The McMurdo Dry Valleys of Antarctica contain perennially
Hoare. Results confirm previous reports that 0, concentrations in the upper water column exceed atmospheric equilibrium and that N, and Ar are supersaturated throughout the water column. The mean supersaturation of N, was found to be 2.0 (*0.37) and Ar was 3.8 (rtl. 1). The ratios of N,/Ar (20.3 +3....
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| Format: | Text |
| Language: | English |
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1997
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.574.140 http://daleandersen.seti.org/Dale_Andersen/Science_articles_files/Andersen et al. 1998.pdf |
| Summary: | Hoare. Results confirm previous reports that 0, concentrations in the upper water column exceed atmospheric equilibrium and that N, and Ar are supersaturated throughout the water column. The mean supersaturation of N, was found to be 2.0 (*0.37) and Ar was 3.8 (rtl. 1). The ratios of N,/Ar (20.3 +3.8), and 02/Ar (22.5 rt4.0) at the ice-water interface are consistent with those previously measured, suggesting that bubble formation is the main process for removing gas from the lake. However, the saturations of N, and Ar greatly exceed those previously predicted for degassing by bubble formation only at the ice-water interface. The data support the hypothesis that removal of gas by bubbles occurs in the water column to a depth of 11 m in Lake Hoare. CO, concentration increases from near zero at the ice-water interface to 80-100 times saturation at and below the chemocline at c. 28 m. There is considerable variability in the gas concentrations throughout the water column; samples separated in depth by one metre may vary by more than 50 % in gas content. It is likely that this phenomenon results from the lack of turbulent mixing in the water column. Methane (c. 2 pg 1.’) was detected below the chemocline and immediately above the sedimentlwater interface at a depth of 30 m. Samples from lakes Vanda, Joyce, and Miers, also show supersaturations of 0,, N2, and Ar at levels similar to levels found |
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