184 
Appendix 6.6.8) Concentrations of chlorpyrifos-methyl were below the LOD in all 
sediment samples from the German Bight and western Baltic Sea. 
Chlorpyrifos-ethyl was found at concentrations from < 10 to 33 ng/kg dw with a median 
of 9 ng/kg dw. About 43 % of the determinations were < LOD. This rendered the 
interpretation of data more difficult. 
The geographical distribution of the insecticide in the North Sea and Baltic Sea is 
shown in Figure 37. In the German Bight, the substance was determined only at stations 
characterised by higher silt levels and TOC values above 3 mg/g. Remarkably, values as 
low as 5 to 14 ng/kg dw were even found at KS 11, the station which normally has the 
highest contamination level. The limited amount of data does not, however, allow a 
statistically valid interpretation of the geographical distribution in terms of spatial 
gradients or input structures. 
Concentrations in the western Baltic Sea were even lower than in the German Bight. 
4 5 6 7 8 9 10 11 12 13 14 15 
56 
55 
54 
ng/kg dw 
-40 
-20 
- 0 
53 
53 
4 
5 6 7 8 9 10 
11 
12 
13 
14 
15 
Figure 37 : Chlorpyrifos-ethyl concentrations [ng/kg] in surface sediments (0-2 cm) 
The estimated “enrichment” of chlorpyrifos-ethyl in sediment as compared to the water 
phase is less than 1000. This means that sediment is not a major sink for this compound 
and will not be a good monitoring matrix.