Occurrence, phase distribution and depositional intensity of dichlorodiphenyltrichloroethane (DDT) and its metabolites in air and precipitation of the Pearl River Delta, China

Concentrations of dichlorodiphenyltrichloroethane (DDT) and its metabolites (designated as DDTs, the sum of o,p′- and p,p′-DDT, o,p′- and p,p′-DDE, and o,p′- and p,p′-DDD) in air and precipitation from the Pearl River Delta (PRD) of China were determined. Total concentrations of DDTs in air (gas+particle) and precipitation (dissolved+particle) were 170±120pgm−3 and 940±180pgL−1 for Dongguan (rural) and 240±120pgm−3 and 790±140pgL−1 for Shunde (rural), respectively, while they were 1550±640pgL−1 in precipitation from Guangzhou (urban). Log-transformed partition coefficients between air and particulate organic matter (logKoa′) of p,p′-DDT, p,p′-DDE, p,p′-DDD, o,p′-DDT, o,p′-DDE, and o,p′-DDD were 9.64±0.58, 10.07±0.56, 9.90±0.76, 10.06±0.66, 10.02±0.72, and 10.13±0.57, respectively; while those between water and particulate organic matter (log Kom′) were 6.58±0.66, 6.36±0.53, 6.01±0.62, 6.41±0.42, 5.98±0.76, and 5.95±0.66, respectively. Total washout ratios by bulk rainfalls ranged from 4600 for o,p′-DDT to 54,000 for p,p′-DDT. Estimated average dry particle and wet depositional intensities in the PRD were 2.1×10−6 and 1.6×10−6gm−2y−1.