Göran Ewald

Influence of trophic status on PCB distribution in lake sediments and biota

We investigated the relationship between trophic status and polychlorinated biphenyl (PCB) distribution in 19 Swedish lakes. We analyzed PCB in water, phytoplankton, zooplankton, fish and sediment during two sampling periods, in spring and summer. The mass of sigma PCB in the lake sediments was positively related to lake trophy, i.e. more PCBs were accumulated and buried in the sediment of eutrophic lakes than in oligotrophic lakes. In the oligotrophic lakes a greater fraction of the total PCB load was dissolved in water. We conclude that this is a result of higher sedimentation rates in eutrophic lakes and relatively lower turnover of organic carbon in the water column of the shallow, eutrophic lakes. In the stratified lakes, the amount of PCB per cubic meter in the epilimnion decreased from spring to summer. We suggest that sedimentation of plankton beneath the thermocline during stratification act as a sink process of PCBs from the epilimnion.

The effect of lake trophy on lipid content and PCB concentrations in planktonic food webs

We investigated the influence of trophic status on the lipid content and polychlorinated biphenyl (PCB) concentrations in planktonic food webs from 19 lakes in southern Sweden. The lipid content in phytoplankton (10-45 mum), microzooplankton (45-150 mum) and large macrozooplankton (>500 mum) was negatively related to the total phosphorus (Tot-P) concentration in lakes. The lipid content in macrozooplankton (>150 Gem) and young-of-the-year roach (Rutilus rutilus) was not related to Tot-P in lakes. On a dry mass basis (ng/g dry mass), the sum of PCB concentrations in phytoplankton and microzooplankton was negatively related to Tot-P in lakes. Thus, the PCB concentrations in phytoplankton and microzooplankton were explained by the decreasing lipid content of these fractions with increasing trophic status of lakes; and when normalized to lipid content (ng/g extractable lipid) we found no differences in PCB concentrations among lakes. We conclude that the lipid content of phytoplankton increased with increased nutrient stress, explaining the negative relationship between lake trophy and phytoplankton organochlorine (OC) concentrations on a dry mass basis. The relationship found between lipids and lake trophy in producers was not transferred in the food chain. (Less)

Differences between Bligh and Dyer and Soxhlet extractions of PCBs and lipids from fat and lean fish muscle: Implications for data evaluation

Abstract Both Bligh and Dyer extraction using chloroform/ methanol and Soxhlet extraction using hexane/acetone were employed for extracting total lipid and polychlorinated biphenyls (PCBs) from muscle tissue in four species of fish: herring (Clupea harengus), salmon (Salmo salar), cod (Gadus morhua) and Northern pike (Esox lucius), all caught in the southern part of the Baltic Sea. The Bligh and Dyer method allowed a greater amount of total lipid but a lesser amount of total PCBs to be extracted than the Soxhlet method with hexane/acetone did. For all the fish except cod, the sample wet weight PCB concentrations differed significantly for the two extraction methods. When the sample PCB was normalized to extracted total lipid, the differences in the yield of the two methods increased due to differences in total lipid yield. This was most pronounced for the lean fish (cod and pike). When the two methods were compared in terms of efficiency in the extraction of different PCBs, a relationship of this to PCB congener lipophilicity, expressed in terms of Kow, could be shown. Differences between methods and variability within the data provided from the first method were highest for the PCB congeners in the lipophilicity regions of log Kow 7.5. The study indicated that comparability is better for PCB analysis data from triacylglycerol-rich samples (herring and salmon) than from lean samples (cod and pike). The results suggest that in order to avoid comparisons of data from different samples being misleading, PCB pattern and/or single congener data should be obtained using the same extraction technique.

Floods and health in Gambella region, Ethiopia: a qualitative assessment of the strengths and weaknesses of coping mechanisms

Background: Floods are the most frequent and devastating type of natural disaster worldwide, causing unprecedented deaths, diseases, and destruction of property and crops. Flooding has a greater impact in developing countries due to lack of sufficient disaster management structures and a lack of economic resources. Objective: This study was conducted with the aim of contributing to the knowledge base of development strategies that reduce flood-related health risks in developing countries. The study focused particularly on assessing the flood risks and health-related issues in the Gambella region of Ethiopia; with the intent of producing relevant information to assist with the improvements in the efficacy of the current flood coping strategies in the region. Methods: Data were gathered through interviews with 14 officers from different government and non-governmental organizations and a questionnaire survey given to 35 flood victims in Itang woreda. A qualitative approach was applied and the data were analyzed using content analysis. Results: It was found that flooding is a common problem in Gambella region. The findings also indicate that the flood frequency and magnitude has increased rapidly during the last decade. The increase in floods was driven mainly by climate change and changes in land use, specifically deforestation. The reported main impacts of flooding on human health in Gambella region were deaths, injuries, and diseases such as malaria and diarrhea. Another notable consequence of flooding was crop destruction and subsequent malnutrition. Conclusions: Three weaknesses that were identified in the current coping strategies for flood-related health impacts in Gambella region were a lack of flood-specific policy, absence of risk assessment, and weak institutional capacity. This study recommends new policy approaches that will increase the effectiveness of the current flood coping strategies to sustainably address the impact of flooding on human health.

Distribution of 14C from ingested, radiolabelled dichlorostearic, stearic and oleic acids in body and in lipids of perch, Perca fluviatilis

Distribution of C-14 from ingested, radiolabelled dichlorostearic, stearic and oleic acids in body and in lipids of perch, Perca fluviatilis

Chlorinated fatty acids - Environmental pollutants with intriguing properties

Abstract The chlorine bound in chlorinated fatty acids (ClFAs) have been concluded to contribute to a major part of the extractable organically bound chlorine found in fish and other aquatic biota. Despite ClFAs giving rise to toxic effects they appear not to be recognised as “xenobiotic” compounds by the organism. They are readily accumulated via food and incorporated into complex lipids to approximately the same extent as unchlorinated fatty acids and may thus be transferred from prey to predator in the food chain. The ClFAs thus diverge from traditional environmental pollutants, such as PCBs, in several aspects and their fate in the environment can not be predicted by conventional risk assessment methods.

Metabolic fate of 14 C-labelled chlorinated and non-chlorinated fatty acids in goldfish ( Carassius auratus )

In order to study the metabolic fate of chlorinated fatty acids in fish, goldfish were fed either 9,10-dichlorostearic acid or oleic acid, chosen as the unchlorinated analogue, both radiolabelled at either the carboxyl (1st) or the terminal (18th) carbon of the fatty acid chain. By keeping the fish in hermetically closed aquaria, all the respired, assimilated and excreted radioactivity could be accounted for. Fish fed 9,10-dichlorostearic acid labelled in the terminal end respired radioactive CO2 to a much lower degree than fish fed the other test compounds. As a consequence, the radioactivity bound in lipids was higher in the group of fish fed dichlorostearic acid labelled in the terminal end. It is suggested that the chlorine atoms in the middle of the carbon chain obstruct the metabolic turn-over of 9,10-dichlorostearic acid, which may have an impact on the residence time of these compounds in the ecosystem.