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Keywords: carbonaceous aerosol, organic aerosol
Published in RUNG: 10.05.2024; Views: 11; Downloads: 0
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Keywords: covid, aerosol, traffic, PM
Published in RUNG: 10.05.2024; Views: 11; Downloads: 0
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Abstract: The evolution of fine aerosol (PM1) species as well as the contribution of potential sources to the total organic aerosol (OA) at an urban background site in Barcelona, in the western Mediterranean basin (WMB) was investigated. For this purpose, a quadrupole aerosol chemical speciation monitor (Q-ACSM) was deployed to acquire real-time measurements for two 1-year periods: May 2014–May 2015 (period A) and September 2017–October 2018 (period B). Total PM1 concentrations showed a slight decrease (from 10.1 to 9.6 μgm�3 from A to B), although the relative contribution of inorganic and organic compounds varied significantly. Regarding inorganic compounds, SO42- , black carbon(BC) and NH4+ showed a significant decrease from period A to B (21 %, 18% and 9 %, respectively), whilst NO3- concentrations were higher in B (8 %). Source apportionment revealed OA contained 46% and 70% secondary OA (SOA) in periods A and B, respectively. Two secondary oxygenated OA sources (OOA) were differentiated by their oxidation status (i.e. ageing): less oxidized (LO-OOA) and more oxidized (MO-OOA). Disregarding winter periods, when LO-OOA production was not favoured, LO-OOA transformation into MO-OOA was found to be more effective in period B. The lowest LO-OOA-to-MO-OOA ratio, excluding winter, was in September–October 2018 (0.65), implying an accumulation of aged OA after the high temperature and solar radiation conditions in the summer season. In addition to temperature, SOA (sum of OOA factors) was enhanced by exposure to NOx-polluted ambient and other pollutants, especially to O3 and during afternoon hours. The anthropogenic primary OA sources identified, cooking-related OA (COA), hydrocarbon-like OA (HOA), and biomass burning OA (BBOA), decreased from period A to B in both absolute concentrations and relative contribution (as a whole, 44% and 30 %, respectively). However, their concentrations and proportion to OA grew rapidly during highly polluted episodes. The influence of certain atmospheric episodes on OA sources was also assessed. Both SOA factors were boosted with long- and medium-range circulations, especially those coming from inland Europe and the Mediterranean (triggering mainly MO-OOA) and summer breeze-driven regional circulation (mainly LO-OOA). In contrast, POA was enhanced either during air-renewal episodes or stagnation anticyclonic events.
Keywords: aerosol, organic aerosol, source apportionment, PM1, particulate matter
Published in RUNG: 10.05.2024; Views: 11; Downloads: 0
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Abstract: Atmospheric mineral dust consists of tiny mineral particles that are emitted by wind erosion from arid regions. Its particle size distribution (PSD) affects its impact on the Earth's system. Nowadays, there is an incomplete understanding of the emitted dust PSD and a lot of debate about its variability. Here, we try to address these issues based on the measurements performed during a wind erosion and dust emission field campaign in the Moroccan Sahara within the framework of FRAGMENT project.
Keywords: aerosol particles, mineral dust, emission processes, climate
Published in RUNG: 23.10.2023; Views: 934; Downloads: 5
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Abstract: La Paz and El Alto are two fast-growing, high-altitude Bolivian cities forming the second-largest metropolitan area in the country. Located between 3200 and 4050 m a.s.l. (above sea level), these cities are home to a burgeoning population of approximately 1.8 million residents. The air quality in this conurbation is heavily influenced by urbanization; however, there are no comprehensive studies evaluating the sources of air pollution and their health impacts. Despite their proximity, the substantial variation in altitude, topography, and socioeconomic activities between La Paz and El Alto result in distinct sources, dynamics, and transport of particulate matter (PM). In this investigation, PM10 samples were collected at two urban background stations located in La Paz and El Alto between April 2016 and June 2017. The samples were later analyzed for a wide range of chemical species including numerous source tracers (OC, EC, water-soluble ions, sugar anhydrides, sugar alcohols, trace metals, and molecular organic species). The United States Environmental Protection Agency (U.S. EPA) Positive Matrix Factorization (PMF v.5.0) receptor model was employed for the source apportionment of PM10. This is one of the first source apportionment studies in South America that incorporates an extensive suite of organic markers, including levoglucosan, polycyclic aromatic hydrocarbons (PAHs), hopanes, and alkanes, alongside inorganic species. The multisite PMF resolved 11 main sources of PM. The largest annual contribution to PM10 came from the following two major sources: the ensemble of the four vehicular emissions sources (exhaust and non-exhaust), accountable for 35 % and 25 % of the measured PM in La Paz and El Alto, respectively; and dust, which contributed 20 % and 32 % to the total PM mass. Secondary aerosols accounted for 22 % (24 %) in La Paz (El Alto). Agricultural smoke resulting from biomass burning in the Bolivian lowlands and neighboring countries contributed to 9 % (8 %) of the total PM10 mass annually, increasing to 17 % (13 %) between August–October. Primary biogenic emissions were responsible for 13 % (7 %) of the measured PM10 mass. Additionally, a profile associated with open waste burning occurring from May to August was identified. Although this source contributed only to 2 % (5 %) of the total PM10 mass, it constitutes the second largest source of PAHs, which are compounds potentially hazardous to human health. Our analysis additionally resolved two different traffic-related factors, a lubricant source (not frequently identified), and a non-exhaust emissions source. Overall, this study demonstrates that PM10 concentrations in La Paz and El Alto region are predominantly influenced by a limited number of local sources. In conclusion, to improve air quality in both cities, efforts should primarily focus on addressing dust, traffic emissions, open waste burning, and biomass burning.
Keywords: source apportionment, particular air pollution, high altitude, positive matrix factorization, PMF
Published in RUNG: 15.09.2023; Views: 799; Downloads: 5
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