| 1. |
- Ammar, Yosr, et al.
(author)
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Long-term dataset for contaminants in fish, mussels, and bird eggs from the Baltic Sea
- 2024
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In: Scientific Data. - 2052-4463. ; 11:1
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Journal article (peer-reviewed)abstract
- Widespread persistent contaminants are a global environmental problem. In the Baltic Sea, wildlife contamination was first noticed in the 1960s, prompting the Swedish Environmental Protection Agency to establish a comprehensive Swedish National Monitoring Programme for Contaminants in Marine Biota (MCoM) in 1978 run by the Swedish Museum of Natural History. Eight species have been analysed, four fish species (Atlantic herring, Atlantic cod, European perch, viviparous eelpout), one bivalve species (blue mussel), and egg from three bird species (common guillemot, common tern, Eurasian oystercatcher). Here, we present a dataset containing MCoM data from its start until 2021. It includes 36 sets of time-series, each analysed for more than 100 contaminants. The longest time-series is for common guillemot and starts in 1968. We describe the structure of MCoM including historic changes to the number of stations, sample treatment, analytical methods, instruments, and laboratories. The MCoM data is available at the Bolin Centre repository and on GitHub through our R package mcomDb. The latter will be updated yearly with new MCoM records.
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| 2. |
- Bieser, Johannes, et al.
(author)
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The 3D biogeochemical marine mercury cycling model MERCY v2.0 – linking atmospheric Hg to methylmercury in fish
- 2023
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In: Geoscientific Model Development. - 1991-959X .- 1991-9603. ; 16:9, s. 2649-2688
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Journal article (peer-reviewed)abstract
- Mercury (Hg) is a pollutant of global concern. Due to anthropogenic emissions, the atmospheric and surface ocean Hg burden has increased substantially since preindustrial times. Hg emitted into the atmosphere gets transported on a global scale and ultimately reaches the oceans. There it is transformed into highly toxic methylmercury (MeHg) that effectively accumulates in the food web. The international community has recognized this serious threat to human health and in 2017 regulated Hg use and emissions under the UN Minamata Convention on Mercury. Currently, the first effectiveness evaluation of the Minamata Convention is being prepared, and, in addition to observations, models play a major role in understanding environmental Hg pathways and in predicting the impact of policy decisions and external drivers (e.g., climate, emission, and land-use change) on Hg pollution. Yet, the available model capabilities are mainly limited to atmospheric models covering the Hg cycle from emission to deposition. With the presented model MERCY v2.0 we want to contribute to the currently ongoing effort to improve our understanding of Hg and MeHg transport, transformation, and bioaccumulation in the marine environment with the ultimate goal of linking anthropogenic Hg releases to MeHg in seafood.Here, we present the equations and parameters implemented in the MERCY model and evaluate the model performance for two European shelf seas, the North and Baltic seas. With the model evaluation, we want to establish a set of general quality criteria that can be used for evaluation of marine Hg models. The evaluation is based on statistical criteria developed for the performance evaluation of atmospheric chemistry transport models. We show that the MERCY model can reproduce observed average concentrations of individual Hg species in water (normalized mean bias: HgT 17 %, Hg0 2 %, MeHg −28 %) in the two regions mentioned above. Moreover, it is able to reproduce the observed seasonality and spatial patterns. We find that the model error for HgT(aq) is mainly driven by the limitations of the physical model setup in the coastal zone and the availability of data on Hg loads in major rivers. In addition, the model error in calculating vertical mixing and stratification contributes to the total HgT model error. For the vertical transport we find that the widely used particle partitioning coefficient for organic matter of log(kd)=5.4 is too low for the coastal systems. For Hg0 the model performance is at a level where further model improvements will be difficult to achieve. For MeHg, our understanding of the processes controlling methylation and demethylation is still quite limited. While the model can reproduce average MeHg concentrations, this lack of understanding hampers our ability to reproduce the observed value range. Finally, we evaluate Hg and MeHg concentrations in biota and show that modeled values are within the range of observed levels of accumulation in phytoplankton, zooplankton, and fish. The model performance demonstrates the feasibility of developing marine Hg models with similar predictive capability to established atmospheric chemistry transport models. Our findings also highlight important knowledge gaps in the dynamics controlling methylation and bioaccumulation that, if closed, could lead to important improvements of the model performance.
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| 3. |
- Bouchet, Sylvain, et al.
(author)
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Mercury sources and fate in a large brackish ecosystem (the Baltic Sea) depicted by stable isotopes
- 2023
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 57:38, s. 14340-14350
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Journal article (peer-reviewed)abstract
- Identifying Hg sources to aquatic ecosystems and processes controlling the levels of monomethylmercury (MMHg) is critical for developing efficient policies of Hg emissions reduction. Here we measured Hg concentrations and stable isotopes in sediment, seston, and fishes from the various basins of the Baltic Sea, a large brackish ecosystem presenting extensive gradients in salinity, redox conditions, dissolved organic matter (DOM) composition, and biological activities. We found that Hg mass dependent fractionation (Hg-MDF) values in sediments mostly reflect a mixing between light terrestrial Hg and heavier industrial sources, whereas odd Hg isotope mass independent fractionation (odd Hg-MIF) reveals atmospheric inputs. Seston presents intermediate Hg-MDF and odd Hg-MIF values falling between sediments and fish, but in northern basins, high even Hg-MIF values suggest the preferential accumulation of wet-deposited Hg. Odd Hg-MIF values in fish indicate an overall low extent of MMHg photodegradation due to limited sunlight exposure and penetration but also reveal large spatial differences. The photodegradation extent is lowest in the central basin with recurrent algal blooms due to their shading effect and is highest in the northern, least saline basin with high concentrations of terrestrial DOM. As increased loads of terrestrial DOM are expected in many coastal areas due to global changes, its impact on MMHg photodegradation needs to be better understood and accounted for when predicting future MMHg concentrations in aquatic ecosystems.
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| 4. |
- Campeau, Audrey, et al.
(author)
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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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In: Global Biogeochemical Cycles. - : AMER GEOPHYSICAL UNION. - 0886-6236 .- 1944-9224. ; 34:12
-
Journal article (peer-reviewed)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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| 5. |
- Campeau, Audrey, et al.
(author)
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Sources of riverine mercury across the Mackenzie River Basin; inferences from a combined Hg C isotopes and optical properties approach
- 2022
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 806, s. 150808-150808
-
Journal article (peer-reviewed)abstract
- The Arctic terrestrial environment harbors a complex mosaic of mercury (Hg) and carbon (C) reservoirs, some of which are rapidly destabilizing in response to climate warming. The sources of riverine Hg across the Mackenzie River basin (MRB) are uncertain, which leads to a poor understanding of potential future release. Measurements of dissolved and particulate mercury (DHg, PHg) and carbon (DOC, POC) concentration were performed, along with analyses of Hg stable isotope ratios (incl. ∆199Hg, d202Hg), radiocarbon content (∆14C) and optical properties of DOC of river water. Isotopic ratios of Hg revealed a closer association to terrestrial Hg reservoirs for the particulate fraction, while the dissolved fraction was more closely associated with atmospheric deposition sources of shorter turnover time. There was a positive correlation between the ∆14C-OC and riverine Hg concentration for both particulate and dissolved fractions, indicating that waters transporting older-OC (14C-depleted) also contained higher levels of Hg. In the dissolved fraction, older DOC was also associated with higher molecular weight, aromaticity and humic content, which are likely associated with higher Hg-binding potential. Riverine PHg concentration increased with turbidity and SO4 concentration. There were large contrasts in Hg concentration and OC age and quality among the mountain and lowland sectors of the MRB, which likely reflect the spatial distribution of various terrestrial Hg and OC reservoirs, including weathering of sulfate minerals, erosion and extraction of coal deposits, thawing permafrost, forest fires, peatlands, and forests. Results revealed major differences in the sources of particulate and dissolved riverine Hg, but nonetheless a common positive association with older riverine OC. These findings reveal that a complex mixture of Hg sources, supplied across the MRB, will contribute to future trends in Hg export to the Arctic Ocean under rapid environmental changes.
