Japan Geoscience Union Meeting 2016

Presentation information

International Session (Poster)

Symbol A (Atmospheric and Hydrospheric Sciences) » A-GE Geological & Soil Environment

[A-GE05] Subsurface Mass Transport and Environmental Assessment

Mon. May 23, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Shoichiro Hamamoto(Department of Biological and Environmental Engineering, The University of Tokyo), Yasushi Mori(Graduate School of Environmental and Life Science, Okayama University), Hirotaka Saito(Department of Ecoregion Science, Tokyo University of Agriculture and Technology), Ken Kawamoto(Graduate School of Science and Engineering, Saitama University), Ming Zhang(Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology)

5:15 PM - 6:30 PM

[AGE05-P18] Effects of Dissolved Organic Matter on Transport of Cesium in weathered granite soil

*Takahiro Tatsuno1, Thuyet Quoc Dang1, Hiromi Imoto1, Shoichiro Hamamoto1, Taku Nishimura1 (1.Deptartment of Biological and Environmental Engineering, Graduate School of Agricultural and Life Sciences, University of Tokyo)

Keywords:Fukushima, Cesium, Dissolved organic matter, Humic Acid, Fulvic Acid

To grasp migration of radiocesium (Cs) in forest soil has been one of the subjects since the accident of Fukushima Dai-ichi nuclear power plant, Japan. There is a possibility of organic matters in forest soil to have an effect on migration of Cs. In particular, dissolved organic matters (DOM), for example humic acids (HA) and fulvic acids (FA), may affect sorption and transport of Cs in soil. In this research, we studied effect of types of DOM on Cs transport by laboratory batch and column experiments.
Soil sample was collected at an abandonment forest in Iitate, Fukushima, Japan. DOM was extracted from a litter from forest in Chichibu, Saitama. For batch experiments, we measured amounts of organic matter and Cs adsorbed to the soil. Since adsorption of Cs to soil clay cannot complete during percolation of water/solution through soils, we tried three different extent of reaction time 1, 12, 24 hours. For column experiment Cs solution or Cs-DOM mixed solutions were applied by constant ponding depth. Cs concentration in discharge from the bottom of the column was measured. After the halt of the percolation, a portion of soil was sampled at each 2cm thick layer form 0-10cm in depth, and sequential extraction of Cs was conducted.
For batch experiment, there was almost no difference between selectivity constants for Cs with reaction time for 1 to 24 hours. However, determined selectivity constants were smaller than those reported for the equilibrium constant. Amount of HA adsorption was more than other DOMs adsorption. In addition, when Cs-HA mixed solution was reacted for 24 hours, amount of Cs adsorption increased with increase in HA adsorption.
For column experiment, Cs from CsCl solution accumulated within surface 2cm thick layer, while Cs mixed with DOM solutions could move into 10cm deep soil layer. Sequential extraction suggested most of Cs at deeper layer was complexed with organic matter.