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长三角地区地下水位埋深较浅,容易受到污染,受污染的浅层地下水又可能成为农田向环境输送污染物质的主要载体之一。通过对该地区不同种植类型农田(水田、露天菜地)地下水为期12个月的水质监测,分析了地下水水质特征和氮素水质指标(NO3-N、NH4-N)的时空变异特征,结果表明:研究区域农田浅层地下水已受到了污染。参照我国地下水质量标准(GB714848-93),发现SO42-和NH4-N是主要的污染指标。本区域地下水污染与农田施肥密切相关。同时发现研究区域地下水埋深与地下水中各无机离子没有明显相关性。0-300cm农田环境中地下水NO3-N下渗和反硝化作用都很明显。在相同的降雨、施肥状况(氮肥品种与用量、施肥方式)及土壤性质条件下,氮素在水田和露天菜地中均会很快流失,但水田比露天菜地更容易造成污染物的向下迁移,污染地下水。
The groundwater table in the Yangtze River Delta is shallow and prone to pollution. The contaminated shallow groundwater may also become one of the major carriers of pollutants in the farmland to the environment. Through the monitoring of the groundwater quality of different types of farmland (paddy fields, open-air vegetable fields) for 12 months in this area, the temporal and spatial variation characteristics of groundwater quality and nitrogen index (NO3-N, NH4-N) were analyzed. : Study area shallow groundwater in farmland has been contaminated. Reference to China’s groundwater quality standards (GB714848-93), found that SO42- and NH4-N is the main pollution indicators. Groundwater pollution in the region is closely related to farmland fertilization. At the same time, it is found that there is no significant correlation between groundwater depth and inorganic ions in groundwater in the study area. 0-300cm groundwater environment NO3-N infiltration and denitrification are obvious. Under the same conditions of rainfall, fertilization (nitrogenous variety and amount, fertilization mode) and soil properties, nitrogen would be quickly lost in paddy fields and open-air vegetable fields, but paddy fields were more likely to cause pollutants Under the migration, polluting groundwater.