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| 6. |
- Capo, Eric, et al.
(author)
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Deltaproteobacteria andSpirochaetes-Like Bacteria AreAbundant Putative MercuryMethylators in Oxygen-DeficientWater and Marine Particles in theBaltic Sea
- 2020
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In: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; , s. 1-11
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Journal article (peer-reviewed)abstract
- Methylmercury (MeHg), a neurotoxic compound biomagnifying in aquatic food webs, can be a threat to human health via fish consumption. However, the compositionand distribution of the microbial communities mediating the methylation of mercury (Hg) to MeHg in marine systems remain largely unknown. In order to fill this knowledge gap, we used the Baltic Sea Reference Metagenome (BARM) dataset to study the abundance and distribution of the genes involved in Hg methylation (the hgcAB gene cluster). We determined the relative abundance of the hgcAB genes and their taxonomic identity in 81 brackish metagenomes that cover spatial,seasonal and redox variability in the Baltic Sea water column. The hgcAB genes were predominantly detected in anoxic water, but some hgcAB genes were alsodetected in hypoxic and normoxic waters. Phylogenetic analysis identified putative Hg methylators within Deltaproteobacteria, in oxygen-deficient water layers, but also Spirochaetes-like and Kiritimatiellaeota-like bacteria. Higher relative quantities of hgcAB genes were found in metagenomes from marine particles compared to free-living communities in anoxic water, suggesting that such particles are hotspot habitats for Hg methylators in oxygen-depleted seawater. Altogether, our work unveils the diversityof the microorganisms with the potential to mediate MeHg production in the BalticSea and pinpoint the important ecological niches for these microorganisms within themarine water column.
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| 7. |
- Capo, Eric, et al.
(author)
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Expression Levels of hgcAB Genes and Mercury Availability Jointly Explain Methylmercury Formation in Stratified Brackish Waters
- 2022
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 56:18, s. 13119-13130
-
Journal article (peer-reviewed)abstract
- Neurotoxic methylmercury (MeHg) is formed by microbial methylation of inorganic divalent Hg (Hg-II) and constitutes severe environmental and human health risks. The methylation is enabled by hgcA and hgcB genes, but it is not know nif the associated molecular-level processes are rate-limiting or enable accurate prediction of MeHg formation in nature. In this study, we investigated the relationships between hgc genes and MeHg across redox-stratified water columns in the brackish Baltic Sea. We showed, for the first time, that hgc transcript abundance and the concentration of dissolved Hg-II-sulfide species were strong predictors of both the Hg-II methylation rate and MeHg concentration, implying their roles as principal joint drivers of MeHg formation in these systems. Additionally, we characterized the metabolic capacities of hgc(+) microorganisms by reconstructing their genomes from metagenomes (i.e., hgc(+) MAGs), which highlighted the versatility of putative Hg-II methylators in the water column of the Baltic Sea. In establishing relationships between hgc transcripts and the Hg-II methylation rate, we advance the fundamental understanding of mechanistic principles governing MeHg formation in nature and enable refined predictions of MeHg levels in coastal seas in response to the accelerating spread of oxygen-deficientzones.
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| 8. |
- Capo, Eric, et al.
(author)
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Oxygen-deficient water zones in the Baltic Sea promote uncharacterized Hg methylating microorganisms in underlying sediments
- 2022
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In: Limnology and Oceanography. - : Wiley. - 1939-5590 .- 0024-3590. ; 67:1, s. 135-146
-
Journal article (peer-reviewed)abstract
- Human-induced expansion of oxygen-deficient zones can have dramatic impacts on marine systems and its resident biota. One example is the formation of the potent neurotoxic methylmercury (MeHg) that is mediated by microbial methylation of inorganic divalent Hg (HgII) under oxygen-deficient conditions. A negative consequence of the expansion of oxygen-deficient zones could be an increase in MeHg production due to shifts in microbial communities in favor of microorganisms methylating Hg. There is, however, limited knowledge about Hg-methylating microbes, i.e., those carrying hgc genes critical for mediating the process, from marine sediments. Here, we aim to study the presence of hgc genes and transcripts in metagenomes and metatranscriptomes from four surface sediments with contrasting concentrations of oxygen and sulfide in the Baltic Sea. We show that potential Hg methylators differed among sediments depending on redox conditions. Sediments with an oxygenated surface featured hgc-like genes and transcripts predominantly associated with uncultured Desulfobacterota (OalgD group) and Desulfobacterales (including Desulfobacula sp.) while sediments with a hypoxic-anoxic surface included hgc-carrying Verrucomicrobia, unclassified Desulfobacterales, Desulfatiglandales, and uncharacterized microbes. Our data suggest that the expansion of oxygen-deficient zones in marine systems may lead to a compositional change of Hg-methylating microbial groups in the sediments, where Hg methylators whose metabolism and biology have not yet been characterized will be promoted and expand.
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| 9. |
- Chen, Long, et al.
(author)
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A decline in Arctic Ocean mercury suggested by differences in decadal trends of atmospheric mercury between the Arctic and northern midlatitudes
- 2015
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In: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 42:14, s. 6076-6083
-
Journal article (peer-reviewed)abstract
- Atmospheric mercury (Hg) in the Arctic shows much weaker or insignificant annual declines relative to northern midlatitudes over the past decade (2000-2009) but with strong seasonality in trends. We use a global ocean-atmosphere model of Hg (GEOS-Chem) to simulate these observed trends and determine the driving environmental variables. The atmospheric decline at northern midlatitudes can largely be explained by decreasing North Atlantic oceanic evasion. The midlatitude atmospheric signal propagates to the Arctic but is countered by rapid Arctic warming and declining sea ice, which suppresses deposition and promotes oceanic evasion over the Arctic Ocean. The resulting simulation implies a decline of Hg in the Arctic surface ocean that we estimate to be -0.67%yr(-1) over the study period. Rapid Arctic warming and declining sea ice are projected for future decades and would drive a sustained decline in Arctic Ocean Hg, potentially alleviating the methylmercury exposure risk for northern populations.
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| 10. |
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| 11. |
- Dastoor, Ashu, et al.
(author)
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Arctic mercury cycling
- 2022
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In: Nature Reviews Earth & Environment. - : Springer Nature. - 2662-138X. ; 3:4, s. 270-286
-
Research review (peer-reviewed)abstract
- Anthropogenic mercury (Hg) emissions have driven marked increases in Arctic Hg levels,which are now being impacted by regional warming, with uncertain ecological consequences. This Review presents a comprehensive assessment of the present-day total Hg mass balance in the Arctic. Over 98% of atmospheric Hg is emitted outside the region and is transported to the Arctic via long-range air and ocean transport. Around two thirds of this Hg is deposited in terrestrial ecosystems, where it predominantly accumulates in soils via vegetation uptake. Rivers and coastal erosion transfer about 80 Mg year−1 of terrestrial Hg to the Arctic Ocean, in approximate balance with modelled net terrestrial Hg deposition in the region. The revised Arctic Ocean Hg mass balance suggests net atmospheric Hg deposition to the ocean and that Hg burial in inner-shelf sediments is underestimated (up to >100%), needing seasonal observations of sediment-oceanHg exchange. Terrestrial Hg mobilization pathways from soils and the cryosphere (permafrost, ice, snow and glaciers) remain uncertain. Improved soil, snowpack and glacial Hg inventories, transfer mechanisms of riverine Hg releases under accelerated glacier and soil thaw, coupled atmosphere– terrestrial modelling and monitoring of Hg in sensitive ecosystems such as fjords can help toanticipate impacts on downstream Arctic ecosystems.
