187 
6.4.1.4 Discussion 
This is the first time that chlorpyrifos has been detected in the marine environment, 
including concentrations above the LOQ. Although samples from the marine 
environment of the North Sea and Baltic Sea contained no chlorpyrifos-methyl, the 
homologue ester chlorpyrifos-ethyl was identified in most water and biota samples from 
those areas. Positive findings were less frequent in sediment samples. The 
concentrations found in water and sediments were very low, with a median of 26 pg/L 
in water samples, and 9 ng/kg dw in sediments. Considerable bioaccumulation was 
observed in fish liver. The concentrations found in the different matrices are shown in 
Figure 39. 
100000000 
10000000 
1000000 
100000 
O) 
O) 
Q- 
- 10000 
-I 
O) 
1000 
100 
10 
1 
Figure 39: Summary of chlorpyrifos-ethyl concentrations in different marine matrices; min - max range 
and median values 
Based on these data, the enrichment from water to sediment is calculated at about 350, 
that from water to biota (fish liver) at about 14000 (wet weight) and 62000 (lipid 
weight). The relatively low enrichment is in accordance with the moderate log Kow 
value of 3.6 - 4.5. 
— Chlorpyrifos-ehtyl 
< 
X 0.36|ag/kg 
1— ww 
i 9 ng/kg dw 
STTt — 
► 26 pg/L 
— 
— 
— 
Water Sediment Biota (ww) Biota (Iw) 
The distribution pattern and low concentrations observed in water from the North Sea 
and Baltic Sea is best explained by a general low-level background burden with a few