Sentences with phrase «isotopic compositions»

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.

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.

Stable isotopic compositions — variants of particular chemical elements — of such remains, recovered from soil and lake sediment, may help us better understand climate change over a long span of time.

«They tell us the story of the chemical and isotopic compositions of the atmospheric carbon dioxide.»

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.

The combination of geological and taphonomic evidence, the assemblage of small - mammal and avian fossils, and the taxonomic and isotopic compositions of remains from larger mammals indicate that Aramis was predominantly a woodland habitat during Ar.

Working with Miller and doctoral student Abraham Padilla at Vanderbilt, Joe Wooden at Stanford University, Axel Schmitt and Rita Economos from UCLA, Ilya Bindeman at the University of Oregon and Brennan Jordan at the University of South Dakota, Carley analyzed about 1,000 zircon crystals for their age and elemental and isotopic compositions.

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.

Therefore, animals that feed on tropical open - environment grasses (or on grass - eating animals) have different isotopic compositions from those feeding on browse, seeds, or fruit from shrubs or trees.

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

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.

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

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.

The isotopic composition studies had created an «isotopic crisis» for the hypothesis.

Paleontologists will focus especially on the chemical and isotopic composition of Lyuba's baby tusks.

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.

Unlike previous methods, the clumped isotope paleothermometer technique does not rely on assumptions about the isotopic composition of seawater.

Finally, the carbon isotopic composition of Ar.

To create their new temperature record, which spans 3.5 million years at the end of the Cretaceous and the start of the Paleogene Period, the researchers analyzed the isotopic composition of 29 remarkably well - preserved shells of clam - like bivalves collected on Antarctica's Seymour Island.

The dental morphology, wear, and enamel isotopic composition of the Aramis kudu species are all consistent with such placement.

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.

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 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.

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.

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

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).

Frozen water has an isotopic composition that gives clues about past temperatures, Barbante says.

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.

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

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

When I analyzed their isotopic composition, the numbers seemed weird at first because they indicated an essentially freshwater environment.»

«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.

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.

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.

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 oxygen isotopic composition and temperature of Southern Ocean bottom waters during the last glacial maximum.

Sea ice melt (SIM) also has relatively low salinity (S < 5), but its oxygen isotopic composition is similar to that of seawater, from which it is formed (δ18O ≅ 0 to — 6 ‰).

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.