Aristotle University of Thessaloniki, School of Geology, Lab. of Engineering Geology and Hydrogeology, 54124, Thessaloniki, Greece.
Aristotle University of Thessaloniki, School of Geology, Department of Mineralogy-Petrology-Economic Geology, 54124, Thessaloniki, Greece.
Environ Pollut. 2018 Apr;235:632-641. doi: 10.1016/j.envpol.2017.12.117. Epub 2018 Jan 11.
Hexavalent chromium is one of the most toxic and carcinogenic species known and can be released into the environment from several sources. In Sarigkiol basin (N Greece) the presence of Cr(VI) in soil, sediments and groundwater may originate from both natural (ophiolitic rocks and their weathering products) and anthropogenic (dispersed fly ash produced from lignite power plants) sources. In this study, the distribution of contents and origin of environmentally available Cr(VI) in soils, sediments, regoliths and fly ash of Sarigkiol basin is presented. Detailed geochemical and mineralogical studies were performed on soil samples (up to 1 m) and regoliths, while leaching tests were also applied to fresh and old fly ash samples. Leachable chromium from soil and sediment samples generally increased with depth and the highest concentrations were observed near to the power plant of Agios Dimitrios. The speciation of chromium in leachates revealed that Cr(VI) concentrations accounted for more than 96% of total Cr. Leaching tests of regoliths established that the natural contribution of Cr(VI) is up to 14 μg kg. Therefore, the measurement of higher concentrations (up to 80 μg kg) of environmentally available Cr(VI) in soils and sediments can be attributed to the impact/presence of dispersed fly ash in the soils and sediments of the same area. This was also supported by the low correlation recorded between environmentally available chromium and Cr-bearing minerals (mainly serpentine and talc). The influenced zone is located in the eastern part of the basin near the local power plant and surrounds an open conveyor belt that transfers fly ash to an open temporary storage pit. This zone overlies an unconfined porous aquifer thus explaining the elevated concentrations of Cr(VI) in groundwater (up to 120 μg L) previously reported in this area.
六价铬是已知毒性和致癌性最强的物质之一，可通过多种来源释放到环境中。在希腊北部的 Sarigkiol 盆地，土壤、沉积物和地下水中 Cr(VI)的存在可能来自于自然（蛇纹石化岩石及其风化产物）和人为（褐煤火力发电厂产生的分散飞灰）两种来源。本研究介绍了 Sarigkiol 盆地土壤、沉积物、风化壳和飞灰中环境有效态 Cr(VI)的含量分布和来源。对土壤样品（深达 1 米）和风化壳进行了详细的地球化学和矿物学研究，同时还对新鲜和旧飞灰样品进行了淋滤实验。土壤和沉积物样品中的可浸出铬通常随深度增加而增加，在 Agios Dimitrios 火力发电厂附近观察到最高浓度。浸出液中铬的形态表明，Cr(VI)浓度占总铬的比例超过 96%。风化壳的淋滤实验确定，天然 Cr(VI)的贡献高达 14μgkg。因此，土壤和沉积物中环境有效态 Cr(VI)的高浓度（高达 80μgkg）可归因于同一地区土壤和沉积物中分散飞灰的影响/存在。这也得到了环境有效态铬与含铬矿物（主要为蛇纹石和滑石）之间相关性低的支持。受影响的区域位于盆地东部靠近当地火力发电厂的地方，周围是一条将飞灰输送到露天临时储存坑的露天输送带。该区域覆盖着无约束的多孔含水层，这解释了该地区先前报告的地下水 Cr(VI)浓度升高（高达 120μg/L）的现象。
