Abstract
Pollutant runoff from rice paddy fields is one of the most important topics of non-point pollution around Lake Biwa which is the largest lake in Japan. In this study, surveys on pollutant runoff from the paddy fields around Lake Biwa were done for 3 years from 2007 to 2009 during farming periods. In the surveys, samples were collected by continuous water sampling, and chemical substances in each sample such as SS, TN, TP and COD were measured for particulate and dissolved forms respectively. Using results of the surveys, characteristics of pollutant behaviour in the paddy fields during the farming periods were examined. And basic unit runoff loads of pollutants from the paddy fields throughout a farming period were cleared. As a result, some significant knowledge for the environmental management of paddy fields has been obtained.
