Correlation between dissolved 4He concentration and 36Cl in groundwater at Äspö, Sweden
スポンサーリンク
概要
- 論文の詳細を見る
Tunnel excavation at Äspö Island, Sweden, has caused severe groundwater disturbance, gradually extending deeper into the tunnel as present-day Baltic seawater intrudes through fractures connecting to the surface. However, the paleo-hydrogeochemical conditions have remained in the deep highly saline waters that have avoided mixing. A correlation has been observed between dissolved 4He concentration and Cl− ion concentration, measured every two years from 1995 to 2001 at Äspö. Groundwater mixing conditions can be examined by the correlations between 1/Cl, 36Cl/Cl, and 3H concentrations. Subsurface production is responsible for the majority of the 36Cl and excess dissolved 4He of interstitial groundwater in fractures. The secular equilibrium ratio of 36Cl/Cl in rock was theoretically estimated to be (5.05 ± 0.82) × 10−14 based on the neutron flux intensity, a value comparable to the measured 36Cl/Cl ratio in rock and groundwater. The degassing crustal 4He flux was estimated to be 2.9 × 10−8 not, vert, similar 1.3 × 10−6 (ccSTP/cm2a) using the HTO diffusion coefficient for the Äspö diorite. The 4He accumulation rate ranges from 6.8 × 10−10 (for the in situ accumulation rate) to 7.0 × 10−9 (ccSTP/(gwater · a) considering both 4He in situ production and the degassing flux, assuming 4He is accumulated constantly in groundwater. By comparing the subsurface 36Cl increase with 4He concentrations in groundwater, the 4He accumulation rate was determined from data for groundwater arriving at the secular equilibrium of 36Cl/Cl. The 4He accumulation rate was found to be (1.83 ± 0.72) × 10−8 ccSTP/(gwater · a) without determining the magnitude of degassing 4He flux.
論文 | ランダム
- プレート境界地震とアスペリティ・モデル
- 地震波でみた東北日本沈み込み帯の水の循環 : スラブから島弧地殻への水の供給
- 中国が地球環境保全問題の鍵を握る--「脱化石燃料社会へ」の変換の日中共同提案を訴える
- 化学者のための現実的エネルギー講座(第2回)21世紀のエネルギー需要見通し--化石燃料が当分最大
- 1930年代に発生したM 7クラスの宮城県沖地震の震源再決定 : 1978年宮城県沖地震のアスペリティでのすべりだったのか?