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首页> 外文期刊>Environmental Science & Technology >Particulate-Phase and Gaseous Elemental Mercury Emissions During Biomass Combustion: Controlling Factors and Correlation with Particulate Matter Emissions
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Particulate-Phase and Gaseous Elemental Mercury Emissions During Biomass Combustion: Controlling Factors and Correlation with Particulate Matter Emissions

机译：生物质燃烧过程中的颗粒相和气态元素汞排放：控制因素和与颗粒物排放的相关性

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Mercury emissions from wildfires are significant natural sources of atmospheric mercury, but little is known about what controls speciation of emissions important to mercury deposition processes. The goal of this study was to quantify gaseous elemental mercury (GEM) and particulate-phase mercury (PHg) emissions from biomass combustion to identify key factors controlling the speciation. Emissions were characterized in an exhaust stack 17 m above fires using a gaseous mercury analyzer and quartz-fiber filters. Fuels included fresh and air-dried leaves, needles, and branches with different fuel moistures (9-95% of dry weight) and combustion properties (e.g., from <10 to 90% of fire durations characterized by flaming phases). Fuel moisture was the overall driving factor defining emissions, with GEM being the dominant fraction (>95%) in low moisture fuels and substantial PHg contributions-up to 50% of total mercury emissions-in fresh fuels. High PHg emissions were observed during smoldering combustion whereas flaming-dominated fires showed insignificant PHg emissions. PHg mass emissions were correlated with paniculate matter (PM; r~2 = 0.67), organic carbon (OC; r~2 = 0.63) and sulfur (S; r~2 = 0.46) mass emissions, but not with elemental carbon (EC) nor with the total mercury emissions. These data suggest that the formation of PHg involves similar processes as the formation of particulate OC, for example condensation of volatile species onto preexisting smoke particles during cooling and dilution. Based on the observed relationship between PM and OC mass concentrations and published emission inventories, we estimate global PHg emissions by wildfires of 4-5 Mg yrr~(-1).
机译：野火产生的汞排放是大气中汞的重要自然来源，但对于控制对汞沉积过程重要的排放物形态的控制知之甚少。这项研究的目的是量化生物质燃烧产生的气态元素汞（GEM）和颗粒相汞（PHg）排放量，以确定控制物种形成的关键因素。使用气态汞分析仪和石英纤维过滤器，在火灾上方17 m处的排气烟囱中对排放进行表征。燃料包括新鲜的和风干的叶，针和具有不同燃料水分（干重的9-95％）和燃烧特性（例如，以燃烧相为特征的燃烧持续时间的<10％至90％）的树枝。燃料水分是决定排放的总体驱动因素，在低水分燃料中，GEM是主要成分（> 95％），在新鲜燃料中，PHg的贡献最大，占汞排放总量的50％。在阴燃燃烧过程中观察到较高的PHg排放，​​而以火焰为主的火势显示微不足道的PHg排放。 PHg质量排放与颗粒物质（PM; r〜2 = 0.67），有机碳（OC; r〜2 = 0.63）和硫（S; r〜2 = 0.46）相关，而与元素碳（EC ）或总汞排放量。这些数据表明，PHg的形成与颗粒状OC的形成过程类似，例如，在冷却和稀释过程中，挥发性物质会凝结在预先存在的烟雾颗粒上。根据观测到的PM和OC质量浓度与已公布的排放清单之间的关系，我们估计4-5 Mg yrr〜（-1）的野火造成的全球PHg排放。

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