| 1. |
- Bengtson, Curt, et al.
(författare)
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Deposition and Uptake of Nitrogen Oxides in Scots Pine needles (Pinus Sylvestris L.)
- 1982
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The deposition and uptake of nitrogen oxides in Scots pine needles were studied in exposure systems in the field and at the laboratory. For NO2 the deposition and uptake is a first order process determined by the stomatal conductance. The deposition velocities per needle area unit were during summer conditions determined to 0.65-1.67 mm x s-1 for daytime and 0.28 -0.78 m x s-1 for night time condition. Long term exposure of current needles to a concentration of 200 ug /m3 led to a decrease in transpration (stomatal conductance) after about 10 days exposure. One year old needles did not show any physiological effects at these concentrations. Short term studies of the deposition of NO showed that this was substantially lower than that for NO2
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| 2. |
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| 3. |
- Bengtson, Stefan, 1947-, et al.
(författare)
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Deep-biosphere consortium of fungi and prokaryotes in Eocene sub-seafloor basalts.
- 2014
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Ingår i: Geobiology. - : Wiley. - 1472-4677 .- 1472-4669. ; 12:6, s. 489-496
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Tidskriftsartikel (refereegranskat)abstract
- The deep biosphere of the subseafloor crust is believed to contain a significant part of Earth’s biomass, but because of the difficulties of directly observing the living organisms, its composition and ecology are poorly known. We report here a consortium of fossilized prokaryotic and eukaryotic microorganisms, occupying cavities in deep-drilled vesicular basalt from the Emperor Seamounts, Pacific Ocean, 67.5 meters below seafloor (mbsf). Fungal hyphae provide the framework on which prokaryote-like organisms are suspended like cobwebs and iron-oxidizing bacteria form microstromatolites (Frutexites). The spatial interrelationships show that the organisms were living at the same time in an integrated fashion, suggesting symbiotic interdependence. The community is contemporaneous with secondary mineralizations of calcite partly filling the cavities. The fungal hyphae frequently extend into the calcite, indicating that they were able to bore into the substrate through mineral dissolution. A symbiotic relationship with chemoautotrophs, as inferred for the observed consortium, may be a prerequisite for the eukaryotic colonization of crustal rocks. Fossils thus open a window to the extant as well as the ancient deep biosphere.
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| 4. |
- Bengtson, Stefan, 1947-, et al.
(författare)
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Fungus-like mycelial fossils in 2.4-billion-year-old vesicular basalt.
- 2017
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Ingår i: Nature Ecology & Evolution. - : Springer Science and Business Media LLC. - 2397-334X. ; 1:6, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Fungi have recently been found to comprise a significant part of the deep biosphere in oceanic sediments and crustal rocks. Fossils occupying fractures and pores in Phanerozoic volcanics indicate that this habitat is at least 400 million years old, but its origin may be considerably older. A 2.4-billion-year-old basalt from the Palaeoproterozoic Ongeluk Formation in South Africa contains filamentous fossils in vesicles and fractures. The filaments form mycelium-like structures growing from a basal film attached to the internal rock surfaces. Filaments branch and anastomose, touch and entangle each other. They are indistinguishable from mycelial fossils found in similar deep-biosphere habitats in the Phanerozoic, where they are attributed to fungi on the basis of chemical and morphological similarities to living fungi. The Ongeluk fossils, however, are two to three times older than current age estimates of the fungal clade. Unless they represent an unknown branch of fungus-like organisms, the fossils imply that the fungal clade is considerably older than previously thought, and that fungal origin and early evolution may lie in the oceanic deep biosphere rather than on land. The Ongeluk discovery suggests that life has inhabited submarine volcanics for more than 2.4 billion years.
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| 5. |
- Brorström, Eva, et al.
(författare)
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PAH-innehåll i grönkål och almblad i Göteborgsområdet.
- 1982
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Kvalitativt och kvantitativt PAH-innehåll i grönkål och almblad har studerats i Göteborgsområdet. Grönkål odlades dels nära en motorväg dels på tre lokaler inne i centrala Göteborg och almblad insamlades i anslutning till dessa lokaler. Resultaten visar att PAH-innehållet i det studerade växtmaterialet är högt, speciellt i de växter som vuxit i centrala staden. PAH-halterna var ca 10 ggr högre i de prover av grönkål som exponerats sex månader jämfört med övriga prover som var exponerade tre månader. PAH-profilerna från de olika lokalerna var sinsemellan i stort sett lika och överensstämde dessutom väl med PAH-profiler från undersökta luftprover.
