| 1. |
- McLachlan, Michael S., et al.
(author)
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Using Model-Based Screening to Help Discover Unknown Environmental Contaminants
- 2014
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 48:13, s. 7264-7271
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Journal article (peer-reviewed)abstract
- Of the tens of thousands of chemicals in use, only a small fraction have been analyzed in environmental samples. To effectively identify environmental contaminants, methods to prioritize chemicals for analytical method development are required. We used a high-throughput model of chemical emissions, fate, and bioaccumulation to identify chemicals likely to have high concentrations in specific environmental media, and we prioritized these for target analysis. This model-based screening was applied to 215 organosilicon chemicals culled from industrial chemical production statistics. The model-based screening prioritized several recognized organosilicon contaminants and generated hypotheses leading to the selection of three chemicals that have not previously been identified as potential environmental contaminants for target analysis. Trace analytical methods were developed, and the chemicals were analyzed in air, sewage sludge, and sediment. All three substances were found to be environmental contaminants. Phenyl-tris(trimethylsiloxy)silane was present in all samples analyzed, with concentrations of similar to 50 pg m(-3) in Stockholm air and similar to 0.5 ng g(-1) dw in sediment from the Stockholm archipelago. Tris(trifluoropropyl)trimethyl-cyclotrisiloxane and tetrakis(trifluoropropyl)tetramethyl-cyclotetrasiloxane were found in sediments from Lake Mjosa at similar to 1 ng g(-1) dw. The discovery of three novel environmental contaminants shows that models can be useful for prioritizing chemicals for exploratory assessment.
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| 2. |
- Assefa, Anteneh Taye, et al.
(author)
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Assessment of PCDD/F Source Contributions in Baltic Sea Sediment Core Records
- 2014
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851 .- 1086-931X .- 1520-6912. ; 48:16, s. 9531-9539
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Journal article (peer-reviewed)abstract
- Spatial and temporal trends of sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the Baltic Sea were evaluated by positive matrix factorization (PMF) and principal component analysis (PCA). Sediment cores were sampled at eight coastal, one coastal reference, and six offshore sites covering the northern to the southern Baltic Sea. The cores, which covered the period 1919-2010, were sliced into 2-3 cm disks among which 8-11 disks per core (in total 141 disks) were analyzed for all tetra- through octa-CDD/Fs. Identification and apportionment of PCDD/F sources was carried out using PMF. Five stable model PCDD/F congener patterns were identified, which could be associated with six historically important source types: (i) atmospheric background deposition (ABD), (ii) use and production of pentachlorophenol (PCP), (iii) use and production of tetra-chlorophenol (TeCP), (iv) high temperature processes (Thermal), (v) hexa-CDD-related sources (HxCDD), and (vi) chlorine-related sources (Chi), all of which were still represented in the surface layers. Overall, the last four decades of the period 1920-2010 have had a substantial influence on the Baltic Sea PCDD/F pollution, with 88 +/- 7% of the total amount accumulated during this time. The 1990s was the peak decade for all source types except TeCP, which peaked in the 1980s in the northern Baltic Sea and has still not peaked in the southern part. The combined impact of atmospheric-related emissions (ABD and Thermal) was dominant in the open sea system throughout the study period (1919-2010) and showed a decreasing south to north trend (always >80% in the south and >50% in the north). Accordingly, to further reduce levels of PCDD/Fs in the open Baltic Sea ecosystem, future actions should focus on reducing atmospheric emissions.
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| 3. |
- Assefa, Anteneh Taye, et al.
