Measurements of hydrocarbon air–surface exchange rates over maize

Vertical gradients of volatile organic compounds (VOCs) were measured over a maize (Zea mays) field, in its early growth period, during May 1995, in the Lower Coastal Plains of North Carolina. These measurements were combined with micrometeorological flux measurements to determine emission flux measurements for various VOCs. This measurement program was part of project NOVA (Natural emissions of Oxidant precursors: Validation of techniques and Assessment) to estimate the flux of VOCs. Average emissions of VOCs (and standard error) was estimated to be 4900±700 μg/m2/h out of which emission for methanol averaged (3450±420) μg/m2/h. A methanol emission rate of 35 μg/g/h was calculated for maize from the estimated emission of methanol and biomass density for the site.