I2 TOXIC CONTAMINATION 1972-1979

Average concentration of insecticides in the lake ecosystem [micro (dry wt.)g- 1]

   Description    No. sampl   DDE   Dieldrin    DDD      DDT     Total insecticides
Water                10     0.0001   <0.0001  <0.0001  <0.0001         <0.0002
Bottom sediments     10      0.015    0.004    0.04     0.002           0.061
Plankton             5*1     0.01     <0.01    0.02     0.02            0.06
Oligochaetes         1*1     0.18     0.08     0.33     0.14            0.73
Benthic insects      1*1     0.13     <0.01    0.12     0.11            0.36
Fish
- Dwarf bream        5*2     0.12     0.07     0.16     0.04            0.39
- Spot tail          5*2     0.24     0.04      0.1     <0.01           0.38
- Greenheaded brea   5*2     0.08     0.03      0.1     <0.01           0.22
- Greenheaded brea   5*3     0.13     0.12     0.18     0.14            0.57
Bird
- Cormorant carcas   10       110     0.92     0.81     0.27             130

*1 Each sample consists of a composite collected from all over the lake. *2 Each sample consists of a composite of 10 fish ranging in weight from 6 to 40 g. *3 Individual fish ranging in weight from 578 to 824 g.