Sentences with phrase «carbon isotope ratio»

The results suggest that El Nino and the Southern Oscillation events produce major changes in the carbon isotope ratio in the atmosphere.

The size of the carbon injection is estimated from changes in the stable carbon isotope ratio 13C / 12C in sediments and from ocean acidification implied by changes in the ocean depth below which carbonate dissolution occurred.

It's usually taken to be the fact that as carbon dioxide concentrations in the atmosphere increase, the 1 per cent of CO2 that's the heavier carbon isotope ratio c13 declines in proportion.

Had they eaten monkeys who in turn had eaten fruit, the bones would have the nongrass carbon isotope ratio instead.

Second, the quantity of methane necessary to explain the carbon isotope ratio, as calculated by Dickens, would be much less than that required to warm ocean and atmosphere temperatures to the extent estimated by PETM temperature proxies and calculated by physical climate models.

``... The light carbon isotope ratio found both in the ocean and on land during the PETM is the key to understanding the causes of the rapid changes.

Stable carbon isotope ratio analyses on trace methane from ice samples.

Organic Food One crucial measurement that could help determine the sources of methane on Mars and Titan is the carbon isotope ratio.

Later, additional investigation using carbon isotope ratio testing revealed a foreign, prohibited substance as the likely source for the positive test.

It is measurable in terms of oxygen and carbon isotope ratios and was compared to «environmental archive» data from other parts of the earth.

The carbon isotope ratios present in these fossil teeth revealed that the extinct kangaroo ate plants similar to those consumed by present - day kangaroos in temperate and tropical regions, rather than the plants that now grow in this region.

The team also measured the carbon isotope ratios in the turkey bones to reconstruct their diets.

In 1995 U.S. researchers found that carbon isotope ratios in elephants at Amboseli National Park in Kenya had shifted over decades, reflecting changes in the elephants» diet as they crowded into the park to escape poaching, ate up the park's trees, and switched to grass.

Qualitatively, the slow ventilation is consistent with very saline and very cold deep waters reconstructed for the last glacial maximum (Adkins et al., 2002), as well as low glacial stable carbon isotope ratios (13C / 12C) in the deep South Atlantic.

They limited data sources to locations around the world in which paleoceanographic data also exist, using seven variables: salinity; potential temperature; oxygen isotope ratios in water; carbon isotope ratios in dissolved inorganic carbon; and concentrations of phosphate, nitrate, and dissolved oxygen.

Comparison of stable carbon isotope ratios in the whole wood, cellulose and lignin of oak tree - rings Dr. Ron Towner from the Laboratory of Tree - Ring Research at the University of Arizona explains the principles behind dendrochronology and why this dating

Naidu, A.S., L.W. Cooper, B.P. Finney, R.W. Macdonald, C. Alexander, and I.P. Semiletov, 2000, Organic carbon isotope ratios (δ13C) of Arctic Amerasian continental shelf sediments, Int.

Two proxies apply the fact that biological entities in soils and seawater have carbon isotope ratios that are distinct from the atmosphere (Cerling, 1991; Freeman and Hayes, 1992; Yapp and Poths, 1992; Pagani et al., 2005).

The thread here http://www.realclimate.org/index.php?p=87 that makes that claim does not show that quantitatively (e.g. does not take into account natural variations in carbon isotope ratios).

Here's a link showing one way carbon isotope ratios can vary naturally.

The event was confirmed by the American astronomer J.A. Eddy, using carbon isotope ratios in tree rings.

Now, Hubertus Fischer of the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany, and colleagues have measured carbon isotope ratios in methane from the whole of the last glacial - interglacial transition (between 20,000 and 10,000 years before present) by analysing ice - cores.

This matches the increase, the carbon isotope ratios, the declining oxygen etc etc..

Stable carbon isotope ratios from tree rings record changes in the internal concentration of carbon dioxide and, in the northern Boreal zone, are regarded as a proxy for photosynthetic rate, and therefore summer sunshine.

Cerling3 used carbon isotope ratios in soil carbonate minerals to constrain atmospheric PCo2m portions of the Mesozoic and Cenozoic eras.

Also, the carbon isotope ratios are supposed to show that the increase is anthropogenic (from using burning «old carbon», less C14 or deduced by C13 / C12 ratios, etc..)

