Nitrate in Greenland and Antarctic ice cores: a detailed description of post-depositional processesAnnals of Glaciology, 35, p. 209-216, 2002
Climate and Environmental Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland, also at British Antarctic Survey, Natural Environment Research Council, Madingley Road, Cambridge CB3 0ET, England.
Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721-0011, U.S.A.
E.W. Wolff and R. Mulvaney
British Antarctic Survey, Natural Environment Research Council, Madingley Road, Cambridge CB3 0ET, England.
Alfred Wegener Institute for Polar and Marine Research, P.O. Box 120161, D-27515 Bremerhaven, Germany.
Climate and Environmental Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
National Institute of Polar Research, 9-10 Kaga 1-chome, Itabashi-ku, Tokyo 173-8515, Japan.
Department of Physical Geography and Quaternary Geology, Stockholms Universitet, S-106 91 Stockholm, Sweden.
Alfred Wegener Institute for Polar and Marine Research, P.O. Box 120161, D-27515 Bremerhaven, Germany, also at Institut für Umweltphysik, Universität Heidelberg, Im Neuenheimer Feld 299, D-69120 Heidelberg, Germany.
M.-L. Siggaard-Andersen and J.P. Steffensen
Geofysisk Afdeling, Niels Bohr Instituttet for Astronomi, Fysik og Geofysik, Københavns Universitet
A compilation of nitrate (NO3-) data from Greenland has shown that recent NO3- concentrations reveal a temperature dependence similar to that seen in Antarctica. Except for sites with very low accumulation rates, lower temperatures tend to lead to higher NO3- concentrations preserved in the ice. Accumulation rate, which is closely linked to temperature, might influence the concentrations preserved in snow as well, but its effect cannot be separated from the temperature imprint. Processes involved in NO3- deposition are discussed and shown to be temperature- and/or accumulation-rate-dependent. Apart from Scavenging of nitric acid (HNO3) during formation of precipitation, uptake of HNO3 onto the ice crystal's surface during and after precipitation seems to contribute further to the NO3- concentrations found in surface snow. Post-depositional loss of NO3- from the top snow layers is caused by release of HNO3 and by photolysis of NO3-. It is suggested that photolysis accounts for considerable losses at sites with very low accumulation rates. Depending on the site characteristic, and given that the temperature and accumulation-rate dependence is quantified, it should be possible to infer changes in atmospheric HNO3 concentrations