| 1. |
- Iburg, Sven, et al.
(författare)
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Organic Contaminant Mixture Significantly Changes Microbenthic Community Structure and Increases the Expression of PAH Degradation Genes
- 2020
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Ingår i: Frontiers in Environmental Science. - : Frontiers Media SA. - 2296-665X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- © Copyright © 2020 Iburg, Nybom, Bonaglia, Karlson, Sobek and Nascimento. Studying the effects of chemical contaminants on the structure and function of microbial and meiofauna communities have traditionally focused on specific effects of single contaminants on single species. This has left the complex interactions between mixtures of contaminants and its non-specific toxicity effects on the functions and structure of sediment microbial communities mostly overlooked. In order to improve our insights on such questions, we performed an experiment where Baltic Sea sediments were spiked with an ecologically relevant mixture of seven organic contaminants below specific toxicity levels and used 16S and 18S rRNA metabarcoding from RNA extracts to monitor changes in active microbial and meiofauna diversity and community structure in the spiked treatment compared to controls. In addition, we investigated the effects of exposure to this contaminant mixture on potential nitrification rates and on the expression of key-genes in the microbial nitrification and PAH degradation pathways with qPCR. There were significant differences in both eukaryotic and microbial community structures in sediments spiked with a mixture of organic contaminants. Nematoda showed a significant increase in overall relative abundance to the added contaminants (5.5 ± 1.1% higher in spiked), particularly taxa of the genus Leptolaimus (increased from 10.2 ± 5.4% in the controls to 32.5 ± 10.2% in the spiked treatment). Conversely, a significant decrease in relative abundance from 18.2 ± 5.6% in control to 7 ± 3.4% in of the genus Paraplectana was also detected. Additionally, while the abundance of active PAH degraders was significantly higher in spiked sediments than in the controls, no significant effect of our organic mixture was found on nitrification rates or the expression of AmoA (bacterial ammonia oxidizer gene). Our data indicate that mixtures of organic contaminants can have significant effects on microbenthic community structure even when its individual components are present at concentrations below its specific toxicity. In addition, we suggest that eRNA-based metabarcoding can offer important insights in microbenthic community structure and activities, and further empathizes the potential of meiofauna as bio-indicators of chemical contamination in benthic ecosystems.
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| 2. |
- Hentati-Sundberg, J, et al.
(författare)
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Fueling of a marine-terrestrial ecosystem by a major seabird colony.
- 2020
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Seabirds redistribute nutrients between different ecosystem compartments and over vast geographical areas. This nutrient transfer may impact both local ecosystems on seabird breeding islands and regional biogeochemical cycling, but these processes are seldom considered in local conservation plans or biogeochemical models. The island of Stora Karlsö in the Baltic Sea hosts the largest concentration of piscivorous seabirds in the region, and also hosts a large colony of insectivorous House martins Delichon urbicum adjacent to the breeding seabirds. We show that a previously reported unusually high insectivore abundance was explained by large amounts of chironomids-highly enriched in δ15N-that feed on seabird residues as larvae along rocky shores to eventually emerge as flying adults. Benthic ammonium and phosphate fluxes were up to 163% and 153% higher close to the colony (1,300m distance) than further away (2,700m) and the estimated nutrient release from the seabirds at were in the same order of magnitude as the loads from the largest waste-water treatment plants in the region. The trophic cascade impacting insectivorous passerines and the substantial redistribution of nutrients suggest that seabird nutrient transfer should be increasingly considered in local conservation plans and regional nutrient cycling models.
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| 3. |
- Shekofteh, Atefeh, et al.
