| Title |
Outflow of Dissolved Organic Matter from Agricultural Fields in an Irrigation Period |
| Authors |
심수용 ( Soo Young Shim ) ; 김범철 ( Bum Chul Kim ) ; 호소이요시히코 ( Yoshihiko Hosoi ) ; 마스다다카노리 ( Takanori Masuda ) |
| Keywords |
Dissolved organic carbon; DOC; Paddy field; Non-biodegradable |
| Abstract |
The aim of this study is to quantify and characterize the dissolved organic carbon (DOC) from paddy fields and crop fields in Tottori, Japan. DOC and ultraviolet (UV) absorption were measured in the filtrated water of each sample. The DOC concentration and the SUVA (specific UV absorption) of biodegradation analysis samples were determined around 50 days after their incubation. In the Fukui paddy fields, DOC concentration varied seasonally from 1.1 to 10.1 ㎎ Cl^(-1), becoming higher during heavy runoffs in April, a non-agriculture period. Variations in DOC concentration did not always correspond to rainfall, though. The Obadake paddy fields showed a DOC concentration pattern similar to that of the Fukui paddy fields. The daily DOC discharge per area in the Fukui (up), Fukui (down), Obadake (south) and Obadake (north) paddy fields influent from paddy fields were 0.02, 0.0161, 0.0135 and 0.0027 ㎏ a^(-1) day^(-1), respectively. These differences resulted from differences in agricultural types and customs of farmers according to paddy fields and other kinds of fields. Also, the SUVAs [which are indirect means to evaluate humic substances (hydrophobic fractions)] of the studied influent waters from paddy fields were generally lower than those of the influent waters from crop fields. Nonbiodegradable DOC accounted for 50.2-98% and 46.8-85.5% of the total DOC in the paddy fields and in the crop fields, respectively. |