An unusual isotopic fractionation of boron in synthetic calcium carbonate precipitated from seawater and saline water

摘要: Inorganic calcium carbonate precipitation from natural seawater and saline water at various pH values was carried out experimentally. The results show the clear positive relationships between boron concentration δ 11 B of inorganic with water. However, variations isotopic fractionation calcite seawater/saline are inconsistent hypothesis that B(OH) 4 - is dominant spe-cies incorporated into biogenic structure. factors a synthetic precipitate parent solutions increase systematically as increases, 0.9884 7.60 to 1.0072 8.60 for 0.9826 1.0178 8.75 An unusual factor larger than 1 in precipitated higher observed, which implies substantial amount isotopically heavier 3 species must be preferentially carbonate. propose incorporation attributed formation Mg(OH) 2 calcifying microenvironment during precipitation. preliminary experiment artificial shows enriched precipitation, suggests This result cannot applied explain marine bio-carbonate because possibility environment this study appears infinitesimal. We, however, pay more attention phenomenon observed study, accidentally especially environment.