Impact of organic matter molecular weight on hexavalent chromium enrichment in green microalgae

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作   者：

Mawuli Dzakpasu;  Yifei Du;  Chao Yang;  Wenshan Guo;  Huu Hao Ngo;  Xiaochang C. Wang;  Li Luo;  Xu Jiang; 

作者机构：

International Science & Technology Cooperation Center for Urban Alternative Water Resources Development;  Australia;  NSW 2007;  Key Lab of Northwest Water Resource;  Centre for Technology in Water and Wastewater;  Key Lab of Environmental Engineering;  Sydney;  Xi’an University of Architecture and Technology;  Engineering Technology Research Center for Wastewater Treatment and Reuse;  Zhengzhou 450003;  Yanta Road;  No. 13;  MOE;  Yellow River Institute of Eco-Environmental Research;  University of Technology;  No.6;  Henan Province;  Environment and Ecology;  Shaanxi Province;  China;  Xi’an 710055;  Changchun Road;  Faculty of Engineering and Information Technology; 

关键词：

Extracellular polymeric substances;  Algal organic matter;  Chlorella vulgaris;  Heavy metal;  Molecular weight of dissolved organic matter; 

期刊名称：

Journal of Hazardous Materials

i s s n：

0304-3894

年卷期：

2024 年 470 卷 May 15 期

页   码：

134304.1-134304.11

页   码：

摘   要：

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.