Tracing of aerosol sources in an urban environment using chemical, Sr isotope, and mineralogical characterization

Duarte, Regina M. B. O.; Matos, João T. V.; Paula, Andreia S.; Lopes, Sónia P.; Ribeiro, Sara; Santos, José Francisco; Patinha, Carla; da Silva, Eduardo Ferreira; Soares, Rosário; Duarte, Armando C.

Tracing of aerosol sources in an urban environment using chemical, Sr isotope, and mineralogical characterization

2017

In the framework of two national research projects (ORGANOSOL and CN-linkAIR), fine particulate matter (PM₂.₅) was sampled for 17 months at an urban location in the Western European Coast. The PM₂.₅ samples were analyzed for organic carbon (OC), water-soluble organic carbon (WSOC), elemental carbon (EC), major water-soluble inorganic ions, mineralogical, and for the first time in this region, strontium isotope (⁸⁷Sr/⁸⁶Sr) composition. Organic matter dominates the identifiable urban PM₂.₅ mass, followed by secondary inorganic aerosols. The acquired data resulted also in a seasonal overview of the carbonaceous and inorganic aerosol composition, with an important contribution from primary biomass burning and secondary formation processes in colder and warmer periods, respectively. The fossil-related primary EC seems to be continually present throughout the sampling period. The ⁸⁷Sr/⁸⁶Sr ratios were measured on both the labile and residual PM₂.₅ fractions as well as on the bulk PM₂.₅ samples. Regardless of the air mass origin, the residual fractions are more radiogenic (representative of a natural crustal dust source) than the labile fractions, whose ⁸⁷Sr/⁸⁶Sr ratios are comparable to that of seawater. The ⁸⁷Sr/⁸⁶Sr ratios and the mineralogical composition data further suggest that sea salt and mineral dust are important primary natural sources of fine aerosols throughout the sampling period.

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