Groundwater resources in arid and semi-arid regions are the most and sometimes the only water resource used for agricultural, industrial, and urban water supply. Irregular and immense application of nitrogen fertilizers in the lands under cultivation and nitrate leakage from livestock farming have affected the groundwater quality. In such areas, nitrate is one of the main pollutants in the groundwater. In this study, the temporal and spatial trend of nitrate contamination in 31 wells in Fasarud Plain, southern Iran, from April 2017 to March 2018 were assessed. To survey the geochemical quality of the plain, a geographic information system to expand geographic location maps and spatial distribution maps of nitrate concentration and nitrate pollution index (NPI) was applied. Nitrate concentrations ranged between 2.43 and 96 mg L⁻¹. Results indicated that nitrate temporal trend was increased significantly in most of the wells, and the spatial trend of area percentage of nitrate class 3 (not permissible limit of more than 50 mg L⁻¹) was positive. The greatest quantities of this variable in groundwater samples detected in northern, western, and eastern areas of the plain have a direct relation with the fertilization of agricultural lands. Generally, by ending the irrigation season, nitrate concentration and NPI reduced temporally in the samples and the percentage area of nitrate class 3 decreased gradually, again beginning the agricultural season, the NPI, nitrate concentration, and percentage area of nitrate class 3 began to increase. Overall, the change of nitrate concentration and distribution of agricultural regions have illustrated that nitrate originated from nitrogenous inorganic fertilizers applied within irrigation periods.

干旱和半干旱地区的地下水是用于农业，工业和城市供水的最大，有时是唯一的水资源。在耕地上不规则地大量施用氮肥以及畜牧业产生的硝酸盐泄漏影响了地下水水质。在这些地区，硝酸盐是地下水中的主要污染物之一。在这项研究中，评估了伊朗南部法萨鲁德平原2017年4月至2018年3月31口井中硝酸盐污染的时空趋势。为了调查平原的地球化学质量，应用了一个地理信息系统来扩展地理位置地图和硝酸盐浓度和硝酸盐污染指数（NPI）的空间分布图。硝酸盐浓度范围为2.43至96 mg L^-1。结果表明，大多数井中硝酸盐的时间趋势显着增加，3类硝酸盐的面积百分比的空间趋势（不允许超过50 mg L ^-1的极限））是肯定的。在平原的北部，西部和东部地区检测到的地下水样品中，此变量的最大数量与农田的施肥直接相关。通常，在灌溉季节结束时，样品中的硝酸盐浓度和NPI随时间下降，并且3类硝酸盐的面积百分比逐渐降低，再次从农业季节开始，NPI，硝酸盐浓度和3类硝酸盐的面积百分比开始增加。 。总体而言，硝酸盐浓度和农业地区分布的变化表明，硝酸盐起源于灌溉期内施用的含氮无机肥料。