Neonicotinoid Insecticides Threaten Surface Waters at the National Scale in China

Abstract

This study was conducted in response to the current situation in our country in which neonicotinoid pesticides (NNIs) are used in large quantities and their concentration in surface water is gradually increasing. Based on the species sensitivity distribution (SSD), the hazard quotient (HQ) and probabilistic risk assessment (PRA) were used to compare single and mixture risks of NNIs in the surface water in China. The target and recommended values of NNIs in China's surface water quality supervision were also presented. The results showed that:① in the single acute hazard assessment, imidacloprid (IMI) was the most harmful insecticide, and in the single chronic hazard assessment, imidacloprid (IMI) and acetamiprid (ACE) were more harmful. Furthermore, insects were the most sensitive creatures. ② Hainan province was the region with the highest single acute and chronic hazard in the study area. ③ Based on the joint probability curves of five neonicotinoids, the probability in which 5% of species would be affected by long-term exposure was approximately 91.12%. Thus, the combined ecological risk of these five neonicotinoids cannot be ignored. ④ Based on the toxicity reference value from SSD and the combined results of HQ and PRA, the regulatory values of surface water quality in China were as follows:acetamiprid (ACE) 0.04 μg·L-1, clothianidin (CLO) 0.22 μg·L-1, imidacloprid (IMI) 0.01 μg·L-1, thiacloprid (THI) 0.03 μg·L-1, and thiamethoxam (THIA) 0.24 μg·L-1. In short, the concentration of NNIs in the surface water in China has threatened the safety of aquatic organisms, and its supervision must be improved.