[HCG31-P04] Effects of Soil Organic Matter on Transport of Cesium in weathered granite soil
Keywords:Fukushima, cesium, dissolved organic matter, humic acids, fulvic acids
Soil sample was collected at an abandonment forest in Iitate, Fukushima, Japan. Dissolved organic matter was extracted from a litter from university forest in Chichibu, Saitama. Two Cs solutions are used, high(30mg/L) and low(1000Bq/L) concentration. High concentration solution was stable CsCl solution, and low one was extracted from organic soils in Iitate. The acrylic plastic column having a diameter of 3-cm and a length of 7-cm was used for the experiment. Two different treatments were applied for the repacked soil (control and organic adsorbed soil columns). The control soil column was prepared by repacking air dry soil sample up to 5cm of height. The organic adsorbed soil column was prepared by flowing dissolved organic matter for 24 hours to the control soil column. In the column experiment, Cs or Cs-DOM mixed solutions were applied under a constant ponding depth. Effluent Cs concentration was measured. After the transport experiments, the column was sliced in 1-cm interval and the soil at each section was used for the sequential extraction of Cs.
As a result of preliminary column transport experiment where high concentration Cs solution was applied to the 10cm long soil column, Cs accumulated within surface 4cm thick layer, while Cs mixed with DOM solution could move into 10-cm deep soil layer. Sequential extraction suggested most of Cs at deeper layer was complexed with organic matter.