Determination of13C/12C-Ratios in Rumen Produced Methane and CO2of Cows, Sheep and Camels

This paper addresses possible underlying causes of the observed systematic spacings in the carbon isotopic composition of bone collagen and bone apatite-carbonate when herbivores, omnivores and carnivores are compared. In particular it examines whether the observed systematic spacings are due to dietary differences, or to metabolic differences. It concludes that a simple model for diet-to-collagen isotopic fractionation (based on dietary difference) can account for half of the observed spacing, but probably not more than that. It also examines the role of methanogenesis and argues that this is a feasible explanation for ruminant and, to a lesser extent, hindgut fermenter, spacing values, although again it is difficult to account for the full amount observed. It also considers the implications of observations indicating that much of the change due to different diets in a given species is probably due to isotopic shifts in bone carbonate, rather than collagen.

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“…and leads to the production of isotopically heavy CO 2 at the fermentation site (Schulze et al, 1998).…”

Section: ) Does Methanogenesis Alter the Carbon Isotope Balance?mentioning

confidence: 99%

On bone collagen—apatite‐carbonate isotopic relationships

Hedges

2003

Intl J of Osteoarchaeology

136

104

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“…Among ruminants, a significant part of metabolic CO 2 is lost as methane, a by-product of microbial activity in the rumen (Van Soest, 1994). Because methane is depleted in 13 C by 30-40& relative to food (Rust, 1981), it leaves the remaining metabolic CO 2 enriched in 13 C by several permil (Schulze et al, 1997). This CO 2 then enters the blood stream in the form of bicarbonate which in turn is incorporated into bone and tooth apatite (Metges et al, 1990).…”

Section: Introductionmentioning

confidence: 98%

The isotope record of short- and long-term dietary changes in sheep tooth enamel: Implications for quantitative reconstruction of paleodiets

Zazzo

Balasse

Passey

et al. 2010

Geochimica et Cosmochimica Acta

122

110

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“…a 12‰ difference in d 13 CH 4 for C 3 versus C 4 , as shown by Rust (1981), Metges et al (1990), Ehleringer & Monson (1993), Levin et al (1993), Schulze et al (1998) and Bilek et al (2001). The proportion of C 3 versus C 4 plants will also impact the d 13 CH 4 emitted from wildfires.…”

Section: Source Components Of Pih Yd-pb and Lgm Global Methane Invenmentioning

confidence: 99%

Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice

Whiticar

Schaefer

2007

Phil. Trans. R. Soc. A.

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Upon closer inspection, the classical view of the synchronous relationship between tropospheric methane mixing ratio and Greenland temperature observed in ice samples reveals clearly discernable variations in the magnitude of this response during the Late Pleistocene (!50 kyr BP). During the Holocene this relationship appears to decouple, indicating that other factors have modulated the methane budget in the past 10 kyr BP. The d 13 CH 4 and dD-CH 4 of tropospheric methane recorded in ice samples provide a useful constraint on the palaeomethane budget estimations. Anticipated changes in palaeoenvironmental conditions are recorded as changes in the isotope signals of the methane precursors, which are then translated into past global d 13 CH 4 and dD-CH 4 signatures. We present the first methane budgets for the late glacial period that are constrained by dual stable isotopes. The overall isotope variations indicate that the Younger Dryas ( YD) and Preindustrial Holocene have methane that is 13 C-and 2 H-enriched, relative to Modern. The shift is small for d 13 CH 4 (approx. 1‰) but greater for dD-CH 4 (approx. 9‰). The YD d 13 CH 4 -dD-CH 4 record shows a remarkable relationship between them from 12.15 to 11.52 kyr BP. The corresponding C-and H-isotope mass balances possibly indicate fluctuating emissions of thermogenic gas. This d 13 CH 4 -dD-CH 4 relationship breaks down during the YD-Preboreal transition. In both age cases, catastrophic releases of hydrates with Archaeal isotope signatures can be ruled out. Thermogenic clathrate releases are possible during the YD period, but so are conventional natural gas seepages.

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Determination of¹³C/¹²C-Ratios in Rumen Produced Methane and CO₂of Cows, Sheep and Camels

Cited by 21 publications

References 7 publications

On bone collagen—apatite‐carbonate isotopic relationships

On bone collagen—apatite‐carbonate isotopic relationships

The isotope record of short- and long-term dietary changes in sheep tooth enamel: Implications for quantitative reconstruction of paleodiets

Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice

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