Nitrate contamination in groundwater on an urbanized dairy farm.
Nitrate contamination in groundwater on an urbanized dairy farm.
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DOI：
10.1021/es071551t
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发表时间：
2008-05
影响因子：
11.4
通讯作者：
W. Showers;B. Genna;Timothy McDade;R. Bolich;J. Fountain
中科院分区：
文献类型：
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作者：
W. Showers;B. Genna;Timothy McDade;R. Bolich;J. Fountain
农村农田城市化是全球普遍存在的趋势，维持和保护郊区充足的水供应是一个日益严重的问题。在城市化地区确定地下水污染源是有问题的，但在人口快速增长和发展的地区将变得重要。在美国北卡罗来纳州皮德蒙特一个奶牛场遗址上建造的一个住房开发项目中，利用NO3(Delta15N(NO3)和Delta18ON3)、NH4(Delta15N(NH4))、地下水(Delta2H(Wt)和Delta18O(Wt))和氯/溴比的同位素组成来确定饮用水水井中硝酸盐污染的来源。Delta15N(NO3)和Delta18ON3的组成表明，饮用水井水中硝酸盐水平的升高是废物污染的结果，反硝化作用并未显著降低地下水硝酸盐浓度。地下水中的Delta15N(NO3)和Delta18O(NO3)组分不能区分化粪水和动物粪便污染。受污染最严重的饮用水水井中的氯/溴比率与动物粪便应用领域中发现的比率相似，而高于该地区化粪池中观察到的氯/溴比率。Delta18O(Wt)在一个掩埋的废弃泻湖附近被耗尽，而delta2H(Wt)没有伴随着位移，表明水中的氧气与二氧化碳交换。这种水-二氧化碳交换是由于埋藏的泻湖有机质的减少和好氧土壤中释放的气体的氧化所致。在受污染的饮用水水井中，Delta18O(Wt)没有耗尽，这表明埋在地下的乳制品泻湖不是废物污染源。同位素和氯/溴比值表明，这些饮用水井中的硝酸盐污染不是来自化粪池系统，而是35年奶牛场作业期间从牧场渗入地下水的动物粪便的结果，没有违反任何现有法规。需要制定法律来保护房主的健康，这些房主要求在出售建在城市化农田上的房屋之前对井水进行测试。
Urbanization of rural farmland is a pervasive trend around the globe, and maintaining and protecting adequate water supplies in suburban areas is a growing problem. Identification of the sources of groundwater contamination in urbanized areas is problematic, but will become important in areas of rapid population growth and development. The isotopic composition of NO3 (delta15N(NO3) and delta18O NO3), NH4 (delta15N(NH4)), groundwater (delta2H(wt) and delta18O(wt)) and chloride/bromide ratios were used to determine the source of nitrate contamination in drinking water wells in a housing development that was built on the site of a dairy farm in the North Carolina Piedmont, U.S. The delta15N(NO3) and delta18O NO3 compositions imply that elevated nitrate levels at this site in drinking well water are the result of waste contamination, and that denitrification has not significantly attenuated the groundwater nitrate concentrations. delta15N(NO3) and delta18O(NO3) compositions in groundwater could not differentiate between septic effluent and animal waste contamination. Chloride/ bromide ratios in the most contaminated drinking water wells were similar to ratios found in animal waste application fields, and were higher than Cl/Br ratios observed in septic drain fields in the area. delta18O(wt) was depleted near the site of a buried waste lagoon without an accompanying shift in delta2H(wt) suggesting water oxygen exchange with CO2. This water-CO2 exchange resulted from the reduction of buried lagoon organic matter, and oxidation of the released gases in aerobic soils. delta18O(wt) is not depleted in the contaminated drinking water wells, indicating that the buried dairy lagoon is not a source of waste contamination. The isotope and Cl/Br ratios indicate that nitrate contamination in these drinking wells are not from septic systems, but are the result of animal waste leached from pastures into groundwater during 35 years of dairy operations which did not violate any existing regulations. Statutes need to be enacted to protect the health of the homeowners that require well water to be tested prior to the sale of homes built on urbanized farmland.