Sentences with phrase «isotopic composition of»

1996 Daniel P. Schrag, et al., «Pore Fluid Constraints on the Temperature and Oxygen Isotopic Composition of the Glacial Ocean.»

With regard to the former, I seem to recall reading somewhere that the isotopic composition of the carbon in fossil fuels (and limestone used to make cement) differs from the average composition in current sinks and that can be used to look at where the CO2 is coming from.

The best evidence for the collision theory is the identical isotopic composition of Earth and Moon.

I thought one could get other evidence on these matters by looking at the isotopic composition of the CO2 and also by looking at the correlation between CO2 changes and change in O2.

Ehlers reported at last December's American Geophysical Union meeting that in a climate model, the rise of the Andes themselves alters climate — for example, by changing the source and therefore the isotopic composition of precipitation.

Ice core temperature reconstructions such as Dome C are based on the isotopic composition of the ice.

These findings are based on the isotopic composition of plant leaf waxes in marine sediments.

The methane produced by the burning of biomass, like wood, contains more of the heavier isotope (carbon - 13) relative to the lighter isotope (carbon - 12), than methane which is produced in wetlands,» explains Professor Thomas Blunier, Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen.The researchers have measured the isotopic composition of the methane in ice cores that are drilled up from the Greenland ice cap at the NEEM project in northwestern Greenland.

The hydrogen and carbon isotopic composition of methane from natural gases of various origins

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

Changes in proxy records, either physical (such as the isotopic composition of various elements in ice) or biological (such as the width of a tree ring or the chemical composition of a growth band in coral), do not respond precisely or solely to changes in any specific climate parameter (such as mean temperature or total rainfall), or to the changes in that parameter as measured over a specific «season» (such as June to August or January to December).

... Onset of a major reorganization of the carbon cycle immediately precedes the initiation of extinction and is punctuated by a sharp (3 ‰), short - lived negative spike in the isotopic composition of carbonate carbon.

Oakwood, the tragedy is not what's happening in science — things there are just as they should be: the field continues to develop new data and refined analyses, general conclusions have been reached that a very large majority support, based on well - established principles (properties of CO2, thermodynamics, effects of warmer air on evaporation...) and data (measures of CO2 levels, shifts in isotopic composition of atmospheric CO2, temperature records — instrumental and proxy,...).

It's possible to back out what the isotopic composition of the carbon source was leading to the atmospheric increase through the deglaciation.

Until now, this view was based mainly on reanalysis of ca estimates from the isotopic composition of carbonates in paleosols, the only extensive proxy record to span most of the Phanerozoic.

(Partisan) description: The authors studied the isotopic composition of carbon (δ13C) and hydrogen (δD) in organic matter found in two sediment cores retrieved from Lake Korttajarvi.

The Medieval Warm Period in AD 980-1250 is the most distinctive climate period in the whole sediment sequence identified by changes in sediment colour, X-ray density, varve thickness, LOI, as well as the isotopic composition of hydrogen in kerogen.

Because of these confounding factors, palaeoreconstructions based on the isotopic composition of organic carbon (δ13C) will almost certainly have to be based on the isotopic signatures of organic compounds that can be associated with a single species, or group of physiologically similar species

Charles, C.D., D. Rind, R. Healy, and R. Webb, 2001: Tropical cooling and the isotopic composition of precipitation in general circulation model simulations of the ice age climate.

Within these archives, scientists can measure the isotopic ratios of oxygen and hydrogen to deduce changes over time in the isotopic composition of environmental waters, such as precipitation, seawater, and groundwater.

The classic paleothermometer is the stable - isotopic composition of water in the ice core (10).

Empirically and theoretically, isotopic composition of precipitation and site temperature are strongly correlated in time and space (10, 11); colder places and colder times have isotopically lighter precipitation.»

Changes in proxy records, either physical (such as the isotopic composition of various elements in ice) or biological (such as the width of a tree ring or the chemical composition of a growth band in coral), do not respond precisely or solely to changes in any specific climate parameter (such as mean temperature or total rainfall), or to the changes in that parameter as measured over a specific «season» (such as June - August or January - December).

