Formaldehyde Concentrations in a Hardwood Forest, Measured by Laser Induced Fluorescence

Laser induced fluorescence (LIF) in a White-type cell has been used to measure gas phase formaldehyde at the PROPHET site, located in a mixed deciduous and pine forest in Northern Michigan. Formaldehyde mixing ratios in the low parts per billion range were observed, displaying a diurnal cycle with the highest concentrations occurring in the afternoon and lowest concentrations shortly after midnight. Measurements were carried out simultaneously at two different heights: above the canopy level (~100 feet) and just within the canopy (~60 feet).