海水に対する酸性赤色土の化学的インパクト

• Kombo Mohamed Mkadam

  Graduate school of Engineering and Science, University of the Ryukyus

• Bakari Said Suleiman

  Graduate school of Engineering and Science, University of the Ryukyus

• 新城 竜一

  琉球大学理学部海洋自然科学科

• 渡久 山章

  琉球大学理学部海洋自然科学科

書誌事項

タイトル別名

• Chemical impact of the acidic red soil on seawater

抄録

Red soil contamination into marine ecosystems such as coral reefs and estuaries is a prevalent environmental problem in the Okinawa Islands. This study was conducted to examine the chemical impact of Okinawan red soil on seawater. The different soil weights were mixed and shaken with 100mL of seawater for four hours to obtain the extracts. The pH, concentrations of Na⁺, K⁺, Ca²⁺, Mg²⁺, Al³⁺ and dissolved silica were then determined. The soil is acidic with a pH value of 5.03, dominated by SiO₂ and Al₂O₃. The pH of the Zampa cape seawater was 8.23 and decreased with soil weight to the lowest value of 4.06. The Al concentration in the seawater was 0.0256meqL^-1 and increased with soil to solution ratio to the maximum value of 5.95meqL^-1. The base metal concentrations decreased from the seawater by 23.5%, 8.04%, and 3.59% in extracts for K⁺, Ca²⁺ and Mg²⁺, respectively, while Na⁺ was relatively stable to change. The dissolved SiO₂ increased from 0.430mgL^-1 in the seawater to the maximum value of 20.0mgL^-1 in ground soil. The Summation of decreasing K⁺, Ca²⁺ and Mg²⁺ concentrations and increasing Al³⁺ and H⁺ in the extracts showed a high correlation coefficient (P<0.001), which largely suggests an exchange process. The significant correlations between logarithmic concentrations of Al³⁺ and silica vs. pH (P<0.001) also suggest the importance of H⁺ to release soluble Al as well as hydrogen-promoted weathering of silicates. Physical features such as sedimentation and turbidity do affect coral reefs, but possibly chemical effects such as the elevated Al concentration observed in coastal seawaters may also interfere with the coral's well being at significant red soil-affected areas in the Okinawa Islands.

収録刊行物

• 日本サンゴ礁学会誌

  日本サンゴ礁学会誌 8 (1), 13-23, 2006

  日本サンゴ礁学会

キーワード

• acidic red soil
• seawater
• cation exchange
• dissolution
• aluminum

詳細情報

• CRID: 1390282679461727744
• NII論文ID: 130003670762
• DOI: 10.3755/jcrs.8.13
• ISSN: 18825710
• ISSN: 13451421
• 本文言語コード: en
• データソース種別:
  • JaLC
  • Crossref
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可