Trends in Nitrate Concentrations and Determination of its Origin Using Stable Isotopes (18O and 15N) in Groundwater of the Western Central Valley, Costa Rica
Trends in Nitrate Concentrations and Determination of its Origin Using Stable Isotopes (18O and 15N) in Groundwater of the Western Central Valley, Costa Rica
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DOI：
10.1579/05-r-046r1.1
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发表时间：
2006-08
期刊：
影响因子：
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通讯作者：
J. Reynolds-Vargas;Julio Fraile-Merino;R. Hirata
中科院分区：
文献类型：
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作者：
J. Reynolds-Vargas;Julio Fraile-Merino;R. Hirata
在哥斯达黎加中央谷西部的含水层中，进行了一项研究，以评估硝酸盐浓度的长期趋势，并尝试使用稳定同位素（15 NNO3 −和18 ONO3 −）确定硝酸盐的来源，该地区有100多万人依赖地下水满足日常需求。从20个站点定期采样4至17年的数据表明，在五个站点的硝酸盐浓度的增加趋势，在一个时期内，从10年到40年，将超过建议的最高浓度。同位素分析的结果表明，土地利用模式和地下水中硝酸盐的同位素特征之间的对应关系，并表明，城市化进程没有适当的废物处理系统，其次是咖啡施肥的做法，威胁到该地区的水质。我们的结论是，在这方面的地下水管理是不可持续的，土地利用的替代过程，从农业活动到住宅占用，没有适当的污水处理系统可能会导致显着增加硝酸盐污染物负荷。
Abstract A study was conducted to evaluate long-term trends in nitrate concentrations and to try to identify the origin of nitrate using stable isotopes (15NNO3− and 18ONO3−) in the aquifers of the western Central Valley, Costa Rica, where more than 1 million people depend on groundwater to satisfy their daily needs. Data from 20 sites periodically sampled for 4 to 17 years indicate an increasing trend in nitrate concentrations at five sites, which in a period ranging from 10 to 40 years, will exceed recommended maximum concentrations. Results of isotopic analysis indicate a correspondence between land use patterns and the isotopic signature of nitrate in groundwater and suggest that urbanization processes without adequate waste disposal systems, followed by coffee fertilization practices, are threatening water quality in the region. We conclude that groundwater management in this area is not sustainable, and that land use substitution processes from agricultural activity to residential occupation that do not have proper sewage disposal systems may cause a significant increment in the nitrate contaminant load.