不同磷肥对红壤铜吸附的影响

Effects of Different Phosphate Fertilizers on Copper Sorption in Red Soils

采用等温平衡法,测定了3种性质不同的磷肥(磷酸二铵,钙镁磷肥和磷矿粉)影响下红壤对铜的吸附量,应用Freundlich方程(Cs=KfCen)分析了土壤铜的吸附特征.结果表明,与对照(不施磷肥)相比,磷酸二铵、钙镁磷肥和磷矿粉均会显著提高红壤对铜的吸附,吸附量(Kf值)分别增加44.4%、336%和80.1%;不同种类磷肥改变红壤铜吸附量的次序为:钙镁磷肥>磷矿粉>磷酸二铵.随着非水溶性磷肥(钙镁磷肥和磷矿粉)用量的增加,红壤对铜的吸附能力逐渐增强;而磷酸二铵分别在低(磷铜摩尔比=1∶1)、中用量(磷铜摩尔比=2∶1)显著促进红壤对铜的吸附,而在高用量(磷铜摩尔比=4∶1)下则抑制了红壤对铜的吸附.试验结果表明,在铜污染红壤上,从提高土壤铜阻抗效果与降低农产品质量安全风险的角度出发,磷酸二铵不宜施用;而钙镁磷肥可作为磷肥的最佳肥源.

Sorption batch experiments were explored to investigate the effects of different phosphate fertilizers on copper sorption in red soils.Freundlich equation was used to characterize the sorption of copper and the distribution coefficients of Cu were calculated.The results showed that the sorption of Cu could be described by Freundlich equation（P0.01）well.Compared to the non-phosphorus system,the applied different phosphate fertilizer could increased capacity of sorption of copper in red soils,and total sorption capacity（Kf value）increased 48.6%（diammonium hydrogen phosphate,DAP）,394%（calcium magnesium phosphate,CMP）and 79.9%（phosphate rock,PR）,respectively.At the same time,sorption of Cu increased with the order of CMPPRDAP.When applied at low or medium volume,DAP could significantly increased sorption of copper in red soils,and applied at high volume,DAP could decreased sorption of copper.With the increasing usage of non-soluble phosphates,sorption of copper increased in red soils.High volume CMP was most effective in increasing sorption of copper.It is demonstrated that an appropriate amount of DAP applied to soils is necessary,and CMP is the best phosphate fertilizer in the copper-contaminated red soils.