Applications of Chemical Kinetics in Environmental Systems - Elements of Environmental Engineering: Thermodynamics and Kinetics - page 396

Alewife

15

10

5

0

1 2 3 4 5 6

Age class (year)

Lake trout

25

20

15

10

5

0

0 1 2 3 4 5

Age class (year)

6 7 8 9 10

FIGURE 6.72 Comparison of observed PCB concentrations in alewife and lake
trout. (Reprinted from Thomann, R.V. and Connolly, J.P. 1984. Environmental Science
Technology 18, 68, American Chemical Society. With permission.)

For any species i in the food chain, we have the following rate equation (Connolly
and Thomann, 1992):

rate of increase in body burden = rate of sorption + rate of uptake by ingestion

of lower species − rate of excretion.

Let [A] org, i be the whole weight body burden in the i th species (mol/organism) and
is given as

] org, i W org, i . The rate of sorption is given by the product of the uptake
rate constant for species i , the organism weight, and the aqueous concentration of the
chemical, that is, k si W org, i [

[ A

] w . This is analogous to oxygen uptake from water. k si
has units of dm 3 /d kg of organism. An expression for k si is 10 − 3 W i E/

A

ϕ i , where w i is

the total weight of organism i and ϕ i is the fraction of lipid content (kg lipid/kg wet