Nationwide scaling of neonicotinoid threats in China's aquatic ecosystems: Driven by anthropogenic perturbations and landscape patterns.

Neonicotinoid (NEO) contamination is widespread in China's aquatic ecosystems and has attracted increasing attention. However, nationwide and long-term assessments of NEO distribution remain limited. Therefore, 1443 field concentration records (2018-2023) were analyzed to investigate the distribution, ecological risks, and drivers of six priority NEOs (acetamiprid, imidacloprid, thiamethoxam, dinotefuran, clothianidin, and thiacloprid) in China's aquatic ecosystems. NEO concentrations peaked at 1022.2 ng/L in water and 33.1 ng/g in sediment, with median values of 4.2 ng/L and 0.5 ng/g, respectively. Spatially, NEO pollution was concentrated in China's eastern and southern coastal regions. Temporally, the highest average concentrations of the six NEOs were observed in 2020 for water (12.5 ng/L) and in 2021 for sediment (5.4 ng/g). Four NEOs (viz., imidacloprid, thiamethoxam, clothianidin, and thiacloprid) posed chronic ecological risks in water and sediment. The proportions of moderate-to-high risk sites for the four NEOs ranged from 26% to 56% in water and 19% to 52% in sediment. Furthermore, population density and insecticide application positively influenced NEO concentrations in water and sediment, whereas landscape patterns negatively influenced NEO concentrations in sediments. These findings provide a scientific basis for targeted environmental policy and risk mitigation.