Reshuffling the risk values of pesticides in surface-groundwater systems: Evidence from mining intensity and hydrogeological vulnerabilities

The extensive application of pesticides in agricultural cultivation and crop maintenance has resulted in their widespread occurrence and accumulation across diverse environmental media. This study screened >52 target pesticides occurs in both surface and groundwater, including 16 carbamates, 8 triazines, 6 triazoles, 4 chloroacetanilides, 3 neonicotinoids, 3 pyrazoles, 2 morpholines, and 10 other types of pesticides within the Wulong River Basin, situated on the Shandong Peninsula in China. The target pesticides in surface water ranged from below the limit of quantification (LOQ) to 111.2 ng/L, whereas in groundwater, they ranged from below LOQ to 148.1 ng/L. 63 % (p < 0.05) of the target pesticides follow the migration rule, where the concentration in surface water appears exceeded groundwater. 37 % overcome the pesticide properties and aquifer intrinsic vulnerability and show higher values in groundwater. The risk quotient values for imidacloprid and atrazine exceeded 1 at 86 % of the sampling sites, indicating a high level of chronic ecological risk to aquatic organisms. The assessment of pesticide mixtures posed 15 % to 24 % higher risk levels to aquatic organisms compared to individual pesticides. While the non-carcinogenic risks associated with groundwater across all age groups were below the threshold of 1, there was a significant potential carcinogenic risk, particularly for children, warrants due attention. This study provides a new perspective for the systematic analysis of surface-groundwater systems and identify the exposure potential of pesticides in different water bodies and generate priority levels for risk assessment.