1. |
- Soerensen, Anne L., et al.
(författare)
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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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Ingår i: Global Biogeochemical Cycles. - : American Geophysical Union (AGU). - 0886-6236 .- 1944-9224. ; 32:10, s. 1498-1513
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Tidskriftsartikel (refereegranskat)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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2. |
- Temnerud, Johan, et al.
(författare)
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Spatial patterns of some trace elements in four Swedish stream networks
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 10, s. 1407-1423
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Tidskriftsartikel (refereegranskat)abstract
- Four river basins in southern Sweden, with catchment sizes from 0.3 to 127 km(2) (median 1.9), were sampled in October 2007. The 243 samples were analysed for 26 trace elements (Ag, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Ga, Ge, In, La, Li, Mo, Ni, Pb, Sb, Se, Sn, Tl, Ti, U, V and Zn) to identify spatial patterns within drainage networks. The range and median of each element were defined for different stream orders, and relationships to catchment characteristics, including deposition history, were explored. The sampling design made it possible to compare the differences along 40 stream reaches, above and below 53 stream junctions with 107 tributaries and between the 77 inlets and outlets of 36 lakes. The largest concentration differences (at reaches, junctions and lakes) were observed for lakes, with outlets usually having lower concentration compared to the inlets for As, Ba, Be, Bi, Cd, Co, Cr, Ga, Ge, Ni, Pb, Sn, Ti, Tl, U, V and Zn. Significantly lower concentrations were observed for Cd and Co when comparing headwaters with downstream sites in each catchment. Common factor analysis (FA) revealed that As, Bi, Cr, Ga, Ge, Tl and V co-vary positively with Al, Fe and total organic carbon (TOC) and negatively with La, Li and pH. The strong removal of a large number of trace elements when passing through lakes is evident though in the FA, where lake surface coverage plots opposite to many of those elements. Forest volume does not respond in a similar systematic fashion and, surprisingly, the amount of wetland does not relate strongly to either Fe or TOC at any of the rivers. A better understanding of the quantitative removal of organic carbon and iron will aid in understanding trace element fluxes from landscapes rich in organic matter and iron.
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3. |
- Koch, Alina, 1990-, et al.
(författare)
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Point source characterization of per- and polyfluoroalkyl substances (PFASs) and extractable organofluorine (EOF) in freshwater and aquatic invertebrates
- 2019
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Ingår i: Environmental Science. - : Royal Society of Chemistry. - 2050-7887 .- 2050-7895. ; 21:11, s. 1887-1898
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Tidskriftsartikel (refereegranskat)abstract
- Major point sources of per- and polyfluoroalkyl substances (PFASs) cause ubiquitous spread of PFASs in the environment. In this study, surface water and aquatic invertebrates at three Swedish sites impacted by PFAS point sources were characterized, using homologue, isomer and extractable organofluorine (EOF) profiling as well as estimation of bioaccumulation factors (BAFs) and mass discharge. Two sites were impacted by fire training (sites A and R) and the third by industrial runoff (site K). Mean Σ25PFASs concentration in water was 1920 ng L-1 at site R (n = 3), which was more than 20- and 10-fold higher than those from sites A and K, respectively. PFOS was the most predominant PFAS in all waters samples, constituting 29-79% of Σ25PFAS concentrations. Several branched isomers were detected and they substantially contributed to concentrations in surface water (e.g. 49-78% of ΣPFOS) and aquatic invertebrates (e.g. 15-28% of ΣPFOS). BAFs in the aquatic invertebrates indicated higher bioaccumulation for long chain PFASs and lower bioaccumulation for branched PFOS isomers compared to linear PFOS. EOF mass balance showed that Σ25target PFASs in water could explain up to 55% of EOF at site R. However, larger proportions of EOF (>92%) remained unknown in water from sites A and K. Mass discharges were for the first time estimated for EOF and revealed that high amounts of EOF (e.g. 8.2 g F day-1 at site A) could be transported by water to recipient water bodies relative to Σ25PFASs (e.g. 0.15 g day-1 at site A). Overall, we showed that composition profiling, BAFs and EOF mass balance can improve the characterization of PFASs around point sources.
