中文摘要：

模拟东北林区主要森林凋落物淋洗液中草酸/草酸盐和柠檬酸/柠檬酸盐浓度范围,配制0.5和2.0 mmol/L等不同浓度草酸/草酸盐和柠檬酸/柠檬酸盐溶液,分别用上述溶液以不同的浸提时间和次数浸提处理A1层暗棕壤,探讨不同浸提时间和次数处理时有机酸的磷释放效果,并确定最佳浸提时间。研究旨在探明草酸和柠檬酸对暗棕壤磷的持续活化效应,明确有机酸对暗棕壤磷素的活化程度和动力学特征。结果表明,用草酸/草酸盐和柠檬酸/柠檬酸盐浸提A1层暗棕壤时,随浸提时间延长磷释放量先增后减,有最佳浸提时间,大多数处理为12 h。从磷累积释放量上看,在1-72 h内,上述浸提剂对A1层暗棕壤的磷释放动力学能很好地用对数方程进行拟合。用草酸/草酸盐和柠檬酸/柠檬酸盐溶液连续10次和18次浸提A1层暗棕壤,第2次浸提的释磷量均大于第1次浸提,第3次后大体随浸提次数增加而下降,直到第10次或第18次时,较高浓度处理仍有一定的磷释放,特别是柠檬酸/柠檬酸盐处理;这说明,有机酸对暗棕壤中磷的释放具有累加效应。多次连续浸提时,随浸提次数增加,土壤磷的累积释放量增大,且草酸/草酸盐和柠檬酸/柠檬酸盐对A1层暗棕壤的磷累积释放量与浸提次数间都能很好地用对数方程进行拟合。

英文摘要：

By simulating oxalic/oxalate and citric acid/citrate concentrations in forest litter leachates of northeast China, we prepared 0.5 and 2.0 mmol/L oxalic acid/oxalate and citrate/citrate solutions. Dark brown forest soils of A1 horizon were extracted with different concentrations of oxalic acid/oxalate and citrate/citrate solutions, in which different extraction time and frequencies were set, and the effects of extraction time and frequency on phosphorus release of dark brown forest soils by organic acids were studied, and the optimum extraction time was determined. The aims of this study were to ascertain the effects of oxalic acid and citric acid on phosphorus sustained activation from dark brown forest soils, and clarify the degrees and kinetics of phosphorus activation by organic acids from dark brown forest soils. The results showed that, when extracting A1 horizon of dark brown forest soils with oxalic acid/oxalates and citric acid/citrates, phosphorus release firstly increased and then decreased, and the optimum extraction time was 12 h. As for cumulative phosphorus release, within 1-72 h, phosphorus release kinetics by the above extraction agents could be well fitted by a logarithmic equation. When extracting dark brown forest soils of A1 horizon with oxalic acid/oxalates and citric acid/citrates for 10 times and 18 times respectively, phosphorus release of the second extraction was greater than that of the first one, and after the third extraction, it generally decreased with increasing extraction times. And there were still some high concentrations of phosphorus release till the tenth or eighteenth extraction, particularly in citric acid/citrate treatments, indicating that phosphorus release caused by organic acids was cumulative. Release of cumulative phosphorus increased with increasing extraction times, and those from A1 horizon caused by oxalic acid/oxalates and citric acid/citrates and extraction times could all be well fitted by a logarithmic equation. Our study provides a theoretical basis for the