism. Geofluids, 2019, 1-20, Article ID 4523214.
Open this publication in new window or tab >>Fractionation of Rare Earth Elements in Greisen and Hydrothermal Veins Related to A-Type Magmatism
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2019 (English)In: Geofluids, ISSN 1468-8115, E-ISSN 1468-8123, Vol. 2019, p. 1-20, article id 4523214Article in journal (Refereed) Published
Abstract [en]

This study focuses on concentrations and fractionation of rare earth elements (REE) in a variety of minerals and bulk materials of hydrothermal greisen and vein mineralization in Paleoproterozoic monzodiorite to granodiorite related to the intrusion of Mesoproterozoic alkali- and fluorine-rich granite. The greisen consists of coarse-grained quartz, muscovite, and fluorite, whereas the veins mainly contain quartz, calcite, epidote, chlorite, and fluorite in order of abundance. A temporal and thus genetic link between the granite and the greisen/veins is established via high spatial resolution in situ Rb-Sr dating, supported by several other isotopic signatures (delta S-34, Sr-87/Sr-86, delta O-18, and delta C-13). Fluid-inclusion microthermometry reveals that multiple pulses of moderately to highly saline aqueous to carbonic solutions caused greisenization and vein formation at temperatures above 200-250 degrees C and up to 430 degrees C at the early hydrothermal stage in the veins. Low calculated Sigma REE concentration for bulk vein (15ppm) compared to greisen (75ppm), country rocks (173-224ppm), and the intruding granite (320ppm) points to overall low REE levels in the hydrothermal fluids emanating from the granite. This is explained by efficient REE retention in the granite via incorporation in accessory phosphates, zircon, and fluorite and unfavorable conditions for REE partitioning in fluids at the magmatic and early hydrothermal stages. A noteworthy feature is substantial heavy REE (HREE) enrichment of calcite in the vein system, in contrast to the relatively flat patterns of greisen calcite. The REE fractionation of the vein calcite is explained mainly by fractional crystallization, where the initially precipitated epidote in the veins preferentially incorporates most of the light REE (LREE) pool, leaving a residual fluid enriched in the HREE from which calcite precipitated. Fluorite occurs throughout the system and displays decreasing REE concentrations from granite towards greisen and veins and different fractionation patterns among all these three materials. Taken together, these features confirm efficient REE retention in the early stages of the system and minor control of the REE uptake by mineral-specific partitioning. REE-fractionation patterns and fluid-inclusion data suggest that chloride complexation dominated REE transport during greisenization, whereas carbonate complexation contributed to the HREE enrichment in vein calcite.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2019
National Category
Earth and Related Environmental Sciences
Research subject
Natural Science
Identifiers
urn:nbn:se:lnu:diva-89315 (URN)10.1155/2019/4523214 (DOI)000484731100001 ()
Available from: 2019-09-26 Created: 2019-09-26 Last updated: 2019-09-26Bibliographically approved
Yu, C., Berger, T., Drake, H., Song, Z., Peltola, P. & Åström, M. E. (2019). Geochemical controls on dispersion of U and Th in Quaternary deposits, stream water, and aquatic plants in an area with a granite pluton. Science of the Total Environment, 663, 16-28
Open this publication in new window or tab >>Geochemical controls on dispersion of U and Th in Quaternary deposits, stream water, and aquatic plants in an area with a granite pluton
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2019 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 663, p. 16-28Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Uranium, Thorium, Nemo-boreal catchments, Climate change, Weathering
National Category
Environmental Sciences Geochemistry
Research subject
Natural Science, Environmental Science; Natural Science, Environmental Science
Identifiers
urn:nbn:se:lnu:diva-80032 (URN)10.1016/j.scitotenv.2019.01.293 (DOI)000459858500002 ()30708213 (PubMedID)2-s2.0-85060730596 (Scopus ID)
Available from: 2019-01-30 Created: 2019-01-30 Last updated: 2019-08-29Bibliographically approved
Uddh Söderberg, T., Berggren Kleja, D., Åström, M. E., Jarsjö, J., Fröberg, M., Svensson, P. A. & Augustsson, A. (2019). Metal solubility and transport at a contaminated landfill site – From the source zone into the groundwater. Science of the Total Environment, 668, 1064-1076
Open this publication in new window or tab >>Metal solubility and transport at a contaminated landfill site – From the source zone into the groundwater
