Sentences with phrase «at oxygen isotope»

When the jet stream got loopy In order to track the jet stream's behavior thousands of years ago, Bowen and his fellow researchers looked at oxygen isotope ratios from lake cores and cave formations in the eastern and western United States.

To find out, he looked at the oxygen isotopes in 32 fossil teeth.

Not exact matches

The rover's Sample Analysis at Mars (SAM) instrument that analyzes the soil and atmosphere around the rover using a mass spectrometer, a gas chromatograph and a tunable laser spectrometer to detect oxygen and carbon isotopes in carbon dioxide and methane samples to see if they are biochemical in origin.

The composition of these ice cores, especially the presence of hydrogen and oxygen isotopes, provides a picture of the climate at the time.

The ratio of oxygen isotopes in seawater depends on the water temperature; the value of this ratio at any point in evolutionary time is «frozen» into the chemical composition of certain marine fossils.

They then compared the oxygen isotope ratio in Yonderup dripwater with that predicted by a model (which simulated the dripwater δ18O based on measurements of rainwater δ18O), as well as that measured at a different cave in the region.

According to Robert Clayton, a professor emeritus at the University of Chicago in Illinois who pioneered the use of oxygen isotopes in cosmochemistry, the authors may have done little more than find a more precise method of measurement.

Lydia Hallis, an isotope researcher at Glasgow University, UK, notes that oxygen - 17 can vary among Moon rocks, and so three Apollo samples may not necessarily represent the Moon as a whole.

To figure out those answers, Rybczynski turned to Ash Ballantyne, another grad student at Duke, who was using oxygen isotopes from tree cores to determine historical temperatures.

By looking at the chemistry of rocks deposited during that time period, specifically coupled carbon and sulfur isotope data, a research team led by University of California, Riverside biogeochemists reports that oxygen - free and hydrogen sulfide - rich waters extended across roughly five percent of the global ocean during this major climatic perturbation — far more than the modern ocean's 0.1 percent but much less than previous estimates for this event.

Nevertheless, some scientists claim that ratios of oxygen isotopes in marine fossils from the east coast of the US indicate that the Antarctic ice sheet melted at least partially during the Pliocene.

One way you can tell is by looking at different oxygen isotopes in the fossilized skeletons of ocean microorganisms.

Environmental scientist Suzanna Richter and plant physiological ecologist Brent Helliker, both at the University of Pennsylvania, measured the ratio of two isotopes of oxygen — rarer oxygen - 18 and more common oxygen - 16 — in samples of wood.

Back at their Georgia Tech lab, they analyzed the stalagmites for the ratio of oxygen isotopes contained in samples of calcium carbonate, the material from which the stalagmites were formed.

«Oxygen isotopes in ancient bones and teeth reflect the water animals are living in or drinking,» said Kim, a former postdoctoral researcher at the University of Wyoming.

«When ozone reacts with carbon dioxide in the atmosphere, it transfers its isotopic weirdness to the new molecule,» said Shaheen, who investigated this process of oxygen isotope exchange as a graduate student at the University of Heidelberg in Germany.

The balance of oxygen isotopes within ozone are strikingly weird with enrichment of heavy isotopes through a physical chemical phenomenon first described by co-author Mark Thiemens, a professor of chemistry at UC San Diego, and colleagues 25 years ago.

First, I do think that there is a lot of work to be done in the interpretation of oxygen / hydrogen isotope values obtained at a site, and there's still plenty of disagreement in the paleo - community on how to best connect the isotopic signal in a record with climate.

First, I do think that there is a lot of work to be done in the interpretation of oxygen / hydrogen isotope values obtained at a site, and there's still plenty of disagreement in the paleo - community on how to best connect the isotopic signal in a record with climate.

Measurements of coral Sr / Ca and oxygen 18 isotopes at 5 - year sampling increments for five of the fossil corals (310 annual growth increments) have yielded a semi-continuous record spanning the 8.2 ka event.

Oxygen - isotope (λ 18O) evidence of Holocene hydrological changes at Signy Island, maritime Antarctica Noon, P.E., Leng, M.J. and Jones, V.J. 2003; The Holocene 13: 251 - 263

Mike Flynn November 19, 2015 at 9:33 pm «Measurements of oxygen isotopes from the GISP2 ice core suggest the ending of the Younger Dryas took place over just 40 — 50 years in three discrete steps, each lasting five years.

Calcareous nannofossils from approximately the past 7000 yr of the Holocene and from oxygen isotope stage 5 are present at 39 analyzed sites in the central Arctic Ocean.

Matthiessen, J. & Knies, J. Dinoflagellate cyst evidence for warm interglacial conditions at the northern Barents Sea margin during marine oxygen isotope stage 5.

At high temperatures the isotopes of carbon and oxygen are randomly distributed across the lattice.

The analysis below used the ratio of oxygen isotopes in the stalagmites to estimate the water temperature at the time they were formed.

Shell material was analyzed for stable isotopes of carbon (δ13C) and oxygen (δ18O) in the Earth Systems History Laboratory at Brown University (Providence, RI).

They measure the hydrogen and oxygen isotopes to infer air temperatures at the time the snow fell, and the dust particles give a nice indication of the dusty periods (much of the dust was kicked up far away, in the Gobi Desert, rather than from sources closer to Greenland).

Uses a time series of hydrographic and stable oxygen isotope (δ18O) measurements collected at a near - coastal site in Marguerite Bay to quantify the prevalence of meteoric freshwater (glacial melt plus precipitation) separately from sea ice melt

Who knows, maybe some people read the Wegman Report, look at Table 1, think it actually came as is from Bradley, and confidently write of 1) «ions and isotopes of oxygen and hydrogen», 2) «speleothrems» and 3) «phonology».

As shown in the graph below, cosmic - ray intensity (as measured by the radioactive carbon isotope C - 14) and terrestrial climate (as measured by the oxygen isotope O - 18) correlate in amazing detail over an interval of at least 3000 years (see graph below; the bottom graph is the central section, blown up to reveal detail)

The way plankton absorbed oxygen at a given temperature mattered less than what proportion of each isotope was available in the sea water as ice sheets came and went.

Using oxygen isotopes, the scientists reconstructed the moisture development at these locations, whereby the corresponding delta - 18O - values reflected monsoon intensity.

Although a previous estimate based on this approach yielded a MAT of approximately — 5 °C, additional information from oxygen isotopes in mosses at the site allowed us to calculate isotopic enrichment in the cellulose of fossil trees, thereby reducing assumptions and increasing the precision of our MAT estimates (see the Data Repository).

Carbon and oxygen isotope ratios both shift at the same boundary; the former shows disruption of the carbon cycle, while the latter shows an abrupt warming of about 6 degrees.

Looking at the isotopic record from the PETM, scientists see both carbon and oxygen isotope ratios spiking in exactly the way we expect to see in the Anthropocene record.