| 1. |
- Bignert, Anders, et al.
(author)
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Temporal trends of organochlorines in Northern Europe, 1967–1995. Relation to global fractionation, leakage from sediments and international measures
- 1998
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In: Environmental Pollution. - 0269-7491 .- 1873-6424. ; 99:2, s. 177-198
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Journal article (peer-reviewed)abstract
- The time trend monitoring of organochlorine pollution was carried out in Sweden since the late 1960s. This report presents data on concentrations of DDT, PCB, HCHs and HCB in biota samples collected and analysed annually. All the matrices and compounds studied show a significant decrease over time. The data cover severely polluted Swedish marine and fresh water in southern Sweden as well as locally unpolluted waters in remote northern Arctic regions of Sweden. A total of 13 time series representing different locations and species are presented for the different pollutants. The period studied covers the time when pollution was serious as well as the time of recovery. All monitoring activities were carried out at the same laboratories over the entire study period, which means that comparability over time is good in the sets of data presented. The various time trends show a convincing agreement with trends and annual change over time, although the concentrations differ between the species and locations investigated, the highest concentrations being in the south. Since the annual changes are normally similar regardless of locations and species, spatial variations in concentrations remain over time, although concentrations are lower today. The onset of changes in concentrations over time can be related to international measures or other circumstances that lowered releases into the environment. Similarities in the annual changes, as well as the time when changes began, are discussed with respect to suggested hypotheses on the fate of the investigated organochlorines. It was not possible to verify that the oxygenation of anoxic sediments mobilised old pollution in Baltic sediments. Neither was it possible to conclude that eutrophication has caused a measurable effect on the rate and timing of the decreases. Finally, long-range transport to Arctic regions seems to be due more to a one step transport than to the ‘Grass-hopper’ effect. The comprehensive database used, clearly shows how important it is to have datasets big enough to describe between-year variation before attempting to evaluate the time trend. In addition, if between-year variation is not known, it is then also difficult to evaluate spatial variation on the basis of single year observations.
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| 2. |
- Helander, Björn, 1946-, et al.
(author)
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The Role of DDE, PCB, Coplanar PCB and Eggshell Parameters for Reproduction in the White-tailed Sea Eagle (Haliaeetus albicilla) in Sweden.
- 2002
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In: Ambio. - 0044-7447 .- 1654-7209. ; 31:5, s. 386-403
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Journal article (peer-reviewed)abstract
- The reproduction of white-tailed sea eagles was monitoredin1964–1999 in 3 differently contaminated sub-populations: BalticSea coast (Bp), inland central Sweden (Ip) and Lapland (Lp). 249dead eggs from 205 clutches were obtained for analyses of DDEand PCBs and for eggshell measurements. A desiccation index(Di) value was calculated for each egg as a measure of waterloss through the shell. In the highly contaminated Bp, p,p´-DDEconcentrations in the eggs decreased continuously and 5-foldduring the study period and PCB concentrations decreased 3-fold from the mid 1980s. The PCB pattern changed slightly overtime towards more high-chlorinated congeners but the relativetoxicity of the PCB mixture, expressed as 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ), remained constant and TEQcan be assumed to have decreased in a similar way as PCB overtime. Productivity (P), shell thickness (St), shell index (Si) and Diincreased over time in the Bp but no change in Di or productivityoccurred in the Lp, where residue concentrations were 5–8 timeslower. P of the Bp was not correlated to St or Si but was negatively correlated to Di, DDE and PCB. An S-shaped doseresponse relationship was indicated between P and DDE. After1988, when the PCB/DDE ratio was considerably higher thanpreviously, PCB but not DDE concentrations were significantlyhigher in eggs with dead embryos as compared to undevelopedeggs, implying lethal concentrations of PCB, and a LOEL of 320pg g–1 TEQ is suggested for embryo mortality. In a subset of 21eggs, representing productive and unproductive females, analyzed for a selection of coplanar PCB congeners, tris(4-chlorophenyl) methanol and bis(4-chlorophenyl) sulphone, there wasno evidence for a correlation between P and any of these compounds. A reduction in residue concentrations in old females didnot lead to increased P or improved Di-values, indicating aremaining effect from a previous, higher exposure to contaminants. The inability to reproduce included a high rate ofundeveloped eggs, indicating effects at a prezygotic stage. Pshowed the strongest correlation with Di, and Di was moststrongly correlated to DDE. Thus, the remaining effect of previousexposure resulted in a stronger correlation to the symptom (Di)rather than to the suggested causative agent (DDE). LOEL valuesfor depressed P were estimated at 120 µg g–1 DDE and 500 µgg–1 PCB (lipid basis). It is concluded that the major reason fordepressed P during the study period was DDE, but that effectsalso from PCB were largely concealed by the effects from DDE.
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