Sentences with phrase «isotopic compositions in»

However, both the driving force and the climate reconstructions over the pre-industrial era are based on the analysis of the natural archives of climate sensitive quantities, such as the growth of trees and seashells, and the changes of chemical, biological, and isotopic compositions in lake sediments and ice core samples.

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.

This process is a function of the temperature, so in looking at the isotopic composition in the different dated layers of the ice, scientists can study the temperature of the past.

It is possible to reconstruct past precipitation changes by measuring the stable hydrogen isotopic composition in terrestrial plant waxes because rainfall is the primary source of hydrogen stored in plant material.

The net rate of CH4 emissions is generally estimated from three approaches: (1) extrapolation from direct flux measurements and observations, (2) process - based modelling (bottom - up approach) and (3) inverse modelling that relies on spatially distributed, temporally continuous observations of concentration, and in some cases isotopic composition in the atmosphere (top - down approach).

Not exact matches

The researchers brought together 90 fossils discovered in South Africa, Lesotho, Morocco and China, 63 of which were therapsids belonging to 22 different species, in order to study their oxygen isotopic composition.

Dust found in the ice gives a record of what was in the air thousands of years ago, whether from volcanic eruptions or human activity, and the isotopic composition of the hydrogen and oxygen molecules in the snow give a record of the temperature of the earth at the time.

In 2001, however, a team of scientists reported that the isotopic compositions of a variety of elements in terrestrial and lunar rocks are nearly identicaIn 2001, however, a team of scientists reported that the isotopic compositions of a variety of elements in terrestrial and lunar rocks are nearly identicain terrestrial and lunar rocks are nearly identical.

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 more accurate measurements of oxygen isotopes published in 2016 only confirmed that the isotopic compositions are not distinguishable.

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.

This is a particularly useful region because the oxygen isotopic composition of the seawater is largely determined by the flow of water through the Strait of Gibraltar, which in turn is sensitive to changes in global sea level — in a way like the pinching of a hosepipe.

By contrast, in transpiration, plants simply suck water out of the soil and push it into the air without changing its isotopic composition.

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.

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.

The results, published online today in Science, reveal that the inclusions have a much lighter isotopic signature than does the ocean, suggesting that the composition of seawater has indeed evolved over time.

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.

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.

The researchers analysed quartz crystals from Toba, and found a distinct shift in the isotopic composition towards the outer rim of the crystals.

To better understand the likelihood of such a scenario in the Earth - Moon system's origin, Richard C. Greenwood and colleagues analyzed the oxygen isotopic compositions of a large set of lunar and terrestrial samples.

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.

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).

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

«During photosynthesis plants bind atmospheric carbon, whose isotopic composition is preserved in resins over millions of years, and from this, we can infer atmospheric oxygen concentrations,» explains Ralf Tappert.

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.

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)

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.

The UniChem connectivity search function allows users to find not only exact matches of their chemical structure across 60 million related molecules from 21 data sources worldwide, but also identifies «equivalent» structures that have the same atom connectivity while differing in stereochemistry or isotopic composition, or which exist in a different salt form.

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

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

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.

CO2 produced from burning fossil fuels or burning forests has quite a different isotopic composition from CO2 in the atmosphere.

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.

Next, the methane in this air is combusted to produce carbon dioxide, which is analysed for its carbon isotopic composition — or carbon - 13 to carbon - 12 ratio.

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

[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.

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).

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.»

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

We determined the chemical and isotopic compositions of the liquid CO2 found on Yonaguni IV knoll hydrothermal site, as well as those in hydrothermal fluid venting from the surrounding chimneys.

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.

«Measurement of atmospheric mixing ratios, decline of O2 mixing ratios, pCO2 in the ocean, and the isotopic carbon composition and other stuff tells us about the source of CO2 increases.

Consider the facts: the climate system is indicated to have left the natural cycle path; multiple lines of evidence and studies from different fields all point to the human fingerprint on current climate change; the convergence of these evidence lines include ice mass loss, pattern changes, ocean acidification, plant and species migration, isotopic signature of CO2, changes in atmospheric composition, and many others.

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.

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.

(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.

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.

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,...).

... 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.

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).