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| 6. |
- Chi Fru, Ernest, et al.
(författare)
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Biogenicity of an Early Quaternary iron formation, Milos Island, Greece
- 2015
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Ingår i: Geobiology. - : Wiley. - 1472-4677 .- 1472-4669. ; 13:3, s. 225-244
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Tidskriftsartikel (refereegranskat)abstract
- A ~2.0-million-year-old shallow-submarine sedimentary deposit on Milos Island, Greece, harbours an unmetamorphosed fossiliferous iron formation (IF) comparable to Precambrian banded iron formations (BIFs). This Milos IF holds the potential to provide clues to the origin of Precambrian BIFs, relative to biotic and abiotic processes. Here, we combine field stratigraphic observations, stable isotopes of C, S and Si, rock petrography and microfossil evidence from a ~5-m-thick outcrop to track potential biogeochemical processes that may have contributed to the formation of the BIF-type rocks and the abrupt transition to an overlying conglomerate-hosted IF (CIF). Bulk δ13C isotopic compositions lower than -25‰ provide evidence for biological contribution by the Calvin and reductive acetyl–CoA carbon fixation cycles to the origin of both the BIF-type and CIF strata. Low S levels of ~0.04 wt.% combined with δ34S estimates of up to ~18‰ point to a non-sulphidic depository. Positive δ30Si records of up to +0.53‰ in the finely laminated BIF-type rocks indicate chemical deposition on the seafloor during weak periods of arc magmatism. Negative δ30Si data are consistent with geological observations suggesting a sudden change to intense arc volcanism potentially terminated the deposition of the BIF-type layer. The typical Precambrian rhythmic rocks of alternating Fe- and Si-rich bands are associated with abundant and spatially distinct microbial fossil assemblages. Together with previously proposed anoxygenic photoferrotrophic iron cycling and low sedimentary N and C potentially connected to diagenetic denitrification, the Milos IF is a biogenic submarine volcano-sedimentary IF showing depositional conditions analogous to Archaean Algoma-type BIFs.
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| 7. |
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| 8. |
- Chi Fru, Ernest, et al.
(författare)
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Fossilized iron bacteria reveal pathway to biological origin of banded iron formation.
- 2013
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 4:2050, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Debates on the formation of banded iron formations in ancient ferruginous oceans are dominated by a dichotomy between abiotic and biotic iron cycling. This is fuelled by difficulties in unravelling the exact processes involved in their formation. Here we provide fossil environmental evidence for anoxygenic photoferrotrophic deposition of analogue banded iron rocks in shallow marine waters associated with an Early Quaternary hydrothermal vent field on Milos Island, Greece. Trace metal, major and rare earth elemental compositions suggest that the deposited rocks closely resemble banded iron formations of Precambrian origin. Well-preserved microbial fossils in combination with chemical data imply that band formation was linked to periodic massive encrustation of anoxygenic phototrophic biofilms by iron oxyhydroxide alternating with abiotic silica precipitation. The data implicate cyclic anoxygenic photoferrotrophy and their fossilization mechanisms in the construction of microskeletal fabrics that result in the formation of characteristic banded iron formation bands of varying silica and iron oxide ratios.
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| 9. |
- Drake, Henrik, 1979-, et al.
(författare)
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Anaerobic consortia of fungi and sulfate reducing bacteria in deep granite fractures
- 2017
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8:55, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- The deep biosphere is one of the least understood ecosystems on Earth. Although most microbiological studies in this system have focused on prokaryotes and neglected microeukaryotes, recent discoveries have revealed existence of fossil and active fungi in marine sediments and sub-seafloor basalts, with proposed importance for the subsurface energy cycle. However, studies of fungi in deep continental crystalline rocks are surprisingly few. Consequently, the characteristics and processes of fungi and fungus-prokaryote interactions in this vast environment remain enigmatic. Here we report the first findings of partly organically preserved and partly mineralized fungi at great depth in fractured crystalline rock (-740 m). Based on environmental parameters and mineralogy the fungi are interpreted as anaerobic. Synchrotron-based techniques and stable isotope microanalysis confirm a coupling between the fungi and sulfate reducing bacteria. The cryptoendolithic fungi have significantly weathered neighboring zeolite crystals and thus have implications for storage of toxic wastes using zeolite barriers.
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| 10. |
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