Kinetically inert Cu in coastal waters.
Kinetically inert Cu in coastal waters.
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沿海水域中具有动力学惰性的铜。
DOI：
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发表时间：
2003
影响因子：
11.4
通讯作者：
B. Voelker
中科院分区：
文献类型：
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作者：
M. B. Kogut;B. Voelker
许多研究表明，天然水中的铜和其他金属大多被不明化合物结合，这些化合物被解释为与给定金属可逆络合的强配体。然而，常用的分析技术不能区分强烈但可逆的络合金属和结合在动力学惰性化合物中的金属。在这项工作中，我们使用一种改进的竞争配体交换吸附阴极溶出伏安法，并结合粒度分级，表明在新英格兰沿海五个水域(1-18 nm，占总铜的10-60%)样品中，大部分(如果不是全部)表面上很强(logK>；或=13)结合的铜实际上是以动力学惰性化合物的形式存在的。在超滤检查的五个样品中，有三个样品的0.2微米可过滤的惰性铜的很大一部分被0.02微孔大小的过滤器保留，这表明至少有一些铜在动力学上是惰性的，因为它被物理隔离在胶体材料中。其余的环境铜和加入滴定的铜可逆地结合在络合物中，这些络合物可以被模拟为具有10(10)-10(13)的条件稳定常数。这些络合物的铜结合能力与含有合理浓度的陆源腐殖质的海水相当，约为0.15-0.45 mg C/L。惰性化合物和可逆配体对于测定样品中环境铜水平的[Cu2+]都是重要的。
Many studies have shown that Cu and other metals in natural waters are mostly bound by unidentified compounds interpreted to be strong ligands reversibly complexing a given metal. However, commonly applied analytical techniques are not capable of distinguishing strongly but reversibly complexed metal from metal bound in kinetically inert compounds. In this work, we use a modified competitive ligand exchange adsorptive cathodic stripping voltammetry method combined with size fractionation to show that most if not all of the apparently very strongly (log K > or = 13) bound Cu in samples from five New England coastal waters (1-18 nM, 10-60% of total Cu) is actually present as kinetically inert compounds. In three of the five samples examined by ultrafiltration, a significant portion of the 0.2-microm-filtrable inert Cu was retained by a 0.02-microm-pore size filter, suggesting that at least some of the Cu was kinetically inert because it was physically sequestered in colloidal material. The rest of the ambient Cu, and Cu added in titrations, were reversibly bound in complexes that could be modeled as having conditional stability constants of 10(10)-10(13). The Cu-binding ability of these complexes was equivalent to that of seawater containing reasonable concentrations of humic substances from terrestrial sources, approximately 0.15-0.45 mg of C/L. Both the inert compounds and the reversible ligands were important for determining [Cu2+] at ambient Cu levels in our samples.