红壤中微量元素锌在酸雨淋溶下的释放特征研究

采用室内模拟酸雨淋溶土柱的方法,研究了酸雨淋溶下4种红壤锌的释放特征与规律.结果表明,经过相当于9 150-10 650mm降水量的淋溶后,与对照(pH5.6)相比,pH4.5的酸雨使表层土pH值降低0.15-0.22个单位,但对心层土和底层土影响不明显;pH3.5的酸雨使整个土层pH值发生一定程度的降低,尤其是表层土降低最显著,达0.43-0.60个pH单位.酸雨淋溶下红壤中锌的释放具有前期阶段为快速递减释放和后期阶段为慢速平稳释放的两阶段性特征,锌累积释放量与淋溶量的关系可用二次模型来描述.从长期的淋溶效果来看,酸雨增加了红壤中微量元素锌的淋失.酸雨对锌释放的影响可增加水体中锌的负荷,并导致土壤缺锌;而对受锌污染的土壤,则会加重锌的毒害作用.图3,表3,参8.

Study on release of zinc from red soils under the influence by simulated acid rain

A soil leaching column experiment was designed to investigate the release of zinc from red soils under the influence by simulated acid rain. After 9 150-10 650 mm precipitation leaching, compared with pH5. 6 precipitation, pH4. 5 acid rain made the pH of surface layer soils decline 0. 15-0. 22 units, but had no obvious influence on the pH of center layer and bottom layer soils; pH3.5 acid rain made the pH of entire soil layer some extent decline, especially obvious in surface layer, the pH declined 0.43-0. 60 units. Under the influence by simulated acid rain, there is a two - phase - characteristic of speedy descending release at early stage and slow reposeful release at latter stage. The cumulative release of zinc can be described with quadratic model. On the point of long-term leaching, acid rain can lead the loss of zinc of red soils. This impact of acid rain on release of zinc heightens zinc load in the water, leads soil lacking zinc, and aggravates poison of soils polluted by zinc. 3figs. , 3tabs. , 8refs.