水稻土团聚体中Cu~(2+)的解吸动力学特征

用磁力搅拌法和平衡吸附法研究了水稻土的原土和团聚体颗粒吸附态Cu2+的解吸动力学特征.结果表明,原土和团聚体颗粒Cu2+的解吸率大小顺序为粗粉砂级粉砂级原土砂粒级粘粒级,与其有机质、游离氧化铁、氧化铝含量大小顺序相反.Cu2+解吸过程可分为快、慢两个解吸阶段,快解吸阶段属于非专性吸附态Cu2+的解吸,慢解吸阶段属于专性吸附松结合态Cu2+的解吸.用一级动力学方程、E lovich方程和双常数方程模拟Cu2+的解吸过程,相关性均达显著水平.磨细后的原土Cu2+的解吸速率和解吸进度均大于4个粒组团聚体颗粒.Cu2+的解吸速率和解吸量与土壤表面Cu2+的吸附形态有关.

KINETICS OF Cu~(2+) DESORPTION ON PADDY SOIL AGGREGATES

Characteristics of desorption kinetics of Cu~(2+) on bulk soil and size fractions were investigated by magnetic stirring and batch methods.Results showed that desorption rates were in the order: coarse silt fraction > silt fraction > bulk soil > sand fraction > clay fraction, which was negatively correlated with the amount of organic matters, free iron oxide and aluminum oxide in these size fractions and bulk soil.It was also suggested that Cu~(2+) desorption could be divided into two stages.The initial rapid desorption phase was from non-specific adsorption of Cu~(2+) , and the later slow desorption phase was from specific adsorption of Cu~(2+).The desorption of Cu~(2+) could be well described by first-order equation, Elovich equation and two-constant equation.The rate and content of Cu~(2+) desorption on grounded bulk soil was greater than those of all its size fractions.It was concluded that the rate and content of Cu~(2+) desorption on soil were related to the forms of Cu~(2+) adsorbed on soil surface.