Metal Complexation Properties of Freshwater Dissolved Organic Matter Are Explained by Its Aromaticity and by Anthropogenic Ligands
Metal Complexation Properties of Freshwater Dissolved Organic Matter Are Explained by Its Aromaticity and by Anthropogenic Ligands
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DOI：
10.1021/es103532a
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发表时间：
2011-04-01
影响因子：
11.4
通讯作者：
Smolders, Erik
中科院分区：
文献类型：
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作者：
Baken, Stijn;Degryse, Fien;Smolders, Erik
地表沃茨中溶解有机物（DOM）影响着痕量金属的归趋和环境效应。我们测量了23个DOM样品的反渗透分离在自然，农业和城市地区的淡水中的镉，铜，镍和锌的亲和力的变化。亲和力在统一的pH值和离子组成进行了测定，在低，环境相关的游离镉，铜，镍，锌的活动。DOM的C-标准化金属结合变化4倍（Cu）或约10倍（Cd，Ni，Zn）样品之间。溶解有机碳浓度范围仅为9倍的沃茨，说明DOM质量是一个同样重要的参数，金属络合的DOM量。DOM的紫外吸光度只解释了沃茨中的金属亲和力，表明在这些沃茨中，芳香族腐殖物质是主要的金属螯合剂。较大的金属亲和力被发现从沃茨与城市输入的DOM。Aminopolycarboxylate配体（主要是EDTA）检测浓度高达0.14 μ M，部分解释了较大的金属亲和力。这些表面沃茨中的镍浓度与EDTA浓度密切相关（R-2 = 0.96），这是由形态计算得到的支持。它的结论是，金属络合在沃茨与人为排放是大于估计模型，只考虑到结合腐殖物质。
Dissolved organic matter (DOM) in surface waters affects the fate and environmental effects of trace metals. We measured variability in the Cd, Cu, Ni, and Zn affinity of 23 DOM samples isolated by reverse osmosis from freshwaters in natural, agricultural, and urban areas. Affinities at uniform pH and ionic composition were assayed at low, environmentally relevant free Cd, Cu, Ni, and Zn activities. The C-normalized metal binding of DOM varied 4-fold (Cu) or about 10-fold (Cd, Ni, Zn) among samples. The dissolved organic carbon concentration ranged only 9-fold in the waters, illustrating that DOM quality is an equally important parameter for metal complexation as DOM quantity. The UV-absorbance of DOM explained metal affinity only for waters receiving few urban inputs, indicating that in those waters, aromatic humic substances are the dominant metal chelators. Larger metal affinities were found for DOM from waters with urban inputs. Aminopolycarboxylate ligands (mainly EDTA) were detected at concentrations up to 0.14 mu M and partly explained the larger metal affinity. Nickel concentrations in these surface waters are strongly related to EDTA concentrations (R-2 = 0.96) and this is underpinned by speciation calculations. It is concluded that metal complexation in waters with anthropogenic discharges is larger than that estimated with models that only take into account binding on humic substances.