ON THE DEGRADATION OF METHYL-BROMIDE IN SEA-WATER

Methyl bromide degradation in sea water can be described by a summatio n of the hydrolysis and chloride ion exchange reactions. Laboratory ex periments covered chloride concentrations of 0.1 to 1.0 mol/l, and tem peratures from 20 to 60 degrees C. The first-order hydrolysis rate con stant is k(H2O) = (5.7 +/- 0.6) x 10(11) e(-(12455+/-240)/T) sec(-1) a nd the second-order chloride ion exchange rate constant deduced from t he experiments is k(Cl-.) = (1.09 +/- 0.21) x 10(13) e(-(12724+/-560)/ T) 1/mol.sec. At a sea water surface temperature of 21.9 degrees C and a chloride concentration of 0.56 mol/l, the calculated degradation ha lf-life of methyl bromide in sea water is 4 days. At 35 degrees C, tau (1/2) = 22 hr.