Occurrence, distribution and ecological risk assessment of the herbicide simazine: A case study

The occurrence and distributions of simazine, and its environmental behaviors were studied in Taizi River, China. Results showed that concentration of simazine in surface water and suspended solids (SS) were in the range of 35-1150 ng L^-1and 0.00-1075 ng g^-1 with mean value of 240.26 ng L^-1 and 311.68 ng g^-1, respectively. A significant correlation between the concentrations of simazine and organic carbon was observed in both surface water and SS (r₁ = 0.82, n₁ = 15, r₂ = 0.68, n₂ = 10). and organic carbon in SS was more adsorptive to simazine. Moreover, the concentrations of simazine in groundwater were negatively correlated to the well depths and the distances to the corn fields, and higher concentration of simazine corresponds to younger groundwater. The criterion continuous concentration (CCC) of simazine to Chinese native aquatic species was derived based on the species sensitivity distribution (SSD) to assess the ecological risk. The CCC for simazine was derived to be 4.8 μg L^-1. Furthermore, Ecological risk assessment through risk quotient (RQ) showed that simazine presented low risk (RQ < 0.1) in some of sampling sites, while simazine posed medium risk (0.1 < RQ < 1) only on a few sampling sites nearby corn fields. The study contributed a better sight on the presence of simazine in river and its ecological risk to native aquatic species, and provided information for further studies of simazine potential hazards to the aquatic ecosystem.