Groundwater chemical baseline values to assess the Recovery Plan in the Matanza-Riachuelo River basin, Argentina.
Groundwater chemical baseline values to assess the Recovery Plan in the Matanza-Riachuelo River basin, Argentina.
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DOI：
10.1016/j.scitotenv.2015.10.006
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发表时间：
2016-01
期刊：
影响因子：
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通讯作者：
M. E. Zabala;Sandra Martinez;M. Manzano;Luis Vives
中科院分区：
文献类型：
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作者：
M. E. Zabala;Sandra Martinez;M. Manzano;Luis Vives
马坦扎-里亚丘埃洛河流域两个开采最多的含水层正在执行马坦扎-里亚丘埃洛流域管理局《综合环境卫生计划》的框架内进行监测。在这种情况下，这项工作确定了地下水化学类型及其背后的自然过程；确定时空变化；确定化学成分的变化范围，并提出天然化学背景的上限浓度。研究了3个含水层（上含水层、Puelche含水层顶部和底部）共1007个样品。由于该区域没有实际确定基线值的具体准则，所使用的方法遵循评估欧洲水指令的欧洲项目的建议。地下水组成在化学相和矿化程度上都很稳定，干湿期的变化总体上比较微妙。除少量样品为Ca-HCO3、na - clso4和Na-Cl型外，大部分为na - hco3型。ca - hco3水是碳酸钙溶解的结果，na - hco3水是阳离子交换和碳酸盐溶解的结果，而na - clso4和Na-Cl水与原生水和与下伏和上覆沉积物侵蚀的旧海水混合是最相关的过程。自然背景上限的建议值考虑了地质和全新世海潮对沿海地下水基线的影响。通过这项研究，可以了解Matanza-Riachuelo河流域地下水系统的初始化学条件，并为流域当局开始评估趋势和监测恢复计划提供参考。同时，也为该地区今后的研究开创了先例。
The two most exploited aquifers in the Matanza-Riachuelo River basin are being monitored in the framework of the Integrated Environmental Sanitation Plan that implements the Basin Authority, Autoridad de Cuenca Matanza Riachuelo. In this context, this work identifies the groundwater chemical types and the natural processes behind them; determines spatial and temporal changes; establishes ranges of variation for chemical components, and proposes concentration values for the upper limit of the natural chemical background. A total of 1007 samples from three aquifer-layers (Upper Aquifer, top and bottom of Puelche Aquifer) have been studied. As concrete guidelines for practical determination of baseline values are not available in the region, the methodology used follows the proposals of European projects which assessed European water directives.The groundwater composition is very stable in terms of both chemical facies and mineralization degree, and the changes observed in the dry and wet periods analysed are subtle in general. Most of the groundwater is Na-HCO3type, except a few samples that are Ca-HCO3, Na-ClSO4and Na-Cl types. The Ca-HCO3waters are the result of calcium carbonate dissolution, Na-HCO3waters result from cation exchange and carbonate dissolution, while in the Na-ClSO4and Na-Cl waters, mixing with connate and with encroached old marine water from the underlying and overlying sediments are the most relevant processes. The proposed values for the upper limit of the natural background consider the influence of geology and Holocene marine ingressions in the baseline of coastal groundwater.This study allowed to know the initial chemical conditions of the groundwater system of the Matanza-Riachuelo River basin and to establish the reference from which Basin Authority can start to evaluate trends and monitor the recovery plan. At the same time, it sets a precedent for future studies in the region.