This research aims to determine the hydrogeochemical characteristics, origin, and geochemical evolution of the Cr enriched alkaline waters in the ultramafic rock-related water bodies of Loutraki basin in Northeast Peloponnese, Greece. The significance of the particular research lies in the fact that Cr occurrence raises concerns with respect to health risks associated with the utilization of such aquifers for drinking water supply. Therefore, the investigation of water–rock interaction processes leading to Cr mobilization in such environments is of great importance. A total of 41 water samples including groundwater from the alluvial and fractured aquifers as well as surface water were collected and analyzed for major and trace elements during the wet and dry seasons of 2015. Solid samples including soils, sediments and rocks were also collected to provide evidence of elemental mobilization due to water–rock interaction, with special focus on Cr. Τhe main Cr-bearing minerals identified were Cr-spinel, ferrichromite, magnetite, clinopyroxene, chlorite and serpentine. The observed dissolution textures within the magnetite rim and across the magnetite–chromite boundary indicate that these latter can be also active sources of Cr(III). Both groundwater and surface waters are of Mg–HCO₃ type due to CO₂-driven dissolution of serpentine minerals and Mg-carbonates/hydroxides. The formation of hydromagnesite aggregates is attributed to precipitation from Mg²⁺-rich alkaline waters. The highest Cr(VI) concentrations were measured in the alluvial aquifer (6.7–74.3 μg L⁻¹) and the lowest in the fractured ophiolitic aquifer (1.9–14.3 μg L⁻¹); while in surface water, the maximum measured Cr(VI) concentration was up to 3.9 μg L⁻¹. Finally, the identification of Mn-rich hematite indicates that the oxidation of Cr(III) to Cr(VI) is probably performed by manganese–iron oxides.

本研究旨在确定希腊伯罗奔尼撒东北部Loutraki盆地超镁铁质岩石相关水体中富Cr碱性水的水文地球化学特征，成因和地球化学演化。这项特殊研究的意义在于，铬的出现引起人们对与利用这种含水层作为饮用水供应有关的健康风险的关注。因此，研究在这种环境下导致Cr迁移的水-岩相互作用过程非常重要。总共收集了41个水样，包括来自冲积层和裂隙含水层的地下水以及地表水，并分析了2015年干湿季节的主要和微量元素。固体样品包括土壤，还收集了沉积物和岩石，以提供因水-岩相互作用而元素动员的证据，特别是铬。鉴定出的主要含铬矿物为铬尖晶石，亚铁铬铁矿，磁铁矿，斜辉石，绿泥石和蛇纹石。在磁铁矿边缘和磁铁矿-铬铁矿边界之间观察到的溶解质地表明，后者也可能是Cr（III）的活性来源。地下水和地表水均为Mg–HCO 在磁铁矿边缘和磁铁矿-铬铁矿边界之间观察到的溶解质地表明，后者也可能是Cr（III）的活性来源。地下水和地表水均为Mg–HCO 在磁铁矿边缘和磁铁矿-铬铁矿边界之间观察到的溶解质地表明，后者也可能是Cr（III）的活性来源。地下水和地表水均为Mg–HCO₃型是由于CO ₂驱动的蛇纹石矿物和碳酸镁/氢氧化物的溶解。菱镁矿聚集体的形成归因于富含Mg ^2+的碱性水的沉淀。在冲积层中测得的最高Cr（VI）浓度为（6.7-74.3μgL ^-1），而在碎屑蛇纹岩含水层中测得的最低浓度为（1.9-14.3μgL ^-1）；而在地表水中，Cr（VI）的最大测量浓度最高为3.9μgL ^-1。最后，富锰赤铁矿的鉴定表明，Cr（III）氧化为Cr（VI）可能是由锰铁氧化物完成的。