| With the accelerated development of the agricultural modernization,the application of pesticide has increased dramatically.Incorrect and large-scale use of pesticide enter the environment along with rainfall,runoff,infiltration and other ways,which has a negative impact on the aquatic ecological environment and human life.Therefore,it is very necessary to analyze the pesticide residues in the environment and evaluate the risk,so as to identify the pollutants with higher risk and provide references for the pesticide use standards and risk control.In this paper,the pesticide in the water and sediment of a certain river(Fu River)were screened to find out the pesticide with prominent residues in the region as the research object,and the analysis and detection methods of target pesticide in environmental water were established.The residues of target pesticide in the river and three sewage treatment plants with different treatment processes were analyzed,and the ecological risk to aquatic organisms was evaluated.The main contents of the research are as follows:(1)Pesticide residues in 19 water samples and 17 sediment samples from a river were screened by LC-quadrupole-time-of-flight MS(LC-Q-TOF/MS)and GC-quadrupole-time-offlight MS(GC-Q-TOF/MS).The result showed that 20 pesticides were detected in the water,mainly including herbicides and fungicides,and the detection rate of atrazine was as high as 100%.There were many kinds of pesticide detected in the middle and lower reaches of Fu River,and the pollution was relatively serious.A total of 4 pesticides were detected in the sediment,and the detection rate of diphenylurea was as high as 100%.The pollution mainly came from the surrounding farmland,industrial and domestic sewage in this area.Due to the high detection rate and wide distribution of atrazine,triazine pesticide represented by atrazine were identified as the research object,and its residual characteristics in the environment were further studied.(2)The analytical method of 11 triazine pesticides in environmental water was established by SPE-GC/MS.Under the optimal conditions,the linearity of 11 triazine pesticides was good in the range of 0.05 ~ 1 mg/L,the correlation coefficient was higher than 0.99,the detection limit was 15~47 ng/L,the recovery rate was in the range of 80%~110%,and the relative standard deviation was 2.20%~11.45%.The method was suitable for trace detection of triazine pesticide in environmental water.(3)The residual characteristics of triazine pesticide in three sewage treatment plants with different treatment processes and Fu River were analyzed,and their ecological risk to three aquatic organisms(algae,water fleas and fish)with different nutrition levels were evaluated.Five target pesticides were detected in sewage treatment plants,the concentration range was n.d.~140 ng/L,and the removal rate was between 10% and 60%.The removal effect of CASS process was relatively good.The removal of pesticide in wastewater had poor performance,which may be due to the metabolites or conversion products of pesticides,hydrolysis,and desorption and adsorption of particles in the wastewater treatment process.The Environmental Relevance of Pesticides from Wastewater treatment plants Index(ERPWI)showed that atrazine,simetryn,simazine and prometryne were at high risk to algae,5 target pesticides were at medium or lower risk to daphnia and fish.3 target pesticides were detected in Fu River,the concentration range was 15-50 ng/L,risk quotient(RQ)showed that all three triazine pesticides were at medium risk to algae,low or no risk to daphnia and fish. |
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