Abstract:

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.

Key words: iron species, iron transformation, LUCC, marshy waters, paddy waters, wetland, Sanjiang Plain