电动模拟土壤酸化及其交换性离子组成变化

土壤酸化及其环境效应研究是土壤环境领域的重要内容。自行设计了模拟土壤酸化的电动装置,该装置由直流电源、反应槽、石墨电极组成,并采用四种不同类型土壤,研究了电动模拟土壤酸化后土壤pH、交换性酸和交换性阳离子组成的变化。实验结果显示,经电动处理后土壤pH发生明显变化,土壤pH由阳极到阴极逐渐升高,pH变幅为水稻土燥红土红壤赤红壤,水稻土的pH变化比红壤更为明显;土壤交换性H+和Al~(3+)含量在阳极附近最高,交换性Al~(3+)占交换性酸总量达65%以上;交换性Ca~(2+)、Mg~(2+)、K~+和Na~+表现出离阳极越远,含量越大的规律,其中交换性Ca~(2+)和Mg~(2+)在模拟酸化后含量变化较大,而交换性K~+和Na~+的变化幅度相对较小。结果表明,电动处理可快速获得不同pH梯度的土壤样品,并模拟了土壤酸化过程中的阳离子迁移过程,是模拟土壤酸化及其效应研究的有效方法。

Soil Acidification Simulation and Exchangeable Cation Change by Electrokinetics Method

Soil acidification and its environment effects are the important issues in soil and environmental sciences.In this study,an electrokinetic device was developed for simulating soil acidification process.The device consisted of DC power,reaction tank and graphite electrode.The electrokinetic device was used to simulate soil acidification of four soil types.After simulating soil acidification with electrokinetic device,pH,exchangeable acid and exchangeable cation composition in soil were determined.Results showed that soil pH changed greatly in electrokinetics treatment.The soil close to anode had the lowest pH value,whereas the soil close to cathode had the highest pH value.The lowest pH in soil near the anode was 3.23 while the highest pH in soil near the cathode was 9.3.The pH change in paddy soil exhibited more obviously than that in red soil.The soil close to anode had the highest contents of soil exchangeable acid.The proportion of exchangeable Al3+ was more than 65％ in exchangeable acid.The exchangeable Ca2+,Mg2+,K+,Na+ contents were higher in soil close to anode than in soil close to cathode.The change of exchangeable Ca2+ and Mg2+ content was more distinct than that of exchangeable K+ and Na+.Results indicated that electrokinetics device could simulate the cation transformation during soil acidification process,which could produce different pH gradient.It was a useful tool for the research about soil acidification and its environment effects.