水生环境中溶解的有机物 (DOM) 通过络合显着影响重金属的行为和命运,而界面机制和过程仍然缺乏细节。在这里,通过荧光激发-发射矩阵光谱 (EEM) 结合主成分系数,平行探索了源自城市化河流丘陵 (NDOM)、农村 (RDOM) 和城市 (UDOM) 地区的 DOM 的 Cu (II) 结合特征因子分析 (PARAFAC)、移动窗口二维相关光谱 (MW2DCOS) 和结构方程模型 (SEM)。通过EEM-PARAFAC从滴定剂中提取出8种成分,即酚类物质(C1)、酪氨酸类物质(C2)、可见色氨酸类物质(C3)、紫外色氨酸类物质(C4)、近生生物生产(C5),废水衍生的有机物 (C6)、微生物类腐殖质 (C7) 和黄腐类物质 (C8)。有趣的是,NDOM 只包含 C1、C3、C5 和 C8,而几乎所有组件都存在于 RDOM(C2 除外)和 UDOM(C4 除外)中。这NDOM中C1的f值(1.239)远高于RDOM(0.134)和UDOM(0.115),C8也是如此。这表明来自原生来源的苯酚样和黄腐样样在与 Cu (II) 的络合中表现出很大的结合率。此外,UDOM 的 C3 和 C5 表现出比 NDOM 和 RDOM 更高的f值(0.591 和 1.983),表明 Cu (II) 对生活和工业废水中的类蛋白质具有很强的结合能力。MW2DCOS 显示 NDOM 和 RDOM 中的苯酚样和蛋白质样对于 160 μmol L −1 Cu (II) 的结合是必不可少的,而 NDOM 和 UDOM 中的黄腐酸样可以与 10 μmol L −1显着反应铜(二)。基于SEM,Cu(II)浓度对C7或C8的荧光强度具有负直接影响,而通过影响C5对C7或C8表现出间接正影响,C6也是如此。这表明 Cu (II) 对 C8 显示出间接的积极影响。这项研究可能会进一步了解 Cu (II) 在河流中的环境行为。
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Applying EEM-PARAFAC combined with moving-window 2DCOS and structural equation modeling to characterize binding properties of Cu (II) with DOM from different sources in an urbanized river
Dissolved organic matter (DOM) in aquatic environment distinctly affects the behavior and fate of heavy metals via complexation, while the interfacial mechanisms and processes are still lacking in detail. Here, Cu (II) binding characteristics of DOM originated from hilly (NDOM), rural (RDOM) and urban (UDOM) regions in an urbanized river was explored by fluorescence excitation-emission matrix spectroscopy (EEM) combined with principal component coefficients, parallel factor analyses (PARAFAC), moving-window two-dimensional correlation spectroscopy (MW2DCOS) and structural equation modeling (SEM). Eight components were extracted from the titrants through EEM-PARAFAC, i.e., phenol-like substance (C1), tyrosine-like substance (C2), visible tryptophan-like substance (C3), ultraviolet tryptophan-like substance (C4), recent biological production (C5), wastewater-derived organic matter (C6), microbial humic-like substance (C7) and fulvic-like substance (C8). Interestingly, NDOM only contained C1, C3, C5 and C8, while nearly all components were found in RDOM (except for C2) and UDOM (except for C4). The f value of C1 (1.239) in NDOM was much higher than those in RDOM (0.134) and UDOM (0.115), so was of C8. It indicated that phenol-like and fulvic-like derived from autochthonous sources exhibited great binding ratios in the complexation with Cu (II). Moreover, C3 and C5 from UDOM exhibited higher f values (0.591 and 1.983) than those from NDOM and RDOM, suggesting that Cu (II) has a great binding capacity on protein-like from domestic and industrial wastewater. The MW2DCOS revealed that phenol-like and protein-like in NDOM and RDOM were essential for the binding of 160 μmol L−1 Cu (II), whereas fulvic-like in NDOM and UDOM could react significantly with 10 μmol L−1 Cu (II). Based on SEM, Cu (II) concentration had a negative direct effect on the fluorescence intensity of C7 or C8, whereas it showed an indirect positive effect on C7 or C8 through influencing C5, so was C6. It suggested that Cu (II) showed an indirect positive effect on the C8. This study might present a further comprehend of the environmental behaviors of Cu (II) in rivers.