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2019 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 668, p. 1064-1076Article in journal (Refereed) Published
Abstract [en]

Risks associated with metal contaminated sites are tightly linked to material leachability and contaminant mobility. In this study, metal solubility and transport were characterized within a glass waste landfill through i) lysimeter-collection of pore water and standardized batch leaching tests, ii) soil profiles extending from the landfill surface, through unsaturated soil underneath, and into the groundwater zone, and iii) groundwater samples upstream, at, and downstream of the landfill. The soil analyzes targeted both pseudo-total and geochemically active concentrations of contaminant metals (As, Cd, Pb, Sb) and basic soil geochemistry (pH, org. C, Fe,Mn). Water samples were analyzed for dissolved, colloid-bound and particulate metals, and speciation modelling of the aqueous phase was conducted. The results revealed a highly contaminated system, with mean metal concentrationsin the waste zone between 90 and 250 times the regional background levels. Despite severe contamination of the waste zone and high geochemically active fractions (80–100%) of all contaminant metals as well as elevated concentrations in landfill pore water, the concentrations of Cd and Pb decrease abruptly at the transition between landfill and underlying natural soil and no indication of groundwater contamination was found. The efficient cation retention is likely due to the high pH. However, the sorption of As and Sb is weaker at such high pH,which explains their higher mobility from the pore water zone into groundwater. The field soil:solution for Pb, ranging from 140 to 2,900,000 l kg−1), despite little variability in basic geochemical variables, which we suggest is due to waste material heterogeneity.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Soil and groundwater metal pollution, Glass waste, Soil:Solution partitioning (Kd), Leachability, Mobility, Colloids
National Category
Environmental Sciences
Research subject
Natural Science, Environmental Science
Identifiers
urn:nbn:se:lnu:diva-81555 (URN)10.1016/j.scitotenv.2019.03.013 (DOI)000462776800098 ()2-s2.0-85062735396 (Scopus ID)
Funder
The Geological Survey of Sweden (SGU), 36-1778/2014
Available from: 2019-04-01 Created: 2019-04-01 Last updated: 2019-08-29Bibliographically approved
Yu, C., Drake, H., Lopez-Fernandez, M., Whitehouse, M., Dopson, M. & Åström, M. E. (2019). 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-variation. Chemical Geology, 522, 192-207
Open this publication in new window or tab >>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-variation
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2019 (English)In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 522, p. 192-207Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Pyrite, Iron isotopes, Equilibrium Fe-isotope fractionation, Magnetite sulfidization, Partial pyritization, Fractured crystalline bedrock
National Category
Earth and Related Environmental Sciences
Research subject
Natural Science, Environmental Science
Identifiers
urn:nbn:se:lnu:diva-84618 (URN)10.1016/j.chemgeo.2019.05.026 (DOI)000480330600016 ()2-s2.0-85066994013 (Scopus ID)
Funder
Swedish Research Council, 2017-05186Swedish Research Council, 2014-4398Swedish Research Council Formas, 2017-00766
Available from: 2019-06-05 Created: 2019-06-05 Last updated: 2019-08-29Bibliographically approved
Yu, C., Boily, J.-F., Shchukarev, A., Drake, H., Song, Z., Hogmalm, K. J. & Åström, M. E. (2018). A cryogenic XPS study of Ce fixation on nanosized manganite and vernadite: Interfacial reactions and effects of fulvic acid complexation. Chemical Geology, 483, 304-311
Open this publication in new window or tab >>A cryogenic XPS study of Ce fixation on nanosized manganite and vernadite: Interfacial reactions and effects of fulvic acid complexation
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2018 (English)In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 483, p. 304-311Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Cryogenic XPS, Manganite, Vernadite, Oxidative scavenging, Ce anomaly
National Category
Earth and Related Environmental Sciences
Research subject
Natural Science
Identifiers
urn:nbn:se:lnu:diva-72684 (URN)10.1016/j.chemgeo.2018.02.033 (DOI)000429492300027 ()2-s2.0-85042905870 (Scopus ID)
Available from: 2018-04-13 Created: 2018-04-13 Last updated: 2019-08-29Bibliographically approved
Lopez-Fernandez, M., Åström, M. E., Bertilsson, S. & Dopson, M. (2018). Depth and Dissolved Organic Carbon Shape Microbial Communities in Surface Influenced but Not Ancient Saline Terrestrial Aquifers. Frontiers in Microbiology, 9, Article ID 2880.
