scholarly journals A systematic look at chromium isotopes in modern shells – implications for paleo-environmental reconstructions

2018 ◽  
Author(s):  
Robert Frei ◽  
Cora Paulukat ◽  
Sylvie Bruggmann ◽  
Robert M. Klaebe
Keyword(s):  
Isotope Fractionation ◽  
Redox State ◽  
Surface Seawater ◽  
Ambient Seawater ◽  
Growth Zones ◽  
Vital Effects ◽  
Biogenic Carbonates ◽  
Definition Of ◽  
Isotope System ◽  
Chromate Ion

Abstract. The chromium isotope system (53Cr / 52Cr expressed as δ53Cr relative to NIST SRM 979) in marine biogenic and non-biogenic carbonates is currently being evaluated as a proxy for the redox state of the ocean. Previous work has concentrated on using corals and foraminifera for this purpose, but investigations focusing on the behavior of Cr in bivalves as potential archives are lacking. Due to their often good preservation, fossil marine biogenic carbonates have the potential to serve as useful archives for the reconstruction of past ocean redox fluctuations and eventually link those to climatic changes throughout Earth’s history. Here, we present an evaluation of the Cr isotope system in shells of some modern bivalves. Shell species from Lucidinadae, Cardiidae, Glycimerididae, and Pectenidae, collected systematically from one Mediterranean location (Playa Poniente, Benidorm, Spain) over a three year period, reveal δ53Cr values ranging from 0.15 to 0.65 ‰, values that are systematically below the local seawater δ53Cr value of 0.83 ± 0.05 ‰. This attests for significant reduction of dissolved seawater chromium in the process leading to calcification and thus for control of Cr isotope fractionation during biological routes. A similar, constant offset in δ53Cr values relative to surface seawater is observed in shells from Mytilius edulis from an arctic location (Godhavn, Disko Bay, Greenland). Chromium concentrations in the studied shells are significantly controlled by organic matter and typically range from 0.020 to 0.100 ppm, with some higher concentrations of up to 0.163 ppm recorded in Pectenidae. We also observe subtle, species-dependent differences in average Cr isotope signatures in the samples from Playa Poniente, particularly of Lucidinadae and Cardiidae, with considerably depressed and elevated δ53Cr values, respectively, relative to the other species investigated. Within-species heterogeneities, both in Cr concentrations and δ53Cr values, are favorably seen to result from vital effects during shell calcification rather than from heterogeneous seawater composition. This is because we observe that the surface seawater composition in the particular Playa Poniente location remained constant during July month of the three years we collected bivalve samples. Within single shell heterogeneities associated with growth zones reflecting one to several years of growth, both in δ53Cr and Cr concentrations, are observed in a sample of Placuna placenta and Mimachlamys townsendi. We suspect that these variations are, at least partially, related to seasonal changes in δ53Cr of surface seawaters. Recognizing the importance of organic substances in the bivalve shells, we propose a model whereby reduction of Cr(VI) originally contained in the seawater as chromate ion and transported to the calcifying space, to Cr(III), is effectively adsorbed onto organic macromolecules which eventually get included in the growing shell carbonates. This study, with its definition of statistically sound offsets in δ53Cr values of certain bivalve species from ambient seawater, forms a base for futures investigations aimed at using fossil shells as archives for the reconstruction of paleo-seawater redox fluctuations.

scholarly journals A systematic look at chromium isotopes in modern shells – implications for paleo-environmental reconstructions

2018 ◽  
Vol 15 (16) ◽  
pp. 4905-4922 ◽  
Author(s):  
Robert Frei ◽  
Cora Paulukat ◽  
Sylvie Bruggmann ◽  
Robert M. Klaebe
Keyword(s):  
Isotope Fractionation ◽  
Redox State ◽  
Surface Seawater ◽  
Ambient Seawater ◽  
Growth Zones ◽  
Vital Effects ◽  
Biogenic Carbonates ◽  
Definition Of ◽  
Isotope System ◽  
Chromate Ion

