The Research On Screening Of Priority Pollutants In The Water Environment And Potential Ecological Risk Assessment In Shaying River Basin

The Shaying River Basin is the sub-basin of the Huaihe River Basin with the most serious pollution problems.In recent years,the water environment quality of the Shaying River Basin has been improved with the advancement of national water environmental protection work.However,the amount of discharged pollutants and the total types of emissions also increased during the continuous advancement of urbanization and industrialization.The existing management methods are difficult to meet the requirements of continuous improvement of the water environment quality of the Shaying River Basin under the new normal.At present,the pollutants monitored in Shaying river basin are mainly conventional indicators,so it is difficult to realize the monitoring of all pollutants in the whole basin,and impossible to carry out targeted management on the pollutants that cause major pollution in the water environment.In this study,the spatial and temporal distribution characteristics of heavy metals and organic pollutants in the water environment of Shaying river basin were analyzed throμgh high-throμghput screening of heavy metals and organic pollutants in the water environment of 41 points in the Shaying river basin during the wet season,flat season and the dry season.Combined with the screening technology of EPA for prior control pollutant,a list of prior control pollutant in Shaying river basin was proposed,and environmental risks of some prior control pollutant were evaluated to provide support for water environmental management in the basin.The main findings of this paper are as follows:(1)Various types of semi-volatile organic compounds(SVOCs)in the surface water of the Shayji River Basin are at ng/L and μg/L levels,the Jialu River,Sha River,and Shuangyu River are seriously polluted.The content of pollutants in the flat season is higher than the other two seasons;the content of SVOCs in the sediment is between ng/g and μg/g levels,the Li River and Sha River are seriously polluted.The content of pollutants is basically following the sequence: dry season> wet season > flat season.As for volatile organic compounds(VOCs),53,46,and 46 kinds were detected in the surface water during the wet,flat,and dry seasons,respectively.The concentrations of each pollutant were between ng/L and μg/L and the content of pollutants in the flat season is higher than the other two seasons;21 and 47 kinds of VOCs were detected in the dry season and flat season in the sediment respectively.The concentrations of each pollutant were between ng/g and μg/g and the content of pollutants in the flat season is higher than the dry seasons.As for antibiotics,17,15 and 16 kinds of antibiotics were detected during the wet,flat,and dry seasons,respectively.The erythromycin and roxithromycin had the highest detection rates.The total antibiotic concentrations in each tributary and main stream are the highest in Jialu river while lowest in Li river and the content of antibiotics in the flat season is higher than the other two seasons.As for heavy metals,the area with high content in surface water is mainly located in the Jialu River.The content of Hg exceeded the Environmental Quality Standard for surface water(GB 3838—2002),and the content of heavy metals in the flat season is higher than the other two seasons;In the sediment,the content of heavy metals in Beiru River,Li River and Ying River are relatively high.The content of Hg and Cd exceeds the soil background value of Henan Province and the content of heavy metals in the flat season is higher than the other two seasons.(2)Using the superior pollutant screening technology of US EPA to rank the pollutants according to their comprehensive scores.A total of 40 priority pollutants in 8 categories has screened in the Shaying River Basin.They were 10 kinds of heavy metals,13 kinds of organic pesticides,3 kinds of substituted benzenes,9 kinds of halogenated aliphatic hydrocarbons,1 kind of aniline,1 kind of phthalates,2 kinds of polychlorinated biphenyls and 1 kind of polycyclic aromatic hydrocarbons.(3)The risk assessment in the aquatic environment for priority control pollutants selected in this study with heavy metals(chromium,copper,arsenic,lead,mercury,cadmium)and polycyclic aromatic hydrocarbons(benzo [a] pyrene)were conducted.The results showed that there is a certain ecological risk of heavy metals in the surface water of the Shaying River Basin.The main pollution factor causing the ecological risk is Hg and ecological risk in dry season is higher than in wet season and flat season.The heavy metals in the sediments are at high risk levels in all three periods,and the probability of ecological risks in the wet season is less than the other two seasons,the main pollution factors that cause ecological risks are Hg and Cd.Benzo [a] pyrene in surface water in the wet season of the Shaying River Basin has a higher ecological risk while the low possibility of risk in dry and flat season;the low potential ecological risk of benzo [a] pyrene in the sediment,but the probability of ecological risk at individual points is always the highest in the whole river basin which should be payed priority attention.