Groundwater forms the main freshwater supply in arid and semi-arid areas, and contamination of this precious resource is complicated by the slow rate of recharge in these areas. Nitrate contamination of groundwater is a global water quality problem, as it entails threat to human health as well as aquatic ecosystems. Source identification of contamination is the cornerstone and a prerequisite for any effective management program of water quality. Stable isotope composition of the dissolved nitrate (\({{\rm{\delta}}^{15}}{\rm{N - N}}{{\rm{O}}_{{3^ - }}}\) and \({{\rm{\delta}}^{18}}{\rm{N - N}}{{\rm{O}}_{{3^ - }}}\)) has been applied to identify \({\rm{N}}{{\rm{O}}_{{3^ - }}}\) sources and the main transformation processes in the upper aquifer system (A1/2, A4, and B2/A7 aquifers) in the Wadi Shueib catchment area, Jordan. Moreover, the stable isotope compositions of the groundwater (δ²H-H₂O and δ1⁸O-H₂O) in conjunction with the groundwater hydrochemistry were integrated to investigate the origin and evolution of the groundwater. Results revealed that groundwater in the study area is fresh and hard-very hard water, and mainly a Ca-Mg-Cl type. \({\rm{N}}{{\rm{O}}_{{3^ - }}}\) concentration was in the range of 7.0–74.0 mg/L with an average of 37.0 mg/L. Most of the samples showed concentration higher than the natural background concentration of \({\rm{N}}{{\rm{O}}_{{3^ - }}}\) (5.0–10.0 mg/L). The δ²H-H₂O and δ¹⁸O-H₂O values indicated that the groundwater is meteoric, and of Mediterranean origin, with a strong evaporation effect. The \({{\rm{\delta}}^{15}}{\rm{N - N}}{{\rm{O}}_{{3^ - }}}\) values ranged between 6.0‰ and 11.3‰ with an average of 8.7‰, and the \({{\rm{\delta}}^{18}}{\rm{N - N}}{{\rm{O}}_{{3^ - }}}\) values ranged between 1.6‰ and 5.9‰ with an average of 3.4‰. These values are in conformity with the stable isotope composition of nitrate derived the nitrification of wastewater/manure, and soil NH₄. Nitrification and denitrification are the main transformation processes affecting nitrogen species. Statistical analysis revealed no significant differences in the δ²H-H₂O and δ¹⁸O-H₂O values, and \({{\rm{\delta}}^{15}}{\rm{N - N}}{{\rm{O}}_{{3^ - }}}\) and \({{\rm{\delta}}^{18}}{\rm{N - N}}{{\rm{O}}_{{3^ - }}}\) values for the three aquifers (A1/2, A4, and B2/A7), indicating that the groundwater of these aquifers has the same origin, and a common source of pollution.

地下水是干旱和半干旱地区的主要淡水供应，这些珍贵资源的污染由于这些地区补给速度缓慢而变得复杂。地下水的硝酸盐污染是一个全球性的水质问题，因为它威胁着人类健康以及水生生态系统。污染源识别是任何有效水质管理计划的基础和前提。溶解硝酸盐（\（{{\ rm {\ delta}} ^ {15}} {\ rm {N-N}} {{\ rm {O}} _ {{3 ^-}}}的稳定同位素组成\）和\（{{\ rm {\ delta}} ^ {18}} {\ rm {N-N}} {{\ rm {O}} _ {{3 ^-}}} \）））应用于识别\（{\ rm {N}} {{\ rm {O}} _ {{3 ^-}}}} \）约旦Wadi Shueib集水区的上部含水层系统（A1 / 2，A4和B2 / A7含水层）的水源和主要转换过程。此外，地下水（δ的稳定同位素组合物² H-H ₂ O和δ1 ⁸ O - H ₂ O）与水化学地下水一起被整合到调查地下水的起源和演化。结果表明，研究区的地下水是淡水和非常硬的水，主要为Ca-Mg-Cl型。\（{{rm {N}} {{\ rm {O}} _ {{3 ^-}}} \}的浓度范围为7.0–74.0 mg / L，平均为37.0 mg / L。大多数样品显示浓度高于自然背景浓度。\（{\ rm {N}} {{\ rm {O}} _ {{3 ^-}}} \）（5.0–10.0 mg / L）。的δ ² H-H ₂ O和δ ¹⁸ O - H _2个O值表明，地下水是大气，和地中海来源的，具有较强的蒸发效果。的\（{{\ RM {\增量}} ^ {15}} {\ RM {N - N}} {{\ RM {ö}} _ {{3 ^ - }}} \）值6.0之间的范围内‰和11.3‰，平均为8.7‰，以及\（{{\ rm {\ delta}} ^ {18}} {\ rm {N-N}} {{\ rm {O}} _ {{3 ^ -}}} \）值的范围在1.6‰和5.9‰之间，平均为3.4‰。这些值与源自废水/粪便硝化作用的硝酸盐和土壤NH ₄的稳定同位素组成一致。硝化和反硝化是影响氮物质的主要转化过程。统计分析表明在δ无显著差异² H-H ₂ O和δ ¹⁸ O - H ₂ O值，和\（{{\ RM {\增量}} ^ {15}} {\ RM {N - N}} {{\ rm {O}} _ {{3 ^-}}} \）和\（{{\ rm {\ delta}} ^ {18}} {\ rm {N-N}} {{\ rm {O}} _ {{{3 ^-}}} \\）值的三个含水层（A1 / 2，A4和B2 / A7），表明这些含水层的地下水来源相同，并且是常见的污染源。