土壤中 pH 值依赖型磷酸盐吸附的竞争与协同作用：LCD 模型。
Competitive and synergistic effects in pH dependent phosphate adsorption in soils: LCD modeling.
机构信息
Department of Soil Quality, Wageningen University P.O. Box 47, 6700 AA, Wageningen, The Netherlands.
出版信息
Environ Sci Technol. 2011 Oct 1;45(19):8420-8. doi: 10.1021/es201844d. Epub 2011 Sep 6.
The pH dependency of soluble phosphate in soil was measured for six agricultural soils over a pH range of 3-10. A mechanistic model, the LCD (ligand charge distribution) model, was used to simulate this change, which considers phosphate adsorption to metal (hydr)oxides in soils under the influence of natural organic matter (NOM) and polyvalent cations (Ca(2+), Al(3+), and Fe(3+)). For all soils except one, the description in the normal pH range 5-8 is good. For some soils at more extreme pH values (for low P-loading soils at low pH and for high P-loading soils at high pH), the model over predicts soluble P. The calculation shows that adsorption is the major mechanism controlling phosphate solubility in soils, except at high pH in high P-loading soils where precipitation of calcium phosphate may take place. NOM and polyvalent cations have a very strong effect on the concentration level of P. The pattern of pH dependency of soluble P in soils differs greatly from the pH effects on phosphate adsorption to synthetic metal (hydr)oxides in a monocomponent system. According to the LCD model, the pH dependency in soil is mainly caused by the synergistic effects of Ca(2+) adsorption to oxides. Adsorption of Al(3+) to NOM adsorbed plays an important role only at a pH < 4.5. Presence of NOM coating strongly competes with phosphate for the adsorption and is an important factor to consider in modeling phosphate adsorption in natural samples.
土壤中可溶性磷酸盐的 pH 依赖性在六种农业土壤上进行了测量，pH 范围为 3-10。使用一种机械模型，即 LCD（配体电荷分布）模型，来模拟这种变化，该模型考虑了自然有机物（NOM）和多价阳离子（Ca(2+)、Al(3+)和 Fe(3+)）影响下土壤中磷酸盐对金属（氢）氧化物的吸附。除了一种土壤外，对于正常 pH 范围 5-8 的所有土壤，描述都很好。对于一些在更极端 pH 值下的土壤（对于低磷负荷土壤在低 pH 值下，以及对于高磷负荷土壤在高 pH 值下），该模型过高地预测了可溶性 P。计算表明，吸附是控制土壤中磷酸盐溶解度的主要机制，除了在高磷负荷土壤中高 pH 值下可能发生磷酸钙沉淀的情况。NOM 和多价阳离子对 P 的浓度水平有很强的影响。土壤中可溶性 P 的 pH 依赖性模式与单一组分系统中磷酸盐对合成金属（氢）氧化物吸附的 pH 效应有很大不同。根据 LCD 模型，土壤中的 pH 依赖性主要是由 Ca(2+)吸附到氧化物的协同效应引起的。只有在 pH < 4.5 时，Al(3+)对 NOM 吸附物的吸附才起着重要作用。NOM 涂层的存在强烈地与磷酸盐竞争吸附，这是在自然样品中模拟磷酸盐吸附时需要考虑的一个重要因素。
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