(författare)
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Geochemical and petrographic identification of stone quarries used for the construction of the Anahita Temple of Kangavar (West Iran)
- 2020
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Ingår i: Heritage Science. - : Springer Science and Business Media LLC. - 2050-7445. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The archaeological site of the Anahita Temple in Kangavar is one of the best-known stone monuments in western Iran and dates back to the Persian Empireperiodof Iranian history (about 550 BC to 650 AD). The Temple was constructed on a semi-artificial hill out of large stone blocks, many of which are cubic in shape, and short thick columns. In the Kangavar area (basin) there are various sites in which there is evidence of stone extraction. The aim of this paper is to characterize the stones used in the Anahita Temple of Kangavar and their correlations with the quarrying activities observed in the Kangavar regions. In fact, we tried to find out which of these quarries may have been the source of the stone blocks used in the construction of the Anahita Temple. To this end the stones used in the Temple have been characterized by conducting a multi-analytical study involving chemical, mineralogical and textural analyses including XRF, XRD and thin section petrography. The results show that although all the quarries could have provided the stone used in the construction of the Temple, the largest, most probable source was the Chel Maran quarry. It is due to the more similarity of stones used in the Anahita Temple and the samples from this quarry from geochemical point of view as well as the archaeological evidences present in this quarry. The results are also useful for conservators to select appropriate materials for reconstruction of the decayed parts of the Anahita Temple.
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| 4. |
- Sjöström, Jenny K., et al.
(författare)
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Paleodust deposition and peat accumulation rates : bog size matters
- 2020
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Ingår i: Chemical Geology. - : Elsevier. - 0009-2541 .- 1872-6836. ; 554
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Tidskriftsartikel (refereegranskat)abstract
- We present a high-resolution peat paleodust and accumulation rate record spanning the last 8300 years from Draftinge Mosse (400 ha), southern Sweden (57 degrees 06'27.6 '' N 13 degrees 42'54.1 '' E). The record was analysed for peat accumulation rates (PAR), elemental concentrations, mineralogy, and plant macrofossil content. Five periods of increased mineral deposition were recorded. The first event occurred between similar to 6280 and similar to 5570 cal BP, during the fen to bog transition. This is followed by four atmospheric mineral dust events (DE) which were recorded in the ombrotrophic section of the sequence at (cal BP): similar to 2200; similar to 1385-1150; similar to 830-590, and from similar to 420 to the present. Statistical analysis and elemental ratios indicated that both the mineralogy and grain size shifted when the system transitioned from fen into bog, showing that the governing transport process shifted with the peat-land succession stages. This highlights the importance of identifying peatland succession stages within peat paleodust studies. Following all four DE, increases in PAR were observed, implying a coupling to dust deposition. Comparison of DE and PAR with a paleodust record from Store Mosse, a 20 times larger bog located ca 18 km away (Kylander et al. 2016), showed that both PAR and dust deposition are largely represented by single-core reconstructions, indicating that they are driven by a common climate forcing mechanism. However, higher PAR and dust deposition rates were observed in the more moderately sized Draftinge Mosse, suggesting that the size of the bog is important to consider in peat paleodust studies. Furthermore, the smaller bog responded more rapidly to hydrological changes, indicating that the size of the bog affects its' buffering capacity. Authigenic carbonates, observed here during episodes of rapid peat growth, coincide with changes in REE ratios, indicating that authigenic peat processes potentially cause REE fractionation.
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| 5. |
- Zhang, Yi Ge, et al.
(författare)
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Refining the alkenone-pCO2 method II : Towards resolving the physiological parameter ‘b’
- 2020
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 281, s. 118-134
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Tidskriftsartikel (refereegranskat)abstract
- Haptophyte algal biomarkers called alkenones are widely used to reconstruct atmospheric CO2 in Earth’s Cenozoic history. This method is based on the notion that the algal carbon isotope fractionation during photosynthesis, as represented by ep37:2, is a function of seawater CO2 concentration and algal physiology. Constraining the algal physiological parameter, known as the ‘b’ term, is the key for successful applications of the alkenone-CO2 method. Using sensitivity analyses, we show that the growth rate (µ), cell size (r), and membrane permeability (P) are the most important variables to determine b. For all life on Earth, body size is a key factor that regulates metabolic rates. Exploiting the interdependence between phytoplankton cell size and growth rate, and specifically, the r – µ relationship for coccolithophores, we show that the length of fossil coccoliths (Lcoccolith) produced by ancient alkenone-synthesizers can be used to estimate r and therefore µ. Combining our new Lcoccolith data and published ep37:2 from the South China Sea Site MD01-2392, existing results from ODP Site 925, and ice core CO2, we determined the cell membrane permeability (P = 5.09 10-5 m s-1) for the Pleistocene community employing a bootstrap resampling technique. These new methods of constraining r, µ and P, combined with proxy-derived temperature (T), led us to rebuild b as a variable for each sample individually, which is subsequently used for alkenone-CO2 calculations. Application of this approach established pCO2 of the last 3 glacial-interglacial cycles, which turns out to be comparable with the ice core data in both the amplitude of changes and absolute values. It also reconciles the published Eocene – Oligocene alkenone-CO2 data which showed large geographical differences, with the new estimates much more consistent among different sites, and in line with other proxy-based results and ice sheet model predictions.