(author)
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Temporal Trends of PCDD/Fs in Baltic Sea Sediment Cores Covering the 20th Century
- 2014
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 48:2, s. 947-953
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Journal article (peer-reviewed)abstract
- The pollution trend of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the Baltic Sea region was studied based on depth profiles of PCDD/Fs in sediment cores collected from six-offshore areas, eight coastal sites impacted by industrial/urban emissions, and one coastal reference site. A general trend was observed for the offshore and coastal reference sites with substantial increase in PCDD/F concentrations in the mid-late 1970s and peak levels during 1985-2002. The overall peak year for PCDD/Fs in Baltic Sea offshore areas was estimated (using spline-fit modeling) to 1994 +/- 5 years, and a half-life in sediments was estimated at 29 +/- 11 years. For the industrial/urban impacted coastal sites, the temporal trend was more variable with peak years occurring 1-2 decades earlier compared to offshore areas. The substantial reductions from peak levels (38 +/- 11% and 81 +/- 12% in offshore and coastal areas, respectively) reflect domestic and international actions taken for reduction of the release of PCDD/Fs to the environment. The modeled overall half-life and reductions of PCDD/Fs in offshore Baltic Sea sediment correspond well to both PCDD/F trends in European lakes without any known direct. PCDD/F sources (half-lives 30 and 32 years), and previously modeled reduction in atmospheric deposition of,PCDD/Fs to the Baltic Sea since 1990. These observations support previous findings of a common diffuse source, such as long-range air transport of atmospheric emissions, as the prime source of PCDD/Fs to the Baltic Sea region. The half-life of PCDD/Fs in Baltic Sea offshore sediments was estimated to be approximately 2 and 4-6 times longer than in semirural and urban European air, respectively. This study highlights the need for further international actions to reduce the levels of PCDD/Fs in Baltic Sea air specifically and in European air in general.
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| 4. |
- Klemedtsson, Leif, 1953, et al.
(author)
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Skogaryd – Integration of terrestrial and freshwater greenhouse gas sources and sinks
- 2010
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In: 1st COST meeting ‘Belowground carbon in Europeanforest’, Birmensdorf, Switzerland, 26–28 January 2010..
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Conference paper (other academic/artistic)abstract
- Forests play an important role in the global carbon (C) cycle, and management as well as climate can cause major effects on the balance of C between the atmosphere and the plant/soil system. With re-gard to our commitments to the Kyoto and post-Kyoto actions on climate change, we need reliable predictions on how this balance is affected by management and climate. In 2006 the Skogaryd Research Forest was established in the southwest of Sweden (58°23’N, 12°09’E). The overall goal is to quantify net greenhouse gas (GHG) fluxes from drained spruce forest, by determining the individual fluxes and pools of C and nitrogen and elucidating their connection to site fertility, drainage status and abiotic parameters and then use the generated data in GHG models, for model validations and ultimately emissions predictions. During 2006-2009 the research has fo-cused on two sites, mineral and organic, dominated by Norway spruce (Picea abies). Both sites are drained fertile soils but with different land-use history that have affected their physical properties. Measurements includes: net ecosystem exchange of CO2, Shoot photosynthesis and respiration at different locations within the canopy, stem respiration, emissions of N2O and CH4 using manual cham-bers, soil respiration with automatic chambers including a trenching experiment where root-, mycelia-, and heterotrophic respiration are separated, fine root production using minirhizotrons, and mycelia production. The organic site also includes a wood ash experiment. From 2010 the research will be expanded to the whole watershed, from the mire system via streams, riparian zones, forests, to lakes and the subsequent exchange between the atmosphere and surface waters. Different terrestrial and limnic ecosystems will be linked holistically, using site specific tech-niques at different scales, from aircraft (km2) to chambers (m2) to create integrated models that can be used to quantify net GHG flux for management strategies.
