Sentences with phrase «as isotopic»

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).

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.

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).

We assumed only that due to the biological and physical effects the ratio fabsorbed (t) / (total CO2 content of then air) is more or less constant, hence a simple response pulse response exp -LRB-- t / lifetime) is applied to the anthropic time series of coal, gas, oil and cement which have different delta13C As the isotopic signature of (CO2 natural)(t) is slowly decreasing because plants living days or centuries ago are now rotting and degassing and as molecules entered in the ocean decades ago are now in the upwellings after a slow migration along the equal density surface from the high latitudes where those surface are surfacing at depth zero, there are common sense constraints or bounds on the possible evolution of the delta13C of the natural out - gassed CO2 molecules.

You seem to have a lot of enjoyment in getting to understand the fine detail such as isotopic examinations and the like.

Today, researchers are able to extract vast amounts of information using current methods — such as precise digital measurement and categorization of the bones, examination of the conditions in which the bone fragments were preserved, as well as isotopic and genetic analysis.

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.

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.

Not exact matches

Lactation counseling increases breast - feeding duration but not breast milk intake as measured by isotopic methods

The ratio of strontium to calcium in a given layer of coral reef — as well as the amount of a heavier isotope of oxygen in the carbonate itself — reflect the temperature in this historical record, but the isotopic information also reveals rainfall.

«As an industrial civilization, we're driving changes in the isotopic abundances because we're burning carbon,» Frank says.

«Essentially, we found that these elements have unique isotopic fingerprints, meaning we can use them as diagnostic tools to quantify mountaintop mining's relative contribution to contamination in a watershed,» said Avner Vengosh, professor of geochemistry and water quality at Duke's Nicholas School of the Environment.

The probability that the impactor just happened to have the same isotopic signature as Earth was vanishingly small.

But planetary bodies that formed in different parts of the solar system generally have different isotopic compositions, so different that the isotopic signatures serve as «fingerprints» for planets and meteorites from the same body.

But all that we can observe now is what has been preserved as rocks, and the isotopic patterns could have been modified in the process.»

Cuffey developed a technique to combine these temperature measurements, which are smoothed as a result of heat diffusion in the ice, with isotopic measurements of old ice to come up with an estimated temperature of 11.3 degrees, plus or minus 1.8 degrees Celsius, warming since the depths of the ice age.

They plan to explore what other traces of elements are present in the inclusions, as well as make measurements of the isotopic composition of some elements, which could reveal exactly how the metal forms and how it interacts with rocks in the mantle.

As a result, methane emissions have distinct isotopic values: Methane emitted from any microbially driven source such as wetlands or agriculture have values of about -60 ‰ (signifying a relatively low ratio of carbon - 13 to carbon - 12); oil, gas, and coal emissions have an average carbon isotopic value of -37 ‰; and tree and crop burning averages about -22 As a result, methane emissions have distinct isotopic values: Methane emitted from any microbially driven source such as wetlands or agriculture have values of about -60 ‰ (signifying a relatively low ratio of carbon - 13 to carbon - 12); oil, gas, and coal emissions have an average carbon isotopic value of -37 ‰; and tree and crop burning averages about -22 as wetlands or agriculture have values of about -60 ‰ (signifying a relatively low ratio of carbon - 13 to carbon - 12); oil, gas, and coal emissions have an average carbon isotopic value of -37 ‰; and tree and crop burning averages about -22 ‰.

Yehoshua Kolodny at the Hebrew University in Jerusalem doubts whether the isotopic make - up of the T. rex skeleton is the same as it was when the animal was alive.

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

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.

However, explaining why the Earth and Moon don't then themselves have unique isotopic characteristics, as most planets in the Solar System do, has been challenging.

The authors also monitored the isotopic 13C composition of CO2, which serves as a fingerprint of emissions from coal - fired power plants and matched it to that of the local coal.

Their hydrogen isotopic composition can be used as an indicator of past precipitation intensity.

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.

But if most of Earth's water was delivered via later meteorites, this would have shown up as a greater isotopic difference than what the researchers measured — as water - bearing meteorites have unusual mixtures of oxygen isotopes.

