名山河流域水稻土组分对微团聚体吸附-解吸锌的影响

通过模拟-培养试验和选择溶解法,研究了四川省名山河流域水稻土各土壤组分对原土和不同粒径微团聚体吸附解吸Zn2+能力的影响.结果表明:原土和不同粒径微团聚体对Zn2+的吸附与有机质、游离氧化铁、无定形氧化铁、阳离子交换量(CEC)含量极显著相关,原土去除各土壤组分前后对Zn2+的吸附均用Freundlich方程拟合最佳,对Zn2+的吸附能力大小顺序为:小于0.002mm0.25～2mm原土0.002～0.053mm0.053～0.25mm.与未去除土壤组分相比,去除土壤组分的原土和微团聚体对Zn2+的吸附量均有一定程度的减小,吸附量的减小以0.002mm粒径最高,0.25～0.053mm粒径最低,原土介于各微团聚体中间.去除有机质后,0.002mm、0.053～0.25mm和原土吸附Zn2+的减少量依次为39.56%±1.97%、26.68%±4.21%和36.39%±2.31%;去除游离氧化铁后,吸附Zn2+的减少量依次为30.41%±1.91%、20.14%±3.33%和28.73%±1.22%;去除无定形氧化铁后,吸附Zn2+的减少量依次为22.12%±1.27%、12.43%±2.11%和20.15%±2.62%.吸附减少量大小顺序为:去除有机质去除游离氧化铁去除无定形氧化铁,不同处理间差异极显著.去除各土壤组分后,原土和各粒径微团聚体对Zn2+的非专性吸附量显著上升,增加了Zn2+在土壤中的流动性;而专性吸附量降低,降低了原土和各粒径微团聚体对Zn2+的缓冲能力和固持能力.

Effects of soil components on zinc sorption-desorption by microaggregates in a paddy soil in Mingshan River watershed

By using simulation-incubation test and selective dissolution method, this paper studied the effects of soil components on the zinc sorption-desorption by the microaggregates from a typical paddy soil in Mingshan River watershed. The Zn2+ sorption capacity of bulk soil and microaggregates was significantly correlated with the contents of soil organic matter, free oxide iron, amorphous oxide iron, and cation exchange capacity. Whether or not the soil components were removed, the Zn2+ sorption by the bulk soil and microaggregates fitted well to the Freundlich isotherm model, and the Zn2+ sorption capacity was in the order of <0.002 mm microaggregates >0.25-2 mm microaggregates > bulk soil >0.002-0.053 mm microaggregates >0.053-0.25 mm microaggregates. After the removal of the soil components, the Zn2+ sorption capacity by bulk soil and microaggregates decreased, and the decrement was in the order of <0.002 mm microaggregates > bulk soil >0.053-0.25 mm microaggregates, compared with that before the removal of the soil components. After the removal of organic matter, the decrement of the Zn2+ adsorption capacity of <0.002 mm microaggregates, 0.053-0.25 mm microaggregates, and bulk soil was 39.56% +/- 1.97%, 26.68% +/- 4.21%, and 36.39% +/- 2.31%; after the removal of free oxide iron, the decrement was 30.41% +/- 1.91%, 20.14% +/- 3.33%, and 28.73% +/- 1.22%; and after the removal of amorphous oxide iron, the decrement was 22.12% +/- 1.27%, 12.43% +/- 2.11%, and 20.15% +/- 2.62%, respectively. The decrement of Zn2+ sorption by bulk soil and microaggregates after the removal of the soil components was in the order of removal of organic matter > removal of free oxide iron > removal of amorphous oxide iron, and the difference among the treatments was significant. After the removal of the soil components, the non-specific adsorption of Zn2+ by bulk soil and microaggregates increased significantly, which increased the Zn2+ mobility in soil, while the specific adsorption decreased, resulting in the decrease of the buffering- and retention capability of the bulk soil and microaggregates to Zn2+.