| 21. |
- Assefa, Anteneh, et al.
(författare)
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Airborne dioxins and other POPs in the Baltic Sea environment: the potential of using metals as source markers
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Atmospheric sources are major contributors of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the Baltic Sea environment. In this study, we investigated the potential of using trace metals along with PCDD/F levels and seasonal trends as markers of important source types for PCDD/Fs in air. Levels of PCDD/F congeners (n=17) and metals (n=16) were measured in summer and winter air using high volume sampling at a rural field station (Aspvreten, Sweden). During winter, levels were on average 20 times higher than in summer (5.1 ± 5.8 fg TEQ m-3 and 0.26 ± 0.18 fg TEQ m-3, respec- tively) mostly due to a higher fraction of PCDFs. The increased levels were pronounced in air masses from southern (S) and eastern (E) compass sectors. Most of the detected metals (n=12) were positively and significantly correlated with the PCDF congeners for all compass sectors (Cd, Co, Cu, Fe, K, Mn, Pb, Sb, and Zn) during winter season. The average correlation coefficient (r) value for the correlation between PCDF congeners and these metals was 0.85 and p values generally below <0.05. In contrast, polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) showed no significant correlations with detected metals except for HCB and Cr (r=0.60 and p<0.01). The wide range of candidate metals as source markers for PCDD/F emissions, and the lack of an up-to-date extensive compilation of source characteristics for metal emission from various sources, limited the use of the metals as source markers in the current study. Although, the study was not able to pin-point primary PCDD/F sources for Baltic air, we demonstrated a promising approach for source tracing of PCDD/F in air.
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| 22. |
- Assefa, Anteneh, et al.
(författare)
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Source-apportionment shows why dioxin levels have not declined in Baltic fish
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, “dioxins”) in fatty fish of the Baltic Sea have remained high despite declines in environmental levels since the 1980s. This has raised human health concerns and restricted marketing of Baltic herring and salmon within the European Union. Thus, there is an urgent need to identify and control current PCDD/F emission sources. Analysis presented here explains why PCDD/Fs levels in fish have stopped declining or even increased in recent decades. We show that contributions of “thermal” sources (e.g., waste incineration) of PCDD/Fs to Baltic fish have declined since the 1990s, but not contributions of sources associated with the manufacture and use of chlorophenols (particularly tetrachlorophenol and pentachlorophenol, TCP and PCP, respectively). Moreover, the discrepancy between declines in levels of dioxins in abiotic compartments (e.g. sediments and air), and stable or increasing levels in biota can be explained by the persistently high bioavailability of PCDD/Fs associated with TCP and PCP type sources.
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| 23. |
- Assefa, Anteneh, et al.
(författare)
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Sources of dioxins in Baltic Sea herring: A modelling study for identification of dioxin sources and quantification of their temporal and spatial impacts
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This study presents a step-by-step statistical analysis for tracing dioxins sources that have contributed to levels in Baltic herring during the last decades. The study is based on the concentrations of the 17 toxic (2,3,7,8-substituted) dioxin congeners in herring and sediment from the Baltic Sea, and it evaluates how the impacts of the sources may have changed during the studied periods, i.e. 1990–2009 in the Bothnian Bay, 1979–2009 in the Bothnian Sea and 1988–2009 in the Baltic Proper. The modelling technique used (PMF) extracted three dioxin patterns in herring that could be used to obtain source patterns after applying transformation factors. The transformed patterns were compared to real dioxin source patterns available through previous measurement and modelling studies. The identified sources included tetrachlorophenol (TCP), pentachlorophenol/atmospheric background (PCP/AB) and emissions from thermal activities.The results indicate that the thermal source type has been the major contributor of dioxins to Baltic herring during the pre-and post-2000 periods (72% and 59%, respectively). Its impact appears, however, to have declined by 19% in the Bothnian Bay, by 67% in the Bothnian Sea, and by 48% in the Baltic Proper (TEQ-basis). On the other hand, the relative importance of TCP and PCP/AB appear to have increased over time, from 1.4% and 1.5% to 19% and 6.6% in the Bothnian Bay, from 3.3% and 7.2% to 12% and 10% in the Bothnian Sea, and from 8.9% and <1% to 33% and 13% in the Baltic Proper. Comparisons using absolute values (pg TEQ g-1 lipid weight) indicate an increase of the TCP source by five times in the Bothnian Bay from the pre-2000 to the post-2000 period, a slight increase in the Bothnian Sea, and more than a doubling of the levels in the Baltic Proper. The agreement between the trends in the three sub-basins is a good indication for an increased impact of the TCP source during recent years (post-2000). Corresponding analysis for the PCP/AB source type, indicate slightly decreased TEQ levels from the PCP/AB source type in the Bothnian Sea (by ~50%), more than twice as high in the Bothnian Bay, and more than triplicated in the Baltic Proper. While the declining trends of the thermal source type encourages continuing management efforts for air emissions, the apparent increase of TCP and PCP/AB call for more attention to such sources in the Baltic Sea. As the use of technical products containing TCP and PCP have been banned/restricted since the 1970s and 1980s, more focus on contaminated sites may be required in the mitigation actions of such sources.
