摘要
湖南省洞庭湖地区是中国酸雨沉降和土壤酸化严重的地区之一,酸雨沉降具有明显的季节性和地域性差异,酸雨沉降与土壤酸化具有较好的空间对应性,但土壤酸化的程度还取决于土壤中盐基离子的含量。在土壤酸化较严重的地区,垂向上,土壤酸化深度已达50cm左右,土壤酸化伴随着大量的可溶性铝的溶出。在土壤pH值与盐基离子、氮和硫含量的关系曲线上,存在着pH值突变的临界点(临界点pH值为8),在碱性范围内,硅酸盐和铝硅酸盐矿物的水解使大量盐基离子溶出,中和了因SO42-和NO3-的输入而造成的土壤酸化,但当pH值下降到小于7·25的中酸性范围时,酸性物质和碱性物质组成的土壤缓冲体系失去缓冲作用,酸性物质略有增加,就会导致土壤迅速酸化。
Acid deposition and soil acidification occur more severely in the Dongting Lake region in Hunan Province, South China. Acid deposition appears to be seasonal. Regional differences show a close spatial correlation with soil acidification, whereas the extent of soil acidification depends on the content of electropositive ions. In severely acidified areas, soil acidification may occur at a depth of about 50 cm, and much AI dissolves out along with the soil acidification. There is a critical point on the curve of soil pH vs. the content of basic cations, S and N, which is corresponding to a pH of 8. In alkaline conditions, a large quantity of basic cations is dissolved owing to the hydrolysis of silicates and aluminosilicates. Hence the soil acidity that is due to the input of SO4^2- and NO3^- is neutralized. However, when the pH is below 7.25, the buffer system set up by acid and alkaline materials in soil is no longer effective. A little increase of acid material will rapidly trigger the soil acidification.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2006年第1期105-112,共8页
Earth Science Frontiers
基金
中国地质大调查项目(200414200011:中国区域生态地球化学评价方法体系研究
200314200021:湖南洞庭湖区农业生态地球化学评价)
关键词
土壤酸化
盐基离子
缓冲作用
soil acidification
basic catiom buffering
