ABSTRACT

The objectives of this study are to characterize the input signal of a shallow carbonate aquifer in northeastern France and to clarify the recharge and groundwater mineralization processes, by analysing the chemical and isotopic (δ¹⁸O, δ²H) composition of rain and groundwater. The groundwater isotopic signature was very close to the calculated local meteoric water line and showed a narrow range, which is explained by the buffer effect of the matrix-dominated chalk aquifer. Nevertheless, intensive fracture networks can exist at local scale and lead to rapid aquifer response to rainfall, as attested by observed large variations in groundwater isotopic and chemical signatures at one specific site. Main factors controlling the groundwater mineralization are highlighted, including the input signal, water-rock interactions and human activities. Moreover, groundwater isotopic signatures are related to groundwater ages and historical climate conditions, showing that groundwater isotopic signal could also be used as a record of climate changes.

摘要

本研究的目的是通过分析化学和同位素 (δ ¹⁸ O, δ ²H) 雨水和地下水的组成。地下水同位素特征与计算的当地大气水线非常接近，并显示出一个狭窄的范围，这是由基质为主的白垩含水层的缓冲作用所解释的。然而，密集的裂缝网络可以在局部范围内存在，并导致含水层对降雨的快速响应，这一点已在一个特定地点观察到地下水同位素和化学特征的巨大变化证明了这一点。重点介绍了控制地下水矿化的主要因素，包括输入信号、水-岩相互作用和人类活动。此外，地下水同位素特征与地下水年龄和历史气候条件有关，表明地下水同位素信号也可以作为气候变化的记录。