低分子量有机还原性物质与土壤的相互作用 Ⅱ.低分子量有机还原性物质与土壤作用的化学反应

INTERACTION BETWEEN LOW-MOLECULAR-WEIGHT ORGANIC REDUCING SUBSTANCES AND SOILS Ⅱ.CHEMICAL REACTIONS OF LOW-MOLECULAR-WEIGHT REDUCING SUBSTANCES WITH SOILS

论述了有机还原性物质与土壤作用的吸附、氧化还原和络合反应。土壤对该类物质的吸附量达加入量的60%～75%,其中强、弱还原性有机物质各约占1/2。负电荷物质的吸附量随土壤铁、锰氧化物及其所带负电荷量而变,并表现为电性吸附。对含—COOH、—C—NOH2功能团物质的吸附佐证了固相表面存在络合作用;在氧化-还原平衡中该类物质作为电子供体还原了铁、锰而自身被氧化;络合态亚铁、亚锰的形成服从络合-离解平衡,有机配位体的数量和H+离子争夺配位体的络合基可对其产生强烈的影响。

A study on chemical reactions concerning adsorption,oxidation-reduction and complexation of low-molecular weight organic reducing substances with soil was carried out.Results show as follows： About 60%~75% of the total organic reducing substances added was adsorbed by the soil,consisting roughly by half and half of strongly and weakly reducing organic substances.The adsorption of negatively charged substances varied with the content of Fe/Mn oxides and the negative charge they bear in the form of electrostatic adsorption.The adsorption of-COOH/-C=O—NH2 containing functional groups demonstrated existence of complexation on the solid surface;In redox equilibrium organic reducing substances acted as electron donor reducing Fe2O3 and MnO2 and got oxidated themselves;The complexation process was controlled by chelation-dissociation equilibrium in the solution and strongly affected by the amount of ligands and the amount of complex radicals that compete for ligands with hydrogen ions.