Heterogeneous phototransformation of o,p′-DDT in four typical Chinese basins: Effects of suspended particulate matter composition and toxicity evaluation of intermediates

The photoreactions on suspended particulate matter (SPM) surface were a non-negligible environmental transformation process for hydrophobic organic pollutants in river water environments. Herein, SPM samples from four representative basins in China—the Yangtze River, Yellow River, Pearl River, and Haihe River—were chosen and focused on the effects of differences in the SPM composition on the phototransformation behavior of 2,4′-dichlorodiphenyl trichloroethane (o,p′-DDT). The experimental results demonstrated a lower light-screening effect, lower organic carbon content, and higher proportions of carbonate minerals and quartz components conducive to the photodegradation of o,p′-DDT on the SPM surface. The compositional characteristics of endogenous dissolved organic matter (DOM) also influenced the generation of reactive oxygen species (ROS) by SPM. Mass spectrometry analysis revealed that although the SPM from different basins did not alter the types of o,p′-DDT products, it influenced their yields. The estrogenic effects of the products were preliminarily assessed through molecular docking with the human estrogen receptor, and the phototransformation process on the surface of Haihe River SPM might have a more substantial estrogenic effect. These findings deepened the understanding of the regional differences in pollutant fate and might provide reference information for the management and regulation of pollutants in different regions.