Abstract
Some dissolved organic matter (DOM) have recalcitrant characteristic and are accumulated in lake and that could be one of facters of organic pollution. To clarify the characteristics of effluent of DOM and hydrophobic acids including humic substances, one of recalcitrant DOM, quantities of irrigation and surface drainage water, concentrations of DOM and hydrophobic acids in inflowing and outflowing water have been investigated during a irrigation period in a paddy field. The concentrations of DOM and hydrophobic acids in ponded water were higher than those in irrigation water, and have been decreasing with percolating through soil. In dpths of 0.3m, percolating loads decreased to 59% DOM, 66% hydrophobic acids. In dpth of 1.0m, percolating loads decreased to 35% DOM, 31% hydrophobic acids. So it's a effective practice to make the ponded water outflow through the soil for control of DOM and hydrophobic acids loads from paddy fields.