Regarding the link between fossil - fuel burning and the CO2 increase, there's the changing ratios carbon isotope ratios in the atmosphere and the decreasing oxygen concentration.

«The rapid decrease in carbon isotope ratios in the top panel is indicative of a large increase in atmospheric greenhouse gases CO2 and CH4 that was coincident with an approximately 5 °C global warming (centre panel).»

Not exact matches

The new Schmidt grant will allow the Scripps team to chip away at a years - long backlog of air samples to measure changes in the ratio of carbon isotopes, which provides information about manmade sources of CO2.

Animals that live in the sea have ratios of carbon and nitrogen isotopes that differ from those found in terrestrial animals, and this isotopic signature is passed on to the people who eat them.

«We took a sample every 10 metres,» says Louis Honegger, a researcher at UNIGE, «measuring the ratio between 13C (heavy carbon stable isotope) and 12C (light carbon stable isotope).

To figure that just how much the efficiency improves, Keeling and his colleagues examined the ratio of CO2 having the isotope carbon 13 versus its lighter and much more prevalent cousin, carbon 12.

Each nuclear sample has a host of distinctive attributes, including the exact mix of impurities, the ratio of different radioactive isotopes, even embedded carbon compounds that indicate the sample's age.

As the 2 - to -5-inch-long bivalves grew, their shells incorporated atoms of the elements oxygen and carbon of slightly different masses, or isotopes, in ratios that reveal the temperature of the surrounding seawater.

The researchers suspected that the ants provide D. major with nutrients in return for shelter To test this idea, they looked at the ratios of different isotopes of carbon and nitrogen in the plant's tissues.

Their carbon - isotope ratio shows that all of a sudden there was a lot more light carbon - 12 — the kind that living organisms favor, the kind in seafloor hydrates — in the water around the forams.

Isotope ratios (the ratio of carbon - 13 to carbon - 12, for example) are different in human foods than in the wild plants and animals that black bears naturally eat in Yosemite, partly due to the large amounts of meat and corn - based foods in our diets.

When they analyzed these samples, they discovered that the ratio of the carbon isotope 13C to 12C was higher during the glaciation than after the ice had melted.

She then compared the ratio of the two isotopes of carbon (carbon 13 and carbon 12) in them and found that the heavier carbon 13 predominated and matched the ratio found in carbon - containing chemicals created in space.

Using spectroscopy, stable isotope ratios (carbon, nitrogen and sulphur) were investigated in the collagen of the bones, along with the ratio of strontium to calcium in the bone mineral.

In fact food scientists can tell or could tell if allegedly pure maple syrup had been doctored with additional sweeteners by measuring the carbon - isotope ratios, but what's now an environmentally changed isotope ratio could make it harder to see if maple syrup or other foods are being altered before being sold.

As photosynthesis favours the lighter isotope, carbon 12, over the heavier carbon 13, this «light» ratio finding suggests that organic material from biological sources may have been more abundant in diamond - forming zones early in the Earth's history than we find today,» explained Suzette Timmerman, lead author on the study.

Correction: This article has been updated to clarify that it is the ratio of different carbon isotopes, not just the presence of those isotopes, that is characteristic of organic origin.

Two of these graphite flecks had a high carbon - 12 to carbon - 13 isotope ratio, a characteristic feature of organic origins as life preferentially absorbs carbon - 12 (PNAS, doi.org/8jk).

Plants take up isotopes, or variants, of carbon and nitrogen in ratios that differ from one place to the next.

• There's more to life than that: we meant to say that graphite flecks in 4.1 - billion - year - old zircon crystals had a ratio of carbon - 12 to carbon - 13 isotopes that is characteristic of organic origins (24 October, p 12).

Eggshells contain carbon, which comes from the birds» diets, and because different plants have different ratios of carbon isotopes, the shells can be used as a rough record of what birds ate.

The authors used highly sensitive instruments mounted on towers as well as soil chambers to continuously measure the ratio of two isotopes of carbon, which differ by their atomic mass.

Because photosynthesis, but not respiration, prefers the lighter carbon isotope, the researchers could detect the separate carbon flows from each of the two processes by measuring the ratio of the two carbon isotopes.

By measuring the ratio of carbon isotopes in the samples the team collected, they were able to tell how much carbon was from fossil fuel combustion.