This research addressed nonpoint source (NPS) pollution characteristics in a reclaimed rice paddy field. The paddy has an area of around 2,998 ha and is divided as two sub-watersheds, whose areas are 1,181 ha and 1,817 ha, respectively. Monitoring of hydrologic runoff and NPS pollution was undertaken during three-month period from June to August, 2008. Totally, three sampling trips were made when rainfall depth were 66.0 mm, 23.5 mm, and 23.0 mm, respectively. Generally pollution load increased with the heavier cultivation activity in Korea.
Exported pollutants from the rice paddy, including TSS, TN and TP, have same levels as forest discharge. Organic nitrogen is main pattern but it mainly exists in the forms of dissolved organic nitrogen (DON). For phosphorus, dissolved inorganic phosphorus (DIP) takes the main part although part of them is associated with fine particles. This is different compared with other watersheds, where particles-associated phosphorus is the main form.
Keywords : Nitrogen, Nonpoint source pollution, Phosphorus, Rice paddy, Runoff