| Clarifying the residual characteristics of herbicides is a key basis for assessing ecological risks.Taking soil,water and sediment in the Nandu River Basin as the research object,this paper detects the residues of nine herbicides in soil,water and sediment by Qu ECh ERS combined with UPLC-MS/MS,and analyzes their spatiotemporal variation characteristics and ecological risks,which provides a theoretical basis for the assessment of the ecological risk of herbicides in the Nandu River Basin.The main findings are as follows:(1)Qu ECh ERS combined with UPLC-MS/MS was used to detect the residual level of nine herbicides in soil,water and sediment.The mass concentration of nine herbicides in soil was in the range of 0.5-100 μg/L,the linear relationship was good,the correlation coefficient(r)was between 0.9848-0.9994,the average recovery range was 70.9%-118.3%,the relative standard deviation(RSDs)was between 2.11%-23.64%,and the limit of quantification(LOQ)of the method was ≥0.06 μg/kg.The linear relationship between the nine herbicides in the water body was good in the range of 0.5-100 μg/L,r was between0.9903-0.9992,the average recovery range was 72.12%-117.4%,RSDs were between1.7%-10.6%,and LOQ ≥0.1 μg/L.The linear relationship between 9 herbicides in sediment was good in the range of 0.5-100 μg/L,r was between 0.9889 and 0.9991,the average recovery ranged from 71.8% to 114.5%,RSDs ranged from 2.34% to 14.95%,and LOQ ≥0.06 μg/kg.(2)Set up 36 points in the Nandu River basin to collect soil,water and sediment samples in four time periods(November,March,June and September).The test results showed that the total concentration of herbicide residues in soil with time was 0.31-21.87μg/kg,0.52-68.22 μg/kg,1.76-26.75 μg/kg and 0.65-500.20 μg/kg,respectively.The residue was the highest in March and September,and the residue concentration gradually decreased in November and June,and the herbicides with high detection rates were dimethyltetrachloride,atrazine,butachlor,etc.,and the spatial distribution was obvious,mainly concentrated in the middle and lower reaches of the Nandu River Basin.The total concentration residue range of herbicide in water with time was 0.41-9.19μg/L,0.26-1.79μg/L,0.05-1.37μg/L,and 0.20-11.24μg/L,respectively.Higher detection rates were atrazine,acetochlor and butachlor.The total concentration residue ranges of herbicide in sediment over time were 0.83-55.20μg/kg,0-98.90μg/kg,0-40.44μg/kg,and 0.73-73.32μg/kg,respectively.Total residues were higher in September and March,with seven points high in September and five points with higher total herbicide residues in March.Moreover,the spatiotemporal variation of herbicide residues in water and sediment is generally similar to that in soil.(3)Ecological risk assessment was carried out on the residue level of herbicides in soil,water bodies and sediments in the Nandu River Basin,and the risk entropy value of herbicides to sensitive organisms was calculated by using the risk entropy value method,and the results showed that the risk entropy of acetochlor and butachlor in soil and sediment was medium or high risk,atrazine,acetochlor,prochlor and butachlor in water were medium and high risk,and pesticide residues showed certain temporal and spatial distribution characteristics.Most of the points with high risk entropy were concentrated in the middle and lower reaches of the Nandu River Basin in March and September. |
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