Open this publication in new window or tab >>Depth and Dissolved Organic Carbon Shape Microbial Communities in Surface Influenced but Not Ancient Saline Terrestrial Aquifers
2018 (English)In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 9, article id 2880Article in journal (Refereed) Published
Abstract [en]

The continental deep biosphere is suggested to contain a substantial fraction of the earth's total biomass and microorganisms inhabiting this environment likely have a substantial impact on biogeochemical cycles. However, the deep microbial community is still largely unknown and can be influenced by parameters such as temperature, pressure, water residence times, and chemistry of the waters. In this study, 21 boreholes representing a range of deep continental groundwaters from the Aspo Hard Rock Laboratory were subjected to high-throughput 16S rRNA gene sequencing to characterize how the different water types influence the microbial communities. Geochemical parameters showed the stability of the waters and allowed their classification into three groups. These were (i) waters influenced by infiltration from the Baltic Sea with a "modern marine (MM)" signature, (ii) a "thoroughly mixed (TM)" water containing groundwaters of several origins, and (iii) deep "old saline (OS)" waters. Decreasing microbial cell numbers positively correlated with depth. In addition, there was a stronger positive correlation between increased cell numbers and dissolved organic carbon for the MM compared to the OS waters. This supported that the MM waters depend on organic carbon infiltration from the Baltic Sea while the ancient saline waters were fed by "geogases" such as carbon dioxide and hydrogen. The 16S rRNA gene relative abundance of the studied groundwaters revealed different microbial community compositions. Interestingly, the TM water showed the highest dissimilarity compared to the other two water types, potentially due to the several contrasting water types contributing to this groundwater. The main identified microbial phyla in the groundwaters were Gammaproteobacteria, unclassified sequences, Campylobacterota (formerly Epsilonproteobacteria), Patescibacteria, Deltaproteobacteria, and Alphaproteobacteria. Many of these taxa are suggested to mediate ferric iron and nitrate reduction, especially in the MM waters. This indicated that nitrate reduction may be a neglected but important process in the deep continental biosphere. In addition to the high number of unclassified sequences, almost 50% of the identified phyla were archaeal or bacterial candidate phyla. The percentage of unknown and candidate phyla increased with depth, pointing to the importance and necessity of further studies to characterize deep biosphere microbial populations.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2018
Keywords
16S rRNA gene, amplicon sequencing, deep subsurface, groundwaters, chemistry, microbial diversity
National Category
Microbiology
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-79095 (URN)10.3389/fmicb.2018.02880 (DOI)000451406100001 ()2-s2.0-85057582575 (Scopus ID)
Funder
Swedish Research Council, 2014-4398; 2012-3892; 2017-04422
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2019-08-29Bibliographically approved
Drake, H., Mathurin, F. A., Zack, T., Schäfer, T., Roberts, N., Whitehouse, M., . . . Åström, M. E. (2018). Incorporation of Metals into Calcite in a Deep Anoxic Granite Aquifer. Environmental Science and Technology, 52(2), 493-502
Open this publication in new window or tab >>Incorporation of Metals into Calcite in a Deep Anoxic Granite Aquifer
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2018 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 52, no 2, p. 493-502Article in journal (Refereed) Published
Abstract [en]

