The behavior of nitrate in shallow aquifers depends on several factors, such as geomorphology, soil type, thickness of the vadose zone, and its lithology, sampling period, among others. In the free aquifer of the basin of the La Ballenera creek in southeastern of Buenos Aires province, Argentina, nitrate varies in a range between 4 and 250 mg/L in samples taken in spring and winter. This basin has a large agricultural production where fertilizers are applied, and nitrates come from them. Statistical analysis of the data allow to make conclusion about the main factors that influence the variation of the nitrate content in aquifers, in this case are the lithology and the thickness of the vadose zone, related to the different transit times. The results obtained can be extrapolated to analogous basins, considering that in the spatial analysis of nitrates the heterogeneities of the system should be considered. The importance of characterizing a system with more than one sampling at several sufficiently spaced times is emphasized.

浅层含水层中硝酸盐的行为取决于几个因素，例如地貌，土壤类型，渗流带厚度，岩性，取样时间等。在阿根廷布宜诺斯艾利斯省东南部的La Ballenera小河盆地的自由含水层中，春季和冬季采集的样品中硝酸盐的变化范围为4至250 mg / L。该盆地有大量的农业生产，施用化肥，而硝酸盐则来自化肥。数据的统计分析可以得出有关影响含水层中硝酸盐含量变化的主要因素的结论，在这种情况下，是与不同穿越时间相关的渗流层的岩性和厚度。所得结果可以外推到类似盆地，考虑到在硝酸盐的空间分析中应考虑系统的异质性。强调了表征在几个足够间隔的时间具有多个采样的系统的重要性。