Biotransport of Organic Pollutants to an Inland Alaska Lake by Migrating Sockeye Salmon (Oncorhynchus nerka)

Persistent organic pollutants such as polychlorinated biphenyls (PCBs) and the pesticide DDT, known to harm wildlife, have been shown to reach pristine Subarctic and Arctic areas by global atmospheric transport. Another transport route for pollutant entry into these ecosystems is provided by migrating salmon. Pollutant transport was studied in a population of sockeye salmon (Oncorhynchus nerka) in the Copper River, Alaska during their 410 km spawning mighration. Pollutants accumulated by the salmon during their ocean life stage were not eliminated during migration, but were transported to the spawning lakes and accumulated in the freshwater food web there. The influence of the biotransported pollutants was investigated by comparing pollutant levels and compositions in atmospheric deposition as well in two different populations of arctic grayling (Thymallus arcticus). One grayling population was in the salmon spawning lake and the other in a nearby lake not hosting anadromous fish, but receiving pollutants only via atmospheric deposition. The grayling in the salmon spawning lake were found to have concentrations of organic pollutants more than two times higher than those of the grayling in the salmon-free lake, and the pollutant composition resembled that found in salmon. Thus, in the studied Alaska river system, biotransport was found to have a far greater influence than atmospheric input on the PCB and DDT levels in lake biota.Il a été prouvé que des polluants organiques persistants comme les diphényles polychlorés (PCB) et le pesticide D.D.T., dont on connaît les répercussions néfastes sur la faune, se répandent dans des zones subarctiques et arctiques vierges par le biais du transport atmosphérique global. Les saumons en migration offrent une autre voie de transport pour l'entrée des polluants dans ces écosystèmes. On a étudié le transport des polluants dans une population de saumon sockeye (Oncorhynchus nerka) remontant le fleuve Copper, en Alaska, durant la migration de frai de 410 km. Les polluants accumulés par le saumon au cours de sa vie océanique n'étaient pas éliminés durant la migration, mais étaient transportés dans les frayères des lacs où ils s'accumulaient dans le réseau trophique de l'eau douce. On a étudié l'influence des polluants bio-transportés en comparant les niveaux et les compositions de polluants dans les retombées atmosphériques ainsi que dans deux populations distinctes d'ombre arctique (Thymallus arcticus). Une des populations d'ombre se trouvait dans le lac où frayaient les saumons et l'autre dans un lac voisin, ne contenant pas de poissons anadromes, mais recevant des polluants uniquement par retombées atmosphériques. On a trouvé que l'ombre qui se trouvait dans le lac où frayaient les saumons avait des concentrations en polluants organiques deux fois plus grandes que l'ombre qui se trouvait dans le lac sans saumons, et la composition des polluants ressemblait à celle que l'on retrouvait dans le saumon. Ainsi, dans le réseau fluvial de l'Alaska qui faisait l'objet de cette étude, on a trouvé que le transport biologique avait une influence beaucoup plus importante que les retombées atmosphériques sur les niveaux de PCB et de D.D.T. dans le biote lacustre

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

Role of Lipids in the fate of organochlorine compounds in Aquatic Ecosystems

Both results of laboratory experiments and material collected in the field have shown the lipid composition in organisms to have a significant effect on the bioaccumulation of pollutants and on the lipid steady-state concentrations of pollutants there. The redistribution of persistent organic pollutants which occurs in organisms as a consequence of the depletion of lipid depot, was studied in a population of migrating Pacific salmon (Oncorhynchus nerka). Concominant with an increase in lipid pollutant concentration during their river ascent, pollutants were shown to be redistributed from the muscle tissue to the lipid-rich gonads of the salmon Furthermore, the lipids were found to act as compartments for pollutant transportation, the salmon bringing pollutants to their spawning lake. Such 2biotransport2 can significantly influenced the pollutant levels in the biota of the spawning lake. This highlighted one route for pollutant transfer between ecosystems. In the assessment of lipid-pollutant interactions, the analytical methods employed are of great importance. Efficiency in extracting both total lipids and organic pollutants of varying lipophilicity from the fish muscle was shown to be related to the lipid composition of the sample in question. This reduces the comparability of results obtained by different extraction methods and from different species. A further ecotoxicological aspect of lipids that was discussed concerns altered lipids containing organic pollutants, specifically chlorinated fatty acids. These cause toxic effects and diverge from other anthropogenic organic pollutants in that responses of the organism aimed at excretion of them appeare not to occure. Such chlorinated fatty acids are incorporated into complex lipids within the organism and may be transferred then within the food-chain. They are suggested as being 2biologically stable2 pollutants. Based on the results presented in this thesis I conclude that lipids have a strong influence on the distribution of lipophilic organic pollutants at every level of organisation in an ecosystem and that they should be of major concern in analytical work and in data evaluation within ecotoxicology