Understanding metal scavenging by calcite in deep aquifers in granite is of importance for deciphering and modeling hydrochemical fluctuations and water–rock interaction in the upper crust and for retention mechanisms associated with underground repositories for toxic wastes. Metal scavenging into calcite has generally been established in the laboratory or in natural environments that cannot be unreservedly applied to conditions in deep crystalline rocks, an environment of broad interest for nuclear waste repositories. Here, we report a microanalytical study of calcite precipitated over a period of 17 years from anoxic, low-temperature (14 °C), neutral (pH: 7.4–7.7), and brackish (Cl: 1700–7100 mg/L) groundwater flowing in fractures at >400 m depth in granite rock. This enabled assessment of the trace metal uptake by calcite under these deep-seated conditions. Aquatic speciation modeling was carried out to assess influence of metal complexation on the partitioning into calcite. The resulting environment-specific partition coefficients were for several divalent ions in line with values obtained in controlled laboratory experiments, whereas for several other ions they differed substantially. High absolute uptake of rare earth elements and U(IV) suggests that coprecipitation into calcite can be an important sink for these metals and analogousactinides in the vicinity of geological repositories.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Earth and Related Environmental Sciences
Research subject
Natural Science
Identifiers
urn:nbn:se:lnu:diva-70485 (URN)10.1021/acs.est.7b05258 (DOI)000423012200013 ()29251499 (PubMedID)2-s2.0-85041450605 (Scopus ID)
Available from: 2018-02-05 Created: 2018-02-05 Last updated: 2019-08-29Bibliographically approved
Åström, M. E., Yu, C., Peltola, P., Reynolds, J. K., Österholm, P., Nystrand, M. I., . . . Ojala, A. E. .. (2018). Sources, transport and sinks of beryllium in a coastal landscape affected by acidic soils. Geochimica et Cosmochimica Acta, 232, 288-302
Open this publication in new window or tab >>Sources, transport and sinks of beryllium in a coastal landscape affected by acidic soils
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2018 (English)In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 232, p. 288-302Article in journal (Refereed) Published
Abstract [en]

Beryllium (Be) sources, transport and sinks were studied in a coastal landscape where acidic soils (acid sulfate soils) have developed after drainage of fine-grained sulfide-bearing sediments. The study included the determination of total abundance and speciation of Be in a variety of solid and aqueous materials in both the terrestrial and estuarine parts of the landscape. A major feature was that despite normal (background) Be concentration in the sulfide-bearing sediments, the Be leaching from these sediments after O2-exposure and acid sulfate soil development were extensive, with concentrations up to 76 μg L−1 in soil water, 39 μg L−1 in runoff and 12 μg L−1 in low-order streams. These high Be concentrations were mainly in the solution form (i.e., passing a 1 kilodalton filter) and modelled to be dominated by free Be2+. The extensive Be release within, and leaching from the acid sulfate soils was controlled by pH, with a critical value of 4.0 below which the Be concentrations increased strongly. Although plagioclase and mica were most likely the main carriers of Be within these soils, it is suggested that other minerals such as Be hydroxides, Al hydroxides carrying Be, and Be sulfides are the main contributors of the abundance of dissolved Be in the acidic waters. When the acidic and Be-rich creek water was neutralized in the estuary of relatively low salinity, the dominating solution form of Be was removed by transformation to particles, reflected in the suspended particulate matter that had hydroxylamine hydrochloride extractable Be up to 17 mg kg−1 and ammonium acetate EDTA extractable Be up to 4 mg kg−1. In corresponding pristine materials (parent material of the acid sulfate soils) in the catchment, the median Be extractability with these reagents were only 0.3 and 0.05 mg kg−1, respectively. As the Be-rich suspended particulate matter ultimately became benthic sediment, the Be was preserved in terms of total concentrations but underwent to some extent changes in speciation, including release from hydroxides and concomitant scavenging by organic matter and particle surfaces.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Earth and Related Environmental Sciences
