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SIZE DEPENDENT MODEL OF HAZARDOUS SUBSTANCES IN Q AQUATIC FOOD CHAIN
Citation:
Thomann, R. SIZE DEPENDENT MODEL OF HAZARDOUS SUBSTANCES IN Q AQUATIC FOOD CHAIN. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-78/036.
Description:
A model of toxic substance accumulation is constructed that introduces organism size as an additional independent variable. The model represents an ecological continuum through size dependency; classical compartment analyses are therefore a special case of the continuous model. Size dependence is viewed as a very approximate ordering of trophic position. The analysis of some PCB data in Lake Ontario is used as an illustration of the theory. A completely mixed water volume is used. Organism size is considered from 100 micrometers to 1,000,000 micrometers. PCB data were available for 64 micrometers net hauls, alewife, smelt, sculpin and coho salmon. The analysis indicated that about 30% of the observed 6.5 micrograms PCB/gm fish as the coho salmon size range is due to transfer from lower levels in the food chain and about 70% from direct water intake. The model shows rapid accumulation of PCB with organism size due principally to decreased excretion rates and decreased biomass at higher trophic levels.