The Spatial Variation in Organotin Contamination in Different Environmental Media: A Case of the Lower Yangtze River in China

With the global ban on tributyltin (TBT), the pollution of triphenyltin (TPhT) is an emerging issue in some aquatic ecosystems. In this study, we investigated the concentrations of typical butyltin and phenyltin compounds in the surface water and sediments in the lower Yangtze River, analyzed their occurrence and sources, and assessed their ecological risks. The findings indicate that butyltin and phenyltin compounds are widespread. The total concentration of organotin compounds in surface water was as high as 42.41 ng Sn/L, with an average of 25.71 ng Sn/L, and the total concentration of organotins in sediments reached up to 111.5 ng Sn/g dw, averaging 61.1 ng Sn/g dw. Since the implementation of the AFS Convention, the concentration of organotins in surface water has been significantly reduced. However, the ecological risk of TBT is still high, and the risk of TPhT is also noteworthy. The findings also suggest that the primary source of butyltins in the lower Yangtze River is historical input residues. In contrast, the main source of PhTs is the recent input of agricultural runoff. Therefore, organotin contamination in the lower Yangtze River has changed, but its governance still presents challenges.