عنوان
پدید آورنده
موضوع
رده
کتابخانه
محل استقرار
TLpq2386253686
انگلیسی
A Study of in situ Cosmogenic 14C and Paleoatmospheric 14CH4 from Accumulating Ice at Summit, Greenland
[Thesis]
Hmiel, Benjamin
Petrenko, Vasilii V
University of Rochester
2020
294
Ph.D.
University of Rochester
2020
This body of work expands the understanding of in situ cosmogenic 14C production and retention in the upper layer of accumulating ice sheets and presents new measurements of 14CH4 that improve our understanding of the fossil component of the CH4 budget. Samples were collected at Summit, Greenland from the firn air open porosity, the firn matrix and from ice below the depth of bubble closure. Large volume (~100L STP) air samples requiring ~1000kg ice/sample were collected for measurements of 14CH4 and 14CO via on site melt-extraction. Air for 14CO2 analysis was extracted via sublimation of ~1 kg ice samples using a new technique developed as part of this thesis. A model of firn gas transport and in situ cosmogenic 14C production was used to interpret the 14CO results, finding that only ~0.5% of in situ cosmogenic 14C produced in the firn is retained by the accumulating ice crystal lattice. Further, production rates of 14C in ice from deeply-penetrating muons are found to be overestimated by a factor of 3-4. The in situ cosmogenic 14CO2 component in accumulating ice is demonstrated be smaller in magnitude than the combined uncertainty from measurement and model characterization of paleoatmospheric 14CO2 bubble trapping.
Carbon-14
Cosmogenic isotopes
Firn air
Fossil methane
Ice cores
Methane
Hmiel, Benjamin
Petrenko, Vasilii V
مطالعه متن کتاب p
[Thesis]
276903
a
Y
