三江平原土地利用变化对水体中铁环境行为的影响

三江平原湿地农田化对铁的赋存形态、迁移转化特征及输出量产生影响。以湿地沼泽水体和稻田水体为研究对象，利用切向超滤技术分离铁的形态，研究土地利用变化前后铁的形态、迁移转化特征的差异。结果表明：湿地农田化后水体中可溶态总铁质量浓度下降16.9%;由于水体pH值的升高，Fe²⁺质量浓度下降56.3%，非溶解态酸性不稳定铁含量显著升高。沼泽水和稻田水在迁移过程中，铁均以络合态铁和酸性不稳定态铁2种形态迁移。沼泽水在迁移过程中Fe2+和络合态铁含量下降，酸性不稳定态铁含量升高，胶体态铁含量变化不大；稻田水在迁移过程中，络合态铁和酸性不稳定态铁含量下降，Fe²⁺和胶体态铁含量较稳定。2种水体铁形态的转化有较大差异：日间沼泽水中非溶解态的酸性不稳定态铁向可溶态铁转化；稻田水体可溶态铁向酸性不稳定态铁转化。

The Effect of LUCC on the Environmental Behavior of Iron in Waters

The conversion from marshy land to cropland had influenced the iron species, transportation, transformation and output flux. The authors studied iron species and transformation in marshy water and paddy water employing the cross-flow filtrate technique. The result showed that the concentration of total dissolved iron decreased 16.9% and Fe²⁺ content reduced 56.3% resulting from pH value increase in waters, and the acid-labile iron increased significantly after the conversion of marshy land to cropland. Iron transport primarily as complexed and acid-labile iron in both paddy and marshy waters. The concentration of complexed and ferrous iron decreased in the process of iron transportation in marshy water, while the acid-labile iron increased. The complexed and acid-labile iron content decreased when paddy water flowed into canal. The differences of iron transformation between two water bodies were significant. In the day-time, the acid-labile iron would change to dissolved iron gradually in marshy water, conversely dissolved iron would be transformed into acid-labile iron in paddy water.