The oxygen to carbon dioxide ratios observed in emissions from a wildfire in Northern California

At Trinidad, California we observed elevated CO2 concentrations and concomi tant lowered O-2 levels coincident with forest fires 70 kin distant (from 1 0/8/99 to 10/21/99). The precision of our O-2 data, 1 mu mol O-2 /mol dry a ir, revealed the reduction of atmospheric oxygen resulting from the combust ion of biomass, and the stoichiometric ratios (-O-2/CO2) of the wildfire em issions. Estimates of daily -O-2/CO2 ratios were obtained by regression of CO2 against corresponding O-2 data (R-2, 0.86 to 0.96). Daily -O-2/CO2 rati os changed from 1.15 to 1.41 on a particularly smoky day that coincided wit h elevated levels of CH4 and increased CH4/CO2 ratios. The change to a high er ratio during smoky conditions illustrates the association between changi ng emissions and -O-2/CO2 ratios, possibly due to changing wildfire dynamic s.