Himalayan Geology, Vol. 39 (1), 2018, pp. 121-132, Printed in India
Hydrochemistry of meltwater draining from Dokriani Glacier during early and late ablation season, West Central Himalaya
SAMEER K. TIWARI*1, AMIT KUMAR2, ANIL K. GUPTA3, AKSHAYA VERMA2, RAKESH BHAMBRI2, SHIPIKA SUNDRIYAL2, JAIRAM YADAV2
1Wadia Institute of Himalayan Geology, Dehradun 248001, India
2Centre for Glaciology, Wadia Institute of Himalayan Geology, Dehradun 248001, India
3Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721302, India
*Email (Corresponding author): stiwariisr@gmail.com
Abstract: A systematic geochemical study on seasonal variation of major ions has been carried out to investigate the source of dissolved ions and to understand the chemical weathering processes controlling the glacial meltwater of the Dokriani Glacier near the snout. The study is conducted on 220 samples of meltwater wherein calcium (Ca+2) and magnesium (Mg) are the two major cations, whereas sulfate (SO4-2) is the leading anion followed by bicarbonate (HCO3-). The contribution of high ratios of (Ca+2+Mg+2)/(Na++ K+), Ca+2/Na+, Mg+2/Na+, HCO3-/Na+ and low ratio of (Na++ K+)/TZ+ for pre-monsoon and post monsoon seasons suggests the predominance of weathering of carbonate minerals which is the major source of dissolved solutes followed by silicate weathering in the meltwater of Dokriani Glacier. The equivalent ratios of Na+/Cl− and K+/Cl− 5.4 ± 2.4; 5.75 ± 1.8 in the pre-monsoon and 14.2 ± 7.9; 17.0 ± 10.5 in the post-monsoon, respectively, are much higher as compared to the sea water (i.e. Na+/Cl− = 1.0 and K+/Cl− = 0.2) indicating considerable contribution from congruent weathering and other atmospheric inputs to the meltwater. The average C ratio (ratio of HCO3- to HCO3- + SO4-2) for the meltwater is 0.38 and 0.07 in the pre- and post-monsoon respectively; this strongly exhibits that major portion of sulphate was supplied from sulphide oxidation. TDS flux of the Dokriani Glacier was calculated using discharge and TDS of meltwater. The TDS has a fluctuating nature throughout the day, with average TDS higher during afternoon and early evening, while a lower TDS is observed during night and early morning. Monthly mean of TDS flux for pre- and post-monsoon are estimated to be 141.5, 248.8 and 361.3 t month-1, respectively.
Keywords: Hydrochemistry, Chemical weathering, Dokriani Glacier, Diurnal variation, Glacial meltwater.
