Chemistry of Supraglacial Ponds in the Debris-Covered Area of Lirung Glacier in Central Nepal Himalayas

Abstract

Glacial meltwater samples were collected from 15 supraglacial ponds at elevations ranging between 3989 and 4292 m above sea level in the debris-covered area of Lirung glacier in central Nepal Himalayas, from November 2010 to October 2011 on a bimonthly basis. We examined elevation trends, and their control by seasonality, dominant geochemical processes, and seasonal dynamics in these supraglacial ponds. Concentration of some parameters showed a decreasing trend with elevation but with high variability and modulation by seasons, being more prevalent in the post-monsoon. Sulfate is the only parameter showing significant elevation trends regardless of the season, although the trend is also affected by the monsoon. The concentrations of major chemical solutes were highest during post-monsoon season and lower in the pre-monsoon and monsoon seasons, indicating influence of seasonality on dissolution, dilution, and hydrological processes. Contribution to chemical loads from marine aerosols to these pond water appeared to be minor except for sodium and magnesium. Chemical weathering of carbonate and silicate minerals fueled by dissolution of pyrite appeared as the dominant geochemical processes.

Seasonal variations of biogeochemical matter export along the Langtang-Narayani river system in central Himalaya

“…These sites (LNS-5 and LNS-6) situated at the MCT region where pCO 2 is comparatively high, and correlated with elevated levels of sulfate, calcium and alkalinity and lower pH (Table 3 and Table S1). Latter observations were previously linked to sulfide oxidation and carbonate dissolution, while from sub-catchments metamorphic CO 2 may contribute to the observed alkalinity fluxes (Galy and France-Lanord, 1999;France-Lanord et al, 2003;Evans et al, 2008;Wolff-Boenisch et al, 2009;Bhatt et al, 2016).…”

“…Sulfide oxidation, often coupled with carbonate dissolution, influences the flux of dissolved inorganic carbon (DIC) in subglacial drainage systems within the Himalayan region and elsewhere (Tranter and Raiswell, 1991;Tranter et al, 1993;Galy and France-Lanord, 1999;Hasnain and Thayyen, 1999;Bhatt et al, 2000;Millot et al, 2003;Bhatt et al, 2009;Wolff-Boenisch et al, 2009;Bhatt et al, 2016;Torres et al, 2017). Sulphur oxidation may also be a relevant long-term source of CO 2 to the atmosphereocean system over long geological time scales (Torres et al, 2014).…”

Supraglacial Ponds Regulate Runoff From Himalayan Debris‐Covered Glaciers

“…Interannually, debris redistribution and change in surface topography result in variation in pond positions (Narama et al, ; Watson et al, ), and as ponds attain their local hydrological base level, they may evolve into larger scale lakes (Thompson et al, ; Mertes et al, ). Observations of supraglacial pond water quality confirm that hydrological linkages do exist between ponds (Bhatt et al, ; Takeuchi et al, ), and pond extent may be governed by the evolving development and (re)organization of supraglacial drainage systems (Miles, Steiner, et al, ; Watson et al, , Watson, Quincey, Carrivick, Smith, Rowan, et al, ). Yet the extent to which these ponds impact upon meltwater generation and modify the seasonal hydrograph remains poorly quantified.…”