The application of chemical and organic fertilizers to agricultural lands increases nutrient pools and affects soil and water quality. Understanding changes in groundwater quality due to the anthropogenic activities over time is important to human and ecosystem health. In 2017, we resampled 58 wells monitored in the year 2000 to evaluate the rate of changes in groundwater quality and water quality indices over time in response to agricultural and industrial activities and climate changes. The groundwater in two sampling years was dominated by Ca–HCO₃ water type. The mean groundwater pH, electrical conductivity (EC), calcium (\({\text{Ca}}^{2 + }\)), magnesium (\({\text{Mg}}^{2 + }\)), and sodium (\({\text{Na}}^{ + }\)) concentrations did not significantly change over time, while a significant buildup in bicarbonate \(({\text{HCO}}_{3}^{ - } )\) (189–305 mg l⁻¹), nitrate (\({\text{NO}}_{3}^{ - }\)) (41–56 mg l⁻¹), chloride (\({\text{Cl}}^{ - }\)) (57–77 mg l⁻¹) and a significant decrease in sulfate (\({\text{SO}}_{4}^{2 - }\)) (159–91 mg l⁻¹) and potassium (\({\text{K}}^{ + }\)) (3–2 mg l⁻¹) was observed. In 2000, 45% of the water samples were classified as high salinity hazard, and this value increased to 52% by 2017, indicating that salinity of the water samples increased over 17 years. In 2000, only 25% of the total area had a \({\text{NO}}_{3}^{ - }\) value greater than 50 mg l⁻¹; and this value increased sharply to 62% by 2017, indicating that \({\text{NO}}_{3}^{ - }\) concentrations significantly increased with approximately 2.2% annually in groundwater, over 17 years. Approximately, 55% of the groundwaters with \({\text{NO}}_{3}^{ - }\) concentration values of less than 40 mg l⁻¹ in 2000 shifts one to four categories upward in 2017. The percentage of water samples which was shifted to the next category with \({\text{NO}}_{3}^{ - }\) concentration higher than 50 mg l⁻¹ and approaching the limit of the World Health Organization was doubled in 2017 compared with 2000. High application of chemical and manure fertilizers in excess of crop needs should be avoided in the studied area to prevent continued increases in groundwater \({\text{NO}}_{3}^{ - }\) concentrations.

中文翻译：

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17年后的地下水地球化学变化调查：以伊朗西部为例

在耕地上施用化学和有机肥料会增加养分储备并影响土壤和水质。了解人类活动引起的地下水质量随时间的变化对人类和生态系统健康至关重要。2017年，我们对2000年监测的58口井进行了重新采样，以评估地下水质量和水质指数随农业和工业活动以及气候变化而随时间变化的速率。在两个采样年中，地下水以Ca-HCO ₃水类型为主。地下水平均pH值，电导率（EC），钙（\（{\ text {Ca}} ^ {2 +} \）），镁（\（{\ text {Mg}} ^ {2 +} \）） ，和钠（\（{\ text {Na}} ^ {+} \））的浓度并没有随时间显着变化，而碳酸氢盐\（（{{text {HCO}} _ {3} ^ {-}）\）（189–305 mg l ^-1），硝酸盐（\（ {\ text {NO}} _ {3} ^ {-} \））（41–56 mg l ^-1），氯化物（\（{\ text {Cl}} ^ {-} \））（57–77 mg l ^-1）和硫酸盐（\（{\ text {SO}} _ {4} ^ {2-} \）））（159–91 mg l ^-1）和钾盐（\（{ {K}} ^ {+} \））（3–2 mg l ^-1） 被观测到。2000年，有45％的水样本被归类为高盐度危害，到2017年，该值增加到52％，这表明水样本的盐度在17年中增加了。在2000年，只有25％的总面积\（{{text {NO}} _ {3} ^ {-} \）值大于50 mg l ^-1；并且该值到2017年急剧增加到62％，表明\（{\ text {NO}} _ {3} ^ {-} \）的浓度在17年中以每年约2.2％的速度显着增加。大约55％的地下水中\（{{text {NO}} _ {3} ^ {-} \）的浓度值小于40 mg l ^-1在2000年，水的样本量在2017年上升了1-4个类别。\（{\ text {NO}} _ {3} ^ {-} \）浓度高于50 mg l ⁻的水样所占的百分比¹和接近世界卫生组织的限制增加了一倍，2017年有超过作物需要，应在研究区避免化学和肥料肥料高2000年申请，以防止继续增加地下水比较\（{\ {文字NO }} _ {3} ^ {-} \）浓度。