EMISSION AND CRUST ENRICHMENT FACTORS FOR TRACE ELEMENTS (PM2.5) EMITTED BY THE VEHICLE FLEET IN THE METROPOLITAN AREA OF SÃO PAULO, BRAZIL

Air pollution can cause several negative impacts on health and the environment. In large urban centers, this pollution is directly related to anthropogenic activities, mainly activities in the transportation sector. This study analyzed data on black carbon, fine particulate material (PM2.5) and its main trace elements from automotive vehicles (S, P, K, V, Cr, Fe, Cu, Ni, Zn, Cd, Br and Pb), collected during a long sampling period, carried out in the Metropolitan Area of São Paulo (MASP), Brazil. The filters used were analyzed by various analytical techniques, enabling the identification of the different elements present in the samples, their respective concentrations and the main sources of these pollutants and their contributions to the sampled total. Thus, it was possible to separate the total contributions of each source and use only the contributions of anthropogenic origin to define the emission factors (EF) and the crustal enrichment factors (EFc) for the different studied pollutants. We used these factors to compare different environments/studies. We chose two studies carried out previously, also in the MASP, in the Jânio Quadros (TJQ) and Rodoanel (TRA) tunnels, and found that these tunnels are respectively 2.3 and 3.8 times more polluted than the region from our study.

大气污染会对人体健康与生态环境造成诸多负面影响。在大型城市中心城区，这类污染与人为活动直接相关，其中尤以交通领域的活动为主要诱因。本研究针对巴西圣保罗都会区 (Metropolitan Area of São Paulo, MASP) 长期采样获取的数据集展开分析，该数据集涵盖黑碳 (black carbon)、细颗粒物 (fine particulate material, PM2.5) 及其来自机动车排放的主要痕量元素（硫S、磷P、钾K、钒V、铬Cr、铁Fe、铜Cu、镍Ni、锌Zn、镉Cd、溴Br以及铅Pb）。研究采用多种分析技术对实验所用的采样滤膜进行检测，从而实现对样品中各类元素的定性识别、各元素对应浓度的定量测定，以及此类污染物主要来源及其在采样总质量中占比的解析。借此可分离出各污染源的总贡献量，并仅以人为源的贡献份额为依据，为本次研究涉及的各类污染物确定排放因子 (emission factors, EF) 与地壳富集因子 (crustal enrichment factors, EFc)。研究人员借助上述因子对不同环境下的相关研究开展对比分析。我们选取了此前同样在圣保罗都会区开展的两项隧道监测研究——雅尼奥·夸德罗斯隧道 (Jânio Quadros, TJQ) 与罗多安尼尔隧道 (Rodoanel, TRA)，经对比发现这两座隧道的污染程度分别为本研究采样区域的2.3倍与3.8倍。