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| 6. |
- Ecke, Frauke, et al.
(författare)
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Spatio-temporal variation of metals and organic contaminants in bank voles (Myodes glareolus)
- 2020
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 713
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Tidskriftsartikel (refereegranskat)abstract
- Environmental contamination with metals and organic compounds is of increasing concern for ecosystem and human health. Still, our knowledge about spatial distribution, temporal changes and ecotoxicological fate of metals and organic contaminants in wildlife is limited. We studied concentrations of 69 elements and 50 organic compounds in 300 bank voles (Myodes glareolus), Europe's most common mammal, sampled in spring and autumn 2017–2018 in five monitoring areas, representing three biogeographic regions. In addition, we compared measured concentrations with previous results from bank voles sampled within the same areas in 1995–1997 and 2001. In general, our results show regional differences, but no consistent patterns among contaminants and study areas. The exception was for the lowest concentrations of organic contaminants (e.g. perfluorooctane sulfonate, PFOS), which were generally found in the northern Swedish mountain area. Concentrations of metals and organic contaminants in adults varied seasonally with most organic contaminants being higher in spring; likely induced by diet shifts but potentially also related to age differences. In addition, metal concentrations varied between organs (liver vs. kidney), age classes (juveniles vs. adults; generally higher in adults) as well as between males and females. Concentrations of chromium and nickel in kidney and liver in the northernmost mountain area were lower in 2017–2018 than in 1995–1997 and in three of four areas, lead concentrations were lower in 2017–2018 than in 2001. Current metal concentrations (except mercury) are not expected to negatively affect the voles. Concentrations of hexachlorobenzene displayed highest concentrations in 2001 in the mountains, while it was close to detection limit in 2017–2018. Likewise, PFOS concentrations decreased in the mountains and in south-central lowland forests between 2001 and 2017–2018. Our results suggest that season, age class and sex need to be considered when designing and interpreting results from monitoring programs targeting inorganic and organic contaminants in wildlife.
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| 7. |
- Finlay, Roger, et al.