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| 12. |
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| 13. |
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| 14. |
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| 15. |
- Faxneld, Suzanne, et al.
(author)
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Lab intercalibration for chlorinated, brominated, and perfluorinated substances in biota – freshwater and marine monitoring programmes
- 2022
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Reports (other academic/artistic)abstract
- Within the National Monitoring of Contaminants in Biota, Stockholm University has analysed chlorinated pesticides and PCBs (CLC), brominated compounds (BFR) and perfluoroalkyl substances (PFAS) since the start of the time period (the earliest samples from the end of 1960s). However, from 2021 and 2022 the analyses will instead be performed by the Swedish Food Agency (CLC, BFR) and Swedish University of Agricultural Sciences (PFAS). Therefore, there is a need for comparisons between the laboratories in order to investigate if conversion factors will be needed for any of the substances. Thus, the aim of this report was to compare concentrations of CLC, BFR and PFAS analysed at different laboratories.Samples from fish (marine and freshwater), blue mussels and guillemot eggs were analysed at the different laboratories. Thereafter concentrations were compared using t-tests and conversion factors were calculated.Results for CLCs and BFRs showed, with the exception of BDE-100 and BDE-154, that differences were small between Stockholm University and Swedish Food Agency.We therefore recommend that no conversions should be used for the CLCs or BFRs, but suggest a re-evaluation of BDE-100 and -154 at a later stage.For most PFASs too many data points were below LOQ for reliable conversion factors to be calculated. Differences were seen between Stockholm University and Swedish University of Agricultural Sciences for l-PFOS, b-PFOS, and PFOS (sum of l-PFOS and b-PFOS) when considering all samples. However, the samples were run in two batches at Stockholm University (separated time-wise, but also from two different environments – freshwater and marine). When splitting the data into these two batches, only one showed a significant statistical difference between the labs. Due to the few number of samples, the possible batch effect and the relative small difference between labs (l-PFOS: 23% for all samples combined), it is not recommended to apply conversion factors.In this report, we conclude that no conversion factors will be used to adjust the data from the national monitoring programmes for contaminants in marine and freshwater biota.
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| 16. |
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| 17. |
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| 18. |
- Faxneld, Suzanne, et al.
(author)
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The Swedish National Monitoring Programme for Contaminants in Freshwater Biota (until 2018 year’s data)
- 2020
-
Reports (other academic/artistic)abstract
- The report summarises the monitoring activities within the National Swedish Contaminant Programme for freshwater biota. Each monitored contaminant has been examined in pike, perch or Arctic char from 32 lakes from the north to the south in Sweden. No general trend could be seen for mercury, and all samples were above the EU threshold. Lead was generally decreasing and concentrations were below the target level in all lakes. Cadmium concentrations showed no consistent trends over the monitored period, and cadmium concentrations were below the target level in all lakes. Nickel, arsenic, and copper showed upward trends in 30-50 % of the sampling sites. For zink, silver, and aluminium there were no clear temporal trends. Tin concentrations were below the limit of quantification for most sampling sites and throughout all years of sampling.In general, downward trends were seen for; PCBs, HCHs, DDT, DDE and PCDD/Fs in all species (with a few exceptions). The chlorinated compounds generally showed a somewhat higher concentration in the southern parts of Sweden. Most chlorinated compounds were below the suggested target levels. No general trend was seen during the monitoring period for PBDEs. However during the most recent 10 year period, downward trends were seen in pike from Bolmen. The concentration of HBCDD was under LOQ in a majority of the samples.Several of the perfluorinated carboxylic compounds showed an increase in concentration in arctic char, while no trend was seen for PFOS. In perch, PFOS has decreased since 1980 while upward trends were seen for several carboxylic acids from 1980. Higher concentrations of perfluorinated compounds can in general be seen in the southern part of Sweden. In all lakes, PFOS is below the target level for all species.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
- Faxneld, Suzanne, et al.
(author)
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Utvärdering av limniska övervakningsprogrammet för miljögifter i biota
- 2022
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Reports (other academic/artistic)abstract
- Inom övervakningsprogrammet för miljögifter i limnisk biota samlas fisk in årligen från 32 sjöar. Metaller analyseras årligen i alla sjöar medan klorerade pesticider, PCB:er, bromerade och perfluorerade ämnen samt dioxiner analyseras årligen i nio av sjöarna och med ett omdrev på två-tre år för de resterande sjöarna. Tidstrenderna för de flesta sjöar visar på nedåtgående trender, med några få undantag. De 32 sjöarna finns representerade med flera sjöar i varje vattendistrikt och enligt den typologiindelning som används inom övervakningsprogrammet för Trendstationer Sjöar som SLU utför, representerar NRM:s sjöar 75% av SLU:s sjötyper. Därmed finns en relativt bra representation av dessa sjötyper. Däremot har man i påverkansanalysen från VISS konstaterat att några av sjöarna inom övervakningsprogrammet är påverkade, både av jordbruk men även av några miljögifter. Detta innebär att de påverkade sjöarna inte är helt representativa när det gäller att fungera som referenssjöar för vissa miljögifter. Vidare visar analyserna att några sjöar grupperar sig ihop gällande högre halter av en del miljögifter, det gäller bl.a. dioxiner, PCB:er, PFAS och vissa metaller. Inom övervakningsprogrammet utförs i dag ett omdrev för analyser av organiska miljögifter om två-tre år. En statistisk utvärdering hur detta omdrev påverkar möjligheten att upptäcka trender har gjorts i rapporten och man kan se att för att uppnå samma statistiska styrka som vi får vid att mäta varje år vid 10 års mätningar behöver vi istället mäta 12 år om vi analyserar vartannat år och 15 år om vi mäter vart tredje år. Vidare ser vi att kvalitetsmålet att upptäcka tidstrender på 10% i enskilda sjöar inom en 10-års period sannolikt inte nås för >50% av sjöarna även om man skulle analysera varje år. Vilket visar på att kvalitetsmålen så som de är uppsatta i dag inte kan efterlevas och vi rekommenderar därför en översyn av kvalitetsmålen. En jämförelse mot kraven inom Vattenförvaltningsförordningen har även gjorts och där kan man se att vi i dag inte mäter vissa ämnen som det krävs att man ska mäta (PAH:er) men att det även är ämnen som vi i dag mäter men inte behöver mäta, så länge de inte finns med i en påverkansanalys (klorerade pesticider och PCB:er). Förutom att kunna följa trender över tid är ett annat syfte med övervakningsprogrammet att bidra med referenser till regionala/lokala övervakningsprogram. För att kunna skapa ett bra underlag så att dessa övervakningsprogram kan använda referensdata rekommenderar vi att det tas fram referensvärden på vattendistriktsnivå och att dessa presenteras i de framtida limniska sakrapporterna.
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| 23. |
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| 24. |
- Faxneld, Suzanne, et al.
(author)
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Övervakning av metaller och organiska miljögifter i limnisk biota (fram till 2019 årsdata)
- 2021
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Reports (other academic/artistic)abstract
- The report summarises the monitoring activities within the National Swedish Contaminant Programmefor freshwater biota. Each monitored contaminant has been examined in pike, perch or Arctic char from32 lakes from the north to the south in Sweden.No general trend could be seen for mercury, and all samples were above the EU threshold. Lead wasgenerally decreasing and concentrations were below the target level in all lakes. Cadmiumconcentrations showed no consistent trends over the monitored period, and cadmium concentrationswere below the target level in all lakes. Chromium concentrations are below the limit of quantification(LOQ) in most lakes after 2010. For nickel, arsenic, copper, zink, silver, and aluminium there were noclear temporal trends, with both upward and downward trends. Tin concentrations were below the LOQfor most sampling sites and throughout all years of sampling.In general, downward trends were seen for; PCBs, HCHs, DDT, DDE and PCDD/Fs in all species (with afew exceptions). The chlorinated compounds generally showed a somewhat higher concentration in thesouthern parts of Sweden. Most chlorinated compounds were below the suggested target levels.No general trend was seen during the monitoring period for PBDEs. However during the most recent 10year period, downward trends were seen in pike from Bolmen. The concentration of HBCDD was underLOQ in a majority of the samples.Several of the perfluorinated carboxylic compounds showed a non-linear increase in concentration inarctic char, while no trend was seen for PFOS. In perch, PFOS has decreased since 1980 while upwardtrends were seen for several carboxylic acids from 1980. Higher concentrations of perfluorinatedcompounds can in general be seen in the southern part of Sweden. In all lakes, PFOS is below thetarget level for all species.
