Fluxes of isoprene and monoterpenes from a tundra ecosystem.

Whole system fluxes of isoprene from a moist acidic tundra ecosystem and leaf level emission rates of isoprene and monoterpenes from two important species in that same ecosystem ( Salix pulchra and Betula nana) were measured during the summer of 2005 to assess the contribution of biogenic volatile organic compounds on the chemistry of the Arctic atmosphere. The measurements took place in the Imnavait Creek watershed near the Toolik Field Station on the north slope of the Brooks Range (69° N, 149° W). The whole system fluxes were measured in conjunction with a project that is determining the net carbon exchange of the ecosystem through both atmospheric and hydrological processes (Marc Steiglitz, PI). The maximum rate of isoprene flux measured was over 1 mg C m-2 hr-1 with an air temperature of 22° C and a PAR level over 2000 μmol m-2 s-1. Leaf level isoprene emission rates for S. pulchra reached 20 nmol m-2 s-1 (38 ug C gdw -1 hr-1 ), which was over 1% of the net carbon assimilated. These significant rates of isoprene emission need to be further investigated in field studies and will have major impacts of efforts to model tropospheric chemistry in the Arctic.