蛇紋岩体の地化学環境を利用したCO_2固定研究(<シンポジウム特集>蛇紋石環境と深く関わる層状ケイ酸塩)

概要

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To reduce anthropogenic CO_2 emissions in the atmosphere is one of the effective options to avoid global warming. The groundwater in serpentinites distributed widely in Japan is alkaline and Mg-rich. Mg-carbonate minerals precipitated by the reaction between the alkaline groundwater and CO_2 are commonly attached to the serpentinite. The carbonate minerals are valuable for the long-term CO_2 fixation, because they are chemically stable and do not diffuse CO_2 by dissolving them as long as the serpentinite-groundwater system retains alkaline condition. The purpose of in situ experiment is to develop the efficient CO_2 fixation system with the serpentinite. The in situ experiment was carried out at the Saru-gawa serpentinite massif in Hokkaido, Japan. CO_2 gas was injected into the primary groundwater (pH=10) through the bore hole. The primary groundwater acidified by injection of the CO_2 gas dissolved serpentine (Mg_3Si_2O_5(OH)_4) and brucite (Mg(OH)_2) in the host serpentinite to produce the Mg-rich acidic groundwater. The Mg-rich groundwater migrated into the serpentinite-groundwater system and neutralized by the alkaline primary groundwater to precipitate Mg-carbonate minerals. The occurrence of the carbonate with serpentinite in a state of nature and the results from the in situ experiment show that the implication between the serpentinite-groundwater system and CO_2 would be useful for the CO_2 fixation.
2007-02-16