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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
Sallstedt, T., Ivarsson, M., Drake, H. & Skogby, H. (2019). Instant Attraction: Clay Authigenesis in Fossil Fungal Biofilms. Geosciences, 9(9), 1-21, Article ID 369.
Open this publication in new window or tab >>Instant Attraction: Clay Authigenesis in Fossil Fungal Biofilms
2019 (English)In: Geosciences, E-ISSN 2076-3263, Vol. 9, no 9, p. 1-21, article id 369Article, review/survey (Refereed) Published
Abstract [en]

Clay authigenesis associated with the activity of microorganisms is an important process for biofilm preservation and may provide clues to the formation of biominerals on the ancient Earth. Fossilization of fungal biofilms attached to vesicles or cracks in igneous rock, is characterized by fungal-induced clay mineralization and can be tracked in deep rock and deep time, from late Paleoproterozoic (2.4 Ga), to the present. Here we briefly review the current data on clay mineralization by fossil fungal biofilms from oceanic and continental subsurface igneous rock. The aim of this study was to compare the nature of subsurface fungal clays from different igneous settings to evaluate the importance of host rock and ambient redox conditions for clay speciation related to fossil microorganisms. Our study suggests that the most common type of authigenic clay associated with pristine fossil fungal biofilms in both oxic (basaltic) and anoxic (granitic) settings are montmorillonite-like smectites and confirms a significant role of fungal biofilms in the cycling of elements between host rock, ocean and secondary precipitates. The presence of life in the deep subsurface may thus prove more significant than host rock geochemistry in directing the precipitation of authigenic clays in the igneous crust, the extent of which remains to be fully understood.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
clay authigenesis, fossil fungi, igneous crust, cryptoendoliths, subseafloor habitats
National Category
Microbiology Earth and Related Environmental Sciences
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-89710 (URN)10.3390/geosciences9090369 (DOI)000487634500006 ()
Available from: 2019-10-18 Created: 2019-10-18 Last updated: 2019-10-18Bibliographically 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
Tillberg, M., Ivarsson, M., Drake, H., Whitehouse, M. J., Kooijman, E. & Schmitt, M. (2019). Re-Evaluating the Age of Deep Biosphere Fossils in the Lockne Impact Structure. Geosciences, 9(5), 1-22, Article ID UNSP 202.
Open this publication in new window or tab >>Re-Evaluating the Age of Deep Biosphere Fossils in the Lockne Impact Structure
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2019 (English)In: Geosciences, E-ISSN 2076-3263, Vol. 9, no 5, p. 1-22, article id UNSP 202Article in journal (Refereed) Published
Abstract [en]

Impact-generated hydrothermal systems have been suggested as favourable environments for deep microbial ecosystems on Earth, and possibly beyond. Fossil evidence from a handful of impact craters worldwide have been used to support this notion. However, as always with mineralized remains of microorganisms in crystalline rock, certain time constraints with respect to the ecosystems and their subsequent fossilization are difficult to obtain. Here we re-evaluate previously described fungal fossils from the Lockne crater (458 Ma), Sweden. Based on in-situ Rb/Sr dating of secondary calcite-albite-feldspar (356.6 +/- 6.7 Ma) we conclude that the fungal colonization took place at least 100 Myr after the impact event, thus long after the impact-induced hydrothermal activity ceased. We also present microscale stable isotope data of C-13-enriched calcite suggesting the presence of methanogens contemporary with the fungi. Thus, the Lockne fungi fossils are not, as previously thought, related to the impact event, but nevertheless have colonized fractures that may have been formed or were reactivated by the impact. Instead, the Lockne fossils show similar features as recent findings of ancient microbial remains elsewhere in the fractured Swedish Precambrian basement and may thus represent a more general feature in this scarcely explored habitat than previously known.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
Impact structure, fungal hyphae, in situ radiometric dating, secondary minerals, stable isotopes
National Category
Microbiology Earth and Related Environmental Sciences
Research subject
Environmental Science, Paleoecology
Identifiers
urn:nbn:se:lnu:diva-86865 (URN)10.3390/geosciences9050202 (DOI)000470966100011 ()2-s2.0-85067627284 (Scopus ID)
Available from: 2019-07-16 Created: 2019-07-16 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
Drake, H., Ivarsson, M., Tillberg, M., Whitehouse, M. & Kooijman, E. (2018). Ancient Microbial Activity in Deep Hydraulically Conductive Fracture Zones within the Forsmark Target Area for Geological Nuclear Waste Disposal, Sweden. Geosciences, 8(6), Article ID 211.
Open this publication in new window or tab >>Ancient Microbial Activity in Deep Hydraulically Conductive Fracture Zones within the Forsmark Target Area for Geological Nuclear Waste Disposal, Sweden
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2018 (English)In: Geosciences, E-ISSN 2076-3263, Vol. 8, no 6, article id 211Article in journal (Refereed) Published
Abstract [en]

Recent studies reveal that organisms from all three domains of life—Archaea, Bacteria, and even Eukarya—can thrive under energy-poor, dark, and anoxic conditions at large depths in the fractured crystalline continental crust. There is a need for an increased understanding of the processes and lifeforms in this vast realm, for example, regarding the spatiotemporal extent and variability of the different processes in the crust. Here, we present a study that set out to detect signs of ancient microbial life in the Forsmark area—the target area for deep geological nuclear waste disposal in Sweden. Stable isotope compositions were determined with high spatial resolution analyses within mineral coatings, and mineralized remains of putative microorganisms were studied in several deep water-conducting fracture zones (down to 663 m depth), from which hydrochemical and gas data exist. Large isotopic variabilities of δ13Ccalcite (−36.2 to +20.2‰ V-PDB) and δ34Spyrite (−11.7 to +37.8‰ V-CDT) disclose discrete periods of methanogenesis, and potentially, anaerobic oxidation of methane and related microbial sulfate reduction at several depth intervals. Dominant calcite–water disequilibrium of δ18O and 87Sr/86Sr precludes abundant recent precipitation. Instead, the mineral coatings largely reflect an ancient archive of episodic microbial processes in the fracture system, which, according to our microscale Rb–Sr dating of co-genetic adularia and calcite, date back to the mid-Paleozoic. Potential Quaternary precipitation exists mainly at ~400 m depth in one of the boreholes, where mineral–water compositions corresponded

