Widory, D. (David)
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- Elucidating the sources and dynamics of PM10 aerosols in Cienfuegos (Cuba) using their multi-stable and radioactive isotope and ion compositions(Elsevier, 2020) Morera-Gómez, Y. (Yasser); Alonso-Hernández, C. M. (Carlos Manuel); Cartas-Aguila, H.A. (Héctor A.); Santamaria-Ulecia, J.M. (Jesús Miguel); Elustondo, D. (David); Lasheras, E. (Esther); Bagur, M. (Marjorie); Widory, D. (David)In this study, PM10 aerosol samples were collected at 4 urban and 1 rural sites in the region of Cienfuegos (Cuba) and analyzed for their chemical compositions (total carbon (TC), total nitrogen (TN), NH4+, Cl−, NO3− and SO42−) and their stable carbon (δ13C) and nitrogen (δ15N), and radioactive (210Pb, 7Be, 137Cs and 40K) isotope systematics, in order to better constrain both their sources of pollution and their atmospheric dynamics. The average PM10 concentrations varied from 21.67 ± 8.54 μg m−3 at the rural site to 39.01 ± 8.23 μg m−3 at an urban site characterized by high road traffic. Chemical compositions showed low variability and similar abundances of the ionic species, but we observed strong correlations between i) NH4+ and SO42− that indicates the formation of secondary ammonium bisulfate (NH4HSO4), and ii) between PM10 and TC highlighting the significant influence of carbonaceous aerosols. We are reporting here the first 210Pb aerosol concentrations in this region and demonstrate that, coupled with the corresponding 7Be concentrations, they allow characterizing the dynamics of the regional continental air masses. δ13C values in PM10 appear to be controlled by i) emissions from different types of combustion sources, including fossil fuel and biomass burning and ii) carbonate inputs from the industrial activities located around the limestone quarries, east of the city. δ15N values presented large isotope variations that can be explained by kinetic processes and the exchange between gas (NH3) and particle (NH4+) phases during the formation of secondary NH4HSO4, a reaction that was enhanced as Cl− concentrations decreased, revealing the preponderant role of local emissions in the budget of the aerosol nitrogen. This study confirms that isotope analysis is reliable for tracing the origin of aerosols and highlight the importance of a multi-isotope approach.
- Carbonaceous fractions contents and carbon stable isotope compositions of aerosols collected in the atmosphere of montreal (Canada): seasonality, dources, and implications(Original Research, 2021) Morera-Gómez, Y. (Yasser); Cong, Z. (Zhiyuan); Widory, D. (David)With the objective of better understanding the sources and dynamics of carbonaceous fractions of the aerosols present in the atmosphere of Montreal, we implemented here an online wet oxidation/isotope ratio mass spectrometry (IRMS) method to simultaneously measure both water-soluble organic carbon (WSOC) content and the corresponding δ 13C of aerosol samples collected at four monitoring stations over a 1- year period representing distinct types of environmental conditions (i.e., background, road traffic, industrial, and downtown). We coupled these data with the corresponding concentrations of other carbon fractions: total carbon (TC), elemental carbon plus organic carbon (EC + OC), and carbonates. Results show that TC (6.64 ± 2.88 µg m−3 ), EC + OC (4.98 ± 2.23 µg m−3 ), and carbonates (1.71 ± 1.09 µg m−3 ) were characterized by lower concentrations in winter and higher ones between spring and early autumn, with all fractions expectedly showing significantly lower concentrations for aerosols collected at the background station. We observed a seasonal dependence of the δ 13CEC + OC (−25.31 ± 0.94h) with the EC + OC/total suspended particles (TSP) ratio: (i) an increase of the ratio during late spring, summer and early autumn associated to road traffic emissions characterized by a δ 13C of ∼ −25h and (ii) lower ratios during the winter months indicating the influence of two distinct emission sources, a first one with a δ 13C ∼ −27h, suggesting the local influence of combined biomass burning from residential heating and of fossil fuel combustion, and a second one with a δ 13C ∼ −21h, likely related to more regional emissions. WSOC (1.14 ± 0.67 µg m−3 ) presented a similar seasonal pattern for all monitoring stations, with low concentrations in winter, early spring and late autumn that rapidly increased until summer. Our results indicate that this seasonality is controlled by higher anthropogenic contributions from southern Canada and northeastern United States regions and probably from biogenic emissions during the warm months. Moreover, δ 13CWSOC (−25.08 ± 1.47h) showed a 13Cdepletion in summer, indicating higher fossil fuel and biogenic contributions, whereas the higher isotope compositions observed in winter may result from the photochemical aging of regional aerosols. Ultimately, we identified the influence of local industrial emissions late in 2013 as well as the impact of aerosol emissions associated to the Lac-Mégantic rail disaster that occurred on July 6, ∼200 km east of Montreal.
