Sentences with phrase «isotopic concentration»

Their analysis showed a 3 - to 4 - ppm (parts per million) difference between the oxygen isotopic concentrations of the lunar rocks and the terrestrial basalts, but no significant difference between the lunar samples and terrestrial olivine, a common mineral in Earth's subsurface.

That the isotopic concentrations remain fixed?

Not exact matches

Low background atmospheric concentrations, together with well - known and often distinct isotopic characteristics (variants of lead with different atomic weights) of industrial sources make lead an ideal tracer of industrial pollution.

They found a sharp dip in methane concentrations after 1992; that dip corresponded with a decrease in a source with a carbon isotopic value of about -40 ‰.

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.

Each sample is brought to the surface, analyzed for its nitrate concentration and labeled with an isotopic signature.

The team presents new isotopic data showing that a burst of oxygen production by photosynthetic cyanobacteria temporarily increased oxygen concentrations in Earth's atmosphere.

«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.

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.

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 dataset contains nitrate concentration and isotopic composition (d15N, d18O, D17O) measurements on the WAIS Divide WDC06A ice core.

Instead of CO2 concentrations being about 15 p.p.m.v. lower, the CO2 / temperature shift can also be explained by isotopic composition overestimating temperature by about 1 °C.

His point three is not about whether the current concentrations of CO2 are human - produced (as you say, the isotopic ratios seem conclusive), but how much of the measured warming is due to CO2 concentrations.

If he wanted to apply his scientific credentials to a scientific matter in climate, he might turn to what the isotopic ratio of carbon (13C / 12C) needs to be in atmospheric CO2 concentration to constitute a fingerprint of human origin.

It's not just the isotopic signature, or the decline of atmospheric oxygen concentrations — which is the signature of the source of the CO2 being combustion... It's also this simple mass balance argument.

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).

High methane concentrations in well - ice - bonded sediments and gas releases suggest that pore - space hydrate may be found at depths as shallow as 119 m. Geochemical and isotopic determinations suggest that the methane hydrate observed in the core hole is biogenic (microbial) in origin.

«The Concentration and Isotopic Abundances of Carbon Dioxide in the Atmosphere.»