农田灰钙土中有机质和碳酸钙对Zn吸附-解吸行为的影响

采用序批平衡法,研究了Zn在去除有机质及去除碳酸钙前后灰钙土的吸附-解吸行为.结果表明,在试验土壤中吸附量均随着加入Zn浓度的增加而增加,且去碳酸钙土对Zn吸附固定能力明显低于灰钙土,即有机质对灰钙土Zn的吸附影响小于碳酸钙;去有机质及去碳酸钙前后灰钙土对Zn的吸附过程不适合用Langmuir方程描述,而Freundlich方程能够很好地拟合,调整后的决定系数R2′均大于0.90,达到极显著水平(P0.01);去除有机质和碳酸钙后灰钙土对Zn的解吸率都升高,且灰钙土去碳酸钙后解吸率略高于去有机质;去除有机质及碳酸钙前后灰钙土的解吸量均随吸附量的升高而升高,且去碳酸钙土解吸量最大,去有机质土次之,灰钙土最小;土壤有机质和碳酸钙对Zn均有较强的络合吸附效应,能有效降低Zn的迁移活性,从而促进吸附,抑制解吸.

Effect of organic matter and calcium carbonate on behaviors of zinc adsorption-desorption on/from Ningxia farmland sierozem soils

The laboratory batch experiments were conducted to studied the effect of organic matter and calcium carbonate on adsorption-desorption behaviors of zinc of sierozem soils in Ningxia farmland. The results showed that the adsorption capacity increased with increasing initial zinc concentrations in the sierozem. The adsorption capacity of zinc in soils removed calcium carbonate were lower than that with calcium. Organic matter had weaker effect on adsorption behaviors of zinc in sierozem soils than calcium carbonate. The adsorption process of zinc could be well described by Freundlich equation than Langmuir equation in different organic and carbonate content sierozem soil. The adjusted coefficient of determination R2' were greater than 0.90, reached a significant level (P<0.01). The desorption rates of zinc in the sierozem soil increased after removal of organic matter and calcium carbonate, and the desorption rate of soils removed calcium carbonate was slightly higher than the soils removed of organic matter. The sorption increased with the increasing adsorbance after removal of organic matter and calcium carbonate, and the sorption of the soils removed calcium carbonate was maximum, followed by the the soils removed organic matter, and the sorption of sierozem soils was minimum. The organic matter and calcium carbonate in soils could effectively reduce the migration activity of zinc for effect of complexation adsorption, leading to promoting the adsorption and inhibiting the desorption of zinc.