El-Zanan Hazem S, Zielinska Barbara, Mazzoleni Lynn R, Hansen D Alan
Desert Research Institute, Reno, NV 89512, USA.
J Air Waste Manag Assoc. 2009 Jan;59(1):58-69. doi: 10.3155/1047-3289.59.1.58.
Particulate matter (PM) with an aerodynamic diameter < or = 2.5 microm (PM2.5) was collected daily (mid-July 1998 to the end of December 1999) over a 24-hr sampling period in a mixed light industrial-residential area in Atlanta, GA, to provide a subset of data for the Aerosol Research and Inhalation Epidemiology Study (ARIES). This study included the measurement of organic carbon (OC), elemental carbon (EC), and individual organic compounds. OC and EC average mean concentrations were 4.50 +/- 0.33 and 2.08 +/- 0.19 microg/m3, respectively. The ratio of organic matter mass (OM) to OC in PM2.5 aerosols in Atlanta was measured using three different approaches: (1) solvent extract residue gravimetric masses to individual OC concentrations of sequential apolar to polar solvent extracts (dichloromethane, acetone, and water); (2) mass balance of the PM2.5 measured gravimetric mass minus the mass concentrations of the inorganic/elemental constituents to the total OC concentration; and (3) polar organic compound speciation with the concentration weighted ratio to the total OC concentration. We found very good agreement between approach 1 and 2. The average OM/OC ratio calculated from the extract residue mass was 2.14 +/- 0.17. The average OM/OC ratio determined by mass balance was 2.16 +/- 0.43 for the whole period. The concentration weighted ratio calculated from the concentrations of polar organic compounds ranged between 1.55 and 1.72, which was likely a lower limit for the ratio because of the limited number of the polar organic compounds that can be quantified using gas chromatographic methods. We found seasonal differences with an OM/OC range of 1.77 in December 1999 to 2.39 in July 1999. These results suggest that the previously accepted value of 1.4 for the OM/OC ratio was too low even for urban locations during the winter months. Molecular-level speciation of the PM2.5-associated organic compounds showed that the concentrations of the molecular markers for wood smoke represented approximately 12-15% of the total polar organic compound concentrations during the winter months.
在佐治亚州亚特兰大市的一个工业与住宅混合区域，于1998年7月中旬至1999年12月底，每天在24小时采样期内收集空气动力学直径小于或等于2.5微米的颗粒物（PM2.5），以提供气溶胶研究与吸入流行病学研究（ARIES）的一部分数据。该研究包括对有机碳（OC）、元素碳（EC）和单个有机化合物的测量。OC和EC的平均浓度分别为4.50±0.33和2.08±0.19微克/立方米。使用三种不同方法测量了亚特兰大市PM2.5气溶胶中有机物质量（OM）与OC的比值：（1）依次用非极性到极性溶剂（二氯甲烷、丙酮和水）萃取后的溶剂萃取残余物重量法质量与单个OC浓度之比；（2）PM2.5重量法测量质量减去无机/元素成分质量浓度后的质量平衡与总OC浓度之比；（3）极性有机化合物形态分析，其浓度加权比与总OC浓度之比。我们发现方法1和方法2之间有很好的一致性。从萃取残余物质量计算出的平均OM/OC比值为2.14±0.17。整个时期通过质量平衡确定的平均OM/OC比值为2.16±0.43。根据极性有机化合物浓度计算的浓度加权比在1.55至1.72之间，由于可用气相色谱法定量的极性有机化合物数量有限，这可能是该比值的下限。我们发现存在季节差异，1999年12月的OM/OC范围为1.77，1999年7月为2.39。这些结果表明，即使在冬季城市地区，之前公认的OM/OC比值1.4也过低。与PM2.5相关的有机化合物的分子水平形态分析表明，冬季木材烟雾分子标志物的浓度约占总极性有机化合物浓度的12 - 15%。