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4. |
- Koch, Alina, 1990-, et al.
(författare)
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Quantification of Biodriven Transfer of Per- And Polyfluoroalkyl Substances from the Aquatic to the Terrestrial Environment via Emergent Insects
- 2021
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 55:12, s. 7900-7909
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Tidskriftsartikel (refereegranskat)abstract
- Emergent aquatic insects are important food subsidies to riparian food webs but can also transfer waterborne contaminants to the terrestrial environment. This study aimed to quantitatively assess this biodriven transfer for per- and polyfluoroalkyl substances (PFAS). Aquatic insect larvae, emergent aquatic insects, terrestrial consumers, sediment, and water were collected from a contaminated lake and stream and an uncontaminated pond, and analyzed for PFAS and stable isotopes of carbon and nitrogen. Top predators in this study were spiders, which showed the highest average ∑24PFAS concentration of 1400 ± 80 ng g–1 dry weight (dw) at the lake and 630 ng g–1 dw at the stream. The transfer of PFAS from the lake to the riparian zone, via deposition of emergent aquatic insects, was 280 ng ∑24PFAS m–2 d–1 in 2017 and only 23 ng ∑24PFAS m–2 d–1 in 2018. Because of higher production of emergent aquatic insects, the lake had higher PFAS transfer and higher concentrations in terrestrial consumers compared to the stream, despite the stream having higher PFAS concentration in water and aquatic insect larvae. Our results indicate that biodriven transfer of PFAS from the aquatic systems and subsequent uptake in terrestrial food webs depend more on emergence amounts, i.e., aquatic prey availability, rather than on PFAS concentrations in water and aquatic prey.
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5. |
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6. |
- Buffam, Ishi, et al.
(författare)
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Landscape-scale variability of acidity and dissolved organic carbon during spring flood in a boreal stream network
- 2007
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 112
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Tidskriftsartikel (refereegranskat)abstract
- Acidity is well known to influence stream biota, but the less well-studied spatial and temporal distributions of acidity are likely to play a larger ecological role than average values. We present data on spatial variability of chemical parameters contributing to acidity during winter baseflow and spring flood periods in Krycklan, a fourth-order boreal stream network in northern Sweden. Fifteen stream sites were monitored in subcatchments spanning 3 orders of magnitude in size and representing a wide range of percent wetland. At baseflow, pH ranged from 3.9 to 6.5 at the different sites. Baseflow dissolved organic carbon (DOC) concentration varied by an order of magnitude and was positively correlated with subcatchment percent wetland, resulting in high spatial variability in dissociated organic acids (OA(-)). During spring flood, DOC and OA(-) increased in forested sites and decreased in wetland sites, resulting in reduced spatial variability in their concentrations. In contrast, base cations and strong acid anions diluted throughout the stream network, resulting in decreased acid neutralizing capacity (ANC) at all sites. The spatial variability of base cations increased slightly with high flow. As a result of the changes in OA(-) and ANC, pH dropped at all but the most acidic site, giving a slightly narrowed pH range during spring flood (4.2-6.1). The transition from winter to spring flood stream chemistry could largely be explained by: (1) a shift from mineral to upper riparian organic soil flow paths in forested catchments and (2) dilution of peat water with snowmelt in wetland catchments.
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7. |
- Bäckström, Mattias, et al.
