The aim of this work is to evaluate the nitrate content and its impact on groundwater quality used for supply in dairy farms in a sector of the Pampas Plain in relation to specific point sources of pollution. Samples were collected in nine dairy farms during the months of June, August and November 2017 and April 2018. In all the samples, electrical conductivity and pH were measured in situ with a portable multiparameter equipment and water samples were collected to determine nitrates content. In the April 2018 sampling, carbonates, bicarbonates, chlorides, sulphates, nitrates, sodium, calcium, magnesium, and potassium were also determined. Results show that groundwater is mainly sodium bicarbonate to magnesium calcium bicarbonate type with variable pH and salinity. Nitrates and hardness were above the limits for human and animal consumption. Nitrate contents are significantly correlated with pH, electrical conductivity and hardness, and tend to decrease in wells which are more distant from point sources of pollution. In turn, the incorporation of other ions into the aquifer is evidenced by the increase of chlorides and EC and their correlation with nitrates. It is interpreted that the nitrification process acidifies the medium, triggering the dissolution of carbonates present in the aquifer matrix which increases groundwater hardness. Water quality deterioration could not only put at risk farmers’ health but it also conditions animal production and the dairy farm machinery. This study is the first contribution to defining local guidelines to set a proper water management plan as well as to provide tools to address the problem in other dairy farms in this sector of the Pampas Plain and in other regions.

中文翻译：

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阿根廷潘帕斯平原部分地区奶牛场中的硝酸盐污染及其对地下水质量的影响

这项工作的目的是针对特定污染源来评估潘帕斯平原一个地区的奶牛场中硝酸盐含量及其对地下水质量的影响。在2017年6月，8月和11月以及2018年4月期间，在9个奶牛场中收集了样品。在所有样品中，均使用便携式多参数设备现场测量了电导率和pH值，并收集了水样以确定硝酸盐含量。在2018年4月的抽样中，还确定了碳酸盐，碳酸氢盐，氯化物，硫酸盐，硝酸盐，钠，钙，镁和钾的含量。结果表明，地下水主要为碳酸氢钠至碳酸氢钙镁类型，pH和盐度各不相同。硝酸盐和硬度超过了人类和动物食用的极限。硝酸盐含量与pH，电导率和硬度显着相关，并且在距污染源较远的孔中趋于减少。反过来，氯化物和EC的增加以及它们与硝酸盐的相关性证明了其他离子掺入含水层中。据解释，硝化过程使介质酸化，触发了含水层基质中碳酸盐的溶解，从而增加了地下水的硬度。水质恶化不仅可能危及农民的健康，而且还会影响畜牧生产和奶农机械。