(författare)
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Reviews and syntheses : Biological weathering and its consequences at different spatial levels - from nanoscale to global scale
- 2020
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 17:6, s. 1507-1533
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Forskningsöversikt (refereegranskat)abstract
- Plant nutrients can be recycled through microbial decomposition of organic matter but replacement of base cations and phosphorus, lost through harvesting of biomass/biofuels or leaching, requires de novo supply of fresh nutrients released through weathering of soil parent material (minerals and rocks). Weathering involves physical and chemical processes that are modified by biological activity of plants, microorganisms and animals. This article reviews recent progress made in understanding biological processes contributing to weathering. A perspective of increasing spatial scale is adopted, examining the consequences of biological activity for weathering from nanoscale interactions, through in vitro and in planta microcosm and meso-cosm studies, to field experiments, and finally ecosystem and global level effects. The topics discussed include the physical alteration of minerals and mineral surfaces; the composition, amounts, chemical properties, and effects of plant and microbial secretions; and the role of carbon flow (including stabilisation and sequestration of C in organic and inorganic forms). Although the predominant focus is on the effects of fungi in forest ecosystems, the properties of biofilms, including bacterial interactions, are also discussed. The implications of these biological processes for modelling are discussed, and we attempt to identify some key questions and knowledge gaps, as well as experimental approaches and areas of research in which future studies are likely to yield useful results. A particular focus of this article is to improve the representation of the ways in which biological processes complement physical and chemical processes that mobilise mineral elements, making them available for plant uptake. This is necessary to produce better estimates of weathering that are required for sustainable management of forests in a post-fossil-fuel economy. While there are abundant examples of nanometre- and micrometre-scale physical interactions between microorganisms and different minerals, opinion appears to be divided with respect to the quantitative significance of these observations for overall weathering. Numerous in vitro experiments and microcosm studies involving plants and their associated microorganisms suggest that the allocation of plant-derived carbon, mineral dissolution and plant nutrient status are tightly coupled, but there is still disagreement about the extent to which these processes contribute to field-scale observations. Apart from providing dynamically responsive pathways for the allocation of plant-derived carbon to power dissolution of minerals, mycorrhizal mycelia provide conduits for the long-distance trans-portation of weathering products back to plants that are also quantitatively significant sinks for released nutrients. These mycelial pathways bridge heterogeneous substrates, reducing the influence of local variation in C : N ratios. The production of polysaccharide matrices by biofilms of interacting bacteria and/or fungi at interfaces with mineral surfaces and roots influences patterns of production of antibiotics and quorum sensing molecules, with concomitant effects on microbial community structure, and the qualitative and quantitative composition of mineral-solubilising compounds and weathering products. Patterns of carbon allocation and nutrient mobilisation from both organic and inorganic substrates have been studied at larger spatial and temporal scales, including both ecosystem and global levels, and there is a generally wider degree of acceptance of the systemic effects of microorganisms on patterns of nutrient mobilisation. Theories about the evolutionary development of weathering processes have been advanced but there is still a lack of information connecting processes at different spatial scales. Detailed studies of the liquid chemistry of local weathering sites at the micrometre scale, together with upscaling to soil-scale dissolution rates, are advocated, as well as new approaches involving stable isotopes.
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| 8. |
- Jansen, Joachim, et al.
(författare)
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Drivers of diffusive lake CH4 emissions on daily to multi-year time scales
- 2020
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 17:7, s. 1911-1932
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Tidskriftsartikel (refereegranskat)abstract
- Lakes and reservoirs are important emitters of climate forcing trace gases. Various environmental drivers of the flux, such as temperature and wind speed, have been identified, but their relative importance remains poorly understood. Here we use an extensive field dataset to disentangle physical and biogeochemical controls on the turbulence-driven diffusive flux of methane (CH4) on daily to multi-year timescales. We compare 8 years of floating chamber fluxes from three small, shallow subarctic lakes (2010–2017, n = 1306) with fluxes computed using 9 years of surface water concentration measurements (2009–2017, n = 606) and a small-eddy surface renewal model informed by in situ meteorological observations. Chamber fluxes averaged 6.9 ± 0.3 mg m−2 d−1 and gas transfer velocities (k600) from the chamber-calibrated surface renewal model averaged 4.0 ± 0.1 cm h−1. We find robust (R2 ≥ 0.93, p < 0.01) Arrhenius-type temperature functions of the CH4 flux (Ea' = 0.90 ± 0.14 eV) and of the surface CH4 concentration (Ea' = 0.88 ± 0.09 eV). Chamber derived gas transfer velocities tracked the power-law wind speed relation of the model (k ∝ u3/4). While the flux increased with wind speed, during storm events (U10 ≥ 6.5 m s−1) emissions were reduced by rapid water column degassing. Spectral analysis revealed that on timescales shorter than a month emissions were driven by wind shear, but on longer timescales variations in water temperature governed the flux, suggesting emissions were strongly coupled to production. Our findings suggest that accurate short- and long term projections of lake CH4 emissions can be based on distinct weather- and climate controlled drivers of the flux.
