An in situ study on the distribution, biotransformation and flux of polycyclic aromatic hydrocarbons (pahs) in an aquatic food chain (seston-Mytilus edulisL.-Somateria mollissimaL.) from the baltic: An ecotoxicological perspective

This in situ study is focusing on the distribution, biotransformation and flux of 19 polycyclic aromatic hydrocarbons (PAH19) in the food chain seston‐blue mussel (Mytilus edulis L.)‐common eider duck (Somateria mollissiima L.) as well as the distribution in the gallbladder, liver, adipose tissue and egg of the duck. All samples were collected within the open northern Baltic proper coastal areas. Analyses were carried out by gas chromatography/mass spectrometry with electron impact (GC‐MSEI) and negative ion chemical ionization (GC‐MSNICI). With a multivariate statistical method (SIMCA) a significant change in the PAH composition through the food chain was found. This change probably depends on an increasing metabolic activity with increasing trophic level, due to a selective biotransformation capacity for different PAHs. Decreasing PAH concentrations with increasing trophic level were found. The PAH concentrations in the different eider duck organs were: gallbladder > adipose tissue ≥ liver. The theoretical inhalation of air‐dispersed PAHs was of no significance compared to the exposure from food. The relatively high theoretical PAH flux through the food chain did not result in increasing concentrations with increasing trophic level, which indicates that PAHs are biotransformed quite fast. However, many intermediate metabolites of PAHs have a mutagenic and carcinogenic potential, which makes it important to observe these compounds when assessing ecotoxicological risks

Endocrine disruption in brook trout (Salvelinus fontinalis) exposed to leachate from a public refuse dump

Lake Molnbyggen was previously found to harbour a large number of sexually immature female perch (Perca fluviatilis) suffering from endocrine disruption. In an attempt to pin-point the source of the endocrine-disrupting substance(s) (EDSs), brook trout (Salvelinus fontinalis) from Vadbacken, a stream contaminated by leachate from a public refuse dump and which empties into Lake Molnbyggen, were investigated. In addition, female perch from Lakes Yxen and Kvarntjarn, located up-stream and down-stream of Lake Molnbyggen, were investigated. Only 16.7% of the adult female brook trout in Vadbacken were sexually mature, associated with decreased gonadosomatic index, lower brain aromatase activity, and lower circulating levels of testosterone and 17beta-oestradiol, in comparison to female brook trout from the reference stream Bjorntjarnsbacken. Male brook trout showed decreased gonadosomatic index, in addition to bile duct hyperplasia in the liver, which was also found in female brook trout livers from Vadbacken. In Lake Molnbyggen, 57.6% of the female perch were found to be sexually immature with high frequencies of skin lesions, such as sores and fin erosion, significantly decreased gonadosomatic index, lower aromatase activity, and lower levels of testosterone and 17beta-oestradiol. No signs of reproductive disorders or endocrine disruption were seen in female perch from Lakes Yxen and Kvarntjarn compared to female perch from the reference lake, Lake Djursjon. Since brook trout of both sexes from Vadbacken displayed the same kind of serious adverse impairment of gonad development and endocrine disruption as perch from Lake Molnbyggen, very strong evidence are provided that the refuse dump is the source for the responsible EDS(s), since both Vadbacken and Lake Molnbyggen are known to be contaminated by leachate from that dump. The low levels of PAHs and PCBs in the surface sediments of Lake Molnbyggen suggest that these pollutants are not the responsible EDS(s)

Radiocarbon ages and major n-alkane homologues of peat cores LVPS4 and LVPS5B, Russian Arctic

Coupled analyses of n-alkane biomarkers and plant macrofossils from a peat plateau deposit in the northeast European Russian Arctic were carried out to assess the effects of past hydrology on the molecular contributions of plants to the peat. The n-alkane biomarkers accumulated over 9.6 kyr of local paleohydrological changes in this complex peat profile in which a succession of vegetation changes occurred during a transition from a wet fen to a relatively dry peat plateau bog. This study shows that the contribution of the n-C31 alkane from rootlets to peat layers rich in fine and dark roots is important. The results further indicate that the n-alkane Paq and n-C23/n-C29 biomarker proxies that have been useful to reconstruct past water table levels in many peat deposits can be misleading when the contributions of Betula and Sphagnum fuscum to the peat are large. Under these conditions, the C23/(C27 + C31) n-alkane ratio seems to correct for the presence of Betula and S. fuscum and provides a better description for the relative amounts of moisture. The average chain length (ACL) n-alkane proxy also appears to be a good paleohydrology proxy in having larger values during dry and cold conditions in this Arctic bog setting