Chemical compositions of snow from Mt. Yulong, southeastern Tibetan Plateau

Abstract

The snow and ice in Mt. Yulong offer a unique opportunity to investigate changes in climate and large scale atmospheric circulations over Asia. During February and April 2012, surface snow samples were collected from the Baishui Glacier No. 1 at different altitudes along the eastern slope of Mt. Yulong. Two snowpits were also excavated from Mt. Yulong at altitudes of 4780 and 4730 m a.s.l. in February 2012. The concentrations of inorganic ions were higher at an elevation of 4506 m a.s.l. in the glacier with significant contribution of anthropogenic (mainly NH $_{4}^{\mathrm {+}}$ , SO $_{4}^{\mathrm {2-}}$ , NO $_{3}^{\mathrm {-}})$ and crustal (mainly Ca 2+) constituents. Concentration of HCOO − in surface snow exhibited large variability, ranging from 0.04 to 6.8 μeq L −1, attributed to dominant contribution from biomass burning emissions. Ion balance (ΔC) and Na +/Cl − calculations indicated an excess of cations (particularly higher Ca 2+ concentrations) and Cl − in snow, considering the sea-salt ratio, respectively. Monsoon season (June–September) ion concentrations in snowpit samples were generally two-fold lower than in other seasons. Principal component analysis was used to identify different sources of ions. Three main factors, accounting for more than 80% of the total variance, were related to different sources, including agricultural activities, biomass burning, and crustal aerosols.