Abstract. The chromium isotope system (53Cr ∕ 52Cr, expressed as δ53Cr relative to NIST SRM 979) in marine biogenic and non-biogenic carbonates is currently being evaluated as a proxy for the redox state of the ocean. Previous work has concentrated on using corals and foraminifera for this purpose, but investigations focusing on the behavior of Cr in bivalves as potential archives are lacking. Due to their often good preservation, fossil marine biogenic carbonates have the potential to serve as useful archives for the reconstruction of past ocean redox fluctuations and eventually link those to climatic changes throughout Earth's history. Here, we present an evaluation of the Cr isotope system in shells of some modern bivalves. Shell species from Lucidinadae, Cardiidae, Glycimerididae and Pectenidae, collected systematically from one Mediterranean location (Playa Poniente, Benidorm, Spain) over a 3-year period reveal δ53Cr values ranging from 0.15 ‰ to 0.65 ‰, values that are systematically below the local seawater δ53Cr value of 0.83±0.05 ‰. This attests to a significant reduction of dissolved seawater chromium in the process leading to calcification and thus for control of Cr isotope fractionation during biological routes. A similar, constant offset in δ53Cr values relative to surface seawater is observed in shells from Mytilius edulis from an arctic location (Godhavn, Disko Bay, Greenland). Chromium concentrations in the studied shells are significantly controlled by organic matter and typically range from 0.020 to 0.100 ppm, with some higher concentrations of up to 0.163 ppm recorded in Pectenidae. We also observe subtle, species-dependent differences in average Cr isotope signatures in the samples from Playa Poniente, particularly of Lucidinadae and Cardiidae, with considerably depressed and elevated δ53Cr values, respectively, relative to the other species investigated. Intra-species heterogeneities, both in Cr concentrations and δ53Cr values, are favorably seen to result from vital effects during shell calcification rather than from heterogeneous seawater composition. This is because we observe that the surface seawater composition in the particular Playa Poniente location remained constant during the month of July of the 3 years we collected bivalve samples. Intra-shell heterogeneities – associated with growth zones reflecting one to several years of growth, both in δ53Cr and Cr concentrations – are observed in a sample of Placuna placenta and Mimachlamys townsendi. We suspect that these variations are, at least partially, related to seasonal changes in δ53Cr of surface seawaters. Recognizing the importance of organic substances in the bivalve shells, we propose a model whereby reduction of Cr(VI) originally contained in the seawater as chromate ion and transported to the calcifying space, to Cr(III), is effectively adsorbed onto organic macromolecules which eventually get included in the growing shell carbonates. This study, with its definition of statistically sound offsets in δ53Cr values of certain bivalve species from ambient seawater, forms a base for future investigations aimed at using fossil shells as archives for the reconstruction of paleo-seawater redox fluctuations.

No ion is an island: Multiple ions involved during boron incorporation into CaCO3

2021 ◽  
Author(s):  
Michael Henehan ◽  
Christa Klein-Gebbinck ◽  
Gavin Foster ◽  
Jill Wyman ◽  
Mathis Hain ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Isotope Fractionation ◽  
Isotope Composition ◽  
Boron Isotope ◽  
Minor Role ◽  
Growth Mechanisms ◽  
Minor Elements ◽  
Vital Effects ◽  
Biogenic Carbonates ◽  
Trace And Minor Elements

<p>Boron isotope ratios, as measured in marine calcium carbonate, are a proven tracer of past seawater and calcifying fluid pH and thus a powerful tool for the reconstruction of past atmospheric CO<sub>2</sub> and monitoring of coral physiology. For such applications, understanding the inorganic baseline upon which foraminiferal vital effects or coral pH upregulation are superimposed should be an important prerequisite. Yet, investigations into boron isotope fractionation in synthetic CaCO<sub>3 </sub>polymorphs have often reported variable and even conflicting results, implying that we may not fully understand pathways of boron incorporation into calcium carbonate.  Here we address this topic with experimental data from calcite and aragonite precipitated across a range of pH in the presence of both Mg and Ca. We confirm the results of previous studies that the boron isotope composition of inorganic aragonite precipitates closely reflects that of aqueous borate ion, but that calcites display a higher degree of scatter, and diverge from the boron isotope composition of borate ion at low pH. We discuss these findings with reference to the simultaneous incorporation of other trace and minor elements, and highlight a number of mechanisms by which crystal growth mechanisms may influence the concentration and isotope composition of boron in CaCO<sub>3</sub>. In particular, we highlight the potential importance of surface electrostatics in driving variability in published synthetic carbonate datasets. Importantly for palaeo-reconstruction, however, these electrostatic effects are likely to play a much more minor role during natural precipitation of biogenic carbonates.</p>

scholarly journals Identifying vital effects in <i>Halimeda</i> algae with Ca isotopes

2014 ◽  
Vol 11 (24) ◽  
pp. 7207-7217 ◽  
Author(s):  
C. L. Blättler ◽  
S. M. Stanley ◽  
G. M. Henderson ◽  
H. C. Jenkyns
Keyword(s):  
Isotope Fractionation ◽  
Isotope Composition ◽  
Test Organism ◽  
Isotope Ratios ◽  
First Order ◽  
Geological Past ◽  
Rayleigh Distillation ◽  
Vital Effects ◽  
Specific Factors ◽  
Biogenic Carbonates

