| As an important catchment area of the Dongjiang River,the upper reaches of the Dongjiang River is of great significance for risk control of the water environment.Except for the pollution of conventional pollutants,various types of emerging pollutants have also been concerned widely.In this paper,the pollution of the emerging pollutants was studied comprehensively and systematically,focusing on pollution of the agricultural,aquaculture and industrial in the upper reaches of the Dongjiang River.In wet period(July 2015),dry season(November 2015)and normal river flow period(March 2016),samples were collected at 6 sampling sites in the upper reaches of the Dongjiang River,including Fengshuba reservoir,Longchuan County,Dongyuan power station,Xinfengjiang reservoir and Goddess of Mercy Pavilion.And water quality was studied,focusing on the detection of water and sediments of 8 kinds of organo-chlorine pesticide(OCPs),16 kinds of organophosphorus pesticide(OPPs),8 kinds of pyrethroid pesticide(PYRs),16 kinds of polycyclic aromatic hydrocarbons(PAHs),8 kinds of polychlorinated biphenyls(PCBs),12 kinds of antibiotics,and of water of 295 kinds of antibiotic resistance genes(ARGs).This paper studied their temporal and spatial distribution characteristics and made potential ecological risk assessment,in order to provide the basis for the risk control of typical emerging pollutants in the upper reaches of the Dongjiang River.The main results were as follows:(1)The general pollution status of water quality in the upper reaches of the Dongjiang River was relatively light.The potassium permanganate index and dissolved oxygen were generally surface waterⅠ,ammonia nitrogen and total phosphorus were generally surface waterⅡ,but the total nitrogen pollution was relatively large,which was generally surface waterⅤ.Mesotrophication accounted for 55.56% and olipotrophication accounted for 44.44%,and the mesotrophication was mainly concentrated in the mainstream area.Xinfengjiang Reservoir had a significant purifying effect on the downstream.The non-point source pollution caused by rain erosion was the main source of pollution.(2)The detection rates of OCPs,OPPs,PYRs,PAHs,PCBs and antibiotics in water were 97.22%,93.06%,100%,97.22%,90.97% and 85.65% and their concentration ranged from nd to 198.9 ng/L,from nd to 69.9 ng/L,from nd to 69.9 ng/L,from nd to 198.38 ng/L,from 1.71 to 66.77 ng/L.Their the detection rates were 100%,98.96%,100%,100%,79.17% and 61.11% in sediments and their concentration ranged from 1.54 to 15.87 ng/g,from nd to 15.87 ng/g,from nd to 46.78 ng/g,from 1.44 to 301.86 ng/g,from nd to 0.97 ng/g,from nd to 669.17 ng/g.The detection rate of antibiotic resistance gene in water was 66.29%,relative abundance was from 5.77E-04 to 4.82E-01.The detection rate of all kinds of emerging pollutants were high,indicating that emerging pollutants were widespread in the upper reaches of the Dongjiang River.(3)The pollution trend of pesticides in water was not obvious,which may mainly come from agricultural and urban non-point source pollution,but pesticides in sediments showed obvious difference,and the average concentration was Dongyuan>Longchuan>Guanyinge.PAHs in water was mainly composed of 2 rings and 3 rings.The average proportion of PAHs decreased with the increase of the number of rings,while the 3 rings and 4 rings predominated in the sediments.The concentration of PCBs in water and sediments was not significantly different.Tetracycline in water and sediment,from Longchuan to Dongyuan,had a clear growth,indicating that pollution of tetracycline was serious in Dongyuan.The concentration of norfloxacin was 88.20~669.17 ng/g,which was the main pollutant of antibiotics in sediments.The relative abundance of ARGs was higher in Guanyinge,Longchuan and Xinfengjiang reservoirs,and was not exactly consistent with the distribution of antibiotics.(4)The results of correlation analysis showed that PYRs were negatively related to TP in water.OCPs and OPPs were positively related to turbidity.PCBs were negatively related to temperature.Antibiotics were related to conventional organic pollutants and affected by environmental factors.ARGs and antibiotics were no significant correlation,but ARGs was significant positive correlation with integrase,which showed that the integrase as a mechanism of multi-drug resistance of microorganisms had a great significance for the proliferation and lateral transfer of antibiotic resistance genes.(5)The results of ecological risk assessment showed that there were 16 high risk pollutants(RQ> 1),including 13 kinds of pesticides,1 kind of polychlorinated biphenyls and 2 kinds of antibiotics.And there were 11 kinds of medium risk pollutants(0.1 <RQ <1),including 4 kinds of pesticides,4 kinds of polycyclic aromatic hydrocarbons and 3 kinds of antibiotics.Different types of emerging pollutants had certain risks in the upper reaches of the Dongjiang River,we should carry out the special treatment of trace organic pollutants. |
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