Himalayan ice-core dating with snow algae

Snow algae in shallow ice cores (7 m long) from Yala Glacier in the Langtang region of Nepal were examined for potential use in ice-core dating. Ice-core samples taken at 5350 m a.s.l. in 1994 contained more than seven species of snow algae. In a vertical profile of the algal biomass, 11 distinct algal layers were observed. Seasonal observation in 1996 at the coring site indicated most algal growth occurred from late spring to late summer. Pit observation in 1991, 1992 and 1994 indicated that algal layer formation takes place annually. delta O-18, chemical ions (Na+, Cl-, SO42- and NO3-) and microparticles failed to show any clear seasonal variation, particularly at depths exceeding 2 m, possibly due to heavy meltwater percolation. Snow algae in ice cores would thus appear to be accurate boundary markers of annual layers and should prove useful for ice-core dating in Himalayan-type glaciers.