Research subject
Natural Science, Environmental Science
Identifiers
urn:nbn:se:lnu:diva-74838 (URN)10.1016/j.gca.2018.04.025 (DOI)000432751700015 ()2-s2.0-85047098585 (Scopus ID)
Available from: 2018-06-01 Created: 2018-06-01 Last updated: 2019-08-29Bibliographically approved
Drake, H., Whitehouse, M. J., Heim, C., Reiners, P. W., Tillberg, M., Hogmalm, K. J., . . . Åström, M. E. (2018). Unprecedented 34S-enrichment of pyrite formed following microbial sulfate reduction in fractured crystalline rocks. Geobiology, 16(5), 556-574
Open this publication in new window or tab >>Unprecedented 34S-enrichment of pyrite formed following microbial sulfate reduction in fractured crystalline rocks
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2018 (English)In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 16, no 5, p. 556-574Article in journal (Refereed) Published
Abstract [en]

In the deep biosphere, microbial sulfate reduction (MSR) is exploited for energy. Here, we show that, in fractured continental crystalline bedrock in three areas in Sweden, this process produced sulfide that reacted with iron to form pyrite extremely enriched in S-34 relative to S-32. As documented by secondary ion mass spectrometry (SIMS) microanalyses, the S-34(pyrite) values are up to +132 parts per thousand V-CDT and with a total range of 186 parts per thousand. The lightest S-34(pyrite) values (-54 parts per thousand) suggest very large fractionation during MSR from an initial sulfate with S-34 values (S-34(sulfate,0)) of +14 to +28 parts per thousand. Fractionation of this magnitude requires a slow MSR rate, a feature we attribute to nutrient and electron donor shortage as well as initial sulfate abundance. The superheavy S-34(pyrite) values were produced by Rayleigh fractionation effects in a diminishing sulfate pool. Large volumes of pyrite with superheavy values (+120 +/- 15 parts per thousand) within single fracture intercepts in the boreholes, associated heavy average values up to +75 parts per thousand and heavy minimum S-34(pyrite) values, suggest isolation of significant amounts of isotopically light sulfide in other parts of the fracture system. Large fracture-specific S-34(pyrite) variability and overall average S-34(pyrite) values (+11 to +16 parts per thousand) lower than the anticipated S-34(sulfate,0) support this hypothesis. The superheavy pyrite found locally in the borehole intercepts thus represents a late stage in a much larger fracture system undergoing Rayleigh fractionation. Microscale Rb-Sr dating and U/Th-He dating of cogenetic minerals reveal that most pyrite formed in the early Paleozoic era, but crystal overgrowths may be significantly younger. The C-13 values in cogenetic calcite suggest that the superheavy S-34(pyrite) values are related to organotrophic MSR, in contrast to findings from marine sediments where superheavy pyrite has been proposed to be linked to anaerobic oxidation of methane. The findings provide new insights into MSR-related S-isotope systematics, particularly regarding formation of large fractions of S-34-rich pyrite.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2018
Keywords
continental crust, deep biosphere, microbial sulfate reduction, pyrite, sulfur isotopes
National Category
Environmental Sciences
Research subject
Natural Science, Environmental Science
Identifiers
urn:nbn:se:lnu:diva-77727 (URN)10.1111/gbi.12297 (DOI)000441436700007 ()29947123 (PubMedID)2-s2.0-85052511300 (Scopus ID)
Projects
Characteristics and extent of microbial anaerobic methane oxidation and sulfate reduction in the deep terrestrial subsurface over geological time scalesProduction and consumption of the greenhouse gas methane in the crystalline bedroc
Funder
Swedish Research Council, 2017-05186Swedish Research Council Formas, 2017-00766
Available from: 2018-09-13 Created: 2018-09-13 Last updated: 2019-08-29Bibliographically approved
Projects
Syntrofi och symbios för överlevnad och tillväxt i den djupa terrestra biosfären [202100-6271]; Linnaeus University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3585-2209

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