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首页> 外文期刊>Atmospheric environment >Mass size distributions and size resolved chemical composition of fine particulate matter at the Pittsburgh supersite
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Mass size distributions and size resolved chemical composition of fine particulate matter at the Pittsburgh supersite

机译：匹兹堡超级站点的细颗粒物的质量尺寸分布和尺寸分解的化学成分

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Size-resolved aerosol mass and chemical composition were measured during the Pittsburgh Air Quality Study. Daily samples were collected for 12 months from July 2001 to June 2002. Micro-orifice uniform deposit impactors (MOUDIs) were used to collect aerosol samples of fine paniculate matter smaller than 10 μm. Measurements of PM_(0.056), PM_(0.10), PM_(0.18), PM_(0.32), PM_(0.56), PM_(1.0), PM_(1.8) and PM_(2.5) with the MOUDI are available for the full study period. Seasonal variations in the concentrations are observed for all size cuts. Higher concentrations are observed during the summer and lower during the winter. Comparison between the PM_(2.5) measurements by the MOUDI and other integrated PM samplers reveals good agreement. Good correlation is observed for PM_(10) between the MOUDI and an integrated sampler but the MOUDI underestimates PM_(10) by 20%. Bouncing of particles from higher stages of the MOUDI (>PM_(2.5)) is not a major problem because of the low concentrations of coarse particles in the area. The main cause of coarse particle losses appears to be losses to the wall of the MOUDI. Samples were collected on aluminum foils for analysis of carbonaceous material and on Teflon filters for analysis of particle mass and inorganic anions and cations. Daily samples were analyzed during the summer (July 2001) and the winter intensives (January 2002). During the summer around 50% of the organic material is lost from the aluminum foils as compared to a filter-based sampler. These losses are due to volatilization and bounce-off from the MOUDI stages. High nitrate losses from the MOUDI are also observed during the summer (above 70%). Good agreement between the gravimetrically determined mass and the sum of the masses of the individual compounds is obtained, if the lost mass from organics and the aerosol water content are included for the summer. For the winter no significant losses of material are detected and there exists reasonable agreement between the gravimetrical mass and the sum of the concentrations of the individual compounds. Ultrafine particles (below 100 nm) account on average, for < 5% of the PM_(2.5) mass, and show different composition for the summer and the winter. During the summer the ultrafine mass is 50% carbonaceous material (organic material and elemental carbon) and 50% inorganic (mainly sulfate and ammonium); during the winter these percentages are 70% and 30%, respectively.
机译：在匹兹堡空气质量研究期间测量了尺寸分辨的气溶胶质量和化学成分。从2001年7月到2002年6月，每天采样12个月。使用微孔均匀沉积撞击器（MOUDI）收集小于10μm的细颗粒物质的气溶胶样品。使用MOUDI进行PM_（0.056），PM_（0.10），PM_（0.18），PM_（0.32），PM_（0.56），PM_（1.0），PM_（1.8）和PM_（2.5）的测量可用于整个研究期。对于所有尺寸的削减，均观察到浓度的季节性变化。在夏季观察到较高的浓度，而在冬季观察到较低的浓度。 MOUDI和其他集成式PM采样器对PM_（2.5）的测量结果之间的比较显示出良好的一致性。观察到MOUDI和集成采样器之间的PM_（10）具有良好的相关性，但是MOUDI低估了PM_（10）20％。由于MOUDI的较高阶段（> PM_（2.5））反弹的粒子不是主要问题，因为该区域中的粗粒子浓度较低。粗颗粒损失的主要原因似乎是MOUDI壁的损失。将样品收集在铝箔上以分析含碳材料，并收集在Teflon过滤器上以分析颗粒质量以及无机阴离子和阳离子。在夏季（2001年7月）和冬季密集区（2002年1月）对每日样本进行了分析。在夏季，与基于过滤器的采样器相比，约有50％的有机材料从铝箔中流失。这些损失是由于MOUDI阶段的挥发和反弹。在夏季也观察到MOUDI中硝酸盐的大量流失（超过70％）。如果包括夏季有机物的损失质量和气溶胶水含量，则重量测定的质量与各个化合物的质量之和之间将取得良好的一致性。在冬季，没有发现重大的材料损失，重量质量与单个化合物的浓度之和之间存在合理的一致性。超细颗粒（低于100 nm）平均占PM_（2.5）质量的5％以下，并且在夏季和冬季显示出不同的组成。在夏季，超细物质是50％的含碳物质（有机物质和元素碳）和50％的无机物质（主要是硫酸盐和铵盐）；在冬季，这些百分比分别为70％和30％。

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