红壤酸化过程中铁铝氧化物矿物形态变化及其环境意义

The morphological change of Fe/Al-oxide minerals in red soils in the process of acidification and its environmental significance

铁铝矿物对土壤中有机质的稳定保持具有十分重要的作用。酸化作用的研究表明,随着浸泡时间的增加,红壤中铁铝总量降低,铝溶蚀较严重;红壤中铁铝氧化物的矿物形态变化表现为:游离态晶质铁铝氧化物大量溶出,而无定形和络合态变化不大。酸性条件下有机质溶出显著,说明除了可能发生水解作用外,游离态铁铝的溶出也起着关键性作用。此外,SEM观察也表明酸化作用引起了土壤团聚体结构的破坏。

The interaction between NOM and minerals strongly affects the preservation and dynamic process of soil organic matter and other ecological processes. The study of the preservation and loss of the organic matter in soil is hence of great importance in environ- mental protection. Researches on the effect of simulated acid rain action indicate that, with the increasing soaking time, the gross content of iron and aluminum residues in red soil decreases, and aluminum is eroded and dissolved more significantly. Moreover, the morphological change of Fe/Al-oxide minerals in red soils finds expression in the fact that the crystalline Fe/Al-oxide minerals are dis- solved remarkably, while the amorphous species of iron and aluminum and/or their complexes species change insignificantly or even increase to some extent. The soil organic matter（SOM） is dissolved notably under the condition of acidic pH, it suggests that the dis- solution of the free species of Fe/Al-oxide minerals play a key role, and the hydrolysis of the SOM maybe occurs also. In addition, the SEM analysis shows that the action of simulated acid rain might cause the breakdown of the structure of soil aggregates.