酸雨对土壤元素化学行为的影响

The Effect of Acid Rain on Chemical Activities of Elements in Soil

随着城市工业的发展,酸雨的范围和强度在不断增加,直接或间接破坏了土壤元素间的化学平衡,因而威胁到农业生产的可持续发展.综述了酸雨的污染现状及其对土壤常量元素、重金属元素以及稀土元素化学行为的影响.指出:①碱性土壤的抗酸雨淋溶能力大于中、酸性土壤;②土壤元素的淋溶量一般随酸雨的酸度和淋洗量的增加而上升,其中可交换态金属元素的敏感性显著高于其它形态;③酸雨促进土壤金属元素淋溶的最终结果,一是减轻了重金属对土壤生态系统的污染压力,二是导致植物生长所必需的盐基离子缺乏;④土壤中N,S,P元素的形态和有效性受胶体吸附和微生物转化等多因素的共同影响,在酸雨污染下的变化趋势尚难定论;⑤稀土元素在酸雨条件下的淋失将有利于富稀土地区植物的生长.

With the development of municipal industrialization,both the range and intensity of acid rain are being increased continually. Acid rain can affect the chemical activities of many elements in soil and thus threaten the sustainable development of agricultural production. This paper reviews the current situation about acid rain and its effects on the chemical activities of common elements, heavy-metal elements and rare-earth elements in soil. The conclusions are listed as follows. (1) Alkaline soil has a stronger acid rain-resistance than neutral and acid one. (2) Usually,the larger the acidity and volume of acid rain,the more the mass of elements is dissolved in soil. Moreover, elements existing in exchangeable form are more sensitive to acid rain than those in other forms. (3) On one hand, acid rain may reduce the contents of heavy metals in soil, on the other hand, it may lead to the lack of salifiable ions necessary for plant growth. (4)For N, S and P, their forms and availability are affected by many factors such as colloid absorption,microorganism transformation,etc., thus it is difficult to determine their behaviour in soil under the influence of acid rain. (5) Increment in dissolubility of rare-earth elements will be favourable to plants grown in some area containing rich rare-earth elements.