外源磷对消落区土壤性质及磷释放的影响

THE EFFECT OF ANTHROPOGENIC PHOSPHORUS TO THE CHARACTERISTICS SOIL AND ITS PHOSPHORUS RELEASE IN THE WATER-FLUCTUATION-ZONE

选取三峡库区消落区万州段的紫色冲积土,对消落区土壤添加磷的变化及磷的释放进行实验室模拟试验.结果表明,当外源磷添加量较小(<50 mgP.kg-1土干重)时,上覆水中磷浓度表现为持续上升.当外源磷添加量较大(>50 mgP.kg-1土干重)时,在淹水4周左右达到平衡.随着外源磷添加量的增加,无机磷呈增加趋势;Ca2-P,Fe-P,Ca8-P和Al-P增加程度较大;外源磷添加量较大(>50 mgP.kg-1土)时,O-P也有上升,Ca10-P变化较小.土壤干样与鲜样中磷的最大吸附量(Qm)在不同添加磷情况下变化不显著,磷吸附指数(PSI)、磷最大缓冲能力(MBC)均有显著的下降.表明土壤添加外源磷后土壤有效磷水平增大,同时土壤对磷的吸持能力降低,添加外源磷将增大土壤磷释放的风险.

According to the water-fluctuation-zone（WFZ）＇s alternately waterlogged and drained environment,the experiment for effect of adding anthropogenic phosphorous to soil characteristics and its phosphorous release with the purple alluvial soil from the WFZ of Three Gorges reservoir were carried out.The data showed that when small amount of anthropogenic phosphorous was added to soil,phosphorous concentration in overlying water continued to increase in inundating period.But when anthropogenic phosphorous added was high（〉50mg·kg^-1,dry weight）,phosphorous release reached equilibrium at about 4 weeks,and phosphorous concentration kept stable.The amounts of Ca2-P,Fe-P,Ca8-P,Al-P increased with the increasing quantity of anthropogenic phosphorous added to soil,and O-P also increased when the added anthropogenic phosphorous was enough（〉50mg·kg^-1,dry weight）,but Ca10-P changed little.With the increasing amount of anthropogenic phosphorous added to soil,Qm of both fresh and dried soil samples changed not markedly,but PSI and MBC of both soil samples decreased significantly.Results of this study demonstrate that adding anthropogenic phosphorous into soil make available phosphorous increase and phosphorous adsorption ability of soil decrease,and this heighten the risk of phosphorous release from the soil.