Sentences with word «isotopic»

On the basis of anomalous isotopic compositions of oxygen and magnesium, 14 oxide grains from two primitive meteorites (Bishunpur and Semarkona) have been identified as circumstellar condensates.

Atmospheric scientists call this shift the Suess effect, and the change in isotopic ratios of carbon due to fossil - fuel use is easy to see over the last century.

Evidence from isotopic data on Early Holocene bison and other large herbivores in northern Europe.

LeGrande, A.N., and G.A. Schmidt, 2006: Global gridded data set of the oxygen isotopic composition in seawater.

The correlation of summer precipitation in the Southwestern U.S.A. with isotopic records of solar activity during the medieval warm period.

This age was based on isotopic dating of 5 meteorites and a representative sample of modern Earth lead from a Pacific deep - sea sediment, all of which plot along a linear isochron on a graph of 207Pb / 204Pb versus 206Pb / 204Pb (Patterson, 1956).

Aircraft measurements confirm that methane emissions from northern European wetlands exhibit a uniform regional carbon isotopic signature, despite considerable ground - level heterogeneity.

«In addition, we are currently developing a method that also allows for high - precision hydrogen isotopic measurements on methane in ice cores, which will further improve our emission flux constraints,» revealed Fischer.

Thanks to Stefanie Boesel and Annette Weiske for assistance with isotopic analysis at the Max Planck Institute for Evolutionary Anthropology, Leipzig.

Instead of CO2 concentrations being about 15 p.p.m.v. lower, the CO2 / temperature shift can also be explained by isotopic composition overestimating temperature by about 1 °C.

«ENSO and IOD bring... shift [s] in the seasonal rainfall distribution,» Ghosh said, «which can be easily captured using isotopic fingerprinting of carbonates in growth bands of Achatina fulica snails.»

From what I can tell you really can not use isotopic data to determine this accurately at all.

In the early 1990s, geologists examined a rock section in China that bore the critical fossils of the P - T boundary interleaved with ashy volcanic layers suitable for isotopic dating.

Chemist Matt Hartings of American University in Washington, D.C., says that most chemists who don't think regularly about isotopic abundances or teach general chemistry at college would probably consider the atomic weights as constants.

It took on the order of 100 kyr for the oxygen and carbon isotopic signals in the ocean to return to their original steady - state values after the PETM.

«Most of Earth's water was likely present before the moon - forming giant impact: Oxygen isotopic evidence for accretion of Earth's water before a high - energy moon - forming giant impact.»

Rather than excavate, the team intends to use the Swedish Research Council's largest ever archaeo logical grant to reexamine spectacular existing finds using modern methods such as isotopic analysis.

Its main natural sources are tropical and boreal wetlands, ruminant animals and biomass burning, all of which have different isotopic signatures for carbon and hydrogen.

The stable isotopic composition of the carbon in carbon dioxide over the last 24,000 years illuminates past carbon cycle behavior.

The meteorites are dated by analysing isotopic changes in their matter due to cosmic ray exposure (CRE dating [Eugster, 2003]-RRB-.

Nonetheless, the findings are valuable because isotopic nitrous oxide data from the Arctic and sub-Arctic are extremely rare.

The measurements show that 4 - Vesta contains the same hydrogen isotopic composition as carbonaceous chondrites, which is also that of Earth.

«To cause this type of global isotopic shift, you'd have to take all terrestrial plants and burn them into carbon dioxide,» Kessler says, which seems unlikely.

This time, the dominant carbon isotopic values in the new inputs were about -60 ‰, pointing to a microbially driven source rather than fossil fuel inputs.

How It Works Carbon 3 isotopic forms Carbon - 12, Carbon - 13, Carbon - 14 disabled provides everything date friendship.

When he analyzed isotopic signatures of carbon and nitrogen found in the tissues of some of the small cave crustaceans, he discovered that the animals had a food source fueled by something other than the sun.

This enabled a direct measurement of the 12C / 13C isotopic ratio for the Orion hot core of 14 + / - 1 and an estimated maximum value of 21.

Yet another way is to measure oxygen isotopic variations, which are a function of primarily the temperature but also of where the moisture is coming from.

The study focused on unique isotopic signatures of methane from different sources.

By using isotopic tracers called stable isotopes, researchers showed that seabirds feeding in areas rich in sulfate (a chemical that is an important food for sulfate - reducing bacteria that help break down organic matter) had high levels of mercury.

The same isotopic records show that the Sun seems to have been building up over the last several hundred years to a state of enhanced activity that is the opposite of the suppressed levels of the 17th century Maunder Minimum.

His research is primarily concerned with using novel isotopic techniques to gain insights into how and why the Earth's climate has changed over geological time.

And Hallis suspects that the deepest, most primitive material in the mantle should have an even lighter isotopic composition than the inclusions her team measured.

Two speakers from the Geological Society conference «Past Carbon Isotopic Events and Future Ecologies» came to the SMC to discuss climate clues from the geological record and what they can tell us about present and future changes to the climate.

«Because we extracted high - resolution stable isotopic profiles from these shells, we were able to match them to active spells and breaks in the monsoon,» Thirumalai said.

We did not find isotopic evidence that a global ice sheet impacted overall marine productivity.

The record is compiled from more than 1,200 points of data in the form of fossilized plants and shells, and the carbon isotopic concentration of soil and oceans.

How do water isotopic proxy records capture changes in tropical and extratropical modes of climate variability?

But carbonaceous chondrites are known to have formed later than other meteorites — so it was possible that their peculiar isotopic chemistry reflected changes over time in the disk, rather than a distinct place of origin.