Abstract：
In lightly polluted water containing heavy metals, organic matter, and green microalgae, the molecular weight of organic matter may influence both the growth of green microalgae and the concentration of heavy metals. This study elucidates the effects and mechanisms by which different molecular weight fractions of fulvic acid (FA), a model dissolved organic matter component, facilitate the bioaccumulation of hexavalent chromium (Cr(VI)) in a typical green alga, Chlorella vulgaris. Findings show that the addition of FA fractions with molecular weights greater than 10 kDa significantly enhances the enrichment of total chromium and Cr(VI) in algal cells, reaching 21.58%-31.09 % and 16.17 %-22.63 %, respectively. Conversely, the efficiency of chromium enrichment in algal cells was found to decrease with decreasing molecular weight of FA. FA molecular weight within the range of 0.22 µm-30 kDa facilitated chromium enrichment primarily through the algal organic matter (AOM) pathway, with minor contributions from the algal cell proliferation and extracellular polymeric substances (EPS) pathways. However, with decreasing FA molecular weight, the AOM and EPS pathways become less prominent, whereas the algal cell proliferation pathway becomes dominant. These findings provide new insights into the mechanism of chromium enrichment in green algae enhanced by medium molecular weight FA.
摘要：
在含有重金属的轻度污染水中，有机物,和绿色微藻，有机物的分子量对绿藻的生长和重金属的浓度都有影响。这项研究阐明了不同分子量的富里酸（FA），一种模型溶解的有机物成分，促进六价铬（Cr（VI））在典型的绿藻中的生物积累，普通小球藻.研究结果表明，添加分子量大于10kDa的FA级分可显着增强藻类细胞中总铬和Cr（VI）的富集，达到21.58%-31.09%和16.17%-22.63%，分别。相反，发现藻类细胞中铬的富集效率随着FA分子量的降低而降低。FA分子量在0.22µm-30kDa范围内，主要通过藻类有机物（AOM）途径促进了铬的富集，藻类细胞增殖和胞外聚合物（EPS）途径的贡献很小。然而,随着FA分子量的降低，AOM和EPS途径变得不那么突出，而藻类细胞增殖途径成为主导。这些发现为中等分子量FA增强绿藻中铬的富集机理提供了新的见解。
