中文摘要：

选择柠檬酸、草酸、酒石酸和苹果酸4种土壤中常见有机酸为研究对象,研究了它们与砖红壤反应后,Fe、Al的溶出特征以及P的释放规律,并对上述反应的机制进行了探讨.结果表明,草酸、酒石酸和苹果酸3种有机酸与土壤反应24h后,溶液中总Fe浓度随反应体系pH值升高而降低,但柠檬酸与土壤反应24h后,溶液中总Fe浓度则随反应体系pH值升高而增加.4种有机酸溶出土壤Fe的能力按草酸〉柠檬酸〉酒石酸〉苹果酸的顺序下降,溶出机制主要是络合溶解和还原溶解.溶液中Al的溶出量在4种有机酸-土壤体系中均随体系pH值升高而降低,且按草酸〉柠檬酸≈酒石酸〉苹果酸的顺序下降,溶出机制主要是质子溶解和络合溶解.有机酸对固定态磷素有明显活化效应,在草酸、酒石酸和苹果酸3种有机酸-土壤体系中,溶液中P浓度均随体系pH值升高而降低,但在柠檬酸-土壤体系中,则随体系pH值升高而增加.溶液中Al/P物质的量之比要远大于Fe/P物质的量之比,这表明土壤中P主要结合在铁氧化物表面,其活化与铁氧化物的溶解过程关系密切.此外,Al的存在对草酸活化固定态P有抑制作用。

英文摘要：

In this study,release of Fe,Al and P produced during the interaction between latosol and soil organic acids was investigated together with the mechanisms involved in the processes.Citric,oxalic,tartaric and malic acids were selected because of their wide occurrence in soils.As the results shown,the concentration of aqueous Fe increased with the decrease in pH after 24 h reaction between the soil and oxalic,tartaric or malic acids,while which exhibited reverse trend in the soil-citric acid system.The order of effectiveness of the organic acids for Fe release over the entire pH range examined was oxalic acid citric acid tartaric acid malic acid.The concentration of aqueous Al in all the soil organic acid system decreased with increasing pH,and the ability of organic acids to enhance the dissolution of Al followed the order of oxalic acid citric acid ≈ tartaric acid malic acid.As for oxalic,tartaric or malic acids,the amounts of P released from the soil decreased as the pH increased,while higher P concentration was found at higher pH in the case of citric acid.The molar ratio of Al/P in solutions was much higher than that of Fe/P,indicating that the release of P was more closely related to dissolution of Fe oxides rather than Al oxides.In addition,the presence of Al would inhibit the mobilization of P by oxalic acid.