(författare)
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Mobilisation of heavy metals by deicing salts in a roadside environment
- 2004
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 38:3, s. 720-732
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Tidskriftsartikel (refereegranskat)abstract
- The seasonal variations of some selected heavy metals (Cd, Cu, Pb and Zn) and principal anions in soil solutions were monitored as a function of distance from the road at two field sites in Sweden. During the winter, the conductivity, concentrations of dissolved sodium and chloride increased dramatically due to the application of deicing agents (i.e. NaCl). Due to ion exchange, the pH decreased one unit in the soil solutions, whereas the concentrations of total organic carbon decreased due to coagulation and/or sorption to stationary solids. The heavy metal concentrations increased during the winter, but through different mechanisms. Cadmium concentrations in the aqueous phase increased as a response to ion exchange, possibly also enhanced by the formation of chloride complexes. Similarly, the concentrations of zinc increased, due to ion exchange, with calcium and protons. The mechanisms of mobilisation for copper and lead were not that clear probably due to association with coagulated or sorbed organic matter in combination with colloid dispersion.
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8. |
- Kucner, Tomasz Piotr, PhD, 1988-, et al.
(författare)
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Modelling Motion Patterns with Conditional Transition Map
- 2020
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Ingår i: Probabilistic Mapping of Spatial Motion Patterns for Mobile Robots. - Cham : Springer. - 9783030418076 - 9783030418083 ; , s. 33-64
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Bokkapitel (refereegranskat)abstract
- The key idea of modelling flow of discrete objects is to capture the way they move through the environment. One method to capture the flow is to observe changes in occupancy caused by the motion of discrete objects. In this chapter, we present a method to model and learn occupancy shifts caused by an object moving through the environment. The key idea is observe temporal changes changes in the occupancy of adjacent cells, and based on the temporal offset infer the direction of the occupancy flow.
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9. |
- Lidskog, Rolf, 1961-, et al.
(författare)
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From wicked problem to governable entity? : The effects of forestry on mercury in aquatic ecosystems
- 2018
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Ingår i: Forest Policy and Economics. - Amsterdam : Elsevier. - 1389-9341 .- 1872-7050. ; 90, s. 90-96
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Tidskriftsartikel (refereegranskat)abstract
- In all Swedish lakes, the concentration of mercury (Hg) in fish exceeds the European Union threshold limit. While the ultimate source of Hg is primarily airborne emissions from fossil energy, forestry plays a small but important role because some forestry operations help mobilize and transform Hg, increasing Hg loads in downstream aquatic ecosystems. Simultaneously, climate change is placing additional demands on forests to provide biomass as a substitute for fossil fuel. Thus, decision-makers are facing a complex situation, a “wicked problem,” when it comes to how to handle the problem of forestry’s effects on Hg in aquatic ecosystems while at the same time securing other ecosystem services. In order to explore forestry’s degree of responsibility as well as possible solutions to this problem in Sweden, a transdisciplinary method has been used consisting of a structured dialogue with actors from relevant governmental agencies, forest companies, and forest associations. The analysis shows that while the issue can be addressed constructively, the complex character of the problem requires consideration of not only management practices for forestry but also current regulatory goals and environmental objectives. The Hg problem represents a class of difficult issues for forestry where stand- or property-based production has an impact on a greater spatial scale. This means that regulating the more direct impacts of forestry needs to be weighed against the implications this regulation may have on the overall issue of ecosystem services.
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10. |
- Long, A J, et al.
(författare)
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Final Report of the INQUA Shorelines Subcommission on Western Europe
- 2005
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Ingår i: Journal of Coastal Research. - 0749-0208 .- 1551-5036. ; , s. 43-51
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Tidskriftsartikel (refereegranskat)abstract
- We provide a short report on the final year of the INQUA Shorelines Subcommission on Western Europe (2002-3). This includes a review of activities under four themes: sea-level changes in the next century; sea-level changes along a north-south transect from the uplifting coasts of Fennoseandanvia to the subsiding coasts of the North Sea and the Baltic, and the meta stable areas such as Portugal and France; comparisons between modeled and empirical observations of relative sea-level (RSL) change, and palaeo-tsunami and storm records. We conclude by providing a report on the final 2002 Annual Meeting including its field meeting at Greifswald and Mecklenburg-West Pomerania and provide a list of some recent publications by members of the INQUA Shorelines Subcommission.
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