Use of environmental isotopes to study the effect of climate change on Passu glacier. | [Science, Technology and Development • 2013]

Author(s):

1. SAIRA BUTT: Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad, Pakistan

2. ARIF MAHMOOD: Pakistan Meteorology Department (PMD), Islamabad, Pakistan

3. GHULAM RASUL: Pakistan Meteorology Department (PMD), Islamabad, Pakistan

4. ZAHID LATIF: Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad, Pakistan

5. FURRUKH BASHIR: Pakistan Meteorology Department (PMD), Islamabad, Pakistan

6. M RAFIQUE SHEIKH1: Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad, Pakistan

7. M AZAM TASNEEM: Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad, Pakistan

Abstract:

Isotopic or nuclear techniques are used to find the effect of global warming on glaciers. Nuclear techniques are related to a branch of hydrology known as isotope hydrology in which environmental isotopes are used to solve major problems related to various aspects of water including its origin, age, recharge mechanism and interconnection between different aquifers. The main advantage of isotopic technique is the use of various isotopes as a tracer. Being natural tracer, environmental stable isotopes (oxygen-18, deuterium 2H, etc.) need not be introduced or injected in the system under investigation but they are a part of the hydrological system. Environmental stable isotopes are measured as ratio of most abundant isotopes of a given element to that of less abundant against some reference material. These ratios are measured on gas source mass spectrometers. Tritium, 3H is a short lived radioactive isotope of hydrogen with half-life of 12.43 years and is measured by counting beta decay events in a liquid scintillation counter. Stable isotopes mass spectrometry alongwith tritium dating has been used to determine the source of moisture and the age of ice and melt-water at Passu Glacier. Samples were collected from the stream originating from Passu Glacial Lake which receives melt generated from the seasonal snow cover and glacier melt. Highly depleted values of stable isotopes of hydrogen and oxygen in the samples and highly positive value of deuterium suggests that moisture source of precipitation is from Mediterranean. Tritium values in Passu stream samples from March to August were around 20TU (tritium units) that correspond to the mixing of major part of melt generated from the seasonal snow cover and little from the glacier’s melt. In Passu stream samples high tritium concentrations up to 75TU were observed from September to November, the period after the seasonal snow cover has been completely melted. It shows contribution of pure glacier melt in the Passu Glacial Lake during this period. High tritium concentrations in stream flow samples correspond to 1963-64 open weapons testing peak, causing tritium concentration rise. The presence of high tritium concentration in the Passu stream samples is the most visible sign of glacier melt in the area and the impact of climate change on these glaciers.

Page(s): 74-83

DOI: DOI not available

Published: Journal: Science, Technology and Development, Volume: 32, Issue: 1, Year: 2013

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