Biological Selenium Volatilization: Method of Measurement under Field Conditions

An open-flow chamber sampling system was developed for measurements of selenium (Se) volatilization from soil and vegetated areas under field conditions. This paper provides detailed information on the design, construction, and calibration of the chamber sampling system. Volatile Se was collected using a Plexiglas collection chamber, 0.71 m long, 0.71 m wide, and 0.76 m high; the chamber provided an internal volume of 0.38 m 3 and enclosed a ground area of 0.5 m 2 . Volatile Se produced inside the collection chamber was trapped by activated carbon filters from the air leaving the chamber. The trapped Se was extracted from the charcoal filters in alkaline-peroxide solution. The system has a maximum measurement capacity of 10 mg Se m 2 over a sampling period of 24 h at an air flow rate of 0.43 m 3 h -1 . Measurements of Se volatilization from the soil-halophyte system in central California were carried out to demonstrate the efficiency of this sampling system under field conditions.