Recent high-resolution glaciochemical record from a Dasuopu firn core of middle Himalayas

A 16.8 m firn core of middle Himalayas was recovered on the col of Dasuopu glacier in August 2006, being 7000 m above sea level. A total of 317 samples were measured for stable oxygen isotope ratios (δ ¹⁸O) and major ion concentrations (Na⁺, NH ₄ ⁺ , K⁺, Mg²⁺, Ca²⁺, Cl⁻, SO ₄ ²⁻ , and NO ₃ ⁻ ). The firn core dating and seasonal partitioning were carried out based on the marked seasonal variations along the stable oxygen isotopes and crustal species (Ca²⁺, Mg²⁺) profiles. The multi-parameters and high-resolution glaciochemical data set of Dasuopu firn core recorded the detailed chemical characteristics of precipitation in high-elevation region, middle Himalayas, since 1991 A.D., which mainly originated from the crustal and anthropogenic sources, while the sea-salt contribution was minor. The seasonal variability of major ion concentrations was dominated by the seasonal alternation of the prevalent air mass, atmospheric circulation situation and precipitation regime. Linear regression analysis indicated that most of the variance in annual ionic fluxes can be explained by a linear dependence on snow accumulation rate. Supported by the National Basic Research Program of China (Grant No. 2005CB422004), and the National Natural Science Foundation of China (Grant Nos. 40571039 and 40121101)