My work at UMBS in the summer of 2010 will focus on ambient measurements of total OH reactivity near the forest floor. The sampling setup will consist of an enclosure placed on top of the forest floor to isolate VOC emissions from an area of the forest floor. To accommodate the flowrate needed for total OH reactivity measurements with the IU-TOHLM instrument (~150 - 200 L min-1), based on a design reported by Kovacs and Brune (J. Atmos. Chem. 2001, 39, 105-122) , the enclosed volume should be at least 300 L for a 2-minute total OH reactivity measurement. A 1 m x 1 m rectangular enclosure with a height of 30 cm can enclose this volume. This enclosure will be open at one end to allow for replenishment of air inside the enclosure with ambient air near the forest floor. To investigate the additional VOCs from the forest floor, the OH reactivity will be alternately measured within the enclosure and at a height of ~50-100 cm above the enclosure via two inlets: one located on the closed side of the enclosure, and one located above the enclosure. A solenoid valve system would be used to switch between the two inlets to avoid depletion of the enclosure volume. From these measurements of total OH reactivity, BVOC emission rates can be estimated.