化学的風化作用による大気からのＣＯ２の除去フラックス推定上の問題点　　珪酸塩と炭酸塩風化フラックス

• 鹿園 直建

  慶應義塾大学理工学部応用化学科地球環境化学研究室

書誌事項

タイトル別名

• Removal of CO2 from the Atmosphere by Chemical Weathering: Fluxes due to the Weathering of Silicates and Carbonates.
• カガクテキ フウカ サヨウ ニ ヨル タイキ カラ ノ CO2 ノ ジョキョ フラックス スイテイ ジョウ ノ モンダイテン ケイサンエン ト タンサンエン フウカ フラックス
• Fluxes due to the Weathering of Silicates and Carbonates
• 珪酸塩と炭酸塩風化フラックス

抄録

Previous studies such as that of Meybeck (1987) estimated the CO₂ flux from atmosphere to riverwater due to chemical weathering by assuming that the rate of weathering of silicate rocks and carbonate rocks is proportional to the surface areas of rocks (silicate rocks : carbonate rocks = 7 : 3). However, the dissolution rate of carbonates (calcite and dolomite) is in two to four orders of magnitude higher than silicate (feldspar). This may imply that Meybeck's and other previous approaches lead to a large uncertainty in the estimate of CO₂ flux. However, their estimates are nearly similar to that of Gaillardet et al. (1999), who estimated the contribution of the weathering of silicates and carbonates to riverwater chemistry based on a large volume of analytical and runoff data of the world's 60 major rivers.<BR>The thermochemical calculation in the present study indicates that the chemistry of riverwater having a small runoff is controlled by the solubilities of calcite and Na ·Ca-feldspar (Na : Ca = 1 : 1) at atmospheric P_CO<SUB>2</SUB> (10 ^-3.5 atm) and the world-wide average riverwater chemistry plot is close to the Na ·Ca feldspar-calcite-riverwater equilibrium point. This result reasonably explains the similar estimated values of CO₂ flux obtained by Meybeck (1987) and others and Gaillardet et al. (1999).<BR>The conditions for riverwater saturated with Na ·Ca feldspar and calcite were derived based on a dissolution kinetics-fluid flow coupling model and were expressed as functions of τ (residence time of groundwater) and A/M (A : surface area of mineral, M : mass of water).

収録刊行物

• 地学雑誌

  地学雑誌 111 (3), 360-373, 2002

  公益社団法人 東京地学協会

キーワード

• 化学的風化作用
• 気候変動
• 二酸化炭素
• 珪酸塩
• 炭酸塩
• 水-岩石相互作用

詳細情報

• CRID: 1390282679206147456
• NII論文ID: 110000379994
• NII書誌ID: AN00322536
• DOI: 10.5026/jgeography.111.3_360
• ISSN: 18840884
• ISSN: 0022135X
• NDL書誌ID: 6197165
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I6197165
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可