Is trace metal release in wetland soils controlled by organic matter mobility or Fe-oxyhydroxides reduction?
Is trace metal release in wetland soils controlled by organic matter mobility or Fe-oxyhydroxides reduction?
复制标题
DOI：
10.1016/j.jcis.2007.04.062
复制
发表时间：
2007-10-15
影响因子：
9.9
通讯作者：
Petitjean, Patrice
中科院分区：
文献类型：
--
作者：
Grybos, Malgorzata;Davranche, Melanie;Petitjean, Patrice
采用好氧和厌氧培养实验，研究了土壤还原过程中有机质（OM）释放、铁羟基氧化还原和氧化还原/形态变化对微量金属迁移的影响。厌氧培养过程中释放出大量的Cu、Cr、Co、Ni、Ph、U、Th和稀土元素（REE），并伴随有强烈的Fe（II）和溶解性有机物（DOM）释放。好氧培养在pH 7也导致显着的微量金属和DOM的释放，这表明铁羟基氧化物还原不是唯一的机制控制微量金属的流动性在土壤还原。利用这些结果和氧化还原/形态模拟，确定了四种类型的痕量金属行为：（i）与有机质（OM）结合并通过DOM释放（REE）释放的金属;（ii）与OM和Fe-羟基氧化物结合并通过DOM释放和Fe（III）还原的联合作用释放的金属（iii）仅与土壤Fe-羟基氧化物结合并通过其还原溶解释放的金属（Co）;和（iv）释放机制尚不清楚的金属，因为它们在还原时的行为受氧化还原状态和/或溶液形态变化的影响（Cu、Cr、U和Th）。尽管土壤Fe-羟基氧化物还原过程在控制湿地土壤中的金属流动性方面很重要，但本研究表明，该过程的主导机制是OM释放。因此，OM应系统地监测，致力于了解微量金属在湿地土壤中的流动性的实验研究。由于有机质的释放过程主要受pH值的控制，因此pH值是影响湿地土壤中金属迁移的重要参数。(c)2007年爱思唯尔公司All rights reserved.
Aerobic and anaerobic incubation experiments on a wetland soil samples were used to assess the respective roles of organic matter (OM) release, Fe-oxyhydroxides reduction and redox/speciation changes on trace metal mobility during soil reduction. Significant amounts of Cu, Cr, Co, Ni, Ph, U, Th and Rare Earth Elements (REE) were released during anaerobic incubation, and were accompanied by strong Fe(II) and dissolved organic matter (DOM) release. Aerobic incubation at pH 7 also resulted in significant trace metal and DOM release, suggesting that Fe-oxyhydroxide reduction is not the sole mechanism controlling trace metal mobility during soil reduction. Using these results and redox/speciation modeling, four types of trace metal behavior were identified: (i) metals bound to organic matter (OM) and released by DOM release (REE); (ii) metals bound to both OM and Fe-oxyhydroxides, and released by the combined effect of DOM release and Fe(III) reduction (Ph and Ni); (iii) metals bound solely to soil Fe-oxyhydroxides and released by its reductive dissolution (Co); and (iv) metals for which release mechanisms are unclear because their behavior upon reduction is affected by changes in redox state and/or solution speciation (Cu, Cr, U and Th). Even though the process of soil Fe-oxyhydroxide reduction is important in controlling metal mobility in wetland soils, the present study showed that the dominant mechanism for this process is OM release. Thus, OM should be systematically monitored in experimental studies dedicated to understand trace metal mobility in wetland soils. Due to the fact that the process of OM release is mainly controlled by pH variations, the pH is a more crucial parameter than Eh for metal mobility in wetland soils. (c) 2007 Elsevier Inc. All rights reserved.