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| 25. |
- Faxneld,, Suzanne, et al.
(author)
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Övervakning av metaller och organiska miljögifter i limnisk biota (fram till 2020 års data)The Swedish National Monitoring Programme for Contaminants in Freshwater Biota (until 2020 year’s data)
- 2022
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Reports (other academic/artistic)abstract
- The report summarises the monitoring activities within the National Swedish Contaminant Programme for freshwater biota. Each monitored contaminant has been examined in pike, perch or Arctic char from 32 lakes from the north to the south in Sweden.Mercury concentrations in perch show no spatial pattern across Sweden and there are no consistent time trends for all lakes. Significantly decreasing concentrations in perch are seen in 25 % of the lakes. The mercury concentrations are above the EU threshold for all sampled fish throughout Sweden.Aluminium, arsenic, nickel, and lead generally show decreasing concentrations during the last ten years.Lead shows concentrations below the threshold for all the perch lakes and for cadmium concentrations are below the threshold for all except one perch lake.For the longest time trends in pike, Arctic char and perch (starting in 1970s or 80s) downward temporal trends are observed for the chlorinated compounds, e.g. polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE) polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs). Concentrations of hexachlorobenzene (HCB) and HCHs are below LOQ during the last 15 years. Most chlorinated compounds were below the suggested target levels.There is no general spatial pattern for the polybrominated diphenyl ethers (PBDEs) in perch. Concentrations of PBDEs are generally, in all three species, going down during the last ten years.The concentration of HBCDD was under LOQ in a majority of the samples.Concentrations of PFOS are somewhat similar among perch lakes but with more lakes in the northern part of Sweden having lower concentrations. There is no spatial pattern for the perfluoroalkyl carboxylic acids (PFCAs). For PFOS no clear trends are seen during the last ten years but many lakes show decreasing trends from 2006/2007 until 2020. Significantly decreasing trends are seen for ~30 % of the long-chained PFCAs (PFUnDA, PFDoDA, PFTrDA) during the last ten years.In all lakes, PFOS is below the target level for all species.
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| 26. |
- Haque, Faiz, et al.
(author)
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Per- and polyfluoroalkyl substances (PFAS) in white-tailed sea eagle eggs from Sweden: Temporal trends (1969-2021), spatial variations, fluorine mass balance, and suspect screening
- 2023
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In: Environmental Science. - 2050-7887 .- 2050-7895.
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Journal article (peer-reviewed)abstract
- Temporal and spatial trends of 15 per- and polyfluoroalkyl substances (PFAS) were determined in white-tailed sea eagle (WTSE) eggs (Haliaeetus albicilla) from two inland and two coastal regions of Sweden between 1969 and 2021. PFAS concentrations generally increased from ∼1969 to ∼1990s–2010 (depending on target and site) and thereafter plateaued or declined, with perfluorooctane sulfonamide (FOSA) and perfluorooctane sulfonate (PFOS) declining faster than most perfluoroalkyl carboxylic acids (PFCAs). The net result was a shift in the PFAS profile from PFOS-dominant in 1969–2010 to an increased prevalence of PFCAs over the last decade. Further, during the entire period higher PFAS concentrations were generally observed in coastal populations, possibly due to differences in diet and/or proximity to more densely populated areas. Fluorine mass balance determination in pooled samples from three of the regions (2019–2021) indicated that target PFAS accounted for the vast majority (i.e. 81–100%) of extractable organic fluorine (EOF). Nevertheless, high resolution mass-spectrometry-based suspect screening identified 55 suspects (31 at a confidence level [CL] of 1–3 and 24 at a CL of 4–5), of which 43 were substances not included in the targeted analysis. Semi-quantification of CL ≤ 2 suspects increased the identified EOF to >90% in coastal samples. In addition to showing the impact of PFAS regulation and phase-out initiatives, this study demonstrates that most extractable organofluorine in WTSE eggs is made up of known (legacy) PFAS, albeit with low levels of novel substances.
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| 27. |
- Heimbrand, Yvette, et al.
(author)
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Faktablad från Integrerad kustfiskövervakning 2022:1 Fjällbacka, Västerhavet, 1989–2021
- 2022
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Reports (other academic/artistic)abstract
- Den integrerade kustfiskövervakningen i Fjällbacka visar på en dominans av mesopredatorer som skärsnultra, stensnultra och svart smörbult i provfisket i augusti, och en dominans av rovfiskar som gråsej, vitling och torsk i provfisket under oktober. Fångsten av torsk var dock låg under 2021. Förekomsten av gråsej och svart smörbult har ökat i fångsterna sedan 2002. Även gulål var vanligt förekommande i fångsten både i augusti och oktober och visar en tendens till ökning sedan 2002, vilket även mesopredatorer gör. Hälsotillståndet hos tånglake har blivit sämre, samtidigt som de flesta analyserade miljögifter visar relativt låga och nedåtgående eller oförändrade halter. Liknande förändringar har även observerats i de andra referensområdena för kustfisk, vilket kan tyda på att det är fråga om en likartad och generell inverkan på fisken hälsa längs våra kuster. Det är oroande att tånglakens hälsotillstånd har försämrats i ett referensområde som anses vara relativt opåverkat av direkt mänsklig aktivitet. Det är därför angeläget att klarlägga om det är okända miljögifter, kända miljögifter som inte övervakas idag, eller andra miljöfaktorer som orsakar den försämrade hälsan hos tånglake.
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| 28. |
- Heimbrand, Yvette, et al.
(author)
-
Faktablad från Integrerad kustfiskövervakning 2022:2 Holmöarna, Bottniska viken, 1989–2021
- 2022
-
Reports (other academic/artistic)abstract
- Den integrerade kustfiskövervakningen i Holmöarna visar på en tydlig förändring i fisksamhället från ett abborrdominerat till karpfiskdominerat tillstånd. Abborrens tillväxt har ökat under provfiskeperioden, men storleken på stora abborrar har inte ökat över tid. De arter som har ökat i förekomst är mört och sik, liksom mängden stora individer i fisksamhället (fiskar >30 cm). Hos tånglaken har leversomatiskt index minskat och andelen onormala yngel ökat över tid. Hälsotillståndet hos abborre är påverkat, samtidigt som de flesta analyserade miljö-gifter visar relativt låga och nedåtgående eller oförändrade halter. Inverkan på abborrens hälsotillstånd talar för att fisken är exponerad för något eller några kemiska ämnen som idag inte mäts. Liknande förändringar har även observerats i de andra referensområdena för kustfisk och kan tyda på att det är fråga om en likartad och generell inverkan på fiskens hälsa längs våra kuster. Det är oroande att abborrens hälsotillstånd är påverkat i ett referensområde som anses vara relativt opåverkat av direkt mänsklig aktivitet. Det är därför angeläget att klarlägga om det är okända miljögifter eller kända miljögifter som inte övervakas idag, eller andra miljöfaktorer som orsakar fiskens försämrade hälsa och den begynnande negativa utvecklingen som ses på populationsnivå hos abborren.
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| 29. |
- Heimbrand, Yvette, et al.
