3:00 PM - 3:15 PM
[MIS22-06] Dissolved iron behavior of wetland in snowy area - a case study of Maruyama wetland in Sarufutsu River, Hokkaido -
Keywords:Dissoved iron, Wetland, Redox reaction, Groundwater
The main source of dissolved iron from land is wetlands that exist in the boreal and subarctic zones. While wetlands developed in permafrost zone are governed by the hydrological processes in the very top layer of the ground surface, behavior of dissolved iron in wetlands in areas where snow cover is dominant might be influenced by water flow through out a year. In this report, we present the results of a year-round observation in the Maruyama wetland located in the Sarufutsu River basin, Hokkaido.
Analysis of the soil core suggests that there is a transition from peat-like soil to mineral soil around a depth of 7 m. It is also thought that in the range of about 1 m above this depth, there is a layer in which almost all of the iron that makes up the soil particles is amorphous iron, and the reducing action of iron is strongly at work. Furthermore, the concentration of dissolved iron in the groundwater showed a clear tendency to increase with depth, and at a depth of 5.44 m, a high concentration of dissolved iron of 20-40 mg/L was observed, which corresponded to the depth of the layer where amorphous iron predominated. On the other hand, the concentration of dissolved iron in the soil pore water was highest at a depth of 0.1 m, averaging around 5 mg/L, and there was a large seasonal fluctuation. As a whole, we recognized two different sources, one at the surface and the other at a depth of around 5 m. Although the number of data points was small, an inverse relationship was observed between river water levels and the concentration of dissolved iron, suggesting that groundwater runoff with high concentrations of dissolved iron from deep underground may be making a significant contribution.
Analysis of the soil core suggests that there is a transition from peat-like soil to mineral soil around a depth of 7 m. It is also thought that in the range of about 1 m above this depth, there is a layer in which almost all of the iron that makes up the soil particles is amorphous iron, and the reducing action of iron is strongly at work. Furthermore, the concentration of dissolved iron in the groundwater showed a clear tendency to increase with depth, and at a depth of 5.44 m, a high concentration of dissolved iron of 20-40 mg/L was observed, which corresponded to the depth of the layer where amorphous iron predominated. On the other hand, the concentration of dissolved iron in the soil pore water was highest at a depth of 0.1 m, averaging around 5 mg/L, and there was a large seasonal fluctuation. As a whole, we recognized two different sources, one at the surface and the other at a depth of around 5 m. Although the number of data points was small, an inverse relationship was observed between river water levels and the concentration of dissolved iron, suggesting that groundwater runoff with high concentrations of dissolved iron from deep underground may be making a significant contribution.