名山河流域水稻土组分对微团聚体吸附-解吸铜的影响

以名山河流域典型的水稻土为例,利用模拟-培养试验和选择溶解法,研究各土壤组分对原土和不同粒径微团聚体吸附解吸Cu2+能力的影响.结果表明,去除土壤组分前后的原土和不同粒径微团聚体对Cu2+的吸附均用Langmuir方程拟合效果最佳,原土和不同粒径微团聚体对Cu2+的吸附能力大小顺序为:0.002mm2.000～0.250mm原土0.053～0.002mm0.250～0.053mm.与未去除土壤组分的原土相比,去除土壤组分的原土和微团聚体对Cu2+的吸附量均有所减小,尤其以去除有机质后对Cu2+吸附量的减小最为显著,在0.002mm微团聚体中减小值高达44.50%±2.77%,0.250～0.053mm微团聚体中Cu2+吸附量减小值最低,为37.68%±3.11%.经不同处理后原土和各粒径微团聚体吸附量减少的顺序为:去有机质去游离氧化铁去无定形氧化铁.去除各土壤组分后,原土和各粒径微团聚体对Cu2+的专性吸附降低,非专性吸附显著上升,降低了原土和各粒径微团聚体对Cu2+污染的缓冲能力,同时显示了各土壤组分在专性吸附中的重要性.

Effect of paddy soil components on adsorption and desorption of copper by microaggregates in paddy soil from the Mingshan watershed

Typical paddy soil, collected from the Mingshan River, was used to investigate the effect of paddy soil components on adsorption and desorption of copper by microaggregates in the soil. Simulation and incubation tests were used along with selective dissolution. The results showed that whether or not the paddy soil components were removed, the sorption of Cu2+ by the bulk soil and microaggregates fit well to the Langmuir isotherm model. The Cu2+ capacity was in the order: <0.002mm > 2.000~0.250 mm >bulk soil> 0.053~0.002 mm >0.250~0.053 mm for different size soil particles. The Cu2+ adsorption capacity of bulk soil and microaggregates decreased after removal of soil components, especially after removal of organic matter, up to 44.50% 2.77% in the <0.002 mm and 37.68% 3.11% in the 0.250~0.053 mm sizes. The decrease of Cu2+ adsorption by bulk soil and microaggregates after removal of soil components occurred in the order: removing organic matter > removing free iron oxide > removing amorphous iron oxide. The bulk soil and microaggregates capability to buffer the Cu2+ pollution was decreased with the decrease of specific adsorption after removal of soil components, suggesting the importance of soil components in the specific adsorption. Simultaneously, the non-specific adsorption was increased.