莱西地区施肥对地下水硝酸盐污染的过程

Study of Nitrate Contamination of Groundwater from Fertilization in the Laixi Region

通过实地调查和渗水、硝化、吸附、弥散等室内外试验,获取了所需水文地质参数。利用VS2D/T(Variably Saturat-ed 2-D Flow and Transport Model)模型,建立了莱西地区包气带水流-溶质运移模型,分析了莱西地区施肥过程中对地下水的硝酸盐污染。研究结果表明,氮肥中的硝酸盐对地下水的补给量占当次施肥量的24%和43%,进入到地下水中硝酸盐的平均浓度分别约为130mg/L和177mg/L,远高于当地地下水中硝酸盐63.5mg/L的平均浓度,说明不合理的施用氮肥是造成莱西地区地下水硝酸盐污染的1个主要原因。通过模拟不同灌溉和施肥模式下对地下水的硝酸盐污染,得出灌溉方式的改变对于减少施肥造成的地下水硝酸盐污染的作用最大。

Through the field investigation and infiltration, nitrification, adsorption and dispersion experiments, the required parameters are obtained. By using the VS2D/T model, a fluid flow and solute transport model is established and the process of nitrate contamination of groundwater in the Laixi region is analyzed. The results of simulation reveal that the quantity of nitrogen fertilizer leaked into the groundwater accounts for 24% and 43% of the nitrogen fertilizer totally used. The nitrate concentrations into the groundwater reach 130mg/L and 177mg/L respectively, higher than the average nitrate concentration （63.5mg/L） of the groundwater in that field, which means that unreasonable usage of nitrogen fertilizer is the major reason for the groundwater nitrate contamination in the Laixi region. Through simulating the different types of irrigation and fertilization, it is revealed that the types of irrigation have the greatest influence on decreasing the quantity of nitrate leaked into the groundwater.