Records of climatic changes and volcanic events in an ice core from Central Dronning Maud Land (East Antarctica) during the past century

Abstract

The depth profiles of electrical conductance, δ18O, 210Pb and cosmogenic radio isotopes 10Be and 36Cl have been measured in a 30 m ice core from east Antarctica near the Indian station, Dakshin Gangotri. Using 210Pb and δ18O, the mean annual accumulation rates have been calculated to be 20 and 21 cm of ice equivalent per year during the past ∼ 150 years. Using these acumulation rates, the volcanic event that occurred in 1815 AD, has been identified based on electrical conductance measurements. Based on δ18O measurements, the mean annual surface air temperatures (MASAT) data observed during the last 150 years indicates that the beginning of the 19th century was cooler by about 2°C than the recent past and the middle of 18th century. The fallout of cosmogenic radio isotope 10Be compares reasonably well with those obtained on other stations (73° S to 90° S) from Antarctica and higher latitudes beyond 77°N. The fallout of 36Cl calculated based on the present work agrees well with the mean global production rate estimated earlier by Lal and Peters (1967). The bomb pulse of 36Cl observed in Greenland is not observed in the present studies - a result which is puzzling and needs to be studied on neighbouring ice cores from the same region.