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| 24. |
- Assefa, Anteneh, et al.
(författare)
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Sources of polychlorinated dibenzo-p-dioxins and dibenzofurans to Baltic Sea herring
- 2019
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 218, s. 493-500
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Tidskriftsartikel (refereegranskat)abstract
- Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in herring (Clupea harengus) remain high in several parts of the Baltic Sea, despite declines in PCDD/F emissions since the 1980s. The reasons behind this are not well understood. This study applied a statistical modeling approach where sources of PCDD/Fs that contaminate Baltic biota were quantitatively assessed by analyzing existing datasets. PCDD/F patterns were extracted from a herring dataset using positive matrix factorization (PMF). The extracted biota patterns were transformed into sediment patterns using fish-to-sediment transformation factors, and the resulting patterns were compared with known source PCDD/F patterns. The model distinguished three model patterns, which explained 85% of the data. These patterns were matched to tetra-chlorophenol (TCP), penta-chlorophenol/atmospheric background (PCP/AB), and thermal source patterns, respectively. The thermal source was the largest contributor to toxic equivalents (TEQ) in herring, but the level decreased from 42 ± 9.0 pg TEQ g−1 lipid weight (lw) before year 2000 (pre-2000) to 15 ± 2.4 pg TEQ g−1 lw post-2000, i.e., a decline of around one-third in the original TEQ concentration. The contribution of TCP more than doubled, from 2.1 ± 0.62 pg TEQ g−1 lw to 5.6 ± 1.1 pg TEQ g−1 lw, and the relative contribution of PCP/AB also increased. These increasing trends suggest that, as primary air emissions of PCDD/Fs are managed and levels decline, the impact of TCP and PCP/AB sources on Baltic Sea biota will become more important over time and that PCDD/F-contaminated sites in coastal areas and marine environments require more attention.
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| 25. |
- Assefa, Anteneh Taye, et al.
(författare)
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Assessment of PCDD/F Source Contributions in Baltic Sea Sediment Core Records
- 2014
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Ingår i: 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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Tidskriftsartikel (refereegranskat)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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| 26. |
- Assefa, Anteneh Taye, et al.
