Kinetics of Conversion of Air Bubbles to Air Hydrate Crystals in Antarctic Ice

Price, P. B.

doi:10.1126/science.267.5205.1802

Cited by 35 publications

(33 citation statements)

References 20 publications

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“…At depths below Ϸ10 3 m in both Vostok and GISP2 ice, the air in bubbles has transformed into solid air-hydrate crystals (26), leaving an equilibium concentration of Ϸ2.4 ϫ 10 Ϫ7 mole fraction O 2 dissolved in the lattice. We note that the diffusion rate of H 2 in ice is more than four orders of magnitude greater than that of O 2 , which largely counteracts the differences in their atmospheric abundance.…”

Section: Narrow Spikes Of High-microbial Concentration Correspond To mentioning

confidence: 99%

In situ microbial metabolism as a cause of gas anomalies in ice

Rohde

Price

Bay

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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Isolated spikes of anomalously high concentrations of N2O have been reported at depths in Greenland and Antarctic ice cores corresponding to narrow time intervals over the past Ϸ10 5 years. Now, using a calibrated spectrofluorimeter to map protein-bound Trp, a proxy for microbes, versus depth in the 3,053-m GISP2 ice core, we find six depths at which localized spikes of high cell concentrations coincide with N2O spikes. We show that the excess gases are consistent with accumulation of in situ metabolic wastes during residence times of the excess microbes in the ice. Because of sparseness of N2O measurements and our spectrofluorimetry versus depth, the total number of microbially produced N2O spikes in GISP2 is probably much larger than six. Spikes of excess methanogens coincident with CH4 spikes are found at three depths in the bottom 3% of GISP2, most likely because of methanogenic metabolism in the underlying silty ice, followed by turbulent flow of the lowest Ϸ90 m of ice. The apparent rates of in situ production of N2O and CH4 spikes by metabolism are observed to be consistent with a single activation energy, U, and maintain proportionality to exp(؊U/RT) over the entire temperature range down to ؊40°C. Fluorescence of nonmicrobial aerosols in GISP2 ice is distinguishable from microbial fluorescence by its different emission spectra. Our spectrofluorimetric scans throughout the GISP2 ice core lead us to conclude that both microbes and nonmicrobial aerosols are deposited in discontinuous bursts, which may provide a tool for studying wind storms in the distant past.climate ͉ ice cores ͉ proxy for dust storms ͉ scanning fluorimetry ͉ N2O

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Section: Narrow Spikes Of High-microbial Concentration Correspond To mentioning

confidence: 99%

In situ microbial metabolism as a cause of gas anomalies in ice

Rohde

Price

Bay

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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“…The present study supports this conclusion. If the model of Price [1995] is correct, fractionation during the transition simply causes N2/O 2 to be distributed within each individual clathrate hydrate crystal, because the N2/O 2 ratio in air-bubble coated by a clathrate hydrate shell increases with the growth of the shell. However, the present study shows that'the N2/O 2 ratios in both air-bubbles and clathrate hydrates gradually increase with increases in depth.…”

Section: Fig 1 Shows Depth Profiles Of N2/o 2 Ratios Of Air-bubbles mentioning

confidence: 99%

Extreme fractionation of gases caused by formation of clathrate hydrates in Vostok Antarctic Ice

Ikeda¹,

Fukazawa²,

Mae³

et al. 1999

Geophysical Research Letters

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“…First, bubbles are compressed under hydrostatic pressure (14). Second, gases eventually begin to dissolve in the ice as air hydrates (14,15). Nucleation is kinetically limited, and at ambient temperatures and pressures occurs over order 10 4 yr (15).…”

Section: Physics Of Gases In Glaciersmentioning

confidence: 99%

Gases in ice cores

Bender

Sowers

Brook

1997

Proc. Natl. Acad. Sci. U.S.A.

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Air trapped in glacial ice offers a means of reconstructing variations in the concentrations of atmospheric gases over time scales ranging from anthropogenic (last 200 yr) to glacial͞interglacial (hundreds of thousands of years). In this paper, we review the glaciological processes by which air is trapped in the ice and discuss processes that fractionate gases in ice cores relative to the contemporaneous atmosphere. We then summarize concentration-time records for CO 2 and CH 4 over the last 200 yr. Finally, we summarize concentration-time records for CO 2 and CH 4 during the last two glacial-interglacial cycles, and their relation to records of global climate change.Ice crystals near the surface of a glacier are compressed by the continual addition of snow at the surface. As the ice crystals travel down into the glacier, they grow and reorient themselves into a closer packing. Density rises, open porosity decreases, and by some depth between 40 and 120 m, the crystals are sintered together into an impermeable mass (''glacial ice'') in which about 10% of the volume is composed of isolated bubbles. The gas trapped in these bubbles is close in composition to contemporaneous air and allows us to reconstruct changes in atmospheric chemistry on three important time scales: the last 200 years (relating to anthropogenic change), the Holocene (last 10,000 years), and the last several hundred thousand years (relating to glacial-interglacial cycles). In this paper we discuss the gas trapping process and summarize data on the changes in the greenhouse gas concentrations of air over the three time scales of interest.

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Kinetics of Conversion of Air Bubbles to Air Hydrate Crystals in Antarctic Ice

Cited by 35 publications

References 20 publications

In situ microbial metabolism as a cause of gas anomalies in ice

In situ microbial metabolism as a cause of gas anomalies in ice

Extreme fractionation of gases caused by formation of clathrate hydrates in Vostok Antarctic Ice

Gases in ice cores

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