Particulate matter (PM) pollution is associated with adverse effects on human health and the environment. There is no designated PM_2.5 emission factor for horizontal grain conveyors. Instead, in Washington state, the air permitting agency uses an emission factor for headhouse and grain handling operations to issue permits. There is concern that this factor does not accurately represent the conveyor operations and limits the size and operation of wheat pile facilities. The primary goal of this work was to estimate the PM_2.5 emission rate (which can further be converted to an emission factor) from wheat conveying operations at a large wheat pile storage facility in eastern Washington using an atmospheric tracer ratio method, with CO₂ gas as the tracer. The field study results yield an emission rate of 5.2$\pm$1.7 grams of PM_2.5 per hour and these emissions are due to the transfer point from an upper belt to a lower belt. This rate is approximately 320 times lower than the emission rate for headhouse operations which has been used previously to represent conveyor operations. The emission rate was in relatively good agreement with results of an inverse Gaussian plume model calculation of emissions using measured ambient PM_2.5 levels at a very short distance downwind of the transfer point. A consistent PM_2.5 to tracer gas ratio over the tests showed that PM_2.5 and CO₂ disperse in a similar manner and confirmed that the CO₂ tracer release was a reliable simulation of the PM_2.5 pollutant source over distances involved in the study (less than 10 meters). The results also indicate a need for the Environmental Protection Agency to develop a designated PM_2.5 emission factor for wheat conveyance.

Implications

There are presently no emission factors available for large wheat pile storage facilities where wheat is transferred via long horizontal conveyor belts. As a result, local and state permitting agencies use emission factors for other types of grain handling systems. In this paper, we report the first measurements of PM_2.5 emission rates (that can further be converted to emission factors using a known grain rate on the conveyor) for horizontal grain conveyors used at wheat pile storage facilities. The measured emission rate is much less than the emission rate derived from the surrogate emission factor currently used for permit purposes. This has implications for the size and operation of wheat pile storage facilities.

中文翻译：

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大气示踪比法在小麦堆存储设施中小麦运输作业中PM2.5排放率估算中的应用。

颗粒物（PM）污染与对人类健康和环境的不利影响有关。卧式谷物输送机没有指定的PM _2.5排放因子。取而代之的是，在华盛顿州，空气许可机构使用排放因子进行顶空作业和谷物处理操作，以颁发许可证。令人担心的是，该因素不能准确地代表输送机的运行，并限制了小麦堆场设施的规模和运行。这项工作的主要目的是使用大气示踪比法和CO ₂估算华盛顿州东部一家大型小麦堆存储设施中的小麦运输作业的PM _2.5排放率（可以进一步转换为排放因子）。气体作为示踪剂。现场研究结果表明排放率为5.2$\pm$每小时1.7克PM _2.5，这些排放是由于从上皮带到下皮带的转移点造成的。该速率比顶空作业的排放速率低约320倍，顶空作业的排放速率先前已用于表示输送机作业。排放率与逆高斯羽状流模型的计算结果相对吻合，该模型使用了测量的环境PM _2.5水平在转换点顺风处很短的距离进行排放。测试中一致的PM _2.5与示踪气体比率表明PM _2.5和CO ₂以相似的方式分散，并确认CO ₂示踪剂释放是PM _2.5的可靠模拟研究涉及的距离（小于10米）内的污染物来源。结果还表明，环境保护局需要为小麦运输制定指定的PM _2.5排放因子。

含义

当前，没有通过大型水平堆放传送带转移小麦的大型小麦堆存储设施的排放因子。结果，地方和州许可机构将排放因子用于其他类型的谷物处理系统。在本文中，我们报告了小麦堆存储设施中使用的卧式谷物输送机的PM _2.5排放率的首次测量（可以使用输送机上已知的谷物率将其进一步转换为排放因子）。测得的排放速率远小于目前用于许可目的的替代排放因子得出的排放速率。这对小麦堆存储设施的规模和运行有影响。