(författare)
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Temporal Trends of PCDD/Fs in Baltic Sea Sediment Cores Covering the 20th Century
- 2014
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 48:2, s. 947-953
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Tidskriftsartikel (refereegranskat)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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| 27. |
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| 28. |
- Assefa, Anteneh, 1983-
(författare)
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Tracing and apportioning sources of dioxins using multivariate pattern recognition techniques
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High levels of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in edible fish in the Baltic Sea have raised health concerns in the Baltic region and the rest of Europe. Thus, there are urgent needs to characterize sources in order to formulate effective mitigation strategies. The aim of this thesis is to contribute to a better understanding of past and present sources of PCDD/Fs in the Baltic Sea environment by exploring chemical fingerprints in sediments, air, and biota. The spatial and temporal patterns of PCDD/F distributions in the Baltic Sea during the 20th century were studied in Swedish coastal and offshore sediment cores. The results showed that PCDD/F levels peaked in 1975 (± 7 years) in coastal and 1991 (± 5 years) in offshore areas. The time trends of PCDD/Fs in the sediment cores also showed that environmental half-lives of these pollutants have been shorter in coastal than in offshore areas (15 ± 5 and 29 ± 14 years, respectively). Consequently, there have been remarkable recoveries in coastal areas, but slower recovery in offshore areas with 81 ± 12% and 38 ± 11% reductions from peak levels, respectively.Source-to-receptor multivariate modeling by Positive Matrix Factorization (PMF) showed that six types of PCDD/F sources are and have been important for the Baltic Sea environment: PCDD/Fs related to i) atmospheric background, ii) thermal processes, iii) manufacture and use of tetra-chlorophenol (TCP) and iv) penta-chlorophenol (PCP), v) industrial use of elementary chlo- rine and the chloralkali-process (Chl), and vi) hexa-CDD sources. The results showed that diffuse sources (i and ii) have consistently contributed >80% of the total amounts in the Southern Baltic Sea. In the Northern Baltic Sea, where the biota is most heavily contaminated, impacts of local sources (TCP, PCP and Chl) have been higher, contributing ca. 50% of total amounts. Among the six sources, only Thermal and chlorophenols (ii-iv) have had major impacts on biota. The impact of thermal sources has, however, been declining as shown from source apportioned time-trend data of PCDD/Fs in Baltic herring. In contrast, impacts of chlorophenol-associated sources generally increased, remained at steady-state or slowly decreased during 1990-2010, suggesting that these sources have substantially contributed to the persistently high levels of PCDD/Fs in Baltic biota.Atmospheric sources of PCDD/Fs for the Baltic region (Northern Europe) were also investigated, and specifically whether the inclusion of parallel measurements of metals in the analysis of air would help back-tracking sources. PCDD/Fs and metals in high-volume air samples from a rural field station near the shore of the central Baltic Sea were measured. The study focused on the winter season and air from the S and E sectors, as these samples showed elevated levels of PCDD/Fs, particularly PCDFs. Several metals were found to correlate significantly with the PCDFs. The wide range of candidate metals as source markers for PCDD/F emissions, and the lack of an up-to-date extensive compilation of source characteristics for metal emission from vari- ous sources, limited the use of the metals as source markers. The study was not able to pin-point primary PCDD/F sources for Baltic air, but it demonstrated a new promising approach for source tracing of air emissions. The best leads for back-tracking primary sources of atmospheric PCDD/Fs in Baltic air were seasonal trends and PCDD/F congener patterns, pointing at non-industrial related thermal sources related to heating. The non-localized natures of the sources raise challenges for managing the emissions and thus societal efforts are required to better control atmospheric emissions of PCDD/Fs.
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| 29. |
- Assefa, Anteneh, et al.
(författare)
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Tracing the sources of PCDD/Fs in Baltic Sea air by using metals as source markers
- 2018
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Ingår i: Environmental Science. - Cambridge : Royal Society of Chemistry. - 2050-7887 .- 2050-7895. ; 20:3, s. 544-552
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Tidskriftsartikel (refereegranskat)abstract
- The atmosphere is the major contributor of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the Baltic Sea environment. In this study, we investigated the potential of using metals along with PCDD/Fs as markers of important emission sources of PCDD/Fs in air. The air concentrations of PCDD/F congeners (n = 17), other persistent organic pollutants (n = 8) and metals (n = 16) were determined in summer and winter air using high volume samplers at a rural field station (Aspvreten, Sweden) located close to the Baltic Sea coast. During winter, PCDD/F levels were on average 20 times higher than in summer (5.1 +/- 5.8 fg toxicity equivalents (TEQ) m-3 and 0.26 +/- 0.18 fg TEQ m-3, respectively) mostly due to a higher fraction of PCDFs. The increased levels of PCDD/Fs were pronounced mainly in air masses that had travelled from southern (S) and eastern (E) compass sectors. A principal component analysis (PCA) of metal levels in Scots pine (Pinus sylvestris) needles sampled to reflect various air emission source types helped to identify potential marker metals for selected known atmospheric emission sources of PCDD/Fs and to rank among the candidate source types. Brown coal burning, domestic burning and heavy oil burning appeared to be the source types that contribute most of the PCDD/Fs in Baltic Sea air. The current study demonstrates a successful approach for source tracing of PCDD/Fs in air, where integrated indices from seasonal and spatial patterns of PCDD/Fs as well as metal source markers were used to trace and rank sources.
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| 30. |
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