Ice Core Records for Paleo-Volcanism, Climate, and Snow Accumulation Rates Over the Past 150 Years

Abstract

The annual fallout of radionuclides 32Si, 7Be, 210Pb, and 137Cs in the shelf snow samples collected near the Dakshin Gangotri, East Antarctica, has been estimated. The polar fallout of cosmic-ray produced 32Si estimated to be 2.34 X10-5 dpm cm-2 y-1. The fallout of 7Be and 210Pb is estimated to be 4.2 and 1.86 X 10-2 dpm cm-2 y-1. The depth profiles of electrical conductance, 210Pb, δ18O, and cosmogenic radioisotopes 10Be and 36CI have been measured in a 60 m long ice core. Based on 210Pb and δ18O, the mean annual accumulation rates have been calculated. These rates are 0.20 and 0.23 m of ice equivalent per year during the past ~150 years. Based on electrical conductance measurements and using these accumulation rates, a volcanic event, 'Tambora' that occurred in 1815 AD, was identified. δ18O values suggested that the beginning of the 19th century was colder by about 2°C than the recent past and middle of the 18th century. The fallout of 36CI reported here agrees well with the mean global production rate estimated earlier.