(author)
-
Faktablad från Integrerad kustfiskövervakning 2022:3 Kvädöfjärden, Egentliga Östersjön, 1981–2021
- 2022
-
Reports (other academic/artistic)abstract
- Den integrerade kustfiskövervakningen i Kvädöfjärden har visat på minskande fångster av abborre och rovfisk sedan 2002, men den varma sommaren 2018 vände trenden med en relativt hög fångst av abborre och även gös under senare år. Abborrens tillväxt har ökat över tid, men inte indikatorn L90 som representerar storleken på stora abborrar. Förekomsten av karpfiskar har ökat, medan gädda har minskat i fångsten sedan 2002. Konditionen hos tånglakehonor har försämrats. Andelen onormala yngel hos tånglaken har varierat mellan åren, men var relativt hög under 2021. Hälsotillståndet hos abborre och tånglake är negativt påverkat. Samtidigt är halterna av de flesta analyserade miljögifterna relativt låga med nedåtgående eller oförändrade trender, med undantag av koppar. Liknande förändringar har även observerats i de andra referensområdena för kustfisk och kan tyda på att det är fråga om en likartad och generell påverkan på fiskens hälsa längs våra kuster. Det är oroande att abborrens och tånglakens hälsotillstånd är påverkat i ett referensområde som anses vara relativt opåverkat av direkt mänsklig aktivitet. Det är därför angeläget att klarlägga om det är okända miljögifter, kända miljögifter som inte övervakas idag, eller andra miljöfaktorer som orsakar fiskens försämrade hälsa.
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| 30. |
- Heimbrand, Yvette, et al.
(author)
-
Faktablad från Integrerad kustfiskövervakning 2022:4 Torhamn, södra Egentliga Östersjön, 2002–2021
- 2022
-
Reports (other academic/artistic)abstract
- Den integrerade kustfiskövervakningen i Torhamn visade en tendens till minskning av abborre och ökning av karpfiskar i provfiskefångsten. Abborrens tillväxt har ökat sedan 2002, men indikatorn L90 som representerar storleken på stora abborrar har inte förändrats över tid. Den främmande arten svartmunnad smörbult har påträffats i låga tätheter i provfisket sedan 2015. Sill har ökat i förekomst, medan sarv, id och gädda har minskat. Hälsotillståndet hos abborre i Torhamn har blivit sämre. Inverkan på abborrens hälsotillstånd talar för att fisken är exponerad för något eller några kemiska ämnen. Liknande förändringar har även bserverats i de andra referensområdena för kustfisk, och kan tyda på att det är fråga om en likartad och generell inverkan på fiskens hälsa längs våra kuster. Att abborre växer snabbare är sannolikt en effekt av den ökade vattentemperaturen, dock är abborrarna unga och som äldst 3 år i fångsten 2021. Det är oroande att gädda som är en nyckelart i ekosystemet minskar och att abborrens hälsotillstånd har försämrats i ett referensområde som anses vara relativt opåverkat av direkt mänsklig aktivitet. Det är därför angeläget att klarlägga om det är okända miljögifter eller kända miljögifter som inte övervakas idag, eller andra miljöfaktorer som orsakar den försämrade hälsan hos abborren.
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| 31. |
- Houssami, Nehmat, et al.
(author)
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Interval breast cancer rates for digital breast tomosynthesis versus digital mammography population screening : An individual participant data meta-analysis
- 2021
-
In: EClinicalMedicine. - : Elsevier BV. - 2589-5370. ; 34
-
Journal article (peer-reviewed)abstract
- Background: Digital breast tomosynthesis (DBT) improves breast cancer (BC) detection compared to mammography, however, it is unknown whether this reduces interval cancer rate (ICR) at follow-up. Methods: Using individual participant data (IPD) from DBT screening studies (identified via periodic literature searches July 2016 to November 2019) we performed an IPD meta-analysis. We estimated ICR for DBT-screened participants and the difference in pooled ICR for DBT and mammography-only screening, and compared interval BC characteristics. Two-stage meta-analysis (study-specific estimation, pooled synthesis) of ICR included random-effects, adjusting for study and age, and was estimated in age and density subgroups. Comparative screening sensitivity was calculated using screen-detected and interval BC data. Findings: Four prospective DBT studies, from European population-based programs, contributed IPD for 66,451 DBT-screened participants: age-adjusted pooled ICR was 13.17/10,000 (95%CI: 8.25–21.02). Pooled ICR was higher in the high-density (21.08/10,000; 95%CI: 6.71–66.27) than the low-density (8.63/10,000; 95%CI: 5.25–14.192) groups (P = 0.03) however estimates did not differ across age-groups (P = 0.32). Based on two studies that also provided data for 153,800 mammography screens (age-adjusted ICR 17.69/10,000; 95%CI: 13.22–23.66), DBT's pooled ICR was 16.83/10,000 (95%CI: 11.89–23.82). Comparative meta-analysis showed a non-significant difference in ICR (-0.44/10,000; 95%CI: -11.00–10.11) and non-significant difference in screening sensitivity (6.79%; 95%CI: -0.73–14.87%) between DBT and DM but a significant pooled difference in cancer detection rate of 33.49/10,000 (95%CI: 23.88–43.10). Distribution of interval BC prognostic characteristics did not differ between screening modalities except that those occurring in DBT-screened participants were significantly more likely to be negative for axillary-node metastases (P = 0.005). Interpretation: Although heterogeneity in ICR estimates and few datasets limit recommendations, there was no difference between DBT and mammography in pooled ICR despite DBT increasing cancer detection.
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| 32. |
- Kim, Hyunji, et al.
(author)
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Methylmercury Mass Budgets and Distribution Characteristics in the Western Pacific Ocean
- 2017
-
In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 51:3, s. 1186-1194
-
Journal article (peer-reviewed)abstract
- Methylmercury (MeHg) accumulation in marine organisms poses serious ecosystem and human health risk, yet the sources of MeHg in the surface and subsurface ocean remain uncertain. Here, we report the first MeHg mass budgets for the Western Pacific Ocean estimated based on cruise observations. We found the major net source of MeHg in surface water to be vertical diffusion from the subsurface layer (1.8-12 nmol m(-2) yr(-1)). A higher upward diffusion in the North Pacific (12 nmol m(-2) yr(-1)) than in the Equatorial Pacific (1.8-5.7 nmol m(-2) yr(-1)) caused elevated surface MeHg concentrations observed in the North Pacific. We furthermore found that the slope of the linear regression line for MeHg versus apparent oxygen utilization in the Equatorial Pacific was about 2-fold higher than that in the North Pacific. We suggest this could be explained by redistribution of surface water in the tropical convergence-divergence zone, supporting active organic carbon decomposition in the Equatorial Pacific Ocean. On the basis of this study, we predict oceanic regions with high organic carbon remineralization to have enhanced MeHg concentrations in both surface and subsurface waters.
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| 33. |
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| 34. |
- Kim, Jihee, et al.
(author)
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Mass Budget of Methylmercury in the East Siberian Sea: The Importance of Sediment Sources
- 2020
-
In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851.
-
Journal article (peer-reviewed)abstract
- Biological concentrations of methylmercury(MeHg) are elevated throughout the Arctic Ocean; however, to date, the major sources and the spatial variability of MeHg are not well quantified. To identify the major inputs and outputs of MeHg to the Arctic shelf water column, we measured MeHg concentrations in the seawater and sediment samples from the East Siberian Sea collected from August to September 2018. We found that the MeHg concentrations in seawater and pore water were higher on the slope than on the shelf, while the MeHg concentrations in the sediment were higher on the shelf than on the slope. We created a mass budget for MeHg and found that the benthic diffusion and resuspension largely exceed other sources, such as atmospheric deposition and river water input. The major sinks of MeHg in the water column were dark demethylation and evasion. When we extrapolated our findings on benthic diffusion to the entire Arctic shelf system, the annual MeHg diffusion from the shelf sediments was estimated to be 23,065 ± 939 mol yr−1, about 2 times higher than previously proposed river discharges. Our study suggests that the MeHg input from shelf sediments in the Arctic Ocean is significant and has been previously underestimated.
