DOI: 10.1111/gbi.12155
Scopus记录号: 2-s2.0-84955636798
论文题名: Chromium-isotope signatures in scleractinian corals from the Rocas Atoll, Tropical South Atlantic
作者: Pereira N.S. ; Voegelin A.R. ; Paulukat C. ; Sial A.N. ; Ferreira V.P. ; Frei R.
刊名: Geobiology
ISSN: 1472-4677
EISSN: 1472-4669
出版年: 2016
卷: 14, 期: 1 起始页码: 54
结束页码: 67
语种: 英语
Scopus关键词: carbonate
; chromate
; chromium
; climate change
; coral record
; environmental change
; isotopic composition
; paleoenvironment
; seawater
; skeletal remains
; Atlantic Ocean
; Atlantic Ocean (South)
; Brazil
; Rio Grande do Norte
; Rocas Atoll
; Anthozoa
; Montastraea cavernosa
; Porites
; Scleractinia
; Siderastrea stellata
; chromium
; animal
; Anthozoa
; Atlantic Ocean
; Brazil
; chemistry
; oxidation reduction reaction
; Animals
; Anthozoa
; Atlantic Ocean
; Brazil
; Chromium Isotopes
; Oxidation-Reduction
Scopus学科分类: Earth and Planetary Sciences: General Earth and Planetary Sciences
; Environmental Science: General Environmental Science
; Agricultural and Biological Sciences: Ecology, Evolution, Behavior and Systematic
英文摘要: Chromium-isotope compositions (expressed as δ53Cr) of recent and ancient skeletal and non-skeletal carbonates are currently explored as a (paleo-) redox-proxy for shallow seawater. The idea behind this approach is that biogenic and non-biogenic carbonates could potentially be used as archives recording the Cr-isotope composition of seawater in which they formed, and with this contribute to the reconstruction of past paleo-environmental changes in the marine realm, and potentially to climate changes on land. However, investigations addressing the behavior and uptake mechanism of Cr, and the potential isotope fractionations between seawater and biogenic carbonates are scarce. Here, we present a study of Cr-isotope variations in three species of corals and contemporary seawater from the Rocas Atoll, NE, Brazil. Cr-isotope values of the studied coral species (Siderastrea stellata, Porites sp., and Montastrea cavernosa) vary from -0.5 to +0.33‰ and point to significant isotopic disequilibrium with coexisting seawater characterized by a Cr-isotope value of +0.92 ± 0.2‰. This isotopic offset requires reduction of hexavalent Cr(VI) in the sequestration process of all the studied coral species. Cr-isotope values in a profile across an S. stellata colony returned homogeneous, slightly positively fractioned δ53Cr values of +0.07 ± 0.08‰ (n = 8, 2σ), which we interpret to reflect a constant reductive uptake during the 20-year growth period recorded in this coral. In contrast, samples across a 12-year growth profile from Porites sp. display rather heterogeneous Cr-isotope values with δ53Cr varying from -0.50 to +0.10‰, indicating Cr incorporation under changing redox processes during its growth intervals. We propose a mechanism whereby initial photoreduction of isotopically heavy Cr(VI) to isotopically lighter Cr(III) in the endodermal layer of corals must be followed by efficient and effective re-oxidation of reduced Cr species to favor subsequent chromate (CrO42-) substitution during the calcifying processes ultimately leading to the formation of the coral skeleton. Copyright © 2016 John Wiley & Sons Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/85119
Appears in Collections: 影响、适应和脆弱性
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作者单位: NEG-LABISE, Federal University of Pernambuco, Recife, Brazil; State University of Bahia, Paulo Afonso, Brazil; Department of Geosciences and Natural Resource Management, Nordic Center for Earth Evolution (NordCEE), University of Copenhagen, Copenhagen, Denmark
Recommended Citation:
Pereira N.S.,Voegelin A.R.,Paulukat C.,et al. Chromium-isotope signatures in scleractinian corals from the Rocas Atoll, Tropical South Atlantic[J]. Geobiology,2016-01-01,14(1)