Analysis of the removal efficiency and pathways of urban pesticide non-point source pollution through constructed wetlands
The application of pesticides in urban greening management has become a potential threat to human health due to their residual existence in rainwater runoff.In order to control the inflowing of pesticides into water bodies along with rainwater runoff,we simulated the pesticides-applying mode in green maintenance,and constructed an artificial wetland with composite vertical flow as the ecological riverside to study the removal of thiamethoxam,dimethoprim,and chlorothalonil in mixed pesticide wastewater during three seasons(summer,autumn,and winter).After 3-day wetland treatment for the wastewater containing three pesticides at three different concentrations of 0.1,0.5 and 1.0 mg/L,the removal rates of three pesticides all reached 60.9％-98.3％,while the pesticide removal rate in the control pool was only 0.58％-8.43％.With regards to the pesticide removal efficiency in different seasons,a characteristic of summer＞autumn＞winter was observed.Compared with the control pool,the treated pesticide wastewater showed significantly weaker inhibition on the growth of paramecium.The accumulation of pesticides in wetland substrates and plants was also evaluated.As a result,the removal of pesticides by wetland was achieved through substrate adsorption(38.87％-81.6％),microbial degradation(0.28％-35.74％),and plant absorption(0.02％-4.62％),with substrate adsorption as the main pathway.Overall,our constructed wetland could significantly remove or intercept the strong pesticide load caused by rainwater runoff within a short period,and such a concept could be potentially applied to reduce ecological toxicity from pesticide non-point source pollution in river channels.
万方数据
维普
