Showing papers by "Grant M. Raisbeck published in 1993"
TL;DR: The ice-core record of local temperature, dust accumulation and air composition at Vostok station, Antarctica, now extends back to the penultimate glacial period (∼140-200 kyr ago) and the end of the preceding interglacial as discussed by the authors.
Abstract: The ice-core record of local temperature, dust accumulation and air composition at Vostok station, Antarctica, now extends back to the penultimate glacial period (∼140–200 kyr ago) and the end of the preceding interglacial. This yields a new glaciological timescale for the whole record, which is consistent with ocean records. Temperatures at Vostok appear to have been more uniformly cold in the penultimate glacial period than in the most recent one. Concentrations of CO2 and CH4 correlate well with temperature throughout the record.
555 citations
TL;DR: In situ produced cosmogenic nuclides provide a new technique for constraining exposure ages of glacial deposits as mentioned in this paper, and the exposure ages appear consistent with the few previous age estimates, particularly with an isotope stage 5 age for Taylor II.
136 citations
Journal Article•
TL;DR: The data show that under physiological conditions, namely at normal levels of dietary intake, intestinal Al absorption is approximately 0.04%, and is not significantly enhanced by the presence of citrate, while the amount of Al retained by bone is comparable to that excreted in urine during 48 h.
Abstract: Using the technique of Accelerator Mass Spectrometry (AMS), 26Al has been measured in plasma, liver, urine and bone of normal rats at 8, 24 and 48 hours after ingestion of trace amounts of Al (3.8 ng of 26Al and 63 ng of stable 27Al), both in citrate-free and citrate-containing solutions. Our data show that under physiological conditions, namely at normal levels of dietary intake, intestinal Al absorption is approximately 0.04%, and is not significantly enhanced by the presence of citrate. Interestingly, the amount of Al retained by bone (0.02%) is comparable to that excreted in urine during 48 h (0.02%). Our estimate of gastrointestinal absorption is more than two orders of magnitude smaller than that estimated by Day et al. [1991], also using 26Al, for a single human subject.
40 citations