Deposition of anthropogenic aerosols in a southeastern Tibetan glacier

Measurements of elemental carbon (EC), water-insoluble organic carbon (WIOC), and inorganic ions from a very high resolution snow/firn core retrieved from a glacier on the southeastern Tibetan Plateau reveal increasing concentrations associated with deposition of anthropogenic aerosols during the period 1998-2005. EC, WIOC, and SO₄^2- concentrations in the core were 4.7, 56.0, and 4.2 ng g^-1 in 1998, but increased to 16.8, 144.4, and 162.1 ng g^-1 in 2005, respectively. Comparison of EC to SO₄²⁺ and K⁺ concentrations indicates a relatively greater impact of fossil fuel burning on EC deposition compared to biomass burning. Significant contribution of secondary OC production is apparent from the low EC/WIOC ratios. EC concentrations show large seasonal variability, with nonmonsoon precipitation containing more than double the concentrations found in monsoon snowfall. Since snow cover on the Tibetan Plateau extends to its maximum aerial extent during the nonmonsoon season, the high EC concentrations in snowfall during this time can cause advanced snowmelt and enhanced radiative forcing.