CHEMICAL-EQUILIBRIA OF SELENIUM IN SOILS - A THEORETICAL DEVELOPMENT
CHEMICAL-EQUILIBRIA OF SELENIUM IN SOILS - A THEORETICAL DEVELOPMENT
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DOI：
10.1097/00010694-198708000-00008
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发表时间：
1987-08-01
期刊：
影响因子：
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通讯作者：
LINDSAY, WL
中科院分区：
文献类型：
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作者：
ELRASHIDI, MA;ADRIANO, DC;LINDSAY, WL
热力学数据用于开发与土壤相关的 83 种硒 (Se) 矿物和溶液种类的平衡反应和常数。金属硒酸盐矿物质在通气良好的土壤中的溶解度非常高，预计不会在这些系统中持续存在。研究的 17 种金属亚硒酸盐矿物的溶解度表明，MnSeO3(c) 是唯一可能在强酸性土壤中持续存在的亚硒酸盐矿物。其他亚硒酸盐矿物质似乎太易溶解而无法在土壤中形成，特别是在碱性 pH 范围内。一般来说，金属硒化物矿物在高度还原条件下极难溶于土壤。在研究的17种金属硒化物中，Cu2Se(c)是酸性土壤中最稳定的矿物，PbSe(c)和SnSe(c)在中性和碱性条件下更稳定。这些金属硒化物的配方可以防止元素硒在土壤中沉淀。土壤的氧化还原 (pe+pH) 控制溶液中 Se 的形态。硒酸盐 (SeO42-) 是高氧化还原 (pe+pH > 15.0) 溶液中的主要物质。在中等氧化还原范围（pe+pH 7.5-15.0）中，SeO32-或HSeO3-物质占主导地位，具体取决于pH值。在低氧化还原条件下（pe+pH < 7.5），HSe- 是土壤溶液中的主要物质。只有在强酸性土壤中，H2Se0 物质才会对溶液中的 Se 产生显着贡献。研究发现，所研究的 27 种金属溶液络合物中没有一种对正常耕作土壤中的可溶性硒总量有显着贡献。除 MnSeO3(c) 外，其他已知的亚硒酸盐或硒酸盐矿物预计不会在土壤中持续存在。在中度至高度氧化的条件下，吸附机制可能控制 Se 在固体表面和溶液相之间的分布。然而，在低氧化还原条件下，元素 Se 或金属硒化物矿物，例如 Cu2Se(c)、PbSe(c) 可以控制土壤中 Se 的溶解度。
Thermodynamic data were used to develope equilibrium reactions and constants for 83 selenium (Se) minerals and solution species that relate to soils. The solubilities of the metal-selenate minerals are very high in well-aerated soils and are not expected to persist in these systems. The solubilities of 17 metal-selenite minerals studied suggest that MnSeO3(c) is the only selenite mineral that might persist in strongly acid soils. Other selenite minerals appear to be too soluble to form in soils particularly in the alkaline pH range. Metal-selenide minerals, in general, are extremely insoluble in soils under highly reducing conditions. Of the 17 metal selenides studied, Cu2Se(c) is the most stable mineral in acid soils, and both PbSe(c) and SnSe(c) are more stable under neutral and alkaline conditions. Formulation of these metal-selenides may prevent the precipitation of elemental Se in soils. The redox (pe+pH) of soils controls Se speciation in solution. Selenate (SeO42-) is the major species in solution at high redox (pe+pH > 15.0). In the medium redox range (pe+pH 7.5-15.0) either SeO32- or HSeO3-species is predominant, depending upon pH. At low redox (pe+pH < 7.5), HSe- is the major species in soil solution. Only in strongly acid soils do H2Se0 species contribute significantly to Se in solution. None of the 27 metal solution complexes studied was found to contribute significantly to total soluble Se in normal cultivated soils. Except for MnSeO3(c), none of the other known selenite or selenate minerals is expected to persist in soils. In moderately to highly oxidized conditions it is possible that an adsorption mechanism may control the distribution of Se between solid surfaces and the solution phase. However, at low redox, either elemental Se or a metal-selenide mineral, e.g., Cu2Se(c), PbSe(c) may control Se solubility in soils.