酸性硫酸盐土的酸害暴发机制及其环境影响

酸性硫酸盐土广泛分布于热带亚热带滨海地区，当其中的硫铁矿物质与空气接触或直接暴露地表时会发生氧化而形成强烈酸害，从而导致土壤、水、大气和区域生态系统的退化，最终对动植物生长和人类的健康产生较大影响而成为全球性的热带亚热带滨海环境问题。酸性硫酸盐土的酸害暴发主要包括：（１）硫铁矿的形成、累积与埋藏过程；（２）硫铁矿的氧化与致酸过程；（３）土壤对酸的中和与缓冲过程；（４）土壤中酸的稀释与迁移过程。酸性硫酸盐土的酸害影响是上述四个过程相对强弱与综合作用的结果。酸性硫酸盐土酸害暴发可导致区域土壤环境、水环境和大气环境的酸化，以及大量金属与重金属元素的溶解与释放，引起生物生存环境的恶化与栖息地的丧失，动植物出现变态生长，而且疾病频繁，生产力下降，区域生态系统的结构和功能发生异常，生物多样性下降。

THE PROCESS OF ACID HAZARDS IN ACID SULFATE SOILS AND ITS ENVIRONMENTAL EFFECTS

Acid sulfate soils (ASS) are widely distributed along the coastal areas in tropical and subtropical world. When the iron sulfides (FeS 2) in ASS are exposed to air, oxidation process and acid hazards would take place, which could result in the damages of the environment,and would be very harmful to human, animals and plants. The occurrence of acid hazards are commonly involved in four processes: 1) the formation, accumulation and deposit of FeS 2 in ASS; 2) the oxidation of FeS 2 and formation of acids; 3) the neutralization to the resulting acidity by soil buffering system; 4) the dilution and transportation of the acids. The actual acidity occurring in ASS is determined by the relative intensity and comprehensive result of the four processes. The acid hazards in ASS can cause the acidification of soil, water and atmosphere and the release of harmful metal ions, especially,those of heavy metals. Commonly, in the areas of ASS, owing to the acid influences, the eco-environment is degraded and the habitats are lost, plants and animals grow abnormally with low productivity and take disease frequently, the structure and function of regional ecosystems change and biodiversity declined gradually.