Sentences with phrase «12c isotope ratio»

This leads to a lowering of the atmospheric 13C / 12C isotope ratio, which takes years to centuries to work its way through the carbon cycle (Keeling et al., 1980; Tans et al., 1993; Ciais et al., 1995a, b).

Not exact matches

«We took a sample every 10 metres,» says Louis Honegger, a researcher at UNIGE, «measuring the ratio between 13C (heavy carbon stable isotope) and 12C (light carbon stable isotope).

When they analyzed these samples, they discovered that the ratio of the carbon isotope 13C to 12C was higher during the glaciation than after the ice had melted.

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.

Qualitatively, the slow ventilation is consistent with very saline and very cold deep waters reconstructed for the last glacial maximum (Adkins et al., 2002), as well as low glacial stable carbon isotope ratios (13C / 12C) in the deep South Atlantic.

Minerals and isotopes in these zircons show that water and granite were also present.38 The extremely low ratio of 13C to 12C suggests that all these carbon isotopes were not originally present.

This is because plants have a preference for the lighter isotopes (12C vs. 13C); thus they have lower 13C / 12C ratios.

The change to the 12C: 13C isotope ratio of atmospheric CO2 is in the direction expected if the recent increase in atmospheric CO2 concentration were caused by the anthropogenic emission of CO2.

The fact in point (5) indicates that most of the change to the 12C: 13C isotope ratio of atmospheric CO2 and most of the recent increase in atmospheric CO2 concentration was caused by some unknown, natural (i.e. non-anthropogenic) effect.

Therefore, it is possible that all of the rise in atmospheric CO2 concentration and all of the change to the 13C: 12C atmospheric isotope change were caused by the anthropogenic emission that induced the unknown, natural (i.e. non-anthropogenic) effect that caused the observed change to the 12C: 13C isotope ratio of atmospheric CO2.

Simply, it is possible that none of the rise in atmospheric CO2 concentration and none of the change to the 13C: 12C atmospheric isotope change were caused by anthropogenic emission but were due to the unknown, natural (i.e. non-anthropogenic) effect that caused most of the change to the 12C: 13C isotope ratio of atmospheric CO2.

Richard S Courtney (00:08:00): The change to the 12C: 13C isotope ratio of atmospheric CO2 is in the direction expected if the recent increase in atmospheric CO2 concentration were caused by the anthropogenic emission of CO2.

It is possible that both the effects noted in points 7 and 8 contributed to the change to the 12C: 13C isotope ratio of atmospheric CO2 and to the recent increase in atmospheric CO2 concentration.

The net result is that the 14C intake by the oceans is much faster for 14C (despite the slower intake speed) than for 12C or 13C, as the total 14C in the atmosphere will go down until about the same ratio as for the other isotopes, that is 1:1, then a new equilibrium for 14C is reached.

The ratio of these carbon isotopes generally changes as a function of biological activity, since carbon in living matter tends to be preferentially made up of 12C as opposed to 13C.

The size of the carbon injection is estimated from changes in the stable carbon isotope ratio 13C / 12C in sediments and from ocean acidification implied by changes in the ocean depth below which carbonate dissolution occurred.