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| 35. |
- L. Soerensen, Anne, et al.
(author)
-
The Swedish National Monitoring Programmefor Contaminants in marine biota (until 2019year’s data) : – Temporal trends and spatial variations
- 2020
-
Reports (other academic/artistic)abstract
- The report summarises the monitoring activities within the National Swedish Contaminant Programme inmarine biota.Few trends are found for the biological variables of the biota included in the programme (age, weight,length, and fulton´s condition factor). This is expected, as samples are selectively selected to avoidtrends. However, all variables for Holmöarna in the Bothnian Bay and the fish age at the West Coastsites (Kullen, Fladen and Väderöarna) stands out for herring, cod and perch as having upward trendsover the last 10 years. Since many of the contaminants presented in this report bioaccumulate, this islikely to affect the trends presented below.For the aggregated herring data (on sub-basin scale) on chlorinated pesticides, PCBs, dioxins andfurans, brominated flame retardants and perfluorinated substances (PFAS) a general downward trendfor the last 10 years (2010-2019) is seen for all sub-basins (Southern and Northern Baltic Proper andBothnian Sea and Bay) except the West Coast. On the West Coast, changes are small and often nonsignificant. The contaminant concentrations are in general lowest on the West Coast but theconcentration difference between the West Coast and the other sub-basins has shrunken over the last10 years as the concentrations in the other sub-basins are decreasing towards West Coast levels. Theperfluorinated compound FOSA is an exception to this picture, with 2-4 times higher concentrations onthe West Coast compared to the Baltic Sea. For the metals, no common patterns are seen for theaggregated herring data across the metals or for each specific metal between sub-basins.
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| 36. |
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| 37. |
- Mason, Robert P., et al.
(author)
-
The Global Marine Selenium Cycle : Insights From Measurements and Modeling
- 2018
-
In: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 32:12, s. 1720-1737
-
Journal article (peer-reviewed)abstract
- Anthropogenic activities have increased the selenium (Se) concentration in the biosphere, but the overall impact on the ocean has not been examined. While Se is an essential nutrient for microorganisms, there is little information on the impact of biological processes on the concentration and speciation of Se in the ocean. Additionally, other factors controlling the distribution and concentration of Se species are poorly understood. Here we present data gathered in the subtropical Pacific Ocean during a cruise in 2011, and we used these field data and the literature, as well as laboratory photochemical experiments examining the stability and degradation of inorganic Se (both Se (IV) and Se (VI)) and dimethyl selenide, to further constrain the cycling of Se in the upper ocean. We also developed a multibox model for the biosphere to examine the impact of anthropogenic emissions on the concentration and distribution of Se in the ocean. The model concurs with the field data indicating that the Se concentration has increased in the upper ocean waters over the past 30 years. Our observational studies and model results suggest that Se (VI) is taken up by phytoplankton in the surface ocean, in contrast to the results of laboratory culture experiments. In conclusion, while anthropogenic inputs have markedly increased Se in the atmosphere (42%) and net deposition to the ocean (38%) and terrestrial landscape (41%), the impact on Se in the ocean is small (3% increase in the upper ocean). This minimal response reflects its long marine residence time. Plain Language Summary We measured selenium in water and particles during a cruise in the Pacific Ocean and use this data along with laboratory photochemcial experiments to examine the formation and degradation of the various Se forms in the upper ocean. We also developed a box model to examine how anthropogenic activities have changed the Se concentration throughout the ocean the potential future impacts and to highlight areas of Se biogeochemistry that need further study.
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| 38. |
- Mustamäki, Noora, et al.
(author)
-
Faktablad från Integrerad kustfiskövervakning 2021:2 Västra Hanöbuktens kustvatten – Åhus, 2007–2020
- 2021
-
Reports (other academic/artistic)abstract
- Den integrerade kustfiskövervakningen i Hanöbukten visar att provfiskefångsten domineras av sill och torsk, men även skrubbskädda och rötsimpa var vanligt förekommande. Fångsten av sill har ökat under de fem år provfisket pågått, och fångsten av torsk är lägre under de senaste åren jämfört med 2015 då provfisket startade. Undersökningar av hälsotillståndet hos skrubbskädda visar få förändringar under perioden 2017–2020 vilket tyder på stabil och sannolikt tillfredsställande hälsa. Frekvensen av yttre fysiska avvikelser och skador på fisken (framförallt på torsk) är förhöjd i Hanöbukten jämfört med andra provfisken längs den svenska ostkusten. De bakomliggande orsakerna ill detta är fortfarande inte fastställda. Halterna av de flesta analyserade miljögifterna i sill är stabila eller nedåtgående. Förutom för kvicksilver ligger halterna generellt under de gränsvärden som finns att tillgå.
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| 39. |
- Mustamäki, Noora, et al.
(author)
-
Faktablad från Integrerad kustfiskövervakning 2021:3 Forsmark, 2002–2020
- 2021
-
Reports (other academic/artistic)abstract
- Provfisket visar att fisksamhället vardominerat av abborre och karpfiskar sommört. Abborrarna i området har en relativthög tillväxt, vilket troligtvis beror på detuppvärmda vattnet från kärnkraftverket. Abborrfångsten och därmed rovfiskfångsten har minskat under de senaste tio åren. Under de senaste åren har mycket karpfiskar och speciellt mört fångats. Resultaten från provfisket under det senaste decenniet visar en negativ utveckling av fisksamhället som också ses i många andra områden längs den svenska ostkusten. Mätserien för hälsotillståndet hos abborre i Forsmarks skärgård är kort, men visar ett mycket likartat tillstånd som det i andra referensområden längs den svenska kusten. Här är hälsotillståndet hos fisken negativt påverkat, även om denna utveckling har planat ut något under senare åren. Det är inte sannolikt att hälsotillståndet hos abborren i Forsmark är kopplat till kärnkraftindustrin, utan påvisar en mer generell och omfattande försämring av fiskens hälsa längs våra kuster.
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| 40. |
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| 41. |
- Schartup, Amina T., et al.
(author)
-
Influence of the Arctic Sea-Ice Regime Shift on Sea-Ice MethylatedMercury Trends
- 2020
-
In: Environmental Science & Technology Letters. - : American Chemical Society (ACS). - 2328-8930 .- 2328-8930.
-
Journal article (peer-reviewed)abstract
- Arctic sea ice regulates the air−sea exchange of volatile mercury (Hg) species like dimethylmercury (DMHg) or elemental Hg and is known to host Hg methylating microbes that produce neurotoxic and biomagnifying monomethylmercury (MMHg). Arctic sea ice accounts for 57% of the total primary production in the Arctic Ocean, suggesting that it could be the main source of MMHg to arctic food webs. Despite this, little is known about Hg concentrations and speciation in arctic sea ice. Here, we report Hg species and show the importance of sea-ice composition on sea-ice methylmercury (MeHg = DMHg + MMHg) budgets. We propose that the shift from older sea ice (lower MeHg) to younger sea ice (higher MeHg) resulted in a 40% increase in MeHg (per square meter of sea ice) since 1979 despite a 45% decline in the total sea-ice volume. Approximately 30% of the MeHg sea-ice budget is DMHg, which means that when the seaice melts in the summer it could contribute 0.03−2.7 pmol of DMHg m−2 day−1 to the atmosphere, which is comparable to diffusion from water (0.48−2.8 pmol of DMHg m−2 day−1). This study shows that the MeHg content of rapidly shrinking arctic sea ice and exposure of sea-ice biota may not be declining as previously thought.
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| 42. |
- Schartup, Amina T., et al.
(author)
-
What are the likely changes in mercury concentration in the Arctic atmosphere and ocean under future emissions scenarios?
