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

ISL OpenIR > 青海盐湖研究所知识仓储

	An unusual isotopic fractionation of boron in synthetic calciumcarbonate precipitated from seawater and saline water
	Xiao Yingkai; Li Shizhen; Wei Haizhen; Sun Aide; Zhou Weijian; Liu Weiguo
	2006
发表期刊	SCIENCE IN CHINA SERIES B-CHEMISTRY
ISSN	1006-9291
卷号	49 期号:5 页码:454-465
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 and delta B-11 of inorganic calcium carbonate with the pH of natural seawater and saline water. However, the variations of boron isotopic fractionation between inorganic calcite and seawater/saline water with pH are inconsistent with the hypothesis that B(OH)(4)(-) is the dominant species incorporated into the biogenic calcite structure. The isotopic fractionation factors a between synthetic calcium carbonate precipitate and parent solutions increase systematically as pH increases, from 0.9884 at pH 7.60 to 1.0072 at pH 8.60 for seawater and from 0.9826 at pH 7.60 to 1.0178 at pH 8.75 for saline water. An unusual boron isotopic fractionation factor of larger than 1 in synthetic calcium carbonate precipitated from seawater/saline water at higher pH is observed, which implies that a substantial amount of the isotopically heavier B(OH)(3) species must be incorporated preferentially into synthetic inorganic carbonate. The results propose that the incorporation of B(OH)(3) is attributed to the formation of Mg(OH)(2) at higher pH of calcifying microenvironment during the synthetic calcium carbonate precipitation. The preliminary experiment of Mg(OH)(2) precipitated from artificial seawater shows that heavier B-11 is enriched in Mg(OH)(2) precipitation, which suggests that isotopically heavier B(OH)(3) species incorporated preferentially into Mg(OH)(2) precipitation. 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 and delta B-11 of inorganic calcium carbonate with the pH of natural seawater and saline water. However, the variations of boron isotopic fractionation between inorganic calcite and seawater/saline water with pH are inconsistent with the hypothesis that B(OH)(4)(-) is the dominant species incorporated into the biogenic calcite structure. The isotopic fractionation factors a between synthetic calcium carbonate precipitate and parent solutions increase systematically as pH increases, from 0.9884 at pH 7.60 to 1.0072 at pH 8.60 for seawater and from 0.9826 at pH 7.60 to 1.0178 at pH 8.75 for saline water. An unusual boron isotopic fractionation factor of larger than 1 in synthetic calcium carbonate precipitated from seawater/saline water at higher pH is observed, which implies that a substantial amount of the isotopically heavier B(OH)(3) species must be incorporated preferentially into synthetic inorganic carbonate. The results propose that the incorporation of B(OH)(3) is attributed to the formation of Mg(OH)(2) at higher pH of calcifying microenvironment during the synthetic calcium carbonate precipitation. The preliminary experiment of Mg(OH)(2) precipitated from artificial seawater shows that heavier B-11 is enriched in Mg(OH)(2) precipitation, which suggests that isotopically heavier B(OH)(3) species incorporated preferentially into Mg(OH)(2) precipitation.
文献类型	期刊论文
条目标识符	http://ir.isl.ac.cn/handle/363002/2306
专题	青海盐湖研究所知识仓储中国科学院青海盐湖研究所
推荐引用方式 GB/T 7714	Xiao Yingkai,Li Shizhen,Wei Haizhen,et al. An unusual isotopic fractionation of boron in synthetic calciumcarbonate precipitated from seawater and saline water[J]. SCIENCE IN CHINA SERIES B-CHEMISTRY,2006,49(5):454-465.
APA	Xiao Yingkai,Li Shizhen,Wei Haizhen,Sun Aide,Zhou Weijian,&Liu Weiguo.(2006).An unusual isotopic fractionation of boron in synthetic calciumcarbonate precipitated from seawater and saline water.SCIENCE IN CHINA SERIES B-CHEMISTRY,49(5),454-465.
MLA	Xiao Yingkai,et al."An unusual isotopic fractionation of boron in synthetic calciumcarbonate precipitated from seawater and saline water".SCIENCE IN CHINA SERIES B-CHEMISTRY 49.5(2006):454-465.