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Zinc, lead and cadmium speciation in Dnieper water-bodies

机译：第聂伯河水体中的锌，铅和镉形态

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Data on the concentrations and movements of Zn, Pb and Cd in Dnieper reservoirs and the Dnieper-Bug estuary are considered. There is a clear trend of increasing concentrations, often two- to fourfold, of these materials from the 1960s to the end of the 1980s. Large increases may be explained as the result of increased human impact on the water-bodies and also because of reduced water discharge in the Dnieper River (discharge has been reduced by nearly 10 km3 in recent years). At present, the average concentrations of Zn, Pb and Cd in Dnieper water-bodies are 35.0–50.0, 15.0–18.0 and 0.5–1.8 Μg L–1, respectively. Anodic stripping voltammetry, membrane filtration, ion-exchange and gel permeation chromatography on neutral sephadexes were methods used for analysis. The influence of adsorption and complexation processes on the mobility of Zn, Pb and Cd, and the ratio of their forms were compared. Ratios of free metal ions to ions bound in complexes with natural organic ligands were studied. The binding of metals in complexes with dissolved organic matter (DOM), or their adsorption onto suspended particles, were major processes reducing the concentration of free ions in their most toxic form. The percentage of Zn, Pb, and Cd free ions in the total balance of dissolved forms was no more than 3.6–4.8, 0.2–0.6 and 7.2–9.5%, respectively. The molecular-weight distribution of organic metal complexes and their chemical nature, as well as the potential for complexing of DOM were investigated. Most Zn, Pb and Cd was found as complex compounds with DOM of different chemical natures and molecular weights. Humic substances, particularly fulvic acids, played a major role in the migration of the metals. These ligands bind from 40 to 80% of metals in the composition of organic complexes. Metal complex compounds of relatively low molecular weight (< 5000 Da) predominated in organic complexes of Zn (38–50%), Pb (38–52%) and Cd (22–47%). The role of inorganic ligands in complexation in surface waters was less important.
机译：考虑了第聂伯油藏和第聂伯-布格河口中锌，铅和镉的浓度和移动的数据。从1960年代到1980年代末，这些材料的浓度有明显增加的趋势，通常是其两倍至四倍。人为增加对水体影响的结果，以及由于第聂伯河的排水量减少（近年来，排水量减少了近10 km3），可以解释为大幅增加。目前，第聂伯水体中锌，铅和镉的平均浓度分别为35.0-50.0、15.0-18.0和0.5-1.8毫克L-1。阳极溶出伏安法，膜过滤，离子交换和凝胶渗透色谱法在中性葡聚糖上进行分析。比较了吸附和络合过程对Zn，Pb和Cd迁移率的影响，以及它们的形态比。研究了游离金属离子与结合天然有机配体的离子的比例。金属与溶解有机物（DOM）的结合或吸附到悬浮颗粒上的主要过程是降低最具毒性形式的游离离子的浓度。 Zn，Pb和Cd游离离子在溶解态的总平衡中所占的百分比分别不超过3.6-4.8％，0.2-0.6和7.2-9.5％。研究了有机金属配合物的分子量分布及其化学性质以及DOM的复合潜力。发现大多数Zn，Pb和Cd是具有不同化学性质和分子量的DOM的复杂化合物。腐殖质，特别是黄腐酸，在金属的迁移中起主要作用。这些配体结合了有机配合物组成中40％至80％的金属。相对低分子量（<5000 Da）的金属络合物主要存在于锌（38–50％），铅（38–52％）和镉（22–47％）的有机络合物中。无机配体在地表水中络合中的作用不太重要。

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