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Neonicotinoid (NEO) insecticides have been frequently detected in natural aquatic environments. Nevertheless, the distribution of NEOs in artificial environments is not clear. The Beijing-Hangzhou Grand Canal is the longest canal in the world. The northern Jiangsu segment of the Grand Canal was selected to study the spatiotemporal variation and source of eight NEOs in the canal water and assess their ecological and health risks. The total NEO concentration in the canal water was 12-289 ng L -1 in the dry season and 18-373 ng L -1 in the wet season, which were within the concentration range in other 11 natural rivers worldwide. The average total NEO concentrations were not statistically different between the seasons; only the concentrations of imidaclothiz, thiacloprid (THI), acetamiprid, and dinotefuran were different. At city scale, the total NEO concentration in the dry season showed a decreasing trend along the water flow from Xuzhou City to Yangzhou City. The total NEO concentrations were found to be positively correlated with the sown area of farm crops and the rural labour force, indicating the agricultural influence on the spatial distribution of NEO concentrations. In the wet season, relatively high NEO concentrations were distributed in downstream sites under the influence of artificial regulation. The primary contributor to the NEO inputs into the canal was the nonpoint source in the dry and wet seasons, with a relative contribution of 68 %. THI, imidacloprid, clothianidin and thiamethoxan would produce chronic ecological risks in both seasons. Further consideration needs to be given to the above four NEOs and NEO mixtures. The human health risks that NEOs posed by drinking water were assessed based on the chronic daily intake (CDI). The maximum CDI for adults and children was lower than the reference doses. This suggested public health would not be at risk from canal water consumption., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Contamination of trace metals in urban rivers is a global problem. The objective of this study was to investigate the contamination and ecological risks of trace metals in the Hai River, which receives substantial effluents from the Beijing-Tianjin region. A total of 43 surface water and sediment samples were collected and analyzed for physiochemical properties and toxic elements. The concentrations of Cd, Cr, Ni, Pb, Cu and Zn in the river water met the Chinese environmental quality grade I standards for surface water. The average total concentrations of Zn, Cr, V, Cu, Pb, Ni, Co, Sc and Cd in the sediments were 144.2, 77.5, 70.1, 46.1, 40.1, 29.6, 12.4, 9.9 and 0.26 mg/kg, respectively. The enrichment of Cd, Cr, Cu, Pb and Zn in the sediments was influenced by anthropogenic activity, as indicated by the enrichment factor (EF) and multivariate analysis. The concentrations of Co and Cr in the sediments were predominantly in residual fractions, while relatively higher amounts of Cd, Pb, Zn and Cu were in non-residual fractions. There was a significant correlation between concentrations of Cd, Co, Cr, Cu, Pb and Zn in non-residual fractions and their corresponding EF values (P < 0.01). This result further demonstrated that anthropogenic inputs were an important contributor to metal enrichment. The high bioavailability of Cd and poor bioavailability of Co and Cr in the sediments were demonstrated by the single extraction procedure. The significant correlation between concentrations of Cd, Cu, Pb and Zn in non-residual fractions and their concentrations in EDTA-extractable fractions was established (P < 0.01). This result indicates that single-step EDTA extraction may represent a useful procedure for assessing the bioavailability of Cd, Cu, Pb and Zn in riverine sediments. The ecological risks of the metals studied in the Hai River sediments were at a low level, dominated by the risks imposed by Cd., (Copyright © 2018 Elsevier Inc. All rights reserved.)