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• At least one neonicotinoid was detected in all soil, water and sediment samples. • Transport of raw agricultural products could be a source of NEOs in urban areas. • Pollution of NEOs in rural areas was significantly higher than that in urban areas. • Correlation and migration of NEOs residue in soil-water-sediment systems were studied. • Exposure to the current NEOs residue level of Guangzhou suggests a serious threat to sensitive non-target invertebrates. Residues and distribution of neonicotinoid insecticides (NEOs) in soil-water-sediment systems of the urban and rural areas of Guangzhou, South China were investigated. A total of 104 soil samples from 7 different functional zones and 29 water/sediment samples from creeks were collected. The results showed that at least one neonicotinoid insecticide was detected in all samples. The summed levels of five target neonicotinoids (∑ 5 neonics) were in the range of 0.003–229 ng/g dw for soil samples, 7.94–636 ng/L for water samples, and 0.017–31.3 ng/g dw for sediment samples, with a geometric mean of 0.59 ng/g dw, 153 ng/L and 1.11 ng/g dw, respectively. Soils from agricultural areas contained the highest residual NEOs, followed by commercial, traffic, residential, industrial, educational zones and parks. Among the seven different functional zones studied, imidacloprid was the most dominant NEO in the agricultural areas and commercial zones, whereas acetamiprid was dominant in the other five functional zones with different land-use types. Thiamethoxam and acetamiprid were the main NEOs in water and sediment samples collected from 29 creeks. The pollution of NEOs in soils, water and sediments from rural areas was higher than that in the counterparts from urban areas. Residual concentration of NEOs detected in soils, water and sediments showed significant correlations with each other. The distribution of NEOs in soil-water-sediment systems indicated that NEOs tended to concentrate in water, followed by sediments and soils, especially in urban areas. An evaluation of the exposure to the current level of the ∑ 5 NEOs in Guangzhou suggests a significant risk for aquatic and soil organisms, particularly under chronic exposures. The results of the present study offer valuable data to better understand the contamination and ecological risks of neonicotinoid insecticides in the rapidly developing urbanized region of South China. [ABSTRACT FROM AUTHOR]

The residue levels and composition profiles of phthalate acid esters (PAEs) in water and sediment samples were investigated in eight urban lakes of Guangzhou, China. A total of 23 water and 16 sediment samples were collected. Results showed that all target PAEs were detected with dimethyl phthalate and di(2-ethylhexyl) phthalate as the most abundant compounds. The total concentrations of PAEs from different urban lakes were in the range of 273–1173 ng/L for water and 16.5–242 ng/g for sediments, with the geometric mean of 515 ng/L and 75.0 ng/g, respectively. Zhongshan Park Lake and Liwan Lake were the most highly contaminated with PAEs in water and in sediment, respectively. The spatial distribution of PAEs exhibited that distribution coefficients of PAEs between sediment and water are consistent with hydrophilicity of PAEs, and pollution levels and characteristics of PAEs in different lakes had a close relationship with the geographical location of the lake, industrial and commercial types, population density, and the association between the lake and the Pearl River. According to Pearson correlation analysis, PAEs would be derived from similar or identical sources. Risk assessment suggested that the exposure of PAEs in Guangzhou has a moderate toxicity at the current level. [ABSTRACT FROM AUTHOR]