- 2022
-
In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 836
-
Journal article (peer-reviewed)abstract
- Arctic mercury (Hg) concentrations respond to changes in anthropogenic Hg emissions and environmental change. This manuscript, prepared for the 2021 Arctic Monitoring and Assessment Programme Mercury Assessment, explores the response of Arctic Ocean Hg concentrations to changing primary Hg emissions and to changing sea-ice cover, river inputs, and net primary production. To do this, we conduct a model analysis using a 2015 Hg inventory and future anthropogenic Hg emission scenarios. We model future atmospheric Hg deposition to the surface ocean as a flux to the surface water or sea ice using three scenarios: No Action, New Policy (NP), and Maximum Feasible Reduction (MFR). We then force a five-compartment box model of Hg cycling in the Arctic Ocean with these scenarios and literature-derived climate variables to simulate environmental change. No Action results in a 51% higher Hg deposition rate by 2050 while increasing Hg concentrations in the surface water by 22% and <9% at depth. Both “action” scenarios (NP and MFR), implemented in 2020 or 2035, result in lower Hg deposition ranging from 7% (NP delayed to 2035) to 30% (MFR implemented in 2020) by 2050. Under this last scenario, ocean Hg concentrations decline by 14% in the surface and 4% at depth. We find that the sea-ice cover decline exerts the strongest Hg reducing forcing on the Arctic Ocean while increasing river discharge increases Hg concentrations. When modified together the climate scenarios result in a ≤5% Hg decline by 2050 in the Arctic Ocean. Thus, we show that the magnitude of emissions-induced future changes in the Arctic Ocean is likely to be substantial compared to climate-induced effects. Furthermore, this study underscores the need for prompt and ambitious action for changing Hg concentrations in the Arctic, since delaying less ambitious reduction measures–like NP–until 2035 may become offset by Hg accumulated from pre-2035 emissions.
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| 43. |
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| 44. |
- Skrobonja, Aleksandra, 1990-
(author)
-
Formation, uptake and bioaccumulation of methylmercury in coastal seas : a baltic sea case study
- 2019
-
Doctoral thesis (other academic/artistic)abstract
- Methylmercury (MeHg) is a potent neurotoxin which can bioaccumulate to harmful levels in aquatic food webs. Methylmercury formation is a predominantly biotic process which involves phylogenically diverse microorganisms (e.g. iron- or sulfate-reducing bacteria). The formation of MeHg is related to the presence of organic matter (OM) which contains substrates essential for methylating microbes and reduced sulfur ligands (thiols, RSH) that form strong bonds with inorganic mercury (HgII) and affect its bioavailability. In aquatic systems, MeHg is bio-concentrated from the water column to the base of the food web and this step is crucial for MeHg levels found at higher trophic levels. Trophic transfer processes of MeHg in the food web are also of great importance. Discharge of OM in coastal areas affects light conditions needed for phytoplankton growth, and promotes heterotrophy, i.e. bacteria production. This may lead to a shift from the phytoplankton-based to the longer bacteria-based (microbial loop) food web and influence the amount of bioaccumulated MeHg in higher trophic levels. Methylmercury levels in predatory biota is thus affected by the bioavailability of HgII for methylation (studied in Paper I & II), MeHg speciation in the water column, crucial for MeHg incorporation at the base of the food web (Paper III), and the structure of the pelagic food web (Paper IV).In this thesis, it is shown that OM can act as a predictor of dissolved MeHg levels in estuarine and coastal systems. It impacts MeHg levels both by affecting HgII bioavailability (through Hg complexation with humic matter) and the activity of methylating microbes (providing metabolic electron donors) (Paper I). Moreover, elevated concentrations of particulate and dissolved HgII and MeHg, are associated with the presence of pelagic redoxclines in coastal seas. The redoxcline affects HgII speciation in the water column and its bioavailability for methylation (Paper II). It is further shown that the molecular structure of ligands in MeHg complexes affects the kinetics of MeHg uptake in phytoplankton. Rate constants for association of MeHg to the cell surface of a green algae were higher in treatments containing smaller thiol ligands of simpler structure than in treatments with larger thiols and more “branched” structure (Paper III). Finally, it is demonstrated that MeHg bioaccumulation in zooplankton can increase in systems with highly heterotrophic food webs and enhanced loadings of terrestrial OM (Paper IV). Such conditions are expected to occur in northern latitude coastal systems following climate changes.
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| 45. |
- Skrobonja, Aleksandra, et al.
(author)
-
Multiple impacts of humic-rich dissolved organic carbon on methylmercury accumulation in heterotrophic pelagic food webs
-
Other publication (other academic/artistic)abstract
- In this study we investigate how humic-rich dissolved organic carbon (DOC) impacts the bioaccumulation of methylmercury (MeHg) in coastal pelagic lower food webs. Mesocosm scale ecosystems with four levels of humic-rich DOC (ranging from 4 mg L-1 – no added DOC - up to 8.0 mg L-1) were run for 36 days and the bioaccumulation factor (BAF) of MeHg was determined in four seston size fractions at the end of the experiment. The pelagic food web was highly heterotrophic in all treatments with 72%−88% bacteria production of the total basal production. Increases in humic-rich DOC in coastal areas, manifested in our study as a shift towards more heterotrophic systems, can impact the bioaccumulation of MeHg through multiple processes. We found an increase in dissolved MeHg concentration with increased DOC loading, indicating a shift in partitioning from the particulate to the dissolved phase. However, a separate experiment showed that the presence of the humic-rich DOC lowered the bioavailability of dissolved MeHg with 40% across our study range, supporting previous results that the amount of MeHg incorporated at the base of the food web is not simply determined by the total concentration of dissolved MeHg. Our determined BAFs from the experiment supported this conclusion and we also calculated a corrected BAF’ value that took into account the change in MeHg bioavailability to isolate the impact on biomagnification processes. The range in MeHg log BAF’ values was 4.5−4.7 and 5.8−6.0 for 20-50 μm and >200 μm seston size fractions, respectively. Higher BAF’ values were observed in the highest DOC treatment and in our reference for some seston size classes. The high BAF’ at the highest DOC level may be explained by the large fraction of bacteria production observed for this treatment. The high BAF in the reference system could be explained by a slightly larger proportion of energy going through the autotrophic food web causing a higher trophic transfer efficiency of MeHg at the low trophic levels in the web. Taken together our results demonstrate a complex impact of humic DOC and pelagic food web heterotrophy on MeHg bioaccumulation in seston with partly counteracting processes. A detailed understanding of the factors controlling these multiple processes are important for accurate predictions of the net impact on MeHg bioaccumulation in coastal food webs following different environmental change scenarios.
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| 46. |
- Skrobonja, Aleksandra, et al.
(author)
-
Uptake Kinetics of Methylmercury in a Freshwater Alga Exposed to Methylmercury Complexes with Environmentally Relevant Thiols
- 2019
-
In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 53:23, s. 13757-13766
-
Journal article (peer-reviewed)abstract
- Cellular uptake of dissolved methylmercury (MeHg) by phytoplankton is the most important point of entry for MeHg into aquatic food webs. However, the process is not fully understood. In this study we investigated the influence of chemical speciation on rate constants for MeHg accumulation by the freshwater green microalga Selenastrum capricornutum. We used six MeHg-thiol complexes with moderate but important structural differences commonly found in the environment. Rate constants for MeHg interactions with cells were determined for the MeHg-thiol treatments and a control assay containing the thermodynamically less stable MeHg0H complex. We found both elevated amounts of MeHg associated with whole cells and higher MeHg association rate constants in the control compared to the thiol treatments. Furthermore, the association rate constants were lower when algae were exposed to MeHg complexes with thiols of larger size and more branched chemical structure compared to complexes with simpler structure. The results further demonstrated that the thermodynamic stability and chemical structure of MeHg complexes in the medium is an important controlling factor for the rate of MeHg interactions with the cell surface, but not for the MeHg exchange rate across the membrane. Our results are in line with uptake mechanisms involving formation of MeHg complexes with cell surface ligands prior to internalization.
