模拟酸雨和几种低分子量有机酸淋溶对土壤交换性盐基的影响

采用原状土柱进行模拟淋溶实验,比较研究了模拟酸雨和几种低分子量有机酸对红壤交换性盐基的影响。结果表明:与去离子水对照相比,pH 3．5和pH 4．5模拟酸雨淋洗后,0-20 cm土层土壤交换性K 、Na 、 Ca2 和Mg2 含量增加了5．19％-14．65％,而这种增加主要发生在10-20 cm土层。100 μmol／L和10 mmol／L的柠檬酸、苹果酸和草酸淋洗后,0-20 cm土层土壤交换性K 、Na 、Ca2 和Mg2 含量与模拟酸雨淋洗后的结果相差不大,有的层次甚至还要稍低;而在20-50 cm土层则增加了10．42％-96.41％。有机酸淋洗后,土壤交换性盐基的增加受矿物溶解和盐基迁移两方面的影响,而下层的增加可能主要是盐基迁移的影响,由此可见有机酸或许加快了盐基离子向下迁移的速度和土壤酸化过程。

Effects of Leaching with Simulated Acid Rain and Low Molecular Weight Organic Acids on Soil Exchangeable Base

Effects of leaching with simulated acid rain and low molecular weight organic acids on exchangeable bases of red soil were investigated using undistributed soil columns. The results showed that soil exchangeable potassium, sodium, calcium and magnesium in the 0 - 20 cm soil layer was increased by 5.19% - 14.65% after the soils were leached with simulated acid rain 3.5 and 4.5 in pH, compared with check using deionised water. There was no significant difference in exchangeable potassium, sodium, calcium and magnesium in the 0 - 20 cm soil layer between Treatments Citric acid, Malic acid, Oxalic acid and Treatment Simulated acid rain, but the formers did show increase in the base ions by 10.42% - 96.41% in the 20 - 50 cm soil layer, compared with the latter. The increase of soil exchangeable bases in the subsoil layer can be attributed to dissolution of minerals in the topsoil and leaching of base ions from topsoil. Leaching of base ions from topsoil was the prior mechanism in the study, which indicated that organic acids probably accelerate base ions leaching and soil acidification process.