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

Earth Planet. Sci., Vol. 111, No. 1, p. 39-49, 2002 

V.N. Nijampurkar, D.K. Rao
Physical Research Laboratory, Ahmedabad, India.
H.B. Clausen
Departement of Geophysics, The Niels Bohr Institute of Astronomy, Physics and Geophysics, University of Copenhagen.
M.K. Kaul, A. Chaturvedi 
Geological Survey of India, Antarctica Division, Faridabab, India.

ABSTRACT.
The depth profiles of electrical conductance, d¹⁸O, 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 d¹⁸O, 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 accumulation rates, the volcanic event that occurred in 1815 AD, has been identified based on electrical conductance measurements. Based on d¹⁸O 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^oC 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^oS to 90^oS) from Antarctica and higher latitudes beyond 77^oN. 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.