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| 47. |
- Soerensen, Anne L., et al.
(author)
-
A mass budget for mercury and methylmercury in the Arctic Ocean
- 2016
-
In: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 30:4, s. 560-575
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Journal article (peer-reviewed)abstract
- Elevated biological concentrations of methylmercury (MeHg), a bioaccumulative neurotoxin, are observed throughout the Arctic Ocean, but major sources and degradation pathways in seawater are not well understood. We develop a mass budget for mercury species in the Arctic Ocean based on available data since 2004 and discuss implications and uncertainties. Our calculations show that high total mercury (Hg) in Arctic seawater relative to other basins reflect large freshwater inputs and sea ice cover that inhibits losses through evasion. We find that most net MeHg production (20Mga(-1)) occurs in the subsurface ocean (20-200m). There it is converted to dimethylmercury (Me2Hg: 17Mga(-1)), which diffuses to the polar mixed layer and evades to the atmosphere (14Mga(-1)). Me2Hg has a short atmospheric lifetime and rapidly degrades back to MeHg. We postulate that most evaded Me2Hg is redeposited as MeHg and that atmospheric deposition is the largest net MeHg source (8Mga(-1)) to the biologically productive surface ocean. MeHg concentrations in Arctic Ocean seawater are elevated compared to lower latitudes. Riverine MeHg inputs account for approximately 15% of inputs to the surface ocean (2.5Mga(-1)) but greater importance in the future is likely given increasing freshwater discharges and permafrost melt. This may offset potential declines driven by increasing evasion from ice-free surface waters. Geochemical model simulations illustrate that for the most biologically relevant regions of the ocean, regulatory actions that decrease Hg inputs have the capacity to rapidly affect aquatic Hg concentrations.
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| 48. |
- Soerensen, Anne L
(author)
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Age reading of herring at the Swedish Museum of Natural History– otoliths or scales?
- 2021
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Reports (other academic/artistic)abstract
- The age of all herring used for the Marine Monitoring Programme for Contaminants in Marine Biota are determined in order to be able to normalize fish to a certain age (although age-normalization is currently not included in the contaminant time trend analysis). Historically, scales are used for age reading, which has the advantage that the fish does not need to be opened or thawed in order to do an age determination and specimen selection for the programme. However, other labs have for the last decades started using otoliths for age determination instead. This method is thought to be more accurate. Otoliths can either be read direct under a microscope or they can be sliced and stained before reading. Using otoliths has furthermore been suggested to be faster than for scales.The aim for the project was therefore to 1) test if we could find an effective and fast method for removing otoliths from herring, 2) evaluate if reading otoliths would save time compared to reading scales and 3) to compare the result from the two methods (age from otolith and scale) to see if there was a bias in the “scale age”. Our focus was for this report on reading the otoliths directly under a microscope.An earlier study conducted at the museum also evaluated the use of scales versus otoliths for age determination. In this study the otoliths were sliced and stained, which means that the two studies are not one to one comparable. The focus on the previous study was also limited to our 3rd aim and did not evaluate the time or otolith removal components.
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| 49. |
- Soerensen, Anne L., et al.
(author)
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Converting environmental quality standardsfor evaluation of fish contaminant monitoringdata – tissue conversion factors for mercury,cadmium, lead and selected PFASs
- 2022
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Reports (other academic/artistic)abstract
- The aim of the report is to produce improved estimates of tissue conversion factors (k) to use withinenvironmental monitoring. The contaminant distribution across a range of marine and freshwater fishspecies from Northern Europe freshwater and the Baltic Sea was investigated. New tissue conversionfactors were established and converted threshold limits (C-EQS or C-QS) for tissues of relevance formonitoring (liver and muscle) presented. We further explored inter-species variability in contaminantdistribution, which can result in the need to create species-specific conversion factors.In this study, we use conversion factors that assumes a proportional relation between two tissueconcentrations. We recommend that this method is always used when the aim is to convert betweentissue concentrations for monitoring purposes. This will allow for better transparency and allow for easycomparison between studies, something that is made difficult at the moment due to the use of differentalternative methods for conversion.Based on the analysis we recommend four new threshold value estimates that can be used withinenvironmental monitoring of fish. For mercury (Hg) we only looked at the kmuscle/whole fish and did notconsider liver measurements. We recommend the use of a C-EQSmuscle of 24 ng g-1 ww across all fishspecies. For cadmium (Cd) and lead (Pb) we calculated C-QSliver estimates based on conversion fromboth the QSmuscle-human health and QSwhole fish-sec pois. For Cd, we found significant differences between the twospecies investigated (herring and perch) as well as ten times higher C-QSliver based on the QSmuscle-humanhealth than the QSwhole fish-sec pois. From a precautionary principle we recommend to use the herring specific kand the QS for secondary poising set for whole fish concentration to set the C-QSliver, which lead to a CQSliverfor Cd of 2.6 μg g-1 ww. For lead (Pb), the liver:muscle dataset was considered less robust thanthe liver:whole fish dataset. Also, for Pb significant differences were found between k’s in herring andperch. We recommend using a C-QSliver of 0.3 μg g-1 ww for Pb based on perch data. For PFOS we onlylooked at the kliver/muscle and did not consider whole fish measurements. We recommend the use of a CEQSliverof 153 ng g-1 ww across all fish species despite some differences in k between the six speciesincluded in the estimate. For all contaminants, more data on additional fish species and data on thesame species but better distributed between marine and freshwater environments (for species living inboth like perch) is needed to elucidate the need for species specific and environment specific thresholds.In addition, more observations with concentrations close to the thresholds are needed for Cd and Pb tobring down the uncertainty on the QSliver estimates, which are currently, based on extrapolation of valuesmore than a factor ten below the thresholds.
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| 50. |
- Soerensen, Anne L., et al.
(author)
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Deciphering the Role of Water Column Redoxclines on Methylmercury Cycling Using Speciation Modeling and Observations From the Baltic Sea
- 2018
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In: Global Biogeochemical Cycles. - : American Geophysical Union (AGU). - 0886-6236 .- 1944-9224. ; 32:10, s. 1498-1513
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Journal article (peer-reviewed)abstract
- Oxygen-depleted areas are spreading in coastal and offshore waters worldwide, but the implication for production and bioaccumulation of neurotoxic methylmercury (MeHg) is uncertain. We combined observations from six cruises in the Baltic Sea with speciation modeling and incubation experiments to gain insights into mercury (Hg) dynamics in oxygen depleted systems. We then developed a conceptual model describing the main drivers of Hg speciation, fluxes, and transformations in water columns with steep redox gradients. MeHg concentrations were 2-6 and 30-55 times higher in hypoxic and anoxic than in normoxic water, respectively, while only 1-3 and 1-2 times higher for total Hg (THg). We systematically detected divalent inorganic Hg (Hg-II) methylation in anoxic water but rarely in other waters. In anoxic water, high concentrations of dissolved sulfide cause formation of dissolved species of Hg-II: HgS2H(aq)- and Hg (SH)(2)(0)((aq)). This prolongs the lifetime and increases the reservoir of Hg-II readily available for methylation, driving the high MeHg concentrations in anoxic zones. In the hypoxic zone and at the hypoxic-anoxic interface, Hg concentrations, partitioning, and speciation are all highly dynamic due to processes linked to the iron and sulfur cycles. This causes a large variability in bioavailability of Hg, and thereby MeHg concentrations, in these zones. We find that zooplankton in the summertime are exposed to 2-6 times higher MeHg concentrations in hypoxic than in normoxic water. The current spread of hypoxic zones in coastal systems worldwide could thus cause an increase in the MeHg exposure of food webs.
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