酸沉降下东莞市典型土壤酸化机制研究

Acidification of typical soils under the condition of acid deposition in Dongguan

珠江三角洲地区地下水酸化严重。选取东莞市为典型酸化研究区,研究典型土壤在酸沉降条件下的酸化机制,并探讨其对地下水酸化的影响。利用酸缓冲曲线法和土壤固相组分顺序提取的方法对未明显酸化的水稻土、已酸化的水稻土以及红壤的酸缓冲容量和缓冲能力进行测定。结果显示,持续酸沉降条件下,水稻土和红壤分别在90.8 a和68.3 a后达到酸害水平并加剧地下水酸化。土壤对酸的缓冲能力为:未明显酸化的水稻土>红壤>已酸化的水稻土。土壤的酸缓冲能力主要受活性氧化物含量影响,游离氧化物对其酸缓冲能力影响较小,土壤有机质在酸沉降初期起一定的缓冲作用。

The groundwater was seriously acidified in the Pearl River Delta. Dongguan was selected as a typical study area for acidification research. The acidification mechanism of typical soils were studied under acid deposition conditions,and the effects of soil acidification on groundwater acidification were discussed. The acid buffering capacities of unacidified paddy soil,red soil and acidified paddy soil were measured using acid buffering curve method and soil solid phase composition sequential extraction method. The results showed that the paddy soil and red soil would reach the level of acidification disaster after 90. 8 a and 68. 3 a respectively under continuous acid deposition condition,which would also exacerbate groundwater acidification. The acid buffering capacity of unacidified paddy soil was greater than that of red soil,and the acid buffering capacity of red soil was greater than that of acidified paddy soil. The acid buffering capacity of soil was mainly influenced by the content of active oxide. Free oxide had little effect on acid buffering capacity. The acid buffering effect of soil organic matters were effective in the early stage of acid deposition.