Transformation and sorption of 1,2-dibromo-3-chloropropane in subsurface samples collected at Fresno, California
Deeley, G.M. | Reinhard, M. | Stearns, S.M.
The transformation rate of 1,2-dibromo-3-chloropropane (DBCP) was determined in phosphate buffer solution, in groundwater, and in groundwater/aquifer solid slurries from ambient temperatures to 72 degrees C. From the disappearance data, the apparent Arrhenius constants for DBCP transformation were calculated and found to decrease in Ea with temperature from 19.2 (plus or minus 2.4) kcal mol-1 in the 55 to 72 degrees C range to 12.5 (plus or minus 1.8) kcal mol-1 in the 21 to 55 degrees C range. Low sorption values were an indication that sorption does not play a major role in the aquifer being studied. No significant difference in the disappearance rates was observed in the buffer solution (corrected for buffer effects) and in groundwater with and without solids added. However, in the phosphate buffer solution, dehydrohalogenation appeared to be the favored transformation process in contrast to the groundwater systems where hydrolysis seemed to predominate. This apparent influence of dissolved constituents or temperature on transformation mechanism or rate may restrain the use of direct extrapolation of data between systems. Applying the transformation data from this study to median field parameters, a DBCP half-life of 6.1 yr was calculated for typical groundwater conditions in California (pH 7.8 and 21.1 degrees C).
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