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| 9. |
- Wallman, Karin, et al.
(författare)
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Metallanalys i vatten från Bottenhavet och Bottenviken
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- På uppdrag av Naturvårdsverket har vattenkemiska laboratoriet vid Institutionen för vatten och miljö, SLU tagit fram en metod för analys av metaller i brackvatten och analyserat prover från Bottenhavet och Bottenviken. Halterna av arsenik, kobolt och nickel ökade i sydlig riktning, liksom för vanadin och zink ehuru trenden var mindre tydlig för dem. För bly, kadmium och krom kunde inga spatiala skillnader ses eftersom analysresultaten låg under rapporteringsgränsen. För koppar var halterna vid de nordligaste stationerna RA1 och RA2 lite lägre än vid övriga stationer men längre söderut syntes ingen skillnad.För kadmium, krom, koppar, nickel och bly var medelhalterna vid respektive station i denna studie lägre än gränsvärdena i Havs- och Vattenmyndighetens föreskrifter HVMFS 2019:25. Enligt dessa föreskrifter ska hänsyn tas till den naturliga bakgrunden vid jämförelse med gränsvärden för arsenik och zink, men dessa bakgrundshalter är inte kända i Bottenviken och Bottenhavet. Om den regionala bakgrundshalten som Herbert et.al. tog fram för zink i Östersjön används istället så låg medelhalterna vid alla provpunkter i Bottenhavet utom utsjöstationen C3 över gränsvärdet. Vid stationerna i Bottenviken och C3 i Bottenhavet låg medelhalterna under gränsvärdet men det kan inte uteslutas att anledningen till detta kan vara att halterna på dessa stationer korrigerats för mycket genom att den regionala bakgrundshalten använts istället för den naturliga bakgrundshalten. För arsenik låg medelhalterna i de nordligaste stationerna RA1, RA2 och A5 under gränsvärdet även utan att värdena korrigerats för bakgrundshalterna. För övriga stationer låg medelhalterna över gränsvärdet för arsenik men i och med att ingen korrigering av bakgrundshalt hade gjorts kan ingen slutsats dras av detta.
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| 10. |
- Campeau, Audrey, et al.
(författare)
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Controls on the 14C Content of Dissolved and Particulate Organic Carbon Mobilized Across the Mackenzie River Basin, Canada
- 2020
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Ingår i: Global Biogeochemical Cycles. - : AMER GEOPHYSICAL UNION. - 0886-6236 .- 1944-9224. ; 34:12
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Tidskriftsartikel (refereegranskat)abstract
- The Mackenzie River Basin (MRB) delivers large quantities of organic carbon (OC) into the Arctic Ocean, with significant implications for the global C budgets and ocean biogeochemistry. The amount and properties of OC in the Mackenzie River's delta have been well monitored in the last decade, but the spatial variability in OC sources transported by its different tributaries is still unclear. Here we present new data on the radiocarbon (14C) content of dissolved and particulate OC (Δ14C‐DOC and Δ14C‐POC) across the mainstem and major tributaries of the MRB, comprising 19 different locations, to identify factors controlling spatial patterns in riverine OC sources. The Δ14C‐DOC and Δ14C‐POC varied across a large range, from −179.9‰ to 62.9‰, and −728.8‰ to −9.0‰, respectively. Our data reveal a positive spatial coupling between the Δ14C of DOC and POC across the MRB, whereby the most 14C‐depleted waters were issued from the mountainous west bank of the MRB. This 14C‐depleted DOC and POC likely originates from a combination of petrogenic sources, connected with the presence of kerogens in the bedrock, and biogenic sources, mobilized by thawing permafrost. Our analysis also reveals intriguing relationships between Δ14C of DOC and POC with turbidity, water stable isotope ratio and catchment elevation, indicating that hydrology and geomorphology are key to understanding riverine OC sources in this landscape. A closer examination of the specific mechanisms giving rise to these relationships is recommended. For now, this study provides a road map of the key OC sources in this rapidly changing river basin.
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