ABSTRACT Stable isotopes of water (δ2H, δ18O) and δ13CTIC were used as a tool to trace the recharge processes, natural carbon (organic and inorganic) source and dynamics in the aquifers of the central Gangetic basin, India. Stable isotope (δ2H, δ18O) record of groundwater (n = 105) revealed that the groundwater of Piedmont was recharged by meteoric origin before evaporation, while aquifers of the older and younger alluvium were recharged by water that had undergone evaporation loss. River Ganges and its tributaries passing through this area have very little contribution in recharging while ponds play no role in the recharging of adjacent aquifers. The connectivity of shallow aquifers of aquitard formation (comprised of clay/sandy clay with thin patches of fine grey sand), i.e. 25–60 m below ground level (bgl) with the main upper aquifer (at a depth of >120 m bgl) was found to be higher in older and younger alluvium. Negative values of δ13CTIC (median −9.6 ‰; range −13.2 to −5.4 ‰) and high TIC (median 35 mM; range 31–46 mM) coupled with low TOC (median 1.35 mg/L; range 0.99–1.77 mg/L) indicated acceleration in microbial activity in the younger alluvium, especially in the active floodplain of river Ganges and its proximity.

中文翻译：

---

使用稳定同位素特征描绘恒河盆地中部全新世含水层中地下水补给和碳的来源

摘要 水的稳定同位素（δ2H、δ18O）和 δ13CTIC 被用作追踪印度恒河流域中部含水层补给过程、天然碳（有机和无机）来源和动力学的工具。地下水（n = 105）的稳定同位素（δ2H、δ18O）记录表明，皮埃蒙特的地下水在蒸发前由大气源补给，而较老和较年轻的冲积层的含水层则被蒸发损失的水补给。流经该地区的恒河及其支流对补给作用很小，而池塘对相邻含水层的补给作用不大。弱透水层浅层含水层的连通性（由粘土/砂质粘土和细灰细砂组成），即 发现地面以下 25-60 m (bgl) 和主要上部含水层（深度 >120 m bgl）在较老和较年轻的冲积层中更高。δ13​​CTIC 的负值（中值 -9.6 ‰；范围 -13.2 至 -5.4 ‰）和高 TIC（中值 35 mM；范围 31-46 mM）与低 TOC（中值 1.35 mg/L；范围 0.99-1.77 mg/L） ) 表明在较年轻的冲积层中微生物活动加速，尤其是在恒河及其附近的活跃洪泛区。