[A-HW24] 流域圏生態系における物質輸送と循環：源流から沿岸海域まで

[AHW24-15] 日本の農業地域における地下水のN/P比の特性

*小野寺 真一¹、齋藤 光代²、田村 真之⁴、石田 卓也¹、清水 裕太³ (1.広島大学大学院先進理工系科学研究科、2.岡山大学大学院環境生命科学研究科、3.国立研究開発法人 農業・食品産業技術総合研究機構 西日本農業研究センター、4.広島大学総合科学部)

キーワード：地下水、N/P比、農業地域

Biogeochemical cycling in underground environment is important in proper land management and understanding of natural systems. Nitrogen and phosphorus in groundwater is originated by both natural and anthropogenic processes. Especially for the groundwater in agricultural areas, it is significantly influenced by the inputs of chemical fertilizer and manure. However, the mechanisms of controlling N/P ratio in the groundwater system have not been fully clarified. In this study, we aimed to clarify the effects of lithology and human activity, especially agriculture, on the N/P ratios of groundwater in several agricultural areas in Japan.
We reviewed the previous papers, made a data base and compared all information. The geological factor was significant for phosphate concentrations, on the other hand agricultural factor such as fertilizer application and crop was for inorganic nitrogen concentrations. We confirmed variations of DIN and DIP, from 0 to 30 and from 0 to 3 mg/l, respectively. In addition, N/P ratios were indicated to be from 10 to around 150. The highest phosphate were found in Hachiro-gata, and Ikuchi-shima underlain by alluvial deposit and granitic rock, respectively.
* This research was supported by JSPS Projects (18H04151 and 21KK0192) and APN Project (CRRP2019-09MY-Onodera), in which PI were S.Onodera, respectively.