V N Nijampurkar
Articles written in Journal of Earth System Science
Volume 92 Issue 3 November 1983 pp 255-260
Vertical profiles of137Cs and210Pb have been determined in a 9 m column of ice from accumulation zone of Changme-Khangpu glacier in north Sikkim valley.137Cs activity varies from 4 to 22 dpm/ L. In many samples210Pb occurs at a level of 20 to 65 dpm/ L which is much higher than the expected fallout value.137Cs and210Pb activities correlate well with each other but not with the dust content. Possibility of210Pb production in the nuclear explosions is discussed. Several peaks appear in the depth profile of137Cs and210Pb which can be matched with Chinese atmospheric nuclear explosions with some phase difference if a uniform ice accumulation rate of 0.7 m per year is assumed since 1969.
Volume 111 Issue 1 March 2002 pp 39-49
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.
Volume 128 | Issue 8
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