Modified HNO3 seasonality in volcanic layers of a polar ice core: Snow-pack effect or photochemical perturbation? |
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| Authors: | Paolo Laj Julie M Palais James E Gardner Haraldur Sigurdsson |
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| Institution: | (1) Graduate School of Oceanography, University of Rhode Island, 02882 Narragansett, R.I., USA;(2) Glacier Research Group, University of New Hampshire, 03824 Durham, N.H., USA;(3) Present address: Osservatorio Geofisico, Università di Modena, Via Campi 213/A, 41100 Modena, Italy;(4) Present address: National Science Foundation, Division of Polar Programs, 20550 Washington, DC, USA |
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| Abstract: | Using the chemical composition of snow and ice of a central Greenland ice core, we have investigated changes in atmospheric HNO3 chemistry following the large volcanic eruptions of Laki (1783), Tambora (1815) and Katmai (1912). The concentration of several cations and anions, including SO
4
2–
and NO
3
–
, were measured using ion chromatography. We found that following those eruptions, the ratio of the concentration of NO
3
–
deposited during winter to that deposited during summer was significantly higher than during nonvolcanic periods. Although we cannot rule out that this pattern originates from snow pack effects, we propose that increased concentrations of volcanic H2SO4 particles in the stratosphere may have favored condensation and removal of HNO3 from the stratosphere during Arctic winter. In addition, this pattern might have been enhanced by slower formation of HNO3 during summer, caused by direct consumption of OH through oxidation of volcanic SO2. |
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| Keywords: | Greenland volcanic eruptions H2SO4 HNO3 |
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