Use the data provided below a) What would be the predicted concentration of DDT

Question

Use the data provided below

a) What would be the predicted concentration of DDT due to bioconcentration in the fat of fish that swim in waters containing 15 ppt of the chemical?

b) What would be the predicted concentration of malathion in the fat of fish that swim in waters containing 15 ppt of the chemical?

c) Draw the chemical structures of DDT and malathion. Comment on differences, and why their degrees of bioconcentration are different.

Pesticide Solubility in H2O (ppm) Log K0w Hexachlorobenzene 0.0062 5.5-6.2 DDT 0.0034 6.2 Toxaphene 3 5.3 Dieldrin 0.1 6.2 Mirex 0.20 6.9 Malathion 145 2.9 Parathion 24 3.8 Atrazine 35-70 2.2-2.7

Explanation / Answer

a..to calculate the concentration of chemical in the body of fish we need to calculate bioconcnetration factor(BCF) which is given by

6

also the relaton between BCF and log kow

log BCF = log kow -1.32

log BCF = 6.2-1.32=4.88

antilog of BCF to the base e is 132

so BCF= 132.

now according to the equation

BCF = conc of chemical in fish/ conc of chemical in water

now conc of chemical in water can calculated as conc of DDT × solubility in water

and 15 ppt will be 0.015 ppm so

=0.015× 0.0034= 0.000051

BCF×0.000051=0.0062 ppm= conc in fat of fish

b. similarly for methionine

BCF = 4.8

conc of malathion in water= 145×0.015=2.175

conc of malathion in fish= 4.8×2.175= 10.44 ppm

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