摘要
利用室内模拟酸雨的土柱实验,研究了在红壤表土施用钾肥后酸雨对不同土层交换性阳离子迁移的影响。结果表明,在不同土体深度,表土直接受酸沉降的淋溶,也是最容易发生酸化的土层,pH2.5酸雨淋溶后,表土pH值下降到3.5～4.2,这是铝的缓冲范围,且土壤交换性H+和Al3+含量的增加显示出土壤对酸沉降的缓冲效率和缓冲能力的急剧减弱;pH4.5酸雨淋溶后,A和B层土壤pH值上升了0.3～0.5,其机理与SO2-4的专性吸附释放OH-有关;表土施用钾肥后,K+交换土壤表面的H+和Al3+,引起土壤交换性H+和Al3+向下迁移;不同pH值的酸性降雨引起土壤中交换性阳离子向下迁移和淋失的程度也有明显的差异,pH2.5酸雨淋溶后土壤溶液中钾的含量高于pH4.5酸雨淋溶的,但交换性钾含量低于后者;pH2.5和pH4.5酸雨淋溶后交换性钙的淋失量分别占原土的50%～70%和20%～40%,这表明酸雨淋洗会导致养分库的损耗,造成土壤养分贫瘠。
The influence of simulated acid rain on transferring of exchangeable cations in the profile of red soil is investigated in the lab when surface soil is mixed with KCl. The results indicate that the acid deposition has a direct e ffect on the acidity of surface soil. After leaching of simulated acid rain with pH 2.5, the content of exchangeable Al3+and H+increases, and soil pH value dr ops down to 3.5～4.2 within the ranges of aluminum buffer in surface soil. The c hange of exchangeable Al3+also reflects the sharp decrease of buffer capacity a nd efficiency with the increase of the content of exchangeable Al3+. However, p H value of A and B layers increases 0.3～0.5 after the leaching of simulated aci d rain with pH 4.5. This phenomenon is explained by specific adsorption of <IMG SRC='IMAGE/03090156.JPG' HEIGHT=11 WIDTH=23> that simultaneously releases OH-. The acidity of different acid rain makes the prominent difference of the transfe rring and leaching of base cations downwards along profile. The content of solub le K+of pH 2.5 acid rain leaching is higher than that of pH 4.5, but exchangeab le K+of the former is lower than that of the latter. Leaching amount of exchang eable Ca2+at the pH 2.5 and pH 4.5 acid rains treatment occupies about 50%～70 %and 20%～40%of the original soil, respectively. The decrease of exchangeable Ca2+and K+reflects the depletion of 'nutrient pool'which causes decay of so il fertility.
出处
《地球化学》
CAS
CSCD
北大核心
2004年第1期46-52,共7页
Geochimica
基金
国家自然科学基金(40071046
49831005)
国家重点基础研究发展规划项目(1999011801-3)
关键词
酸雨
阳离子
迁移
红壤
缓冲机制
simulated acid rain
red soils
acidity
buffer mechanism
cations
transferring