Abstract. Geochemical records of biogenic carbonates provide some of the most valuable records of the geological past, but are often difficult to interpret without a mechanistic understanding of growth processes. In this experimental study, Halimeda algae are used as a test organism to untangle some of the specific factors that influence their skeletal composition, in particular their Ca-isotope composition. Algae were stimulated to precipitate both calcite and aragonite by growth in artificial Cretaceous seawater, resulting in experimental samples with somewhat malformed skeletons. The Ca-isotope fractionation of the algal calcite (−0.6‰) appears to be much smaller than that for the algal aragonite (−1.4‰), similar to the behaviour observed in inorganic precipitates. However, the carbonate from Halimeda has higher Ca-isotope ratios than inorganic forms by approximately 0.25‰, likely because of Rayleigh distillation within the algal intercellular space. In identifying specific vital effects and the magnitude of their influence on Ca-isotope ratios, this study suggests that mineralogy has a first-order control on the marine Ca-isotope cycle.

scholarly journals Identifying vital effects in <i>Halimeda</i> algae with Ca isotopes

2014 ◽  
Vol 11 (3) ◽  
pp. 3559-3580 ◽  
Author(s):  
C. L. Blättler ◽  
S. M. Stanley ◽  
G. M. Henderson ◽  
H. C. Jenkyns
Keyword(s):  
Intercellular Space ◽  
Isotope Fractionation ◽  
Isotope Composition ◽  
Test Organism ◽  
First Order ◽  
Geological Past ◽  
Rayleigh Distillation ◽  
Vital Effects ◽  
Specific Factors ◽  
Biogenic Carbonates

Abstract. Geochemical records of biogenic carbonates provide some of the most valuable records of the geological past, but are often difficult to interpret without a mechanistic understanding of growth processes. In this experimental study, Halimeda algae are used as a test organism to untangle some of the specific factors that influence their skeletal composition, in particular their Ca-isotope composition. Algae were stimulated to precipitate both calcite and aragonite by growth in artificial Cretaceous seawater. The Ca-isotope fractionation of the algal calcite is much smaller than that for the algal aragonite, similar to the behaviour observed in inorganic precipitates. However, the carbonate from Halimeda is isotopically heavier than inorganic forms, likely due to Rayleigh distillation within the algal intercellular space. In identifying specific vital effects and the magnitude of their influence on Ca-isotope ratios, this study suggests that mineralogy has a first-order control on the Ca-isotope budget of the carbonate sink and the Ca-isotope composition of seawater.

scholarly journals Oxygen isotope equilibrium in brachiopod shell fibres in the context of biological control

2008 ◽  
Vol 72 (1) ◽  
pp. 239-242 ◽  
Author(s):  
M. Cusack ◽  
A. Pérez-Huerta ◽  
P. Chung ◽  
D. Parkinson ◽  
Y. Dauphin ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Isotope Composition ◽  
Seawater Temperature ◽  
Environmental Data ◽  
Ambient Seawater ◽  
Secondary Layer ◽  
Vital Effect ◽  
Vital Effects ◽  
Stable Oxygen ◽  
Isotope Equilibrium

With their long geological history and stable low-Mg calcite shells, Rhynchonelliform brachiopods are attractive sources of environmental data such as past seawater temperature (Buening and Spero, 1996; Auclair et al., 2003; Brand et al., 2003; Parkinson et al., 2005). Concerns about the influence of vital effects on the stable isotope composition of brachiopod shells (Popp et al., 1986), led to isotope analyses of different parts of brachiopod shells in order to identify those parts of the shell that are influenced by any vital effect and those parts that may be suitable recorders of seawater temperature via stable oxygen isotope composition (Carpenter and Lohmann, 1995; Parkinson et al., 2005). Such detailed studies demonstrated that the outer primary layer of acicularcalcite is isotopically light in both δ18O and δ13C while the secondary layer, composed of calcite fibres, is in oxygen-isotope equilibrium with ambient seawater(Fig. 1) (Parkinson et al., 2005).

