Canopy level flux measurements of 2-methyl-3-buten-2-ol (MBO), acetone, and methanol were made over a subalpine forest in the Rocky Mountains in Colorado in the summer of 1999. The measurements were carried out using a portable relaxed eddy accumulation system that collected samples on adsorbent cartridges. Midday fluxes of acetone were highest at ～2.5 mg of C m{sup}(-2) h{sup}(-1). Methanol and MBO fluxes were ～1.0 mg of C m{sup}(-2) h{sup}(-1) each. These fluxes occurred with average daytime high temperatures of only 18℃. Diurnal fluxes of MBO were strongly correlated with light and temperature. Acetone and methanol did not have simple diurnal patterns. These results indicate that oxygenated volatile organic compounds may make a significant contribution to the flux of reactive carbon to the atmosphere in western U.S. pine forests.
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