Modellering som pedagogisk metod

Att hantera och använda sig av modellerings- och simuleringsverktyg är inte enbart något som en majoritet av våra studenter får stor nytta av i sitt framtida yrkesliv. Det är också användbara pedagogiska verktyg för att nå insikt i hur olika system fungerar, hur vi subjektivt uppfattar att systemen fungerar och även att kommunicera denna uppfattning. I vår undervisning inom Lund University Master’s Programme in International Environmental Science (LUMES) är metoder som “causal loop diagram” och annan “mind mapping” viktiga verktyg för att få studenter med vitt skilda akademiska och kulturella bakgrunder att kommunicera på ett effektivt sätt. Studenterna tvingas även ifrågasätta sina egna värderingar då metoderna förutsätter att de tar klar ställning till hur ett system fungerar. Även för “rena” tekniker/naturvetare har jag funnit att en djupare förståelse för vissa, ofta relativt enkla fenomen och processer, t.ex. kemisk jämvikt, bioackumulation av miljögifter, snabbt och effektivt kan förmedlas med hjälp av att använda modelleringsövningar i undervisningen. Vi jämför de olika studentkategorienas utgångspunkter för att konstruera modeller och visar hur modellering kan användas för olika syften i undervisningen

Methyl mercury production in freshwater microcosms affected by dissolved oxygen levels : Role of cobalamin and microbial community composition

Radiolabelled Hg(NO(NO3)2 was added to microcosms containing water and sediment from a lake contaminated with cellulose fibres and mercury. We found that anoxic incubation resulted in methyl 203Hg concentrations in the water at least an order of magnitude higher than the levels in oxygenated incubation. This was explained by the fact that both the production and the water solubility of methyl mercury were higher under anoxic conditions than under oxic conditions. Demethylation, however, seemed to play a minor role, if any, in regulating methyl mercury concentrations. In the sediment, the level of methyl 203Hg was strongly correlated with the level of cobalamin and the levels of the phospholipid fatty acids i15:0 and 10Mel 6:0, the latter indicating the presence of Desulfobacter, a genus of sulphate-reducing bacteria

Desorption kinetics studies on PAH-contaminated soil under varying temperatures

The purpose of this study was to investigate the effect of temperature on the release of polycyclic aromatic hydrocarbons (PAHs) from aged contaminated soil. The release of fluorene, phenanthrene, anthracene, fluoranthene and pyrene at 7, 15, 18 and 23 °C was studied using a column leaching method with a hydraulic retention time of 0.5 h. As the temperature declined from 23 to 7 °C the concentrations decreased by a factor of 11–12 for all the studied compounds except for anthracene, which only decreased by a factor 7. Rate constants at maximum release rate at the four studied temperatures were assessed. From temperature dependence studies, apparent activation energies of desorption, , were calculated. -values appeared to be in the range of 105–137 kJ mol−1 for the studied PAHs and increased with the LeBas molar volume of the compounds. The increase of with increased molecular size indicates stronger sorption with increased hydrophobicity of the compounds

Bioaccumulation and differential partitioning of polychlorinated biphenyls in freshwater, planktonic food webs

The planktonic food chain phytoplankton - zooplankton - young-of-the-year roach (Rutilus rutilus) was studied in 19 lakes in southern Sweden to investigate the bioaccumulation of polychlorinated biphenyls (PCBs). The Sigma PCB concentrations did not steadily increase with increasing trophic level. The Sigma PCB concentrations in zooplankton (400 ng.g lipid(-1)) were lower than in both phytoplankton (660 ng.g lipid(-1)) and fish (890 ng.g lipid(-1)), which did not differ significantly. Lipid content explained 40% of the total variation in dry weight normalised sigma PCB concentrations in the samples. The PCBs were differentially partitioned between the trophic levels. The logBMFs (biomagnification factors, concentration in predator/concentration in prey) were a function of the logK(ow) of the PCB congeners. The logBMF(zoo/phyto) values were 6. We conclude that no PCBs had higher lipid-normalised concentrations in zooplankton than in phytoplankton and the most lipophilic PCBs had moderately higher concentrations in roach than in zooplankton. PCBs with logK(ow) > 6 decreased in concentration from phytoplankton to zooplankton to roach. We suggest that the concept of biomagnification did not apply to the planktonic food chain investigated in these lakes

A column method for determination of leaching of polycyclic aromatic hydrocarbons from aged contaminated soil

In this study a column leaching method for investigation of hydrophobic organic contaminants (HOCs) leaching from soil was developed. The method set-up is based on a recycled flow of sterile water through a soil column with a sedimentation chamber mounted on top of the column, in connection with on-line filtration. The combination of a sedimentation chamber and an on-line filtration enables the measurement of leaching concentrations from contaminated materials consisting of very fine particle fractions. In addition, by using on-line solid phase extraction, minute amounts of leaching HOCs may be captured and quantified with high accuracy and reproducibility. The method was applied successfully on a contaminated aged soil sample and the leaching behavior of seven PAHs, with three to six aromatic rings, was monitored for more than 1600 h under saturated conditions. The tested PAHs were fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)pyrene and benzo(ghi)peryiene. The method proved to be reliable and capable of providing data on leachable amounts of the PAHs under field-like conditions and over a longer period of time. The results indicated low availability of the studied contaminants since only a minor fraction (0.3%) of the initial amount of PAHs in the soil was removed during the experiment (liquid/solid-ratio of 700 l/kg). Thus PAHs in aged contaminated soil are not to be expected to be released to any great extent only by leaching with water. (C) 2003 Elsevier Ltd. All rights reserved