The chromium cycle in a seasonally anoxic lake
The chromium cycle in a seasonally anoxic lake
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DOI：
10.4319/lo.1992.37.2.0315
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发表时间：
1992-03
影响因子：
4.5
通讯作者：
C. A. Johnson;L. Sigg;Ursula Lindauer
中科院分区：
文献类型：
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作者：
C. A. Johnson;L. Sigg;Ursula Lindauer
在季节性缺氧的瑞士格雷芬塞对铬循环进行了调查。测定了1989年1月至11月的铬(III)、铬(VI)、总溶解(co.45 pm)铬和总铬浓度分布，以及其他氧化还原敏感物种N、Mn、Fe和S。即使在缺氧条件下，铬(V1)仍是优势物种。铬(V_1)浓度范围为1~4 nm。只有在S(-II)和Fe(II)存在的极端还原条件下，才能观察到铬(V1)的还原。结果表明，要使铬(V1)还原成铬(II1)，必须存在合适的还原剂，有机还原剂很可能起到次要的作用。此外，计算表明，在含氧水和亚氧水中都发生了一个缓慢的去除过程，半衰期为100-230d，通过吸附或还原降低了Cr(V1)的浓度。没有检测到溶解的游离铬(II1)物种，这是由于该物种强烈地与表面以及有机配体和胶体结合所致。即使在有氧条件下，沉积物似乎也不是铬(V1)的来源。
The Cr cycle was investigated in seasonally anoxic Greifensee, Switzerland. Cr(III), Cr(VI), and total dissolved (co.45 pm) Cr and total Cr concentration profiles were measured from January until November 1989 together with other redox sensitive species of N, Mn, Fe, and S. Cr(V1) was the predominant species even under anoxic conditions. Concentrations of Cr(V1) ranged from 1 to 4 nM. Reduction of Cr(V1) could be observed only in extremely reducing conditions in the presence of S(-II) and Fe(II). It was concluded that a suitable reducing agent had to be present for the reduction of CR(V1) to Cr(II1) to take place and that organic reductants most probably played a minor role. In addition, calculations indicated the occurrence of a slow removal process, with a half-time of loo-230 d, that reduced Cr(V1) concentrations by either adsorption or reduction in both oxic and suboxic waters. Dissolved free Cr(II1) species were not detected, which was explained by the strong tendency of this species to bind with surfaces and organic ligands and colloids. Even in oxic conditions, the sediments did not appear to be a source of Cr(V1).