Snow sampling

A 4m deep snow profile was sampled at 1cm resolution using ultra clean snow sampling methodology in order to maximise the array of potential measurable trace elements. These will include Al, As, Ba, Be, Cr, Co, Fe, Li, Mn, P, Rb, Sr, Ti, U, V, Zn. Isotopic (δ¹⁸O and δD) and major ion composition will also be measured.

Figure 1: Snow sampling using clean procedure

All sampling vials, 60ml Nalgene HDPE (high density polythene), were pre-cleaned following the procedure of Osterberg et al⁶. Preparation includes soaking in 5% trace metal-grade HNO3 for 1 week, triple rinse in DI (deionised, 18 MΩ) water and again soaked in DI H2O. Sampling equipment was triple rinsed, soaked for 4 weeks and triple rinsed again in DI water.

The sampling surface was pre-cleaned using a clean metal spade and the removal of at least 20cm horizontally immediately prior to sampling with a ceramic (ZrO) knife. 1cm thick samples were cut horizontally across the snow into a HDPE tray and transferred into vials. Tyvek clean suits, facemasks and dust free polyethylene gloves were worn to prevent sample contamination from personnel.

Figure 2: AWS at Evans Piedmont Glacier

Snow profiling

Density and temperature profiling was conducted at 5cm resolution once sampling was complete and the surface was freshly cut back. Cylinders of known volume were hammered into the fresh surface, filled, extracted and weighed to determine precise density measurements.

Physical description notes of crystal structure and the location of hoar horizons are used to provide a preliminary chronology. This was taken both during and after sampling, with the upper section constructed into a thin wall to determine these more clearly (Fig 3.) Stable isotope and chemical species characterised by seasonal changes (e.g. sea salt species Na, Sr) will be used to confirm this chronology.

Automatic weather station (AWS)

Wind speed and direction, air temperature, snow accumulation and temperature, barometric pressure, humidity, and solar radiation are recorded (Fig.2).