کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8863187 1620202 2018 40 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Control of a calcite inhibitor (phosphate) and temperature on ikaite precipitation in Ikka Fjord, southwest Greenland
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Control of a calcite inhibitor (phosphate) and temperature on ikaite precipitation in Ikka Fjord, southwest Greenland
چکیده انگلیسی
Ikaite (CaCO3·6H2O) forms submarine tufa columns in Ikka Fjord, SW Greenland. This unique occurrence is thought to relate to aqueous phosphate concentration and low water temperatures (<6 °C). Phosphate ions are well-known inhibitors of calcite precipitation and Ikka Fjord has a naturally high-phosphate groundwater system that when mixing with seawater leads to the precipitation of ikaite. In the study presented here, experiments simulating conditions of Ikka Fjord show that a) the formation of ikaite is unrelated to the aqueous phosphate concentration (0-263 μmol/kg PO43−) in 0.1 M NaHCO3/0.1 M Na2CO3 solutions mixing with seawater at 5 °C and pH 9.6-10.6, and b) ikaite forms at temperatures up to 15 °C without phosphate and in open beakers exposed to air. Instead, supersaturation of ikaite and the seawater composition are the likely factors causing ikaite to precipitate in Ikka Fjord. This study shows that adding Mg2+ to a NaHCO3/Na2CO3 - CaCl2 mixed solution leads to the formation of ikaite along with hydrated Mg carbonates, which points to the high Mg2+ concentration of seawater, another known inhibitor of calcite, as a key factor promoting ikaite formation. In experiments at 10 and 15 °C, increasing amounts of either nesquehonite (Mg(HCO3)(OH)·2H2O) or an amorphous phase co-precipitate with ikaite. At 20 °C, only the amorphous phase is formed. In warming Arctic seawater, this suggests Mg carbonate precipitation could become dominant over ikaite in the future.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Applied Geochemistry - Volume 89, February 2018, Pages 11-22
نویسندگان
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