|Ajwa, Husein -|
|Qin, Ruijin -|
|Stanghellini, Mike -|
|Sullivan, Dave -|
Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 27, 2012
Publication Date: January 1, 2013
Citation: Gao, S., Ajwa, H., Qin, R., Stanghellini, M., Sullivan, D. 2013. Emission and transport of 1,3-dichloropropene and chloropicrin in a large field tarped with VaporSafeTM TIF. Environmental Science and Technology. 47:406-411. Interpretive Summary: Mandatory emission reduction from soil fumigation targets nonattainment areas in California. Low permeability tarps such as the commercial totally impermeable film or TIF are shown highly effective to reduce fumigant emissions. However, concerns over surge of emission following tarp-cutting and the unknown emissions at TIF tarp edges must be addressed for the safe use of TIF. In collaboration with university researchers, regulatory agency, and industry, a large field study was conducted in 2011. Comprehensive data on emission reduction, and the fate and transport of fumigants in soil were collected in an 8-acre field fumigated with Pic-Clor 60, a mixture of chloropicrin (~60%) and 1,3-dichloropropene. Low emission flux was measured throughout 16 days of tarp-covering period with a total emission loss <10% from the tarped field and < 1% at the tarp edges. Emission flux upon tarp-cutting increased, but was substantially lower than 5 or 6 days of tarp covering. This study demonstrated the ability of TIF to significantly reduce fumigant peak flux and total emission loss and the required longer tarp-covering periods. The results from this research should benefit decision making on use of low permeability tarps in controlling fumigant emissions.
Technical Abstract: Tarping fumigated fields with low permeability films such as commercial Totally Impermeable Film (TIF) significantly reduces fumigant emissions, but it can also increase fumigant residence time in the soil such that extended tarp-covering durations may be required to address potential exposure to workers and bystanders during tarp-cutting and removing activities. In an effort to develop safe practices for using TIF, a large field study was conducted in the San Joaquin Valley of California. Comprehensive data on emissions, fate, and transport of 1,3-dichloropropene and chloropicrin were collected in a 3.3 ha field fumigated with Pic-Clor 60 via broadcast shank application. Low emission flux was observed from the tarped field throughout the tarp-covering period of 16 days with total emission loss of <10% of total applied for both chemicals. Although substantially higher flux was measured at tarp edges, the flux was reduced to nil beyond 2 m of tarp edge with estimated total mass loss of = 1% of total applied to the field. For the tarped field, emission flux increased following tarp-cutting, but was much lower than that from 5 or 6 d tarp-covering periods. This study demonstrated the ability of TIF to significantly reduce field-scale fumigant emissions and collected data for decision-making on safe tarp-cutting times. The use of TIF in soil fumigation will help maintain the availability of soil fumigants to growers and sustain the productivity of many high value crops dependent on soil fumigants.