The southern part of the Plana de Castellón aquifer (Spanish Mediterranean coast) has experienced persistent seawater intrusion over the last 50 years. The salinisation process is related to the lateral advance of the saline wedge and saline upconing as a result of intensive local groundwater pumping. In this context, managed artificial recharge (MAR) was performed to aid in the recovery of this coastal aquifer. The artificial recharge water (ARW) was characterised by very low mineralisation, as evidenced by a mean electrical conductivity of 330 μS/cm, whereas native groundwater (NGW) was brackish, with EC values of approximately 3,000–3,500 μS/cm.

The dynamics of the injected water and physicochemical changes to groundwater during the MAR event were evaluated using a combination of hydrogeochemical methods. EC, chloride ions, nitrate ions, and stable water isotopes (oxygen-18 and deuterium) were used as tracers to quantify the presence of injected water in groundwater (mixing ratios).

Hydrochemical analysis (of major cations and anions) was used to determine changes to water characteristics and hydrogeochemical processes associated with the mixing of ARW and NGW and water-rock interactions. The injection significantly reduced groundwater salinity: EC and major ions rapidly and continuously declined after the first days of recharge. Percentage decreases in electrical conductivity of 80–90% and 30% were detected at 80 and 450 m from the recharge wells (values of 350–550 μs/cm), respectively.

The principal process occurring in the aquifer during injection was dilution due to the displacement of NGW and mixing of ARW and NGW. Carbonate and sulfate mineral dissolution, cation exchange, and redox reactions were also identified, and their magnitudes were estimated. In quantitative terms, cation exchange was the most important geochemical process occurring during the MAR event.

在过去的50年中，普拉纳德卡斯特利翁蓄水层的南部（西班牙地中海沿岸）经历了持续的海水入侵。盐碱化过程与盐水楔的横向行进和由于大量局部地下水泵送而导致的盐水上冲有关。在这种情况下，进行有管理的人工补给（MAR）以帮助恢复该沿海含水层。人工补给水（ARW）的特征是矿化度很低，平均电导率为330μS/ cm，而天然地下水（NGW）则微咸，EC值约为3,000–3,500μS/ cm。

使用水文地球化学方法对MAR事件期间注入水的动态和地下水的理化变化进行了评估。EC，氯离子，硝酸根离子和稳定的水同位素（18号氧和氘）被用作示踪剂，以量化地下水中注入水的存在（混合比）。

通过水化学分析（主要阳离子和阴离子）来确定与ARW和NGW混合以及水-岩相互作用相关的水质和水地球化学过程的变化。注入大大降低了地下水的盐度：补给后的第一天，EC和主要离子迅速且持续下降。在距补给井80和450 m处，电导率分别降低了80-90％和30％（值350-550μs/ cm）。

注入过程中含水层中发生的主要过程是由于NGW的置换以及ARW和NGW的混合而导致的稀释。还确定了碳酸盐和硫酸盐矿物的溶解，阳离子交换和氧化还原反应，并对它们的大小进行了估算。从数量上讲，阳离子交换是MAR事件期间发生的最重要的地球化学过程。