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| 5. |
- Li, Zhe, 1987-
(author)
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An integrated approach to study pharmaceuticals and their microbial transformation products: formation and environmental behavior in water/sediment systems
- 2014
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Licentiate thesis (other academic/artistic)abstract
- Pharmaceuticals are emerging organic micropollutants that are frequently detected in the aquatic environment. While information on their environmental occurrence is substantial, knowledge gaps exist with respect to their environmental transformation. This licentiate thesis focuses on this research deficit by (1) providing and applying tools for identifying biotransformation products, and (2) investigating the behavior of pharmaceuticals and their transformation products (TPs) in two different experimental systems.Study I established a data-processing method based on peak detection, time-trend filtration and structure assignment, and provides an efficient and reliable way for TP identification. Water/sediment tests were carried out with 9 pharmaceuticals. The method for identifying TPs is based on accurate mass data obtained from high resolution mass spectrometry and a comprehensive data-processing workflow. In total, 16 TPs were identified, 11 of which were confirmed by reference standards. Five of the TPs showed a continuous accumulation over the entire incubation period of 35 days.Study II aimed at studying the influence of water/sediment interactions on the environmental behavior of pharmaceuticals and their TPs. An artificial streaming channel was applied to simultaneously determine the concentrations of parent pharmaceuticals and key TPs in both surface water and sediment pore water under defined hydraulic conditions. All pharmaceuticals dissipated from the test system. The benefit from simultaneously analyzing parent compounds and TPs can be illustrated with carbamazepine, which is generally reported to be persistent. In study II, carbamazepine dissipated continuously from the test system, and the formation of a TP shows that this dissipation can be attributed to microbial biotransformation. The results also indicate that transformation predominantly occurs in the hyporheic zone, but also that TPs can be transported back into the streaming channel.This thesis confirms the crucial role of the hyporheic zone for the elimination of organic micropollutants from rivers and streams. Moreover, the developed workflow for TP identification provides opportunities to efficiently identify TPs for additional micropollutants in laboratory and field studies. In future work, we will study the influence of hydraulic conditions on transformation kinetics and formation of characteristic TPs, and we will extend the work to additional pharmaceuticals. Moreover, we will test the applicability of using TPs as indicators for characterizing ongoing biotransformation in field settings, thereby providing a more efficient way of characterizing the environmental fate of pharmaceuticals.
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| 6. |
- Sobek, Anna, et al.
(author)
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A comparison of PCB bioaccumulation factors between an arctic and a temperate marine food web
- 2010
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 408:13, s. 2753-2760
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Journal article (peer-reviewed)abstract
- To test how environmental conditions in the Arctic and the resulting ecological adaptations affect accumulation of persistent organic pollutants (POPs) in the marine food web, bioaccumulation of four polychlorinated biphenyls (PCBs) in an arctic (Barents Sea 77°N - 82°N) and a temperate marine (Baltic Sea 54°N - 62°N) food web were compared. Three different trophic levels were studied (zooplankton, fish, seal), representing the span from first-level consumer to top predator. Previously published high-quality data on PCB water concentrations in the two areas were used for calculation of bioaccumulation factors (BAF). The BAFArctic : BAF Temperate ratios were above 1 for all four PCB congeners in zooplankton (6.4-13.8) and planktivorous fish (2.9-5.0), whereas the ratios were below 1 in seal. The mean ratio between arctic and temperate BAFs for all trophic levels and congeners (BAFArctic : BAFTemperate) was 4.8. When the data were corrected for the seawater temperature difference between the two ecosystems, the ratio was 2.0. We thus conclude that ecological or physiological adaptations of organisms and systems to arctic conditions do at most marginally affect bioaccumulation. Lower seawater temperature lead to a marked thermodynamically favoured passive partitioning to organic matrices and thus elevated ambient BAFs in the Arctic compared with the Baltic Sea. This implies that bioaccumulation in the Arctic may be described in the same way as bioaccumulation in temperate regions, e.g. by the use of mechanistic models parameterised for the Arctic.
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| 7. |
- Sobek, Anna, et al.
