水素・酸素および窒素安定同位体組成からみた甲府盆地東部地下水の涵養源と硝酸イオン濃度分布特性 Identifying the Effects of Groundwater Recharge on Nitrate Concentration in the Eastern Kofu Basin Using ^2H, ^<18>O and ^<15>N
A stable isotopic technique was used to identify the effects of groundwater recharge on nitrate concentration in the alluvial fans of the eastern Kofu basin. Precipitation, groundwater and river water samples were collected from the Fuefukigawa and Hikawa—Kanegawa alluvial fans. The samples were analyzed for nitrate concentration, water δD and δ<sup>18</sup>O and nitrate δ<sup>15</sup>N. A wide range of nitrate concentrations was observed in the groundwater of both alluvial fans. The observed δ<sup>15</sup>N values suggest that the major sources of nitrate are the fertilizers used in orchards. Similarly, the values of δD and δ<sup>18</sup>O shows that precipitation and river water are the sources of groundwater recharge for both aquifers. Furthermore, a strong positive correlation was observed between nitrate concentration and δ<sup>18</sup>O values. Nitrate concentration increases with an increase in δ<sup>18</sup>O value, where lower δ<sup>18</sup>O values correspond to river water and higher δ<sup>18</sup>O values correspond to precipitation. It is suggested that precipitation acts as a carrier and river water acts as a diluent in nitrate loading from terrestrial catchments.
- 水環境学会誌 = Journal of Japan Society on Water Environment
水環境学会誌 = Journal of Japan Society on Water Environment 31(2), 87-92, 2008-02-10
Japan Society on Water Environment