Radionuclide Fluxes in Glaciers and Seasonal Snowpack
Radon concentrations and fluxes were measured for two different seasonal snowpacks, one on Bald Mtn. in Dedham and the other on Baldpate Mtn. in Newry, Maine during the winters of 2003 and 2004. An in-pack chilled mirror hygrometer and temperature logging system was developed to monitor snowpack tem...
| Main Author: | |
|---|---|
| Format: | Text |
| Language: | unknown |
| Published: |
DigitalCommons@UMaine
2004
|
| Subjects: | |
| Online Access: | https://digitalcommons.library.umaine.edu/etd/1228 https://digitalcommons.library.umaine.edu/context/etd/article/2246/viewcontent/BretonDJ2004.pdf |
| Summary: | Radon concentrations and fluxes were measured for two different seasonal snowpacks, one on Bald Mtn. in Dedham and the other on Baldpate Mtn. in Newry, Maine during the winters of 2003 and 2004. An in-pack chilled mirror hygrometer and temperature logging system was developed to monitor snowpack temperature and water vapor density during the radon measurements. Liquid scintillation and gamma spectroscopy analysis of snow samples showed that no particulate radon daughters were trapped in the snow, though substantial concentrations of radon gas were detected in the snowpack. Radon ground flux measurements were performed using a RAD-7 alpha spectrometer and ranged from zero to 0.64 pCi m-2 s-' for frozen and unfrozen ground conditions, respectively. In-pack radon concentration as a function of time was measured using a Honeywell A9000 radon monitor and the RAD-7 instrument and showed average radon concentrations ranging from 10 to 12 pCi L-', though maximum concentrations of over 80 pCi L-' were observed. Wind-driven and natural circulation air flows within the snowpack were shown to be the major factors controlling radon dynamics. Dilution rates of 1.25 pCi L-' h-' were correlated with windspeeds of 9 m s-', while radon concentration rates of 0.8 pCi L-' h-' were observed during periods of calm. Comparison of long term track-etch cup measurements with radon diffusion theory showed that radon within the snowpack rarely exists in steady state distribution due to the ventilation effects of wind and natural circulation air flows. Alpha and gamma spectroscopy analysis was performed for over 60 filtered ice core segments drilled from the glaciers of Mt. Nyainqentanghla and Mt. Everest to establish the depths of fallout horizons used for ice core dating. '37Cs was detected which matched worldwide fallout patterns from 1958 through the present period, including fallout from the Chernobyl accident in 1986 and regional fallout from the Semipalatinsk testing facility in eastern Kazakhstan. Maximum fallout densities of 109.9 ... |
|---|