(author)
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Aerosol-Water Distribution of PCDD/Fs and PCBs in the Baltic Sea Region
- 2013
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47:2, s. 781-789
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Journal article (peer-reviewed)abstract
- Atmospheric deposition is a major pathway of PCDD/Fs to the Baltic Sea. We studied the aerosol-water distribution for aerosols collected close to the Baltic Sea in order to investigate the availability of pollutants sorbed to aerosols deposited on water. Aerosols were analyzed for both total concentration (Soxhlet extraction) and the freely dissolved water concentration (extraction with 17-mu m polyoxymethylene equilibrium passive samplers). Concentrations of PCDD/F and sum PCB-7 in aerosols were 65-1300 pg/g dw TEQ and 22-100 ng/g dw, respectively. Organic carbon (OC)-normalized aerosol water distribution ratios (K-aer-water,K-OC) were consistently lower (factor 2-60) than previously determined sediment organic carbon water distribution ratios (K-sed,K-OC). Hence PCDD/Fs and PCBs entering the Baltic Sea through aerosol deposition seem to be more available for desorption to the water phase than PCDD/Fs and PCBs sorbed to sediment. Further, we investigated whether aerosol water distribution may be predicted from the air aerosol partitioning constant multiplied by the Henry's Law constant. This proposed model for aerosol water distribution underestimated measured values for PCBs by factors of 1-17 and for PCDD/Fs by more than a factor 10. These findings can be used to improve future fate modeling of PCBs and PCDD/Fs in marine environments and specifically the Baltic Sea.
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| 8. |
- Sobek, Anna, et al.
(author)
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Coastal sediments in the Gulf of Bothnia as a source of dissolved PCDD/Fs and PCBs to water and fish
- 2014
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 487, s. 463-470
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Journal article (peer-reviewed)abstract
- High levels of PCDD/Fs and PCBs in Baltic Sea biota have been a matter of great concern during the last decades. We measured the freely dissolved concentrations of PCDD/Fs and PCBs in sediment pore water and bottom water in eight areas along the Swedish coast of the Gulf of Bothnia, by using state-of-the-art passive samplers. Chemical activity ratios (calculated from freely dissolved concentrations in pore water and bottom water based on chemical activity ratios) for PCDD/Fs were higher than 1 at all stations (PCDD/Fs average 27; stdev 22). High activity ratios suggest that the sediments have a potential to act as a source of dissolved PCDD/Fs to the water column. Activity ratios for PCBs varied between 0.3 and 17 (average 2; stdev 4). The concentrations of PCDD/Fs and PCBs in bottom water were significantly correlated with concentrations in sediment pore water (p < 0.00001 to p = 0.03) as well as with concentrations in juvenile perch caught in the same areas (p < 0.00001 to p = 0.02). To our knowledge, this is the first study demonstrating a correlation between in-situ measured freely dissolved PCDD/F concentrations and lipid-normalized contents in stationary fish. Our results confirm that freely dissolved concentrations should be used as chemical predictors of bioaccumulation. The results from this study imply that continued efforts to reduce levels of PCDD/Fs and PCBs in coastal sediments will have positive effects on concentrations of these contaminants in lower trophic levels of Baltic Sea ecosystems.
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| 9. |
- Sobek, Anna, et al.
(author)
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Deep Water Masses and Sediments Are Main Compartments for Polychlorinated Biphenyls in the Arctic Ocean
- 2014
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 48:12, s. 6719-6725
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Journal article (peer-reviewed)abstract
- There is a wealth of studies of polychlorinated biphenyls (PCB) in surface water and biota of the Arctic Ocean. Still, there are no observation-based assessments of PCB distribution and inventories in and between the major Arctic Ocean compartments. Here, the first water column distribution of PCBs in the central Arctic Ocean basins (Nansen, Amundsen, and Makarov) is presented, demonstrating nutrient-like vertical profiles with 5-10 times higher concentrations in the intermediate and deep water masses than in surface waters. The consistent vertical profiles in all three Arctic Ocean basins likely reflect buildup of PCBs transported from the shelf seas and from dissolution and/or mineralization of settling particles. Combined with measurement data on PCBs in other Arctic Ocean compartments collected over the past decade, the total Arctic Ocean inventory of Sigma 7PCB was estimated to 182 +/- 40 t (+/- 1 standard error of the mean), with sediments (144 +/- 40 t), intermediate (5 +/- 1 t) and deep water masses (30 +/- 2 t) storing 98% of the PCBs in the Arctic Ocean. Further, we used hydrographic and carbon cycle parametrizations to assess the main pathways of PCBs into and out of the Arctic Ocean during the 20th century. River discharge appeared to be the major pathway for PCBs into the Arctic Ocean with 115 +/- 11 t, followed by ocean currents (52 +/- 17 t) and net atmospheric deposition (30 +/- 28 t). Ocean currents provided the only important pathway out of the Arctic Ocean, with an estimated cumulative flux of 22 +/- 10 t. The observation-based inventory of Sigma 7PCB of 182 +/- 40 t is consistent with the contemporary inventory based on cumulative fluxes for Sigma 7PCB of 173 +/- 36 t. Information on the concentration and distribution of PCBs in the deeper compartments of the Arctic Ocean improves our understanding of the large-scale fate of POPs in the Arctic and may also provide a means to test and improve models used to assess the fate of organic pollutants in the Arctic.
