The Nubian aquifer of northeastern Africa is one of the largest confined fossil-water aquifer systems in the world. It is central for ongoing water needs and future development goals of Egypt, Libya, Sudan and Chad. Groundwater extraction and consumptive use over the past 40 years have led to a continuous decline of water level and to the reduction and/or cessation of natural flow in artesian wells and springs. This study introduces new noble gas and stable isotope geochemical data from deep groundwater supply wells of the main oases of the Western Desert of Egypt (Bahariya, Farafra, Dahkla, and Kharga) and places these data in the context of a regional compilation of published hydrological and hydrochemical data. Helium isotopes, stable isotope compositions for water (δ²H; δ¹⁸O) and dissolved inorganic carbon (δ¹³C), salt compositions, and [CO₂] suggest deeply derived fluid inputs. Highly variable groundwater temperatures (20–56 °C) also suggest the presence of geothermal inputs that mix with aquifer water. Nubian water displays high P_CO2 (up to three orders of magnitude higher than atmosphere) and hydrochemical analysis using δ¹³C suggests up to ~30% of the CO₂ is derived from deep geologic sources. Helium isotope (³He/⁴He) ratios of samples obtained from the Nubian aquifer range from crustal values of 0.02R_A (where R_A reflects the ³He/⁴He in air or 1.384 × 10⁻⁶) to values of up to 0.36R_A (2.5% mantle helium) in Dahkla Oasis of Egypt and up to 1.4R_A (17% mantle helium) in Libya. Correlations among excess heat, increases in [CO₂], δ¹³C, and ³He/⁴He indicate that small volumes of deeply sourced fluids carrying mantle-derived volatiles are leaking into the Nubian aquifer. Geothermal water apparently ascend along faults and shear zone conduits and mix with regional groundwater. The origin of these volatiles may be partial melts in low velocity upper mantle beneath the aquifer and young magmatism surrounding the Nubian aquifer. Fluid-rock interactions along flowpaths can explain variable associations and correlations among the tracers. Variability of composition and temperature suggest complex fluid mixing within the Nubian aquifer, the existence of fault-bounded hydrologic sub-basins, and a connection between tectonics and water quality. Better understanding of the sources and admixtures of deep geothermal fluid inputs is needed for informed water management.

非洲东北部的努比亚含水层是世界上最大的承压化石水含水层系统之一。它对于埃及、利比亚、苏丹和乍得的持续用水需求和未来发展目标至关重要。过去 40 年的地下水开采和消耗性使用导致水位持续下降，并导致自流井和泉水的自然流量减少和/或停止。本研究介绍了来自埃及西部沙漠主要绿洲（Bahariya、Farafra、Dahkla 和 Kharga）的深层地下水供应井的新惰性气体和稳定同位素地球化学数据，并将这些数据置于已发表的水文区域汇编的背景下。和水化学数据。氦同位素，水的稳定同位素组成（δ ² H；δ ¹⁸O) 和溶解的无机碳 (δ ¹³ C)、盐成分和 [CO ₂ ] 表明深度衍生的流体输入。地下水温度变化很大（20-56°C）也表明存在与含水层水混合的地热输入。努比亚水显示出高P _CO2（比大气高出三个数量级），使用 δ ¹³ C 的水化学分析表明高达约 30% 的 CO ₂来自深层地质来源。从努比亚含水层获得的样品的氦同位素 ( ³ He/ ⁴ He) 比率范围为 0.02R _A的地壳值（其中 R _A反映了³ He/⁴空气中的 He 或 1.384 × 10 ^{-6 ）在埃及}_的达克拉绿洲高达 0.36RA （2.5% 地幔氦），在利比亚高达 1.4RA _（ 17% 地幔氦）。过热、[CO ₂ ]、δ ¹³ C 和³ He/ ^{4增加之间的相关性}他指出，携带地幔衍生挥发物的少量深源流体正在泄漏到努比亚含水层中。地热水明显沿着断层和剪切带管道上升并与区域地下水混合。这些挥发物的来源可能是含水层下方低速上地幔的部分熔体和努比亚含水层周围的年轻岩浆作用。沿流路的流体-岩石相互作用可以解释示踪剂之间的变量关联和相关性。成分和温度的变化表明努比亚含水层内复杂的流体混合，存在以断层为界的水文亚盆地，以及构造和水质之间的联系。需要更好地了解深层地热流体输入的来源和混合物，以便进行明智的水资源管理。