Now, locked in limestone that was formed in shallow seawater offshore of the supercontinent Pangaea, scientists have found an isotopic signal to support a sharp drop in pH. The catastrophe holds a cautionary lesson: Due to the burning of fossil fuels, today's oceans are acidifying at an even faster rate than they were at the time of the extinctions, although it hasn't yet persisted nearly as long.

Referred to as the «lunar isotopic crisis,» this was a problem for the main theory of lunar formation, because it's highly unlikely the isotopes would be exactly the same for two random objects in the solar system.

Rainfall oxygen isotopic ratios are good indicators of the amount of rainfall occurring throughout the region, as determined by a modern - day calibration study recently published by another graduate student in Cobb's lab.

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

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.

Just as radiocarbon dating can place a substance in time, isotopic analysis can also pinpoint its location.

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.

«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 probability that the impactor just happened to have the same isotopic signature as the Earth was vanishingly small.

Despite comparatively intense bombardment by large impactors, chemical and radio - isotopic trace evidence of what appears to be biologically processed carbon in Earth's oldest surviving rocks — from western Greenland's Isua greenstone belt that are as old as 3.85 billion years — suggest that self - replicating, carbon - based microbial life became well developed during Earth's first billion years of existence.

As examples of work in this category, I would mention Judith Lean's tireless efforts on relating luminosity to sunspot number, the work of Bard and colleagues on developing isotopic solar proxies like 10Be, Shindell's work on response to solar ultraviolet variability, and the work of Foukal et al on factors governing solar irradiance variations.

Here, we report surface water dissolved inorganic carbon (DIC) and sedimentary organic carbon concentrations and their isotopic compositions in the rapidly urbanized Jiaozhou Bay in northeast China as well as carbonate parameters in effluents of three large WWTPs around the bay.

Also, the rocks astronauts brought back from the Moon have identical oxygen and titanium isotopic ratios as those on Earth.78 If large impactors came from Earth, most moonquakes should be on the near side.

Isotopic composition can therefore be used as a proxy for historical air temperatures before the period for which we have instrumental measurements.

Carbon - 14 is a weakly radioactive isotope of Carbon; also known as radiocarbon, it is an isotopic chronometer.

Radiocarbon dating (also referred to as carbon dating or carbon - 14 dating) is a method for determining the age of an object containing organic material by How It Works: Carbon has 3 isotopic forms: Carbon - 12, Carbon - 13, and Carbon - 14.

Isotopic analysis is used in a variety of fields across the sciences, such as Geology, Biology, Organic Chemistry, and Ecology.

WRT the source of the CO2, Brian has already pointed out the isotopic signature of the CO2, but over and above this, we've produced about 2x as much CO2 as has gone into the atmosphere!

[Response: Methane is the «usual suspect» for those events, such as the Paleocene Eocene thermal maximum, because it is easier to explain the carbon isotopic spikes if the source is strongly isotopically labeled.

Because carbon cycle processes such as photosynthesis fractionate the heavy isotope 13C from the lighter 12C, isotopic analysis can usually be used to «trace» sources and sinks of carbon.

More than likely, the isotopic signal (the distribution of 13C - depleted carbon that invaded the atmosphere) indicates that carbon should have been «mined» from the Southern ocean as a result of the displacement of southern winds, sea ice, and perturbations to the ocean's biological pump (e.g., Anderson et al., 2009).

The points though are that a) CO2 began to rise when we starting producing it in earnest, b) its isotopic signature demonstrates it comes predominantly from fossil fuels, and c) such an increase has not happened in at least 800,000 years as far as we can tell.

[Response: Unfortunately, you seem to have conveniently forgotten that Keigwin (and Pickart) published a paper in Science just a few years later in 1999 pointing that the appparent cooling (actually, the oxygen isotopic signal in question isn't entirely temperature, it is salinity as well, so the quantative 1 deg cooling estimate you cite is not actually reliable) in the Sargasso Sea is diametrically opposed by a substantial warming at the same time in the Laurentian Fan region of the North Atlantic off the coast of Newfoundland.

Funny how difficult it is for him and his fellow denialati to look at 1) where that carbon came from 2) its isotopic composition 3) the fact that it takes a while for permafrost to melt and oceans to become a source rather than a sink 4) the fact that humans are producing about 2x as much carbon as is going into the atmosphere 5) the remaining CO2 is acidifying the oceans