Lu Zhou, Hebert Vincent R, Miller Glenn C
Laboratory of Quality & Safety Risk Assessment for Ginseng and Antler Products, Jilin Agricultural University, Changchun, 130118, Jilin, China.
Food & Environmental Quality Laboratory, Washington State University, 2710 University Drive, Richland, WA, 99354, USA.
Bull Environ Contam Toxicol. 2017 Feb;98(2):257-261. doi: 10.1007/s00128-016-1993-2. Epub 2016 Dec 19.
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.
温度是影响农田熏蒸时地表挥发的主要环境因素。与太平洋西北地区（PNW）使用甲基钠/钾的熏蒸土壤温度较低，这应会显著降低异硫氰酸甲酯（MITC）的排放速率，从而最大限度地减少非目标移动和旁观者吸入暴露。在此，进行了一系列实验室控制的流通式土壤柱评估，以评估在较低温度范围（2 - 13°C）内的MITC排放。还在允许的最高标签施用温度32°C下进行了评估。所有评估均在注册标签规定的田间持水量下进行，在熏蒸后2天的时间范围内，观察到的MITC累积损失不超过50%。与标签最高温度相比，在PNW较低施用温度下观察到MITC峰值通量降低了三倍。本研究支持美国环境保护局（EPA）当前甲基钠/钾标签语言，该语言表明应避免在土壤温度较高时进行地表熏蒸。
