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 ± 120 pg m−3 and 940 ± 180 pg L−1 for Dongguan (rural) and 240 ± 120 pg m−3 and 790 ± 140 pg L−1 for Shunde (rural), respectively, while they were 1550 ± 640 pg L−1 in precipitation from Guangzhou (urban). Log-transformed partition coefficients between air and particulate organic matter (log Koa′) 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 × 10−6 g m−2 y−1.

► Levels of DDTs in both air and rain are higher in urban area than in rural area of the Pearl River Delta.
► Fresh DDTs occur in the atmosphere, likely from both technical DDTs and dicofol.
► Dry and wet depositional fluxes of DDTs are comparable in the Pearl River Delta.