Abstract Number: 46 Working Group: Aerosol Chemistry
Abstract Exposure to metals from fine and ultrafine particles (UFP, < 100 nm) is of major health concern, especially in heavily industrialized areas. This study aims to better characterize the metal fraction of fine (PM2.5) and UFP emitted in an industrial-marked urban context (Dunkirk harbour, France) and to determine their lung bioaccessibility, in relation with their health impact. UFP and PM2.5 have been collected in specific environments: (i) in an urban area influenced by traffic and industrial emissions and (ii) at the stacks and in the vicinity of a ferromanganese plant, characteristic of the industrial activity in Dunkirk. Metals pulmonary bioaccessibility was determined using a synthetic lung fluid (Gamble solution), and compared to a 4-step sequential extraction method, in order to infer metal speciation. In the urban area, UFP elemental concentrations are primarily related to local sources (traffic and domestic heating), while larger submicronic particles (100 nm to 1 µm) are mainly affected by industrial sources, especially metallurgical plants, the main source of particulate metals in this area. Metal-rich (and low bioaccessible) UFP high concentrations (60% of the total PM2.5 mass) are observed in stack flues and then decrease rapidly in the vicinity of the plant, due to fast changes in temperature and humidity. In parallel, this low metal bioaccessibility increases quickly in the near field, mostly due to mixing processes with other particles sources. This bioaccessibility varies also according to the particle properties (metals chemical speciation and particle size distribution), their origin and formation processes. Far from the industrial zone, the metal bioaccessibility may also be affected by physicochemical transformations of fine particles occurring during atmospheric transport (mixing/agglomeration, aggregation, oxidation or reduction processes). The in-vitro bioaccessibility assessment is of interest to better understand the metal bioavailability and thus for a better appreciation of the health impact of toxic metals.