Question

A 10 kg eagle eats 0.5 kg/day of trout containing 0.1 ppm of PCBs.
a. assume eagle excretes all PCBs with first order rate constant 0.01 /day. estimate steady state PCBS concentration in eagle. 
b. PCBs from an eagle are analyzed and found to contain a high ratio of highly chlorinated to less chlorinated congeners compared with the ratio expected on the basis of known Industrial discharges. what are two plausible explanations

Answer 1

a.

Rate of PCBs concentration in = 0.5 * 10⁶ * 0.1 * 10^-6 = 0.05 mg/day

At steady state, Rate of PCBs concentration out = Rate of PCBs concentration in

k = 0.01 day^-1

For a first order reaction:

k[PCBs] = Rate of PCBs concentration in

[PCBs] = 0.05/0.01 = 5 mg

b.

1) One explanatioon could be different rate constants of highly chlorinated and less chlorinated congeners from eagle. Rate constant of highly chlorinated congener is lower than less chlorinated congener.

2) Less chlorinated congener is consumed more within the eagles body than highly chlorinated congener.