DOI: http://dx.doi.org/10.1065/jss2004.04.100
Background, Goal and Scope. A large share of anthropogenic contamination of the coastal zone is a result of riverine contributions. Accordingly, the pollution of North Sea estuaries and coastal areas by organic xenobiotics is dominantly characterized by land-derived contamination. In a previous study, we identified a high number of organic contaminants in sediments of the German Bight emitted by industrial and municipal sources, primarily as a result of riverine contributions. Furthermore, a group of contaminants was identified representing Elbe-specific marker compounds.
However, quantitative analyses are more adequate to describe the source specificity via the spatial distribution as compared to qualitative analyses. Hence, in the present investigation, the determination of various anthropogenic contaminants has been performed in order to evaluate the proposed Elbe-specific marker compounds.
Methods. Numerous anthropogenic contaminants were quantified in seven surface sediment samples from the German Bight by means of gas chromatographic – mass spectrometric analyses. The analytical procedure includes extraction, removal of sulphur, fractionation, concentration and addition of internal standard.
Results and Discussion. Two groups of Elbe-derived contaminants were differentiated. Substances of the first group appear only at sampling locations directly influenced by the Elbe river and include hexachlorobutadiene and alkylsulfonic acid phenyl esters. The second group consists of compounds, which occur additionally in minor concentrations at sites situated at a greater distance from the coastal area, which are therefore only influenced to a minor degree by the Elbe river. However, their spatial and quantitative distribution characterizes them clearly as Elbe river-derived components. Compounds of the second group are tetra- to hexachlorinated benzenes, mono- and disubstituted chloronaphthalenes, tetrabutyltin, 4,4´-dichlorodiphenylsulfide and DDT related compounds
In order to discern the discussed Elbe marker compounds from non-marker substances, several nonspecific contaminants were analyzed additionally. These contaminants include galaxolide, tonalide, tri-n-butylphosphate, 2,4,4-trimethylpentane-1,3-dioldi-iso-butyrate and 2,2,4,4,6,8,8-heptamethylnonane. No significant accumulation of these compounds was observed at sampling locations mainly influenced by either the Elbe river, or the Ems and Weser rivers.
Conclusions. For the evaluation of the proposed Elbe marker compounds, the quantitative and spatial distribution was investigated and successfully discussed as the most important criterion to define their source specificity. Generally, these results illustrate how quantitative data on source-specific organic contaminants and the corresponding spatial distribution can be used to trace individual riverine contributions to the pollution of coastal areas. This approach might be especially useful to differentiate the contribution of several rivers discharging close together into the marine environment. Fingerprinting the individual riverine contribution additionally allows one to quantify the individual, river-derived contamination. Subsequently, the level of coastal zone contaminations can be reduced more effectively.
Further comprehensive analyses on numerous coastal and estuarine areas have to be done to support this approach. |
