Groundwaters from the deep Dogger and Albian aquifers from the Paris Basin in France have been analyzed for oxygen (H₂O and SO₄), hydrogen (H₂O), carbon, boron, lithium, sulfur (SO₄), strontium, and uranium isotopes. This study aims to establish a natural hydrogeochemical baseline against which any leak of saline fluids from deeper water masses could be evidenced in case of a hypothetic occurrence of non-conventional exploitation of the hydrocarbons that are present in the underlying Liassic shales. Waters from the Dogger and the Albian aquifers have respectively chloride-alkaline and calcium-bicarbonate geochemical facies, although some waters from the Albian aquifer tend to evolve towards the geochemical characteristics of the waters from the Dogger aquifer.

Stable isotopes of the water molecule indicate that waters from the Albian aquifer have a meteoritic origin, whereas saline waters of the Dogger aquifer are mainly influenced by primary and secondary brine inflow from the Triassic evaporitic deposits, and also by diffusive exchanges with the porewaters of the Liassic shales (Bensenouci et al., 2010). Carbon isotopes display δ¹³C values that are much higher (>0‰) in waters from the Dogger aquifer waters than those from the Albian (≤- 9‰). Oxygen and sulfur isotopes of dissolved sulfates measured in the waters from the Dogger indicate that sulfur comes probably from the Triassic evaporites, whose signatures are overprinted by bacterial sulfate reduction. The water from the Pantin well near Paris displays isotopic characteristics that are comparable to the saline waters from the Dogger. On the other hand, dissolved sulfates of the other waters from the Albian indicate two different sources: sulfates derived from sulfides that have undergone abiotic oxidation processes, and atmospheric and/or crustal sources. Uranium activity ratios are very high in most groundwaters from the Albian, especially northwest of the Paris region where ratios as high as 20 have been measured. These activity ratios are in most cases higher than those of the saline waters from the Dogger, and suggest important water/rock interaction processes within the Albian aquifer in agreement with Li isotopes data. Boron and strontium isotopic data suggest that some waters from the Albian record the geochemical influence of saline waters comparable to those of underlying aquifers of the Paris Basin, especially Northeast of Paris, in agreement with recent geophysical studies.

In the present work, we critically evaluate the information that can be derived from each of the tested isotope systematics in terms of leakage and mixing processes as might occur as the result of man-induced hydraulic shortcuts or changes in the pressure gradients between deep groundwater levels. Sulfur, oxygen, strontium and boron reveal the most sensitive indicators of mixing processes, whereas lithium and, in particular, uranium isotope ratios are strongly overprinted by water-rock interaction and redox processes.

来自法国巴黎盆地的深层 Dogger 和 Albian 含水层地下水中的氧（H ₂ O 和 SO ₄）、氢（H ₂ O）、碳、硼、锂、硫（SO ₄)、锶和铀同位素。本研究旨在建立一个自然水文地球化学基线，在假设发生对潜在 Liassic 页岩中存在的碳氢化合物进行非常规开采的情况下，可以根据该基线证明任何来自更深水团的咸水泄漏。Dogger 含水层和 Albian 含水层的水分别具有氯化物-碱性和碳酸氢钙地球化学相，尽管 Albian 含水层的一些水倾向于朝着 Dogger 含水层水的地球化学特征演化。

水分子的稳定同位素表明 Albian 含水层的水具有陨石成因，而 Dogger 含水层的咸水主要受来自三叠纪蒸发沉积物的一次和二次盐水流入的影响，也受与孔隙水的扩散交换的影响。 Liassic 页岩（Bensenouci 等，2010）。碳同位素显示δ ¹³Dogger 含水层水域中的 C 值远高于 Albian 水域中的 C 值 (>0‰) (≤- 9‰)。在 Dogger 的水中测量的溶解硫酸盐的氧和硫同位素表明硫可能来自三叠纪蒸发岩，其特征被细菌硫酸盐还原覆盖。来自巴黎附近 Pantin 井的水显示出与来自 Dogger 的咸水相媲美的同位素特征。另一方面，来自阿尔比安的其他水域的溶解硫酸盐表明有两种不同的来源：来自经历非生物氧化过程的硫化物的硫酸盐，以及大气和/或地壳来源。在阿尔比安地区的大多数地下水中，铀活动比率非常高，特别是在巴黎地区的西北部，已测得比率高达 20。在大多数情况下，这些活动比率高于来自 Dogger 的咸水的活动比率，并且表明与 Li 同位素数据一致的 Albian 含水层中存在重要的水/岩石相互作用过程。硼和锶同位素数据表明，与最近的地球物理研究一致，来自阿尔比安的一些水域记录了咸水的地球化学影响，与巴黎盆地（尤其是巴黎东北部）下伏含水层的影响相当。

在目前的工作中，我们批判性地评估了可以从每个测试的同位素系统学中获得的信息，这些信息可能是由于人为水力捷径或深层地下水位之间压力梯度变化而可能发生的泄漏和混合过程。 . 硫、氧、锶和硼揭示了混合过程中最敏感的指标，而锂，特别是铀的同位素比率则被水-岩石相互作用和氧化还原过程强烈叠加。