This is temperature dependent, is independent of the isotopic composition of the precipitating water (seawater, freshwater etc.) and thus independent of storm tracks, the position of the ITCZ, monsoon strength etc..

Next paper: Bemis, B. E., H. J. Spero, J. Bijma, and D. W. Lea (1998), Reevaluation of the oxygen isotopic composition of planktonic foraminifera: Experimental results and revised paleotemperature equations, Paleoceanography, 13 (2), 150 — 160.

[5] Linsley et al. (2006) reconstructed sea - surface temperature and sea surface salinity in the southwest Pacific starting circa 1600CE by measuring the oxygen isotopic composition of four Porites coral records from Rarotonga and two from Fiji.

«Sediment cores in Arctic lakes show that there have been significant 20th - century declines in the nitrogen isotopic composition of organic nitrogen,» Steig said.

«Pore Fluid Constraints on the Temperature and Oxygen Isotopic Composition of the Glacial Ocean.»

To carry out the study, the researchers developed a new sample extraction and mass spectrometry method that allowed them to precisely measure the carbon isotopic composition of methane in very small ice core samples.

point out that isotopic composition of airborne methane has become lighter since 2008, indicating greater wetland / ruminant emission.

Keep in mind that the classic paper by Hayes et al (1976) showed that isotopic composition of forams in marine cores fluctuated on orbital time - scales in accordance with Milankovitch.

[Response: Your question was not at all vague, I just don't remember hearing much about the isotopic composition of methane in the atmosphere.

One of these differences is in the isotopic composition of the plant materials.

Assessing the anthropogenic influence on atmospheric oxidants using the oxygen isotopic composition of sulfate and nitrate from the WAIS - Divide ice core.

Ice core measurements of the isotopic composition of nitrate: new results and interpretation.

They collect corals of sediments, they take samples of the various calcareous organisms in them and do measurements for instance of the isotopic composition of the shells.

http://adsabs.harvard.edu/abs/1999GBioC..13..445Q «The isotopic composition of atmospheric methane» Quay et al 1999 (This study suggests that ~ 18 % of atmospheric methane in 1999 is from fossil fuel sources)

So planetary scientists must investigate thoroughly the sources, sinks and isotopic composition of this gas, along with other organic molecules and trace constituents in both gaseous and solid samples.

The information about oxygen concentration comes from the isotopic composition of carbon or rather from the ratio between the stable carbon isotopes 12C and 13C.

One of the key new capabilities of the Goddard Astrobiology Analytical Laboratory was instrumentation with high enough sensitivity to determine the isotopic composition of an amino acid molecule, according to Elsila.

As part of the study, Cherney measured the isotopic composition of tail hairs from a mother - calf pair of African elephants at the Toledo Zoo.

The hydrogen isotopic composition of lunar water also varies from region to region, much more dramatically than in Earth.

This temperature curve, established using an isotopic thermometer, is widely applied for reconstruction of past environmental conditions and in this case, is based on the isotopic composition of the oxygen contained in the fossilised remains of fossil marine fish (bone, teeth, scales).

Co-author, Christophe Lécuyer explained: «According to this method, it is possible to calculate the temperature of the water in which these fish lived by applying an equation linking the isotopic composition of the fossilised remains to the temperature of mineralisation of their skeleton.

But we found the isotopic composition of the deep water was similar to that of modern rainfall, which means the system in the Sydney Basin has been relatively stable for thousands of years.

By comparing the results to the isotopic composition of the trapped gas, the researchers revealed how dense the Martian atmosphere was at the time when the gas became trapped in the meteorite.

The Temagami Banded Iron Formation, which was formed 2.7 billion years ago during the Neoarchean period, can be used as an archive because the isotopic composition of many chemical elements such as Hafnium and Neodymium directly mirrors the composition of Neoarchean seawater.

The team believes that the relationship between temperature and the isotopic composition of water vapour changes as climate warms.

However, researchers don't really know the true hydrogen isotopic composition of Earth's water, says Lydia Hallis, a planetary scientist at the University of Glasgow in the United Kingdom and lead author of the new study.

They also used satellite precipitation data to «backsolve» the brine's origins using sodium concentrations, oxygen and hydrogen isotopes, as the isotopic composition of water reflects the condensation temperature and precipitation rate over time.