Chemistry of burning the forest floor during the FROSTFIRE experimental burn, interior Alaska

[i] Wildfires represent one of the most common disturbances in boreal regions, and have the potential to reduce C, N, and Hg stocks in soils while contributing to atmospheric emissions. Organic soil layers of the forest floor were sampled before and after the FROSTFIRE experimental burn in interior Alaska, and were analyzed for bulk density, major and trace elements, and organic compounds. Concentrations of carbon, nutrients, and several major and trace elements were significantly altered by the burn. Emissions of C, N, and Hg, estimated from chemical mass balance quations using Fe ~ AI, and Si as stable constituents, indicated that 500 to 900 g C and up to 0 to 4 x 10- g Hg/m 2 were lost from the site. Calculations of nitrogen loss range from-4 to +6 g/m 2 but were highly variable (standard eviation 19), with some samples howing increased N concentrations post-burn potentially from canopy ash. Noncombustible major nutrients such as Ca and K also were inherited from canopy ash. Thenuogravimetry indicates a loss of thermally labile C and increase.of lignin-like C in char and asia relative to unbnrned counterparts. Overall, atmospheric mpacts of boreal fires include large emissions of C, N and Hg that vary greatly as a tunction of severe fire weather and its access to dee