Hexavalent chromium (Cr (VI)) is an environmental contaminant brining high concerns due to its higher toxicity and mobility in comparison with trivalent chromium Cr(III). Cr (VI) has been linked with several adverse health effects, including respiratory diseases, lung cancer, and skin irritation. The primary sources of it in the environment are industrial activities.Most of the time, fly ash made of lignite can release Cr(VI) when it comes into contact with water in an aquatic environment. The objective of this study is the investigation of Cr (VI) concentration in leachates of fly ash and marl mixtures and the determination of its solubility under different pH conditions. Samples of fly ash were collected from the Power Plant of Agios Dimitrios. Additionally, samples of marl were collected from the mine of South Field, and both samples were mixed and prepared in in different proportions (% w.t.). The leaching experiments were carried out according to the EN-12457/1-4 (2003) standard under different pH conditions and chemical analysis of the leachates were performed by spectrophotometry with diphenylcarbazide (DPC). The environmental footprint of Cr (VI) in the study area was significant, especially in mixtures containing higher concentrations of fly ash. A critical pH range between 6 to 12 is observed. At acidic pH values, a high release of Cr (VI) was observed, while at the mentioned critical values (pH 10–12), a gradual decrease in its leachability was noticed. The high concentrations of Cr (VI) in the industrial area studied require immediate actions in terms of managing and limiting the potential hazardous impacts on the environment and by extension on the public health by developing appropriate prevention strategies.

Graphical abstract

中文翻译：

---

希腊西马其顿萨里吉奥尔盆地飞灰-泥灰岩混合物中六价铬的浸出率：环境危害和潜在的人类健康风险

与三价铬 Cr(III) 相比，六价铬 (Cr(VI)) 具有更高的毒性和迁移性，是一种备受关注的环境污染物。 Cr (VI) 与多种不良健康影响有关，包括呼吸道疾病、肺癌和皮肤刺激。环境中铬的主要来源是工业活动。大多数情况下，褐煤制成的粉煤灰在水生环境中与水接触时会释放出 Cr(VI)。本研究的目的是调查飞灰和泥灰混合物渗滤液中 Cr (VI) 的浓度，并测定其在不同 pH 条件下的溶解度。飞灰样品是从 Agios Dimitrios 发电厂收集的。此外，从 South Field 矿采集了泥灰岩样品，并将两种样品以不同比例（% wt）混合制备。根据EN-12457/1-4（2003）标准在不同pH条件下进行浸出实验，并通过二苯卡巴肼（DPC）分光光度法对浸出液进行化学分析。研究区域中六价铬的环境足迹非常显着，特别是在含有较高浓度飞灰的混合物中。观察到 6 至 12 之间的临界 pH 范围。在酸性 pH 值下，观察到 Cr (VI) 的大量释放，而在上述临界值（pH 10-12）下，注意到其浸出性逐渐下降。研究的工业区域中六价铬的浓度很高，需要立即采取行动，通过制定适当的预防策略来管理和限制对环境的潜在危险影响，并扩大对公众健康的影响。

图形概要