淹水还原条件下红壤中葡萄糖及腐殖酸对铁锰形态的影响

通过设置不同的葡萄糖/腐殖酸配比模拟还原性土壤体系,考察长期(约74 d)淹水培养过程中铁锰元素在土壤溶液/矿物相中的分布形态演变。结果表明:在淹水培养初期,葡萄糖的添加可以促进铁锰离子的还原溶出,同时土壤中可交换态和酸可提取态铁、以及可交换态锰的含量也会随之增加;而腐殖酸的添加则会促进土壤中可氧化态铁/锰含量的升高。随着培养时间的增加,铁锰离子浓度及各个土壤提取形态的铁锰含量大多呈现降低趋势,铁锰元素逐渐转化成提取性更低的矿物形态。因此,淹水环境中铁锰还原溶出-分布形态演变受到土壤中有机物质种类和含量的显著影响,呈现出不同的金属移动性和生物有效性。

Influences of glucose and humic acid on distribution of iron and manganese in red soil under flooding and reducing conditions

Bioreduction processes will influence distribution of metals in anoxic soil environments. To investigate distribution and evolution of iron and manganese in form in soils under long-term (~74 d) anaerobic incubation, reducing soil systems were simulated by setting up different ratios of glucose/humic acid for the soils in the experiment. Results show that at the initial stage of the incubation, addition of glucose prompted reduction and release of iron and manganese ions, and at the same time increased the amounts of exchangeable and acid soluble iron and exchangeable manganese. However, addition of humic acid increased the amounts of oxidizable iron and manganese in the soils. With the incubation going on, the concentrations of metal ions and the amounts of most various extractable forms of iron/manganese were decreasing, suggesting that the iron and manganese in the soil were gradually transformed into mineral phases lower in extractability. Therefore, it is quite obvious that in anaerobic environment, the reduction, release, distribution and transformation of iron and manganese are significantly affected by variety and concentration of the organic substances in the soil, resulting in variability of the metal elements in mobility and bioavailability in the environment.