A Pilot Study on the Construction of Biogeochemical Barriers for Agricultural Non-point Source Pollution Control in the Hongfeng Lake Watershed
When the point source pollution got under control,agricultural non-point source pollution in the watershed gradually became the main contributor to the exogenous inputs of nutrients,such as nitrogen(N)and phosphorus(P)and other nutrients.In this study,agricultural soils in the Hongfeng Lake watershed were chosen as the research object.The biogeochemical barrier was constructed by adding amendments and growing plants,and the interception effect of N and P was comprehensively evaluated.The results show that the addition of Al2(SO4)3,CaCl2 and sodium-based bentonite significantly increased the interception rates of NH4-N,NO3--N and phosphorus,consequently reducing its loss.In addition,the biogeochemical barrier constructed by adding CaCl2 modified sodium-ben-tonite to soils and growing plants intercepted NH4-N、NO3-N and P most effectively with an interception rate of 87％,95％and 93％,respectively.Conversely,FeSO4 amended soils enhanced N03-N leaching and should not be considered.After planting,the plant growth had certain activation effects on soil N and P,which resulted in higher concentrations of NH4-N and dissolved P in simulated runoff,although both were lower than the control.Moreover,the effective P per unit(Olsen-P)of the amended soil was significantly lower than before planting,which reflected the active utilization of soil P by plants.It can be said in conclusion that the biogeochemical barrier constructed by adding Al2(SO4)3,CaCl2 and sodium-bentonite to the soil and planting suitable plants(ryegrass and white clo-ver)can effectively and continuously intercept soil N and P which furthermore promotes plant growth in Hongfeng Lake watershed.This is of great significance for the sustainable control of agricultural non-point source pollution.
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