Submitted to: Journal of Environmental Science and Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/5/1997
Publication Date: N/A
Citation: Interpretive Summary: This paper describes a new chamber design which can be used to measure the volatilization rate of agricultural and/or organic chemicals into the atmosphere. The flow-through chamber has been designed so that the internal conditions inside the chamber closely approximate the model assumptions used to obtain a value for the volatilization rate. The chamber has inlet and outlet air channels which produce a uniform flow velocity across the soil surface. Testing shows that no stagnant air zones exist and that the chamber produces similar total volatilization rates as traditional micrometeorological methods.
Technical Abstract: Dynamic or flow-through chambers are convenient tools for field measurements of gas fluxes from soils to the atmosphere. In this study, a dynamic chamber is designed and fabricated on the basis of aerodynamic considerations so that the conditions assumed for the commonly-used flux model are closely satisfied. The chamber consists of an inlet transition zone, a square main body, and an outlet transition zone. Six equally-spaced air channels are installed in both inlet and outlet transition zones to conduct and spread the flowing air uniformly across the soil surface, which help to produce a simple, horizontal and uniform air stream above the covered soil surface. Aerodynamic tests in the laboratory show that the air sweeps over the entire covered soil surface with a relatively constant velocity at a given air-flow rate and no stagnant air zones are present. The chamber is used in a field fumigation experiment to measure methyl bromide emission at the soil surface. The emission results obtained from the chamber are consistent with those obtained from micrometeorological methods used in the same experiment.