Distribution of DDT residues (DDT,DDD, and DDE) in California soils

DDT residues (DDT, DDD, and DDE, or DDT_R) occur in detectable concentrations in soils from southern California over 20 years after a ban (1973) on the widespread use of the pesticide in the U.S. A comparison of DDT residues found in soils from western Riverside/San Bernardino Counties to a much larger statewide database of Mischke et al. (1985) suggests that a systematic regional variation in relative abundances of DDT_R exists in California soils. It is suggested that factors such as physical/chemical properties of DDT residues, local/regional soil‐forming processes, soil management practices, and climatological regimes may help to explain the observed relative abundances of DDT‐related species in California soils. Knowledge of regional trends in the concentrations and composition of soil DDT_R may be useful in formulating more rational risk‐based soil management strategies where soil DDT_R concentrations are at or above regulatory levels.