An experimental study of magnesium-isotope fractionation in chlorophyll-a photosynthesis

Black, J. Roy; Yin, Qing‐Zhu; Casey, William H.

doi:10.1016/j.gca.2006.06.010

Cited by 115 publications

(105 citation statements)

References 23 publications

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“…Mg has a central role in plant physiology and possibly fractionates during photosynthesis (14). A recent study showed enrichment in light Mg isotopes from the roots to the stems and to the leaves with a maximum Δ leaf-root of 0.65‰ (23).…”

Section: Discussionmentioning

confidence: 99%

“…Magnesium has been suspected of biological fractionation during the synthesis of chlorophyll (14), it is the second most abundant metal after calcium in biological apatite, and the measurement of its variability in mammal bone from various extant ecosystems permits the further assessment of its reliability as a potential new isotopic tracer of diet (15). Moreover, the concentration of Mg in teeth can be high (in the range of 1,000-10,000 ppm).…”

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confidence: 99%

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Magnesium stable isotope ecology using mammal tooth enamel

Martin

Vance

Balter

2014

Proc. Natl. Acad. Sci. U.S.A.

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Geochemical inferences on ancient diet using bone and enamel apatite rely mainly on carbon isotope ratios (δ 13 C) and to a lesser extent on strontium/calcium (Sr/Ca) and barium/calcium (Ba/Ca) elemental ratios. Recent developments in nontraditional stable isotopes provide an unprecedented opportunity to use additional paleodietary proxies to disentangle complex diets such as omnivory. Of particular relevance for paleodietary reconstruction are metals present in large quantity in bone and enamel apatite, providing that biologically mediated fractionation processes are constrained. Calcium isotope ratios (δ 44 Ca) meet these criteria but exhibit complex ecological patterning. Stable magnesium isotope ratios (δ 26 Mg) also meet these criteria but a comprehensive understanding of its variability awaits new isotopic data. Here, 11 extant mammal species of known ecology from a single locality in equatorial Africa were sampled for tooth enamel and, together with vegetation and feces, analyzed for δ 26 Mg, δ 13 C, Sr/Ca, and Ba/Ca ratios. The results demonstrate that δ 26 Mg incorporated in tooth enamel becomes heavier from strict herbivores to omnivores/faunivores. Using data from experimentally raised sheep, we suggest that this 26 Mg enrichment up the trophic chain is due to a 26 Mg enrichment in muscle relative to bone. Notably, it is possible to distinguish omnivores from herbivores, using δ 26 Mg coupled to Ba/Ca ratios. The potential effects of metabolic and dietary changes on the enamel δ 26 Mg composition remain to be explored but, in the future, multiproxy approaches would permit a substantial refinement of dietary behaviors or enable accurate trophic reconstruction despite specimen-limited sampling, as is often the case for fossil assemblages.stable isotopes | magnesium | carbon | equatorial mammals | paleoecology R econstructing the diet of extinct vertebrates is a challenging task, especially when direct evidence such as stomach contents or feeding traces is lacking. Geochemical studies using the 13 C/ 12 C ratio, the strontium/calcium (Sr/Ca) ratio, and the barium/calcium (Ba/Ca) ratio of the mineral fraction of the skeleton, bone, and enamel apatite have proved as useful as other methodologies, such as morphofunctional and microwear analyses (e.g., refs.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Magnesium stable isotope ecology using mammal tooth enamel

Martin

Vance

Balter

2014

Proc. Natl. Acad. Sci. U.S.A.

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“…There are several plausible mechanisms which could fractionate Ca and Mg during weathering, including, incorporation of Ca and Mg into biomass Wiegand et al, 2005;Black et al, 2006), precipitation of secondary carbonate and precipitation of clay phases during incongruent weathering (Tipper et al, 2006a). Here, we re-evaluate the probable fractionation control of solute Ca and Mg isotope ratios.…”

Section: Fractionation Control Of Solute Ca and Mg Isotope Ratiosmentioning

confidence: 97%

Calcium and magnesium isotope systematics in rivers draining the Himalaya-Tibetan-Plateau region: Lithological or fractionation control?

Tipper

Galy

Bickle

2008

Geochimica et Cosmochimica Acta

199

130

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“…For example, Jasper and Silver (1977) reported that Mg can be incorporated into chlorophyll-a and cellular cytoplasm during cyanobacterial growth. Black et al (2006) reported that chlorophyll-a isolated from cyanobacterium Synechococcus elongatus preferentially incorporates light Mg isotopes. This process has also been observed to enrich cells in heavy Zn isotopes (Gélabert et al, 2006).…”

Section: Role Of Cyanobacteria In Mg Concentration and Isotopic Fractmentioning

confidence: 99%

Magnesium isotope fractionation during hydrous magnesium carbonate precipitation with and without cyanobacteria

Mavromatis

Pearce

Shirokova

et al. 2012

Geochimica et Cosmochimica Acta

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How to cite:Mavromatis, Vasileios; Pearce, Christopher R.; Shirokova, Liudmila S.; Bundeleva, Irina A.; Pokrovsky, Oleg S.; Benezeth, Pascale and Oelkers, Eric H. (2012) AbstractThe hydrous magnesium carbonates, nesquehonite (MgCO 3 Á3H 2 O) and dypingite (Mg 5 (CO 3 ) 4 (OH) 2 Á5(H 2 O)), were precipitated at 25°C in batch reactors from aqueous solutions containing 0.05 M NaHCO 3 and 0.025 M MgCl 2 and in the presence and absence of live photosynthesizing Gloeocapsa sp. cyanobacteria. Experiments were performed under a variety of conditions; the reactive fluid/bacteria/mineral suspensions were continuously stirred, and/or air bubbled in most experiments, and exposed to various durations of light exposure. Bulk precipitation rates are not affected by the presence of bacteria although the solution pH and the degree of fluid supersaturation with respect to magnesium carbonates increase due to photosynthesis. Lighter Mg isotopes are preferentially incorporated into the precipitated solids in all experiments. Mg isotope fractionation between the mineral and fluid in the abiotic experiments is identical, within uncertainty, to that measured in cyanobacteriabearing experiments; measured d 26 Mg ranges from À1.54& to À1.16& in all experiments. Mg isotope fractionation is also found to be independent of reactive solution pH and Mg, CO 3 2À , and biomass concentrations. Taken together, these observations suggest that Gloeocapsa sp. cyanobacterium does not appreciably affect magnesium isotope fractionation between aqueous fluid and hydrous magnesium carbonates.

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An experimental study of magnesium-isotope fractionation in chlorophyll-a photosynthesis

Cited by 115 publications

References 23 publications

Magnesium stable isotope ecology using mammal tooth enamel

Magnesium stable isotope ecology using mammal tooth enamel

Calcium and magnesium isotope systematics in rivers draining the Himalaya-Tibetan-Plateau region: Lithological or fractionation control?

Magnesium isotope fractionation during hydrous magnesium carbonate precipitation with and without cyanobacteria

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