A review of spatiotemporal patterns of neonicotinoid insecticides in water, sediment, and soil across China.

Neonicotinoid insecticides (NNIs) have been widely used to control insect pests, while their environmental residues and associated hazardous impacts on human and ecosystem health have attracted increasing attention worldwide. In this study, we examined the current levels and associated spatial and temporal patterns of NNIs in multiple environmental media across China. Concentrations of NNIs in surface water, sediment, and soil were in the range of 9.94-755 ng·L, 0.07-8.30 ng·g DW, and 0.009-356 ng·g DW, respectively. The high levels of NNIs in surface water, such as in Yangtze River (755 ng·L), North River (539 ng·L), Nandu River (519 ng·L), and Minjiang River (514 ng·L), were dominated by imidacloprid, thiamethoxam, and acetamiprid due to their extensive use. The levels of NNIs in sediments were relatively low, and the highest concentration (8.30 ng·g DW) was observed in Dongguan ditch. Sediment-water exchange calculated from fugacity fraction indicated that NNIs in sediment can be released back into the water due to their high solubility and low K. Soils from agricultural zones contained the largest residual NNIs, with imidacloprid concentrations in cultivated soil reaching 119 ng·g DW. The calculated leaching potential showed that clothianidin has the highest migration potential to deep soil or groundwater. The monitored data of NNIs presented a decreasing trend from 2016 to 2018, which might be caused by the implementation of relevant control policies for NNI applications. The high levels of NNIs mainly occurred in southern China due to frequent agricultural activities and warm and humid meteorological conditions. The results from this study improve our understanding of the pollution levels and environmental behavior of NNIs in different environmental media across China and provide new knowledge that is needed for making future control policies for NNIs production and application.