低分子量有机酸对三峡库区消落带典型土壤磷素淋溶迁移的影响

Effect of Low Molecular Weight Organic Acids on Phosphorus Leaching from Typical Soils in Water-level Fluctuation Zone of Three Gorges Reservoir Areas

以三峡库区分布最广的紫色潮土、灰棕紫泥为对象,通过室内间歇式土柱淋洗试验,探讨了淋溶液酸度及低分子量有机酸对土壤磷迁移淋失的影响。结果表明,淋溶液酸度对磷的溶出具有一定影响,溶液偏酸或偏碱均促进了磷的淋出。2种土壤磷的淋出能力差异较大,灰棕紫泥中的磷更易淋出,草酸和柠檬酸可显著促进灰棕紫泥土壤磷的淋失,而对紫色潮土磷淋出的促进作用不明显。随有机酸浓度的增加,促进作用增强,100mmo/L草酸和柠檬酸的处理使灰棕紫泥可溶性总磷累计淋出量分别较对照(0.344mg)增加了4.40,15.32倍。柠檬酸的促进作用高于草酸,两者对磷淋出的影响是其酸解和螯合作用的综合结果。

Two types of typical soils in water-level fluctuation zone of Three Gorges Reservoir areas,including purple soil and grey-brown purple soil,were selected to investigate the effect of leaching solution acidity and low molecular weight organic acid on phosphorus（P）leaching from soil columns,through batch-type soil column leaching experiment in laboratory.The results showed that leaching solution acidity impacted P leaching by a certain degree,over acidity and alkalinity both enhanced P losses.Meanwhile,significant differences of P losses between two soils were observed,where grey-brown purple soil showed the more easily P leaching characteristic.Additionally,oxalic acid and citric acid significantly increased P losses in grey-brown purple soil,while no obviously increasing effects were observed in purple soil.Furthermore,with increasing of organic acid,higher enhancement effect was observed,of which 100mmol/L oxalic acid and citric acid increased 4.4times and 15.32 times of accumulated DTP leaching respectively in comparison with control treatment（0.344mg）.The enhancement of citric acid was higher than oxalic acid,and the P losses due to leaching resulted from the two organic acid could be explained by acidic hydrolysis and complexation together.