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

The depth profiles of electrical conductance, δ¹⁸O,²¹⁰Pb and cosmogenic radio isotopes¹⁰Be and³⁶Cl have been measured in a 30 m ice core from east Antarctica near the Indian station, Dakshin Gangotri. Using²¹⁰Pb 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 isotope¹⁰Be compares reasonably well with those obtained on other stations (73‡ S to 90‡ S) from Antarctica and higher latitudes beyond 77‡N. The fallout of³⁶Cl calculated based on the present work agrees well with the mean global production rate estimated earlier by Lal and Peters (1967). The bomb pulse of³⁶Cl 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.