Location: Water Management ResearchTitle: Fumigant emission reduction using vaporsafe totally impermeable film in large field applications Author
Submitted to: California Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/6/2013
Publication Date: 9/1/2013
Citation: Husein, A., Stanghellini, M., Gao, S., Sullivan, D., Afiqur, K., Qin, R. 2013. Fumigant emission reduction using vaporsafe totally impermeable film in large field applications. California Agriculture. 67(3):147-152. Interpretive Summary: With the phase-out of methyl bromide as a soil fumigant, products containing chloropicrin and 1,3-dichloropropene are becoming the new standard fumigant treatments. These fumigants, however, are highly regulated because of emissions that increase exposure risks and degrade air quality as Volatile Organic Compounds (VOCs). Low permeability Totally Impermeable Film (TIF) has shown significant emission reduction when used to tarp the fumigated field. The concerns over potential exposure risks associated with tarp-cutting have been hindering decisions on the tarp use. With the effort to assist regulatory agencies in making decisions on the adoption of TIF for soil fumigation, two large field trials were conducted from 2009 and 2011 to determine emission reduction by TIF and emissions related to tarp-cutting time. Both ambient air monitoring and direct emission measurement from the tarped ground using flux chambers were conducted. A two-field study in 2009 showed significant emission reduction by TIF in comparison with standard tarp during 6 day tarp covering; however, significantly high emissions (flux and total loss) after tarp cutting were measured from the TIF field indicating high exposure risks. In a 3-field study in 2011, emission losses were determined for tarp-covering periods of 5, 10, or 16 days. Emission flux and total loss after tarp-cutting were significantly reduced by increasing tarp covering period from 5 to 10 days, with small further reduction from 10 to 16 days. Flux measured directly from the field agreed considerably well with the ambient monitoring data. These large field trials demonstrated the ability of TIF to significantly reduce fumigant peak flux and total emissions and identified safe tarp-cutting time for regulation development towards the safe use of TIF.
Technical Abstract: The phase-out of methyl bromide has forced most growers to the use of alternative fumigants, particularly 1,3-dichloropropene (1,3-D) and chloropicrin. These alternatives, however, are tightly regulated due to potential exposure and their negative impact on air quality. Two ambient air monitoring studies were conducted to evaluate the potential of totally impermeable film (TIF) to reduce emissions from shank applications of chloropicrin and 1,3-D. In 2009, a study in Oxnard, CA, demonstrated that TIF reduced chloropicrin and 1,3-D peak emissions by 45% and 38%, respectively, but TIF did not reduce total emissions when it was cut after 6 days. In 2011, a study was conducted in Lost Hills, CA, to evaluate the tarp duration needed to reduce total emissions. Increasing the tarp period from 5 to 10 days decreased chloropicrin and 1,3-D peak emissions by 88% and 78%, and their total emissions by 64% and 43%, respectively. There was little further reduction in emissions when the tarp period was extended from 10 to 16 days. Concurrent dynamic flux chamber results corroborated the ambient air monitoring.