Typical Emerging Pollution Characteristics And Risk Assessment Of Taihu Lake Basin

Emerging pollutants(ECs)are pollutants which have been newly discovered in the environment,or pollutants which have recently attracted attention although they have been recognized earlier.The existence,detection frequency or source of these substances in the environment is unknown,and they may pose potential risk to human health and the ecological environment.Most ECs are not regulated by law,including illicit drugs(IDs),environmental endocrine disruptors(EDCs),pharmaceuticals and personal care products(PPCPs),etc.The large-scale and uninterrupted use and release of ECs can cause their existence in the environment as "pseudo-persistent".In recent years,relevant studies at home and abroad have shown that a variety of ECshave been detected in weastewater treatment plants,river,groundwater,and even drinking water.Located in the core area of the Yangtze River Delta,Taihu Lake is the third largest freshwater lake in China.Taihu Lake Basin is a unique plain river network with a relatively concentrated population and rapid development of industry and agriculture.It is a relatively developed area in China.As the main receiving water body in the coastal area,the industrial,agricultural and domestic weastewater along the lake is directly discharged into Taihu Lake,and the river flows slowly,which seriously affects the ecological environment of the lake.In this study,psychoactive substances,antibiotics,and bisphenols were selected as the target ECs.Ultra-high performance liquid chromatography-mass spectrometry was used to determine the occurrence and distribution of target ECs in the whole Taihu Lake Basin,in the two major rivers in Changzhou,and in the inlet and outlet water of the municipal weastewater treatment plant in Changzhou.The potential aquatic ecological risk of typical ECs was assessed by the risk quotient method;the possible sources of psychoactive substances in Taihu Lake were determined by the principal component analysis;and the illicit drug abuse in Changzhou was evaluated through weastewater epidemiology approach.(1)The results showed that ECs were widespread in the Taihu Lake Basin.In rivers of Taihu Lake,the average concentrations of ECs in winter were:psychoactive substances(42.2 ng/L),macrolides(59.1 ng/L),quinolones(116.3 ng/L),sulfonamides(372.1 ng/L),tetracyclines(4.0 ng/L)and bisphenols(1430.6 ng/L);the average concentrations of ECs in summer were:psychoactive substances(4.2 ng/L),macrolides(114.5 ng/L),quinolones(265.0 ng/L),sulfonamides(136.9 ng/L),tetracyclines(250.2 ng/L),and bisphenols(756.5 ng/L).In surface water samples of Changzhou,the concentrations of ECs in winter were:psychoactive substances(66.6 ng/L),macrolides(184.6 ng/L),quinolones(2.0 ng/L),sulfonamides(23.1 ng/L),tetracyclines(14.2 ng/L)and bisphenols(7437.9 ng/L);the average concentrations of ECs in summer were:macrolides(204.9 ng/L),quinolones(155.9 ng/L),bisphenols(136.5 ng/L),sulfonamides(112.8 ng/L),tetracyclines(75.0 ng/L)and psychoactive substances(4.0 ng/L).(2)The substances detected in Taihu Lake Basin in summer were mainly bisphenol compounds,and the detected areas were mainly in the west of Taihu Lake,Zhushan Bay and Meiliang Bay.The second most frequently detected was sulfonamides antibiotics,mainly in Gonghu Bay.In winter,the detection of tetracycline and bisphenol in each sampling point was relatively consistent,while the detection of quinolones was higher in the west of Taihu Lake and Zhushan Bay.(3)Principal component analysis was carried out on psychoactive substances in the Taihu Lake Basin and the results showed that the discharge of hospital weastewater and weastewater treatment plants may be the two main sources of psychoactive substances in the surface water of the north of Taihu Lake Basin,while psychoactive substances in the rivers of south,east,and west of Taihu Lake Basin were greatly affected by the effluent from weastewater treatment plants.(4)The weastewater epidemiological survey on weastewater treatment plants in Changzhou showed that METH consumption in Changzhou was the highest and should be paid enough attention.(5)The risk entropy method was used to characterize the ecological risks of emerging pollutants in the water environment of the Taihu Lake Basin,and the results showed that the risk of most ECs was low with RQ less than 0.10,while CTC,TC,CLR,BPA and BPF were at medium or high risk.CLR(RQ=35.6)and BPF(RQ=77.8)were the substances at high risk in the surface water of Changzhou in winter.The substance at high risk in summer was CLR(RQ=17.2).In Taihu Lake Basin,the substances at high risk was CLR,with RQ=15.5 and RQ=22.8 in winter and summer,respectively.