Edgerton Eric S, Casuccio Gary S, Saylor Rick D, Lersch Traci L, Hartsell Benjamin E, Jansen John J, Hansen D Alan
Atmospheric Research & Analysis, Inc., Cary, NC 27513, USA.
J Air Waste Manag Assoc. 2009 Jan;59(1):78-90. doi: 10.3155/1047-3289.59.1.78.
The organic carbon (OC) and elemental carbon (EC) content of filter-based, 24-hr integrated particulate matter with aerodynamic diameters between 2.5 and 10 microm (PM10-2.5) was measured at two urban and two rural locations in the southeastern United States. On average, total carbon (OC + EC) comprised approximately 30% of PM10-2.5 mass at these four sites. Carbonate carbon was measured on a subset of samples from three sites and was found to be undetectable at a rural site in central Alabama, less than 2% of PM10-2.5 at an urban site in Georgia, and less than 10% of PM10-2.5 at an urban-industrial site in Alabama. Manual scanning electron microscopy (SEM) and computer-controlled SEM (CCSEM) along with energy dispersive X-ray spectroscopy (EDS) were used to identify individual carbonaceous particles in a selected subset of samples collected at one rural site and one urban-industrial site in Alabama. CCSEM results showed that biological material (e.g., fungal spores, pollen, and vegetative detritus) accounted for 60-70% of the carbonaceous mass in PM10-2.5 samples with concentrations in the range of 2-16 microg/m3. Samples with higher PM10-2.5 concentrations (25-42 microg/m3) at the urban-industrial site were found by manual SEM to have significant amounts of unidentified carbonaceous material, likely originating from local industrial activities. Both filter-based OC and EC concentrations and SEM-identified biological material tended to have higher concentrations during warmer months. Upper limits for organic mass (OM) to OC ratios (OM/OC) are estimated for PM10-2.5 samples at 2.1 for urban sites and 2.6-2.7 for rural sites.
在美国东南部的两个城市和两个农村地点，对基于滤膜的、24小时综合采集的、空气动力学直径在2.5至10微米之间的颗粒物（PM10 - 2.5）中的有机碳（OC）和元素碳（EC）含量进行了测量。平均而言，在这四个地点，总碳（OC + EC）约占PM10 - 2.5质量的30%。对来自三个地点的部分样品测量了碳酸盐碳，发现在阿拉巴马州中部的一个农村地点未检测到，在佐治亚州的一个城市地点占PM10 - 2.5的比例不到2%，在阿拉巴马州的一个城市 - 工业地点占PM10 - 2.5的比例不到10%。利用手动扫描电子显微镜（SEM）、计算机控制扫描电子显微镜（CCSEM）以及能量色散X射线光谱（EDS），对在阿拉巴马州的一个农村地点和一个城市 - 工业地点采集的选定部分样品中的单个含碳颗粒进行了识别。CCSEM结果表明，生物物质（如真菌孢子、花粉和植物碎屑）占PM10 - 2.5样品中含碳质量的60 - 70%，浓度范围为2 - 16微克/立方米。通过手动SEM发现，城市 - 工业地点PM10 - 2.5浓度较高（25 - 42微克/立方米）的样品中有大量未识别的含碳物质，可能源自当地工业活动。基于滤膜的OC和EC浓度以及SEM识别出的生物物质在温暖月份往往浓度更高。估计城市地点PM10 - 2.5样品的有机质量（OM）与OC比率（OM/OC）上限为2.1，农村地点为2.6 - 2.7。
