| Abstract
| - Plastic tarps currently used during soil fumigation tocontrol emissions have been shown to be permeable tofumigant vapors, resulting in appreciable losses to theatmosphere. New low-permeability films are being developedto reduce fumigant emissions and increase efficacy. Arapid, reliable, and sensitive method is required to measurethe permeability of various films that may be used innew management practices. This manuscript presents anapproach for estimating the mass transfer coefficient(h) of fumigant compounds across agricultural films. Theh is a measure of the resistance to diffusion which, unlikeother measures of permeability, is a property of the film-chemical combination and independent of the concentrationgradient across the film. This method uses static sealedcells; fumigant vapor is spiked to one side of the film andthe concentrations on both sides of the film are monitoreduntil equilibrium. An analytical model is fitted to the data toobtain h. This model relies on a mass balance approachand includes sorption to and diffusion across the filmmembrane. The method was tested using two polyethylenefilms and a very low-permeability film and showed thatthe method produces a sensitive and reproducible measureof film permeability.
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