Place, publisher, year, edition, pages
MDPI, 2018
National Category
Environmental Sciences Geosciences, Multidisciplinary Geochemistry Geology
Research subject
Natural Science, Environmental Science
Identifiers
urn:nbn:se:lnu:diva-77641 (URN)10.3390/geosciences8060211 (DOI)000436131300023 ()2-s2.0-85048511199 (Scopus ID)
Funder
Swedish Research Council Formas, 2017-00766Swedish Research Council, 2017-0518
Available from: 2018-09-10 Created: 2018-09-10 Last updated: 2019-08-29Bibliographically approved
Ivarsson, M., Bengtson, S., Drake, H. & Warren, F. (2018). Fungi in Deep Subsurface Environments. In: Sima Sariaslani & Geoffrey Michael Gadd (Ed.), Advances in Applied Microbiology: (pp. 83-116). Academic Press
Open this publication in new window or tab >>Fungi in Deep Subsurface Environments
2018 (English)In: Advances in Applied Microbiology / [ed] Sima Sariaslani & Geoffrey Michael Gadd, Academic Press, 2018, p. 83-116Chapter in book (Refereed)
Abstract [en]

The igneous crust of the oceans and the continents represents the major part of Earth's lithosphere and has recently been recognized as a substantial, yet underexplored, microbial habitat. While prokaryotes have been the focus of most investigations, microeukaryotes have been surprisingly neglected. However, recent work acknowledges eukaryotes, and in particular fungi, as common inhabitants of the deep biosphere, including the deep igneous provinces. The fossil record of the subseafloor igneous crust, and to some extent the continental bedrock, establishes fungi or fungus-like organisms as inhabitants of deep rock since at least the Paleoproterozoic, which challenges the present notion of early fungal evolution. Additionally, deep fungi have been shown to play an important ecological role engaging in symbiosis-like relationships with prokaryotes, decomposing organic matter, and being responsible for mineral weathering and formation, thus mediating mobilization of biogeochemically important elements. In this review, we aim at covering the abundance and diversity of fungi in the various igneous rock provinces on Earth as well as describing the ecological impact of deep fungi. We further discuss what consequences recent findings might have for the understanding of the fungal distribution in extensive anoxic environments and for early fungal evolution.

Place, publisher, year, edition, pages
Academic Press, 2018
Series
Advances in Applied Microbiology, ISSN 0065-2164 ; 102
Keywords
Fungi, Deep biosphere, Igneous crust
National Category
Biological Sciences
Research subject
Natural Science
Identifiers
urn:nbn:se:lnu:diva-81578 (URN)10.1016/bs.aambs.2017.11.001 (DOI)000436595200003 ()29680127 (PubMedID)2-s2.0-85036637880 (Scopus ID)9780128151846 (ISBN)
Available from: 2019-04-02 Created: 2019-04-02 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
Drake, H. & Ivarsson, M. (2018). The role of anaerobic fungi in fundamental biogeochemical cycles in the deep biosphere. Fungal Biology Reviews, 32(1), 20-25
Open this publication in new window or tab >>The role of anaerobic fungi in fundamental biogeochemical cycles in the deep biosphere
2018 (English)In: Fungal Biology Reviews, ISSN 1749-4613, E-ISSN 1878-0253, Vol. 32, no 1, p. 20-25Article in journal (Refereed) Published
Abstract [en]

A major part of the biologic activity on Earth is hidden underneath our feet in an environment coined the deep biosphere which stretches several kilometers down into the bedrock. The knowledge about life in this vast energy-poor deep system is, however, extremely scarce, particularly for micro-eukaryotes such as fungi, as most studies have focused on prokaryotes. Recent findings suggest that anaerobic fungi indeed thrive at great depth in fractures and cavities of igneous rocks in both the oceanic and the continental crust. Here we discuss the potential importance of fungi in the deep biosphere, in particular their involvement in fundamental biogeochemical processes such as symbiotic relationships with prokaryotes that may have significant importance for the overall energy cycling within this vast subsurface realm. Due to severe oligotrophy, the prokaryotic metabolism at great depth in the crust is very slow and dominantly autotrophic and thus dependent on e.g. hydrogen gas, but the abiotic production of this gas is thought to be insufficient to fuel the deep autotrophic biosphere. Anaerobic fungi are heterotrophs that produce hydrogen gas in their metabolism and have therefore been put forward as a hypothetical provider of this substrate to the prokaryotes. Recent in situ findings of fungi and isotopic signatures within co-genetic sulfide minerals formed from bacterial sulfate reduction in the deep continental biosphere indeed seem to confirm the fungi-prokaryote hypothesis. This suggests that fungi play a fundamental biogeochemical role in the deep biosphere.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Anaerobic fungi Continental crust Deep biosphere Geomycology Oceanic crust
National Category
Biological Sciences
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-70483 (URN)10.1016/j.fbr.2017.10.001 (DOI)000425575100003 ()2-s2.0-85032918691 (Scopus ID)
Available from: 2018-02-05 Created: 2018-02-05 Last updated: 2019-08-29Bibliographically approved
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