< CaJ 



Q O 



CUMULATIVE WEIGHT OF SEDIMENT (g/cm2) 



oi O en 



at 



8 



O 



m 



z 



3 



O 



I I I I I I I I I I I I I I I I I I 



II 



0<a 



3 Q. 

 -I 



,1 I I I I I 



Ul- 



1 I 



J L 



o 





OJ OJ 



ro o 



en 



O 



J I ■ ' ' I I ' ' ' ' ' ' ' I I ■ ■ ■ 



en 



en 



SEDIMENT DEPTH (cm) 



Figure 1. Distribution of benthos and cesium-137 in a core from Lake Erie. 



In the absence of sediment mixing the expected distribution of cesium-317 



should reflect the history of atmospheric fallout (dashed line). The 



measured distribution is shown as the solid line histogram. The 



theoretical distribution shown as the continuous curve is based on the 



assumption of steady state mixing to a depth of 8.7 cm. The measured 



distribution of Oligochaete worms is consistent with this mixing depth. 



The results illustate the stratigraphic effects of benthos which are 



observed widely in the Great Lakes. 



203 



