School of Chinese Materia Medica and Yunnan Key Laboratory of Southern Medicinal Resource, Yunnan University of Chinese Medicine, Kunming, 650500, China.
Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, China.
Environ Pollut. 2021 Feb 1;270:116221. doi: 10.1016/j.envpol.2020.116221. Epub 2020 Dec 16.
Dissolved organic matter (DOM) and dissolved ions are two integral parameters to affect the environmental fate of As in different ways. Numerous studies chose surrogate of DOM, humic substances (HSs), to investigate the As complexation behavior. However, microbial secretion (protein and polysaccharide) was also considered for a great proportion in surface aquatic system, and its effect was still not fully understood. The present research distinguished the As complexation behavior with different DOM components (HSs, protein, polysaccharide and synthetic organic matter) in natural and simulated water samples. The results indicated that different DOM components exhibited various binding capacities for As. HSs showed the strongest affinity for As, followed by long-chain compounds (polysaccharide and synthetic organic matter) and proteins. In water source, HSs were probably the primary parameter for As complexation. In eutrophic water system, however, polysaccharide maybe the main DOM component to bind As. Cationic bridge function was prone to occur in the presence of HSs, but not observed in the presence of protein. PO competed for binding sites with As, consequently decreasing the As complexation with all the DOM components. The research implied that a comprehensive and meticulous analyses of DOM fractions and coexist ions are the prerequisite to understanding the behavior of As (or other pollutants) in different natural aquatic systems.
溶解有机物 (DOM) 和溶解离子是影响砷在不同环境中归宿的两个重要参数。许多研究选择 DOM 的替代物，即腐殖质 (HSs)，来研究砷的络合行为。然而，微生物分泌的物质（蛋白质和多糖）在地表水系中也占有很大比例，但其作用仍未被充分了解。本研究区分了不同 DOM 成分（HSs、蛋白质、多糖和合成有机物）在天然和模拟水样中对砷的络合行为。结果表明，不同的 DOM 成分对砷表现出不同的络合能力。HSs 对砷的亲和力最强，其次是长链化合物（多糖和合成有机物）和蛋白质。在水源中，HSs 可能是砷络合的主要参数。然而，在富营养化水体中，多糖可能是与砷结合的主要 DOM 成分。在 HSs 存在的情况下，阳离子桥接作用更容易发生，但在蛋白质存在的情况下则不会观察到。PO43-与砷竞争结合位点，从而降低了所有 DOM 成分与砷的络合作用。研究表明，对 DOM 组分和共存离子进行全面、细致的分析是理解不同自然水生系统中砷（或其他污染物）行为的前提。
