气候变化领域集成服务门户(CCPortal): Heterogeneity and incorporation of chromium isotopes in recent marine molluscs (Mytilus)

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DOI	10.1111/gbi.12336
	Heterogeneity and incorporation of chromium isotopes in recent marine molluscs (Mytilus)
	Bruggmann S.; Klaebe R.M.; Paulukat C.; Frei R.
发表日期	2019
ISSN	14724677
起始页码	417
结束页码	435
卷号	17 期号:4
英文摘要	The mollusc genus Mytilus is abundant in various modern marine environments and is an important substrate for palaeo-proxy work. The redox-sensitive chromium (Cr) isotope system is emerging as a proxy for changes in the oxidation state of the Earth's atmosphere and oceans. However, potential isotopic offsets between ambient sea water and modern biogenic carbonates have yet to be constrained. We measured Cr concentrations ([Cr]) and isotope variations (δ53Cr) in recent mollusc shells (Mytilus) from open and restricted marine environments and compared these to ambient sea water δ53Cr values. We found a large range in mollusc [Cr] (12–309 ppb) and δ53Cr values (−0.30 to +1.25‰) and in the offset between δ53Cr values of mollusc shells and ambient sea water (Δ53Crsea waterbulk Mytilus, −0.17 to −0.91‰). Step digestions of cultivated Mytilus edulis specimens indicate that Cr is mainly concentrated in organic components of the shell (periostracum: 407 ppb, n = 2), whereas the mollusc carbonate minerals contain ≤3 ppb Cr. Analyses of individual Cr-hosting phases (i.e., carbonate minerals and organic matrix) did not reveal significant differences in δ53Cr values, and thus, we suggest that Cr isotope fractionation may likely take place prior to rather than during biomineralisation of Mytilus shells. Heterogeneity of δ53Cr values in mollusc shells depends on sea water chemistry (e.g., salinity, food availability, faeces). The main control for δ53Cr values incorporated into shells, however, is likely vital effects (in particular shell valve closure time) since Cr can be partially or quantitatively reduced in sea water trapped between closed shell valves. The δ53Cr values recorded in Mytilus shells may thus be de-coupled from the redox conditions of ambient sea water, introducing additional heterogeneity that needs to be better constrained before using δ53Cr values in mollusc shells for palaeo-reconstructions. © 2019 The Authors. Geobiology Published by John Wiley & Sons Ltd.
关键词	biomineralization carbonate chromium concentration (composition)isotopic fractionation marine environment mollusc paleoenvironment reconstruction redox conditions seawater shell stable isotope Mollusca Mytilus Mytilus edulis
语种	英语
来源机构	Geobiology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/133224
推荐引用方式 GB/T 7714	Bruggmann S.,Klaebe R.M.,Paulukat C.,et al. Heterogeneity and incorporation of chromium isotopes in recent marine molluscs (Mytilus)[J]. Geobiology,2019,17(4).
APA	Bruggmann S.,Klaebe R.M.,Paulukat C.,&Frei R..(2019).Heterogeneity and incorporation of chromium isotopes in recent marine molluscs (Mytilus).,17(4).
MLA	Bruggmann S.,et al."Heterogeneity and incorporation of chromium isotopes in recent marine molluscs (Mytilus)".17.4(2019).