3.3 Water and snow chemistry
Water samples were collected weekly or bi-weekly at GS1, GS2, GS3 and GS4, and at Hathataga Lake’s north shore. Additional sampling included the three spring branches (S1, S2 and S3) (see results below) on August 14 and September 26, 2019. All samples were filtered (0.45 μm) and stored in 20-ml high-density polyethylene scintillation vials. A ‘ball-in-funnel type collector’ was used to collect liquid precipitation (Prechsl, Gilgen, Kahmen, & Buchmann, 2014). A table tennis ball was placed in a funnel to help seal the sample bottle from evaporation and debris. During rainfall, the ball could float which allowed collection. Snow pits were dug to the ground surface, up to 1.5 m, and sampled at 20 cm intervals on March 27, April 23, May 8, 22, 29 and June 11, 2019. All samples from a single pit were combined into a depth-integrated snowpack sample, which was melted at room temperature and bottled. All samples were refrigerated until analysis.
Samples were analyzed for stable isotope ratios, alkalinity and major ion concentrations. Isotopes were analyzed using cavity-ringdown spectroscopy (Los Gatos Research, Water Isotope Analyzer). The ratios of18O/16O and2H/1H were computed with reference to the Vienna Standard Mean Ocean Water isotopic standard (Coplen, 1995). Precision and accuracy as 1 standard deviation of lab standards are 0.2 ‰ for 18O and 1.0 ‰ for 2H. Alkalinity was determined using a spectrophotometer (Gallery, Discrete Analyzer). An ion chromatograph (Metrohm, 930 Compact IC Flex) was used for major ion analysis.
Electrical conductivity (EC) was measured manually using a handheld meter (VWR International, Conductivity/Temperature Meter) for point measurements and for verifying continuous data.