STABLE ISOTOPIC (8180 & 6D) STUDY OF MANSAR LAKE WATER, JAMMU

Abstract

The study region comprises of the Lower Siwalik rocks of Udhampur district of Jammu. It is composed of fine-grained sandstone alternating with clay bands of lower Siwalik. The Mansar formation is exposed in Anticline (Mansar basin) area. Field visit was conducted in the region for the collection of lake water samples. The field visit was done in the month of January 2015. The temperature, electrical conductivity and the pH as well as the samples in the terms of longitude, latitude were recorded at the time of sampling. The samples were collected and analysed for their isotopic composition at the National Institute of Hydrology, Roorkee. Stable Isotopic compositions (öO and öD) were measured in procured Liquid Water Isotope Analyser and Isotopic Ratio Mass Spectrometer and an attempt has been made to estimate the loss due to evaporation form Lake water on the basis of water samples collected at Mansar Lake in Udhampur district of Jammu. From the data obtained it was observed that as we proceed from July to May in terms of temperature, the study of Mansar Lake has shown gradual decrement in temperature for 8-9 months and alternately decreasing and increasing of temperature during winter. The enrichment in 60 and 6D values was observed in lake water samples clearly indicates that Mansar Lake water is subjected to more evaporative enrichment. The evaporation in certain regions is very high and the lighter isotope evaporate enriching the water body in the heavier isotope. Using the Stable Isotopic Technique (Craig and Gordon model), estimated an average value of evaporation for Oxygen isotope is 5 1 % and 43.11% for Hydrogen isotope.