Environmental Behavior And Environmental Risk Assessment Of Typical Endocrine Disrupting Chemicals In Water Environment

Water environment problem of basin has always been one of the important problems in China's environmental problems.China has high density population and the lack of water resources.The quality of water environment is related to the health of residents.The environmental risk assessment for water environment in the basin provide valuable reference and basis for the safety of ecology and residents in the basin.The Yinma River Basin in the study area is the largest tributary of the second Songhua River,and it is the domestic water and farmland irrigation water source in the basin.The water quality is related to the residents' life and production.Four typical endocrine disrupting chemicals(EDCs)including bisphenol A(BPA),4-teoctylphenol(4TO),estrone(E1)and diethylstilbestrol(DES)were selected as target pollutants.Seventeen sampling points were selected in the Yinma River Basin to investigate the seasonal-spatial distribution of four EDCs in water and sediments.Spatialized expression was performed by ArcGIS.Fugacity fraction was used to investigate the flux distribution in water-sediment system.Based on the background of three water season in the Yinma River Basin,migration and transformation mechanisms of BPA were studied by simulation experiments to investigate the season of BPA in air-water-sediment.The rate of migration and transformation provides parameters for Markov simulation.The actual migration of BPA in water environment is investigated by microcosm experiments.Compared with Markov simulation results to verify the model.BPA equivalent was employed to assess ecological risk of Yinma River Basin.Toxicity data of different trophic levels were collected for determining PNEC of BPA which was calculated by the evaluation factor method.Risk Quotient(RQ)was performed aquatic organism risk assessment in water and sediments of the Yinma River Basin.Geographical localization parameters of the residents was employed to calculate Hazard Quotient(HQ)for accurating assessment of human health risks.Based on the monitoring results of water and sediment samples of four EDCs in the Yinma River Basin.Concentration of EDCs are high in Changchun City,Shuangyang Administrative District and the sewage discharge outlet of the upper reaches.For the whole basin,the concentration of upstream is higher than the downstream in the three water seasons,both in water sediment.From the seasons,the total concentration of EDCs in water and sediment shows: dry season > normal season > wet season.The water-sediment equilibrium distribution results show that the four endocrine disruptors are close to equilibrium,and only E1 appears to migrate from sediment to water during the dry season.Through simulation experiments,the microbial degradation in volatiles and sediments and the adsorption and desorption of sediments in the water-gas-sediment system are the main migration and transformation mechanisms of BPA.There are seasonal differences.The rate shows: wet season > normal season > dry season.Results of the microcosm model of BPA also showed seasonal differences.After obtaining the rate of each migration and transformation mechanism,the numerical simulation of BPA by Markov chain model showed that after 500 hours of degradation,77.9% of BPA volatilized into the atmosphere during normal season,and 19.6% degraded by microorganisms in the sediment.BPA volatilized during wet season is about 90.5%,9.4% of BPA degraded by microorganisms in the sediment.In dry season,80.3% of BPA in water is degraded by volatilization and 11.8% were degraded by microorganisms in the sediment.After 500 hours of degradation,both water and BPA in the three water phases were degraded to negligible concentrations.In the three water seasons,the Markov numerical simulation is consistent with the microscopic experimental results,indicating that the model is accurate and effective.In three water seasons of Yinma River Basin,there are moderate ecological risks in water and high risks in sediments.Changchun City,Shuangyang District,Shitou Koumen Reservoir,the main stream of the Chalu River and the monitoring section at Yantongshan have higher ecological risks.The high ecological risks exist in the sampling points where E1 and DES are monitored.These high-risk areas and high-risk pollutants are the focus of future ecological monitoring and management.According to HQ values of four endocrine disruptors in different seasons of the Yinma River Basin and different target population,it can be seen that in three water seasons,four EDCs have no threaten to the human health of the basin residents.However,according to the HQ value,due to differences in daily drinking water and body weight,health risks of females are generally higher than male.The health of rural residents is susceptible in spring and autumn,and urban residents are susceptible to EDCs in winter.This topic provides guidance for the regulation and control of EDCs in the water environment of the Yinma River Basin and provides a basis for scientific suggestion for the management of EDCs.It fill the gap in the study of EDCs in the Yinma River Basin.The numerical simulation of Markov chain in the migration and transformation of organic pollutants is verified,which provides a new idea for the prediction of environmental behavior of endocrine disruptors.This study used the sensitive bio-toxicity data of the Yinma River Basin to determine the water quality benchmark,making the environmental risk assessment results more accurate and credible.The study has practical significance in ensuring the water environment of the Songhua River Basin and the living or production for residents.