| At present,application of large number of chemicals lacking toxic information results in their occurrences in aquatic environment and risks for ecosystem and human.Therefore,more and more scientists were paid to the potential threat of these chemicals to water quality.In this study,a high-throughput non-target analysis was employed to screen organic compounds in water samples collected from Yongding River Basin,including Guanting Reservoir,Guishui River,Sang-kan River,Yang River and Yongding River.Some of detected compounds were selected to be quantified and assessed for their risks.The compounds with potentials ecological risk were finally identified in the basin.The study is significant for screening organic compounds in water samples and risk assessment for ecosystem and human.Firstly,a high throughput screening method was applied to screen organic compounds in water samples by GC×GC-TOF-MS.The qualitative results of non-target screening revealed that the composition of organic compounds were similar among the sampling sites.The main detected compounds included esters,ketones,alkanes,alcohols,polycyclic aromatic hydrocarbons,pesticides and chlorobenzene.An average of 708,1,549 and 1,230compounds were detected in the Guanting Reservoir,Yang River and Guishui River,respectively.There were 35 kinds of pollutants,including 1,2-dichlorobenzene,1,2-dimethyl butyl phthalate,1-eicosanol,heptacosane,various organophosphorus pesticides and polycyclic aromatic hydrocarbons,which were detected in all of the sampling sites.Then,according to the results of non-target screening,51 compounds including 14OCPs,9 OPs,16 PAHs and 12 CBs were quantified with GC-MS.The results were as follows.1)OCPs:The concentrations of OCPs were generally low compared to the reported rivers before.The residual levels of OCPs were N.D.-35.62 ng/L in Guanting Reservoir,N.D.-39.11 ng/L in Guishuihe River,N.D.-27.82 ng/L in Sang-kan River,2.88-104.06 ng/L in Yang River,N.D.-306.41 ng/L in Yongding River,respectively.2)OPs:Except DMO,8OPs were detected at all sampling sites in the studied area.The concentrations of OPs were N.D.-1054.66 ng/L in Guishui River,399.12-799.64 ng/L in Sang-kan River,47.92-998.25ng/L in Yongding River,344.68-677.37 ng/L in Yang River,209.72-603.14 ng/L in Guanting Reservoir,respectively.It was presumed that the Guishuihe River may be an important source of OPs for the waters of the Guanting Reservoir.The concentrations of OCPs were 292.72-603.14 ng/L in eastern and 209.72-577.51 ng/L in the west,which further explains the impact of Guishuihe River on OPs in the eastern part of Guanting,while the western part of the Guanting Reservoir was affected by the Yang River and the Sang-kan River.3)PAHs:The residual levels of PAHs were 36.90-44.97 ng/L in Sang-kan River,17.52-30.70 ng/L in Yang River,N.D.-22.10 ng/L in Guishui River,7.77-23.84 ng/L in Yongding River,N.D.-19.85 ng/L in Guanting Reservoir,respectively.Compared to the studied before,the concentrations of this study were lower.4)CBs:The concentrations of CBs were detected in the range of 98.66-264.56 ng/L in Yongding River,9.48-218.40 ng/L in Guanting Reservoir,124.61-191.62 ng/L in Sang-kan River,79.62-175.68 ng/L in Yang River and 10.27-124.60 ng/L in Guishui River.Compared to the existing research in China,the CBs concentrations in this study was at a low concentration level.Finally,a risk-based method was developed to prioritize compounds in aquatic environment.ECOSAR model was employed to directly predict the integrated toxicity indexes of 51 organic pollutants with over 60%detection rate from their structure parameter in the study.Among these compounds,48.08%were highly toxic pollutants,35%were toxic pollutants and 5.3%were harmful.The RQ values of most of the organic compounds in the water samples were acceptable for their ecological risk.However,POT,PTM and PAT showed high ecological risks to Otter.Using the models of carcinogenic and non-carcinogenic to assess the health risk of the water,it was concluded that the non-cancer risk values of the target pollutants in this study area were below the limit of 1,and the carcinogenic risk value was lower than 10-6,indicating an acceptable level of risk.The principle component analysis was used to calculate integrated toxicity indexes of 5 risk indexes based on the toxicity data from the ECOSAR model.The results showed that the priority monitoring pollutants were DTT,DDVP,CPF,Acy,Ace,MTO in surface water of the area. |
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