A tandem-column extraction chromatography for Nd separation: minimizing mass-independent isotope fractionation for ultrahigh-precision Nd isotope-ratio analysis

2022 ◽  
Author(s):  
Da Wang ◽  
Richard Carlson
Keyword(s):  
Solar System ◽  
Extraction Chromatography ◽  
Isotope Ratio ◽  
Isotope Fractionation ◽  
Ratio Analysis ◽  
Nd Isotope ◽  
Planetary Differentiation ◽  
Isotope Ratio Analysis ◽  
Isotope System ◽  
Column Extraction

The short-lived 146Sm-142Nd isotope system traces key early planetary differentiation processes that occurred during the first 500 million-years of solar system history. The variations of 142Nd/144Nd in terrestrial samples, typically...

scholarly journals Reply to Nicholson's comment on "Consistent calculation of aquatic gross production from oxygen triple isotope measurements" by Kaiser (2011)

2012 ◽  
Vol 9 (8) ◽  
pp. 2921-2933 ◽  
Author(s):  
J. Kaiser ◽  
O. Abe
Keyword(s):  
Isotope Fractionation ◽  
Direct Calculation ◽  
Original Data ◽  
Delta Method ◽  
Base Case ◽  
Calculation Methods ◽  
Input Parameters ◽  
Net To Gross ◽  
Number Of Publications ◽  
Definition Of

Abstract. The comment by Nicholson (2011a) questions the "consistency" of the "definition" of the "biological end-member" used by Kaiser (2011a) in the calculation of oxygen gross production. "Biological end-member" refers to the relative oxygen isotope ratio difference between photosynthetic oxygen and Air-O2 (abbreviated 17δP and 18δP for 17O/16O and 18O/16O, respectively). The comment claims that this leads to an overestimate of the discrepancy between previous studies and that the resulting gross production rates are "30% too high". Nicholson recognises the improved accuracy of Kaiser's direct calculation ("dual-delta") method compared to previous approximate approaches based on 17O excess (17Δ) and its simplicity compared to previous iterative calculation methods. Although he correctly points out that differences in the normalised gross production rate (g) are largely due to different input parameters used in Kaiser's "base case" and previous studies, he does not acknowledge Kaiser's observation that iterative and dual-delta calculation methods give exactly the same g for the same input parameters (disregarding kinetic isotope fractionation during air-sea exchange). The comment is based on misunderstandings with respect to the "base case" 17δP and 18δP values. Since direct measurements of 17δP and 18δPdo not exist or have been lost, Kaiser constructed the "base case" in a way that was consistent and compatible with literature data. Nicholson showed that an alternative reconstruction of 17δP gives g values closer to previous studies. However, unlike Nicholson, we refrain from interpreting either reconstruction as a benchmark for the accuracy of g. A number of publications over the last 12 months have tried to establish which of these two reconstructions is more accurate. Nicholson draws on recently revised measurements of the relative 17O/16O difference between VSMOW and Air-O2 (17δVSMOW; Barkan and Luz, 2011), together with new measurements of photosynthetic isotope fractionation, to support his comment. However, our own measurements disagree with these revised 17δVSMOW values. If scaled for differences in 18δVSMOW, they are actually in good agreement with the original data (Barkan and Luz, 2005) and support Kaiser's "base case" g values. The statement that Kaiser's g values are "30% too high" can therefore not be accepted, pending future work to reconcile different 17δVSMOW measurements. Nicholson also suggests that approximated calculations of gross production should be performed with a triple isotope excess defined as 17Δ#≡ ln (1+17δ)–λ ln(1+18δ), with λ = θR = ln(1+17&amp;varepsilon;R ) / ln(1+18&amp;varepsilon;R). However, this only improves the approximation for certain 17δP and 18δP values, for certain net to gross production ratios (f) and for certain ratios of gross production to gross Air-O2 invasion (g). In other cases, the approximated calculation based on 17Δ† ≡17δ – κ 18δ with κ = γR = 17&amp;varepsilon;R/18&amp;varepsilon;R (Kaiser, 2011a) gives more accurate results.

Small changes in Cu redox state and speciation generate large isotope fractionation during adsorption and incorporation of Cu by a phototrophic biofilm

2018 ◽  
Vol 220 ◽  
pp. 1-18 ◽  
Author(s):  
Margot Coutaud ◽  
Merlin Méheut ◽  
Pieter Glatzel ◽  
Gleb S. Pokrovski ◽  
Jérôme Viers ◽  
...  
Keyword(s):  
Isotope Fractionation ◽  
Redox State ◽  
Phototrophic Biofilm

scholarly journals Rare Earth Elements in oyster shells: provenance discrimination and potential vital effects

2019 ◽  
Author(s):  
Vincent Mouchi ◽  
Camille Godbillot ◽  
Vianney Forest ◽  
Alexey Ulianov ◽  
Franck Lartaud ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Hydrothermal Activity ◽  
Ostrea Edulis ◽  
Icp Ms ◽  
Significant Difference ◽  
Vital Effects ◽  
Ancient Times ◽  
Biogenic Carbonates ◽  
Bivalve Shells

