冻融作用对东北黑土磷素吸附-解吸过程的影响

冻融作用对土壤理化性质具有重要影响,从而影响土壤中磷素的吸附—解吸特性。以东北黑土为研究对象,采用室内模拟冻融环境的方法,研究了冻融条件下黑土磷素吸附—解吸行为。结果表明,冻融条件下黑土对磷的吸附规律均随着外源磷浓度增加而逐渐增大,当外源磷浓度为120mg/L时吸附曲线出现明显拐点;与未冻融土壤相比,冻融过程中土壤吸附更多的磷,具有更高的磷素吸附率;外源磷浓度低时,冻融作用对土壤磷吸附影响较大,外源磷浓度高时冻融作用对土壤磷吸附影响降低;冻融条件下磷等温吸附曲线采用Langmuir方程拟合的相关性最优,在连续的冻融循环条件下,土壤磷最大吸附量Pmax值逐渐增大,土壤与磷之间结合能力和磷吸附最大缓冲容量也有同样的趋势。

Effects of Freezing-Thawing Cycles on Phosphorus Adsorption and Desorption Characteristics in Black Soil of Northeast China

Freezing-thawing cycles have important effects on physical and chemical properties of soil, which affect adsorption and desorption characteristics of phosphorus in soil. A laboratory experiment was conducted to determine the effects of freezing-thawing on phosphorus adsorption and desorption characteristic of black soil. The results showed that, the trend of phosphorus adsorption in freezing-thawing treatment was that all the phosphorus adsorption capacity increased with the increasing of phosphorus concentration, and there was obvious turning point when the exogenous phosphorus concentration was 120 mg/L. Compared to the no freezing-thawing treatment samples, black soil adsorbed more phosphorus and had higher adsorption rate after freezing-thawing cycles. At low exogenous phosphorus concentration, freezing-thawing cycles have relatively large influence on phosphorus adsorption quantity, on the contrary, at high exogenous phosphorus concentration, the influence reduced. In the condition of freezing-thawing, phosphorus adsorption curves could be well fitted by Langmuir equation. Under the condition of successive freezing-thawing cycles, maximum adsorption capacity P_max, combining ability between soil and phosphorus and phosphorus adsorption maximum buffer capacity has the same trend of gradual increase.