Use of a climate-controlled chamber to investigate the fate of gas-phase anthracene

Air-surface exchange of semivolatile organic compounds (SOC) is an important factor controlling the gas-phase concentrations of these compounds. In this study, the uptake of gas-phase anthracene, an SOC, by the leaves of Ficus benjamina was examined in a large (30 m3) environmentally-controlled chamber. To investigate the effect of climate on air/leaf exchange, the air flowrate, temperature, and relative humidity in the chamber was controlled and continually monitored. The large size of the chamber provides an opportunity to study gas/plant exchange at ambient gas-phase concentrations under realistic meteorological conditions. Here we describe the results of several experiments performed to examine the effect of light, temperature, and relative humidity on the uptake of anthracene by Ficus benjamina. Six to eight plants were placed in the chamber and gas-phase anthracene was injected at a constant flow- rate into the chamber. The lights were turned on and off once daily and air samples were collected regularly. Although the cycle is not predictable, results of three week-long experiments indicate that gas-phase anthracene concentrations in the Ficus-populated chamber vary with light period. Stomatal and cuticular uptake are responsible likely for the varying concentrations.