【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。更多还原

【Abstract】 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 Al 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 SO~2-4 and NO~-3 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.更多还原