Abstract. Rare Earth Elements and yttrium (REY) in seawater originate from atmospheric fallout, continental weathering, and transport from rivers, as well as hydrothermal activity. Previous studies reported the use of REY measurements in biogenic carbonates as a means to reconstruct these surface processes in ancient times. As coastal seawater REY concentrations partially reflect those of nearby rivers, it may be possible to obtain a regional fingerprint of these concentrations from bivalve shells for provenance and environmental monitoring studies. Here, we present a dataset of 260 measurements of REY abundances by LA-ICP-MS from 42 oyster specimens from six locations in France (Atlantic Ocean and Mediterranean Sea), and from two species (Crassostrea gigas and Ostrea edulis). Our study reports that there is no significant difference in concentrations from shell parts corresponding to winter and summer periods for both species. Moreover, interspecific vital effects are reported from specimens from both species and from the same locality. REY profiles and t-distributed Stochastic Neighbour Embedding processing (t-SNE; a discriminant statistical method) indicate that REY measurements from C. gigas shells can be discriminated from one locality to another, but this is not the case for O. edulis, which presents very similar concentrations in all studied localities. Therefore, provenance studies using bivalve shells based on REY have to be first tested for the species, and are not adapted for O. edulis. Other methods have to be investigated to be able to find the provenance of some species such as O. edulis.

High-resolution carbon and oxygen isotope record in modern brachiopod Pictothyris picta collected off Okinoshima, Japan

2021 ◽  
Author(s):  
Kazuma Oikawa ◽  
Hideko Takayanagi ◽  
Kazuyoshi Endo ◽  
Masa-aki Yoshida ◽  
Yasufumi Iryu
Keyword(s):  
Isotopic Composition ◽  
Isotope Fractionation ◽  
Growth Stage ◽  
Cold Season ◽  
Strong Positive Correlation ◽  
Isotopic Equilibrium ◽  
Ambient Seawater ◽  
Kinetic Isotope ◽  
Carbon And Oxygen Isotope ◽  
Fractionation Effect

&lt;p&gt;Carbon (&amp;#948;&lt;sup&gt;13&lt;/sup&gt;C) and oxygen (&amp;#948;&lt;sup&gt;18&lt;/sup&gt;O) isotope composition of Rhynchonelliformea brachiopods (hereafter, called &amp;#8216;brachiopods&amp;#8217;) have been regarded as useful paleoenvironmental indicators throughout the Phanerozoic. However, recent studies have revealed that the isotopic composition in modern brachiopod shells records not only environmental changes in ambient seawater but also is influenced by biological controls such as the chemical/isotopic composition of calcifying fluids and physiological processes (e.g., growth rates, metabolism). The latter is known as biological isotope fractionation effects, such as kinetic, metabolic, and pH effects. Recently, a new calcification mechanism in brachiopod shell formation, ion transport mechanism, was proposed. In this study, we measured &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C and &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O values of the primary (PL) and secondary (SL) shell layers of three &lt;em&gt;Pictothyris picta&lt;/em&gt; (one male and two female specimens) collected at a water depth of~61 m off Okinoshima to improve our understanding of biological isotope fractionation effects during their shell secretion. We obtained ontogenetic-series &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C and &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O profiles from the PL (PL-Ont) and the uppermost SL (SL-Ont) at the sampling resolution of 3 days to 8 months per sample. We obtained inner-series &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C and &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O profiles from the innermost SL (SL-In) as well. The variations in the &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C and &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O profiles of the PL-Ont showed similar trends to those of the SL-Ont. However, the PL-Ont values mostly exhibited relatively lower &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O values than those of the SL-Ont. Cross plots between the &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C and &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O values of the PL-Ont indicated a strong positive correlation and were lower than those of calcite precipitated in isotopic equilibrium with ambient seawater at the fast growth stage, suggesting the significant influence of the kinetic isotope fractionation effect. The SL was precipitated in oxygen isotopic equilibrium with ambient seawater regardless of the growth stage and/or the seasonal changes in living environments. Furthermore, the PL-Ont, SL-Ont, and SL-Inshowed similar &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O values during the cold season, indicating negligible influences of the kinetic, pH, and magnesium effects on &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O composition. The &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C values of the PL-Ont formed at the cold season (= micro-portion formed under the least kinetic isotope fractionation effect) were lower than those of the SL, indicating the stronger metabolic effect on the PL secretion. Our isotopic data showed that the time lag of the PL and the SL formation varies among specimens.&lt;/p&gt;

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