- Carbon and nitrogen isotopes unravels sources of aerosol contamination at caribbean rural and urban coastal sites(Elsevier, 2018) Morera-Gómez, Y. (Yasser); Santamaria-Ulecia, J.M. (Jesús Miguel); Elustondo, D. (David); Alonso-Hernández, C. M. (Carlos Manuel); Widory, D. (David)The constant increase of anthropogenic emissions of aerosols, usually resulting from a complex mixture from various sources, leads to a deterioration of the ambient air quality. The stable isotope compositions (δ13C and δ15N) of total carbon (TC) and nitrogen (TN) in both PM10 and emissions from potential sources were investigated for first time in a rural and an urban Caribbean costal sites in Cuba to better constrain the origin of the contamination. Emissions from road traffic, power plant and shipping emissions were discriminated by coupling their C and N contents and corresponding isotope signatures. Other sources (soil, road dust and cement plant), in contrast, presented large overlapping ranges for both C and N isotope compositions. δ13CPM10 isotope compositions in the rural (average of −25.4 ± 1.2‰) and urban (average of −24.8 ± 1.2‰) sites were interpreted as a mixture of contributions from two main contributors: i) fossil fuel combustion and ii) cement plant and quarries. Results also showed that this last source is impacting more air quality at the urban site. A strong influence from local wood burning was also identified at the rural site. These conclusions were comforted by a statistical analysis using a conditional bivariate probability function. TN and δ15N values from the urban site demonstrated that nitrogen in PM10 was generated by secondary processes through the formation of (NH4)2SO4. The exchange in the (NH4)2SO4 molecule between gaseous NH3 and particle NH4+ under stoichiometric equilibrium may control the observed 15N enrichment. At low nitrogen concentrations in the aerosols, representing PM10 with both the highest primary N and lowest secondary N proportions, comparison with the δ15N of potential sources indicate that emissions from diesel car and power plant emissions may represent the major vectors of primary nitrogen.
- Contents, distribution and sources of lanthanoid elements in rural and urban atmospheric particles in Cienfuegos (Cuba)(Elsevier, 2020) Morera-Gómez, Y. (Yasser); Alonso-Hernández, C. M. (Carlos Manuel); Widory, D. (David); Lasheras, E. (Esther); Santamaria-Ulecia, J.M. (Jesús Miguel); Elustondo, D. (David)This study investigates the contents, distribution patterns, and sources of lanthanoid elements (La to Lu) in aerosols with an aerodynamic diameter ≤10 μm (PM10) in a coastal Caribbean region in order to better constrain the origin of the atmospheric PM contamination. We sampled and analysed PM10 aerosols during 2015 simultaneously at a rural and an urban site in Cienfuegos (Cuba) as well as particles samples from regional contamination sources. Results showed that the sum of the studied lanthanoids concentrations ranged from 0.03 to 13.42 ng m−3 and from 0.51 to 18.75 ng m−3 at the rural and the urban site, respectively. Time variations for the lanthanoid concentrations displayed similar trends and showed that the highest concentrations corresponded to the influence of the African dust for both sites, but presented distinct variability and lower concentrations when dust intrusions were less frequent. The lanthanoid distribution patterns in the rural and urban sites were significantly different, due to the impact of different local combustion sources. Our results were comforted by comparing the degree of fractionation of the lighter and heavier lanthanoids and the δEu and δCe anomalies between our PM10 samples and those of the local sources of contamination. Ultimately, we highlight the added value of lanthanoid elements as reliable indicators for discriminating emission sources and for tracking the origin of atmospheric particulate matter.