模拟酸雨淋溶下红壤中盐基离子释放及缓冲机制研究

通过模拟酸雨淋溶实验，分析在不同酸度酸雨淋溶下红壤中盐基离子释放的规律和特点，研究红壤对酸雨的缓冲机制.结果表明:红壤对酸雨的缓冲主要可分为初级和次级2个缓冲体系，其盐基离子释放主要受H+输入量控制.当H+输入量少时，红壤对酸雨的缓冲以初级缓冲体系交换盐基离子为主；随着H+输入增多，红壤对质子的缓冲进入矿物风化阶段.酸度大的酸雨对红壤的矿物风化作用相对较大.不同酸度酸雨淋溶下，各盐基离子释放量最终趋于稳定.盐基离子对酸雨的敏感性顺序为Ca2+>Mg2+>K+>Na+.结果还表明，Ca2+与Mg2+的释放显著线性相关，n(Ca2+)/n(Mg2+)随酸雨pH和淋溶量增加而增大.强酸性酸雨淋溶下红壤矿物风化所导致的Na+释放的机理和来源可能与K+，Ca2+和Mg2+的不同. 

Release of Basic Cations in Red Soil under Simulated Acid Rain and Buffering Mechanism

The effects of simulated acid rain on releasing base cations of red soil were studied with leaching experiments. Results show that there are two main buffer mechanisms in the red soil, e.g. cations exchange and mineral weathering. The release of base cations was significantly governed by acidic deposition of acid rain.With increasing input of H+, the red soil buffering for acid rain will changefrom primary ion exchange to mineral weathering mechanism. Strong acidic rain causes more mineral weathering in red soil. Under the different acidic leaching, the releasing capacities of base cations leveled off, and the sensitivity on theacidic leaching followed as: Ca2+>Mg2+>K+>Na+. It also has beenfound that there are a good linear relationship between the released Ca2+and Mg2+, and n(Ca2+)/n(Mg2+) increases with increasing pH and leaching volume of acid rain. In contract, the source and releasing mechanism of Na+ resulted from mineral weathering at strong acidiccondition are different from those for K+, Ca2+ and Mg2+.