Viguria Maialen, Ro Kyoung S, Stone Kenneth C, Johnson Melvin H
a NEIKER-Tecnalia, Basque Institute for Agricultural Research and Development , Derio , Bizkaia , Spain.
J Air Waste Manag Assoc. 2015 Apr;65(4):395-403. doi: 10.1080/10962247.2014.996267.
Recently, the U.S. Environmental Protection Agency (EPA) posted a ground-based optical remote sensing method on its Web site called Other Test Method (OTM) 10 for measuring fugitive gas emission flux from area sources such as closed landfills. The OTM 10 utilizes the vertical radial plume mapping (VRPM) technique to calculate fugitive gas emission mass rates based on measured wind speed profiles and path-integrated gas concentrations (PICs). This study evaluates the accuracy of the VRPM technique in measuring gas emission from animal waste treatment lagoons. A field trial was designed to evaluate the accuracy of the VRPM technique. Control releases of methane (CH4) were made from a 45 m×45 m floating perforated pipe network located on an irrigation pond that resembled typical treatment lagoon environments. The accuracy of the VRPM technique was expressed by the ratio of the calculated emission rates (QVRPM) to actual emission rates (Q). Under an ideal condition of having mean wind directions mostly normal to a downwind vertical plane, the average VRPM accuracy was 0.77±0.32. However, when mean wind direction was mostly not normal to the downwind vertical plane, the emission plume was not adequately captured resulting in lower accuracies. The accuracies of these nonideal wind conditions could be significantly improved if we relaxed the VRPM wind direction criteria and combined the emission rates determined from two adjacent downwind vertical planes surrounding the lagoon. With this modification, the VRPM accuracy improved to 0.97±0.44, whereas the number of valid data sets also increased from 113 to 186.
The need for developing accurate and feasible measuring techniques for fugitive gas emission from animal waste lagoons is vital for livestock gas inventories and implementation of mitigation strategies. This field lagoon gas emission study demonstrated that the EPA's vertical radial plume mapping (VRPM) technique can be used to accurately measure lagoon gas emission with two downwind vertical concentration planes surrounding the lagoon.
最近，美国环境保护局（EPA）在其网站上发布了一种地面光学遥感方法，称为其他测试方法（OTM）10，用于测量来自封闭垃圾填埋场等面源的逸散气体排放通量。OTM 10利用垂直径向羽流映射（VRPM）技术，根据测量的风速剖面和路径积分气体浓度（PIC）来计算逸散气体排放质量速率。本研究评估了VRPM技术在测量动物粪便处理 lagoons气体排放方面的准确性。设计了一项现场试验来评估VRPM技术的准确性。甲烷（CH4）的控制释放是通过位于一个类似于典型处理 lagoons环境的灌溉池塘上的45米×45米的浮动穿孔管网进行的。VRPM技术的准确性通过计算排放速率（QVRPM）与实际排放速率（Q）的比值来表示。在平均风向大多垂直于下风垂直平面的理想条件下，VRPM的平均准确性为0.77±0.32。然而，当平均风向大多不垂直于下风垂直平面时，排放羽流没有被充分捕获，导致准确性较低。如果放宽VRPM风向标准并结合从 lagoon周围两个相邻下风垂直平面确定的排放速率，这些非理想风况下的准确性可以得到显著提高。通过这种修改，VRPM的准确性提高到了0.97±0.44，而有效数据集的数量也从113增加到了186。
开发准确可行的动物粪便 lagoons逸散气体排放测量技术对于牲畜气体清单和缓解策略的实施至关重要。这项现场 lagoons气体排放研究表明，EPA的垂直径向羽流映射（VRPM）技术可用于通过围绕 lagoon的两个下风垂直浓度平面准确测量 lagoons气体排放。
