Seawater quality criteria derivation and ecological risk assessment for the neonicotinoid insecticide imidacloprid in China

As a broad-spectrum nicotinoid insecticide, imidacloprid (IMI) has been frequently recorded in seawater environments. Water quality criteria (WQC) is the maximum concentration of chemicals, which will not pose harmful effects on aquatic species in the studied water body. Nevertheless, the WQC is not available for IMI in China, which hinders the risk assessment of this emerging pollutant. This study, therefore, aims to derive the WQC for IMI through the toxicity percentile rank (TPR) and species sensitivity distribution (SSD) methodology, and to assess its ecological risk in aquatic environments. Results showed that the recommended short-term water quality criterion (SWQC) and long-term criterion (LWQC) in seawater were derived as 0.8 μg/L and 0.056 μg/L, respectively. The ecological risk of IMI in seawater shows a wide range with hazard quotient (HQ) values of up to 11.4. The environmental monitoring, risk management and pollution control for IMI, therefore, warrant further study.