模拟酸雨对红壤中铬释放的影响研究

采用室内模拟酸雨淋溶土柱的方法,研究了酸雨淋溶下4种红壤铬的释放特征与规律.结果表明:经过相当于9 150和10 650 mm降水量的淋溶后,与对照(pH为5.6)相比,pH为4.5的酸雨使红壤铬的累积释放量提高4.03%～88.54%,pH为3.5的酸雨使其提高6.75%～308.42%;不同红壤铬的释放量随淋溶量的变化规律较为相似,总体上表现为释放量随淋溶量的增加而缓慢上升.酸雨对红壤铬释放的促进作用一方面是由于酸雨提高了Cr(OH)₃的溶解度;另一方面是由于H+对Cr3+的竞争吸附作用、酸雨所导致的土壤溶液中离子强度增加及酸雨对土壤胶体(主要是铝和铁的氧化物及氢氧化物)的溶蚀作用而降低了Cr(Ⅲ)的吸附量. 

Study on Release of Chromium from Red Soils under the Influence by Simulated Acid Rain

A soil leaching column experiment was designed to investigate the release of Cr 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 release of Cr increase by 4.03%～88.54%, and pH 3.5 acid rain made it increase by 6.75%～308.42%. There is a similar rule of release among different soils: the release of Cr increases slowly with the increase of leaching liquid. The promotion of acid rain on the release of Cr is due to enhancement of the solubility of Cr(OH)₃, while the reduction of the adsorption of Cr(Ⅲ) is because of the competitive adsorption of H+ with Cr3+, the increase of ion strength, and the erosion of acid rain on soil colloids, mainly of aluminum and iron oxides and hydroxides.