Dissolved organic matter (DOM) present in aquatic environments can significantly influence microalgal metabolism and the enrichment of heavy metals. However, the specific mechanism through which typical DOM affects the enrichment of the heavy metal chromium (Cr) in green algae remains unclear. This study investigates the impacts of varying concentrations of humic acid (HA), selected as a representative DOM in water, on the growth, metabolism, and Cr enrichment in Chlorella vulgaris, a typical green alga. The results indicated that low concentrations of HA were capable of enhancing Cr enrichment in C. vulgaris, with the highest Cr enrichment rate recorded at 41.50 % at TOC = 10 mg/L. The enrichment of Cr in algal cells primarily occurred through cell proliferation and complexation reduction of extracellular polymeric substances (EPS). In the presence of HA, C. vulgaris predominantly removed Cr through extracellular adsorption, accounting for 79.76–85.88 % of the total Cr removal. Furthermore, carboxyl complexation and hydroxyl reduction within EPS facilitated both the enrichment of Cr (18.72–21.49 %) and the reduction of Cr(VI) (63.93–74.10 %). These findings provide valuable insights into strategies for mitigating heavy metal pollution and managing associated risks in aquatic environments.

中文翻译：

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腐植酸和 Cr（VI） 对绿色微藻的相互作用：代谢反应和铬富集


水生环境中存在的溶解有机物 （DOM） 会显着影响微藻代谢和重金属的富集。然而，典型 DOM 影响绿藻中重金属铬 （Cr） 富集的具体机制仍不清楚。本研究调查了不同浓度的腐殖酸 （HA），被选为水中具有代表性的 DOM，对小球藻（一种典型的绿藻）的生长、代谢和 Cr 富集的影响。结果表明，低浓度的 HA 能够增强 C. vulgaris 中的 Cr 富集，在 TOC = 10 mg/L 时，Cr 富集率最高，为 41.50 %。藻类细胞中 Cr 的富集主要通过细胞增殖和细胞外聚合物物质 （EPS） 的络合减少发生。在 HA 存在下，C. vulgaris 主要通过细胞外吸附去除 Cr，占总 Cr 去除量的 79.76-85.88%。此外，EPS 中的羧基络合和羟基还原促进了 Cr 的富集 （18.72-21.49%） 和 Cr（VI） 的降低 （63.93-74.10%）。这些发现为减轻重金属污染和管理水生环境中相关风险的策略提供了宝贵的见解。