Acid deposition and its effects on river water and sediments –Evaluation of exchangeable aluminum in sediments as an index of acidification–
- Other Title
- 酸性降下物の河川・堆積物への影響について –堆積物中の交換性アルミニウムを指標とした評価–
- サンセイ コウカブツ ノ カセン タイセキブツ エ ノ エイキョウ ニ ツイテ
Search this article
River sediment is thought to show average composition of the upstream watershed. We examined a method, using exchangeable aluminum Ex-Al, and the effects of acid deposition on influencing water composition. An index of acidification was established. First, the most useful method for measuring Ex-Al in sediment was evaluated. According to the contact tests with atmospheric precipitation and sediments, H+ and SO42- in the precipitation samples were adsorbed to biotite, and the amount of Ex-Al in the sediments increased. Acid deposition, river water composition and Ex-Al in sediments were measured at a mountain region site in southwest Nagano Prefecture, where granite was the basement rock. High acid deposition was measured at this site in the comparison with the mean value at 20 stations in Nagano Prefecture, and the alkalinity of river water was below 0.2 meq/l in this upstream region. Because of this, it was suggested that the experiment catchment area was highly sensitive to acid rain. Ex-Al was detected but quite variable from sediments in this area which received the influence of acid deposition. So sediment Ex-Al is thought to be a good index to show influence of acid deposition on river waters.
Chikyukagaku 29 (2), 137-145, 1995
The Geochemical Society of Japan