Department of Civil Engineering, Florida State University, Tallahassee, FL 32310-6046, USA.
J Air Waste Manag Assoc. 2010 Apr;60(4):460-70. doi: 10.3155/1047-3289.60.4.460.
Landfills represent a source of distributed emissions source over an irregular and heterogeneous surface. In the method termed "Other Test Method-10" (OTM-10), the U.S. Environmental Protection Agency (EPA) has proposed a method to quantify emissions from such sources by the use of vertical radial plume mapping (VRPM) techniques combined with measurement of wind speed to determine the average emission flux per unit area per time from nonpoint sources. In such application, the VRPM is used as a tool to estimate the mass of the gas of interest crossing a vertical plane. This estimation is done by fitting the field-measured concentration spatial data to a Gaussian or some other distribution to define a plume crossing the vertical plane. When this technique is applied to landfill surfaces, the VRPM plane may be within the emitting source area itself. The objective of this study was to investigate uncertainties associated with using OTM-10 for landfills. The spatial variability of emission in the emitting domain can lead to uncertainties of -34 to 190% in the measured flux value when idealistic scenarios were simulated. The level of uncertainty might be higher when the number and locations of emitting sources are not known (typical field conditions). The level of uncertainty can be reduced by improving the layout of the VRPM plane in the field in accordance with an initial survey of the emission patterns. The change in wind direction during an OTM-10 testing setup can introduce an uncertainty of 20% of the measured flux value. This study also provides estimates of the area contributing to flux (ACF) to be used in conjunction with OTM-10 procedures. The estimate of ACF is a function of the atmospheric stability class and has an uncertainty of 10-30%.
垃圾填埋场代表了一个分布在不规则和不均匀表面上的排放源。在美国环保署（EPA）提出的“其他测试方法-10”（OTM-10）方法中，采用垂直径向羽流测绘（VRPM）技术结合风速测量来量化来自此类源的排放，以确定非点源每单位面积每单位时间的平均排放通量。在这种应用中，VRPM 被用作估计穿过垂直平面的感兴趣气体质量的工具。通过将现场测量的浓度空间数据拟合到高斯或其他分布来定义穿过垂直平面的羽流来进行此估计。当将此技术应用于垃圾填埋场表面时，VRPM 平面可能位于排放源区域内。本研究的目的是调查使用 OTM-10 进行垃圾填埋场时存在的不确定性。在排放域中，排放的空间变异性可能导致测量通量值的不确定性为-34%至 190%，当模拟理想情况时。当不知道排放源的数量和位置（典型的现场条件）时，不确定性水平可能更高。通过根据排放模式的初步调查改进现场 VRPM 平面的布局，可以降低不确定性水平。在 OTM-10 测试设置期间风向的变化可能会引入测量通量值的 20%的不确定性。本研究还提供了与 OTM-10 程序一起使用的通量贡献面积（ACF）的估计值。ACF 的估计值是大气稳定度类别的函数，具有 10-30%的不确定性。