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| 10. |
- Sobek, Anna, et al.
(author)
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Dioxiner i Bottenhavet och Bottenviken - pågående utsläpp eller historiska synder
- 2012
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Reports (other academic/artistic)abstract
- Syftet med det här projektet var att undersöka vilka källor som är viktiga för dagensdioxinbelastning i sediment i kustnära områden i Bottenhavet och Bottenviken.Dioxinkoncentrationer i åtta daterade sedimentkärnor från fjärdar med olika typer av historiskoch pågående verksamhet i närområdet analyserades. Dessutom gjordes enkällfördelningsanalys för att tydliggöra bidraget av olika källor och hur det har förändrats övertid. Dioxinkoncentrationer i bottenvatten och sedimentens porvatten har också undersökts föratt få en bild av om sedimenten idag läcker dioxiner till vattenkolonnen, eller om sedimentenfungerar som en sänka och tar upp dioxiner från överliggande vatten. Resultaten visadegenerellt på en mycket tydlig minskning i totalkoncentrationer av dioxiner i de undersöktasedimentkärnorna. Vid de flesta lokalerna var koncentrationerna som högst under 1960-tal till1980-tal och har sedan dess minskat drastiskt fram till idag, med en genomsnittlig minskningpå 73 % från toppnivåerna. Det är därmed tydligt att tidigare åtgärder som förbud motpentaklorfenol och bättre reningsprocesser inom industrin har resulterat i en tydlig minskningav dioxinutsläpp till havsmiljön. Den här studien visar vidare att samtliga av de undersöktakustnära sedimenten läcker ut dioxiner till överliggande vatten. Samtidigt binder dioxinernamycket starkt till det organiska materialet i sedimenten, och det är därmed en mycket litenandel av den totala mängden dioxiner i sedimenten som är tillgängliga för läckage till vattenoch upptag i biota. Genom en källfördelningsanalys där man studerar den relativaförekomsten av olika dioxinkongener och kopplar det till en viss typ av källa, kunde tydligakopplingar göras till tidigare och pågående verksamheter vid de flesta lokalerna. Exempel påhistoriska källor som det fanns tydliga spår av är klorfenolanvändning, som har haft enmycket stor inverkan på flera platser och en påverkan kan fortfarande ses även i ytligasediment. Till skillnad från klorfenolanvändningen visade sig klorgasblekning ha lågpåverkan på de studerade sedimenten. På några platser pekar källfördelningsanalysen pårelativt oförändrade förhållanden även efter topphalterna. Baserat på den här studien kanpågående emissioner därmed inte uteslutas, men det är också mycket troligt att resuspensionhar orsakat en långsam återhämtning av sedimenten på de aktuella platserna. Analyser avutsjösediment visar att för Östersjön som helhet, är det atmosfäriskt relaterade källor inklusiveolika typer av förbränning och högtemperaturprocesser (t.ex. metallindustri) som dominerardagens emissioner.
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