title: Laboratory Measured Emission Losses of Methyl Isothiocyanate at Pacific Northwest Soil Surface Fumigation Temperatures.
abstract: Temperature is a major environmental factor influencing land surface volatilization at the time of agricultural field fumigation. Cooler fumigation soil temperatures relevant to Pacific Northwest (PNW) application practices with metam sodium/potassium should result in appreciably reduced methyl isothiocyanate (MITC) emission rates, thus minimizing off target movement and bystander inhalation exposure. Herein, a series of laboratory controlled flow-through soil column assessments were performed evaluating MITC emissions over the range of cooler temperatures (2-13°C). Assessments were also conducted at the maximum allowed label application temperature of 32°C. All assessments were conducted at registration label-specified field moisture capacity, and no more than 50% cumulative MITC loss was observed over the 2-day post-fumigation timeframe. Three-fold reductions in MITC peak fluxes at cooler PNW application temperatures were observed compared to the label maximum temperature. This study supports current EPA metam sodium/potassium label language that indicates surface fumigations during warmer soil conditions should be discouraged.
authors.affiliation: Laboratory of Quality & Safety Risk Assessment for Ginseng and Antler Products, Jilin Agricultural University, Changchun, 130118, Jilin, China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Food & Environmental Quality Laboratory, Washington State University, 2710 University Drive, Richland, WA, 99354, USA. vhebert@wsu.edu.
authors.forename: Vincent R
authors.initials: VR
authors.lastname: Hebert
authors.affiliation: Department of Natural Resources and Environmental Science, University of Nevada, Reno, 1664 North Virginia Street, Reno, NV, 89557, USA.
authors.forename: Glenn C
authors.initials: GC
authors.lastname: Miller
mesh_terms: D005651:Fumigation; D017879:Isothiocyanates / Q000032:analysis*; D015205:Northwestern United States; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D013696:Temperature
chemical_list: D017879:Isothiocyanates; D012987:Soil; D012989:Soil Pollutants; C005227:methyl isothiocyanate
keywords: Emission loss; Metam sodium; Methyl isothiocyanate; Soil temperature