Investigation on the Relationship between Total Organic Carbon（TOC）and Chemical Oxygen Demand（COD）in the Irrigation and Drainage Systems of Paddy Fields

Abstract

During the transition from chemical oxygen demand (COD) to total organic carbon (TOC) in a system, the relationship between the two can be elucidated. The aims of this study were to obtain the regression between TOC and COD in the irrigation water of paddy fields and to elucidate the effects of farming patterns on the regression using analysis of covariance. A regression, TOC＝0.62×COD＋0.40, was obtained regardless of irrigation/drainage or farming stages. On the other hand, some changes in the water quality or the differences in the irrigationsystemscanaffectthe regression between TOC and COD in the irrigation and drainage system as well as by the farming style.