Characterization of PM2.5 and PM10 fugitive dust source profiles in the Athabasca Oil Sands Region

Geological samples were collected from 27 representative locations in the Athabasca Oil Sands Region (AOSR) in Alberta, Canada. These samples were resuspended onto filter substrates for PM2.5 and PM10 size fractions. Samples were analyzed for 229 chemical species, consisting of elements, ions, carbon, and organic compounds. These chemical species are normalized to gravimetric mass to derive individual source profiles. Individual profiles were grouped into six categories typical of those used in emission inventories: paved road dust, unpaved road dust close to and distant from oil sand operations, overburden soil, tailings sands, and forest soils. Consistent with their geological origin, the major components are minerals, organic and elemental carbon, and ions. The sum of five major elements (i.e., Al, Si, K, Ca, and Fe) and their oxidized forms account for 25–40% and 45–82% of particulate matter (PM) mass, respectively. Si is the most abundant element, averaging 17–18% in the Facility (oil sand operations) and 23–27% in the Forest profiles. Organic carbon is the second most abundant species, averaging 9–11% in the Facility and 5–6% in the Forest profiles. Elemental carbon abundance is 2–3 times higher in Facility than Forest profiles. Sulfate abundance is ~7 times higher in the Facility than in the Forest profiles. The ratios of cation/anion and base cation (sum of Na+, Mg2+, K+, and Ca2+)/nitrogen- and sulfur-containing ions (sum of NH4+, NO2-, NO3-, and SO42-) exceed unity, indicating that the soils are basic. Lead (Pb) isotope ratios of facility soils are similar to the AOSR stack and diesel emissions, while those of forest soils have much lower 206Pb/207Pb and 208Pb/207Pb ratios. High-molecular-weight n-alkanes (C25-C40), hopanes, and steranes are more than an order of magnitude more abundant in Facility than Forest profiles. These differences may be useful for separating anthropogenic from natural sources of fugitive dust at receptors.Implications: Several organic compounds typical of combustion emissions and bitumen are enriched relative to forest soils for fugitive dust sources near oil sands operations, consistent with deposition uptake by biomonitors. AOSR dust samples are alkaline, not acidic, indicating that potential acid deposition is neutralized. Chemical abundances are highly variable within emission inventory categories, implying that more specific subcategories can be defined for inventory speciation.研究样本采集自加拿大阿尔伯塔省阿萨巴斯卡油砂矿区（Athabasca Oil Sands Region, AOSR）的27个代表性点位。将这些样本重悬浮于滤膜基质上，以获取PM2.5与PM10粒径分级的颗粒物样品。对样本中的229种化学组分进行了分析，涵盖元素、离子、碳质组分以及有机化合物。将这些化学组分按重量归一化，以构建单一大气污染源谱。将各单污染源谱归为排放清单中常用的六大类别：铺装道路扬尘、距油砂作业区近距与远距的非铺装道路扬尘、剥离层土壤、尾矿砂以及森林土壤。与样本的地质起源相符，颗粒物的主要组分为矿物、有机碳、元素碳以及离子类物质。五种主要元素（即铝Al、硅Si、钾K、钙Ca与铁Fe）及其氧化形态的总占比分别占颗粒物（PM）总质量的25%~40%与45%~82%。硅是含量最高的元素，在作业区（油砂作业场地）源谱中平均占比为17%~18%，在森林土壤源谱中则为23%~27%。有机碳为第二丰富的组分，在作业区源谱中平均占比为9%~11%，在森林土壤源谱中为5%~6%。作业区源谱中的元素碳含量是森林土壤源谱的2~3倍。作业区源谱中的硫酸盐含量约为森林土壤源谱的7倍。阳/阴离子比值以及碱阳离子（Na+、Mg2+、K+与Ca2+的总和）与含氮、含硫离子（NH4+、NO2-、NO3-与SO42-的总和）的比值均大于1，表明该区域土壤呈碱性。作业区土壤的铅（Pb）同位素比值与AOSR区域的烟囱排放及柴油发动机排放相似，而森林土壤的206Pb/207Pb与208Pb/207Pb比值则显著更低。高分子量正构烷烃（C25~C40）、藿烷与甾烷在作业区源谱中的含量较森林土壤源谱高出一个数量级以上。这些组分差异可用于区分受体点位处扬尘的人为来源与自然来源。研究启示：相较于森林土壤，油砂作业区附近的扬尘源中存在若干典型燃烧排放与沥青相关的有机组分富集现象，这与生物监测器的沉降摄取结果一致。AOSR区域的扬尘样品呈碱性而非酸性，表明潜在的酸性沉降已被中和。同一排放清单类别内的化学组分占比存在显著差异，这意味着可针对清单的组分表征定义更细分的子类别。