Contamination Elbe river derived

Di- and trichlorinated benzenes were detected not only at sample sites mainly influenced by the Elbe river but also at sampling sites G and D, which are mainly influenced by input of the Ems river, with similar concentrations as in samples E and F (see Tab. 2). Hence these lower substituted compounds, which are used as synthetic raw material for many technical products such as antiseptic agents, solvents and additives (Biyant, 1993), are not appropriate marker compounds for tracing Elbe river derived contaminations. In contrast the tetra- to hexachlorinated benzenes, which have formerly been identified as contaminants in particulate matter of the Elbe river system (Schwarzbauer 1997, Schwarzbauer et al. 2001), appeared in the North Sea sediments only at sampling sites A,B,C,E and F (see Tab. 2). Fig. 1 illustrates the spatial distribution of hexachlorobenzene with concentrations between 2 and 50 pg/kg TOC in samples influenced by the Elbe river. 

All anthropogenic land-derived contaminants described above are mainly introduced to the coastal sediments by atmospheric deposition and in higher quantity by riverine contributions. But these compounds can only be linked to multiple sources or widespread technical use and are therefore inappropriate to assess the discharge of the Elbe river to the German Bight. 

The concentrations of tetrabutyl tin range from 130 pg/kg TOC at sample site B to 14 pg/kg TOC at sample sites E and F and is below the LOQ at sample site D. The emission of this well known Elbe-specific compound was formerly linked to an industrial point source situated near the confluence of the Mulde and the Elbe rivers (Wilken et al., 1994, Schwarzbauer, 1997). Mono- and disubstituted chloronaphthalenes were also detected with concentrations between the LOQ at sample sites not influenced by Elbe derived contaminations and 70 and 100 pg/kg TOC at sample site B. These low chlorinated naphthalenes occur in the sediments with patterns similar to those of technical agents (e.g. Halowax 1000) and were formerly identified with comparable isomer distributions in sediments of the Elbe river and its tributaries (Schwarzbauer 1997, Schwarzbauer et al. 2001). On the contraiy the origin of the Elbe specific contaminant 4,4 -d ic h Iorodiphcnylsul tidc detected at sample sites A,B,C,E and F with concentrations ranging from 7 to 45 pg/kg TOC is still unknown. 

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