Croatian Northern Adriatic is an area lacking information on aerosol chemical composition including its organic aerosol chemical composition due to the lack of state-of-the-art measurements and modeling. Understanding the ambient concentrations of Croatian Northern Adriatic aerosol and their sources and transformations also has regional significance for air quality affecting all Adriatic Sea countries (Italy, Slovenia, Croatia, Montenegro and Albania) and Mediterranean region. Significant increase of the PM10 was observed in the summer of 2015 from September 14 – 19 during 5-weeks daily, continuous off-line aerosol sampling with High Volume Air Samplers in the city of Rijeka, Croatia. The same increase in aerosol ambient concentrations was recorded at the several ground based measurement stations in city of Rijeka wider area. Regionally, similar increase in PM10 was measured at the several background stations operated by Italian Regional Environmental Protection Agency of region Marche (ARPAM). Increase in Aerosol Optical Depth (AOD) up to 0.7 was measured by NASA MODIS instruments aboard the Terra and Aqua satellites over Tyrrhenian and Adriatic Sea and land area of Northern Italy and Croatia thus providing additional evidence of dust outbreak. To study the observed aerosol’s increase, we applied WRF-Chem 3.7.1 on-line with MOZART chemical mechanism in combination with two aerosol modules: MOZART-GOCART (chem_opt = 112) and MOZART-MOSAIC (chem_opt=201). Chemical boundary conditions were obtained from MOZART global model, anthropogenic emission sources (with anthro_emiss preprocessor) from EDGAR-HTAP data base and biogenic emissions from MEGAN model. Gaseous dry deposition was simulated by Wesely scheme. Despite the coarse WRF-Chem grid resolution, for both chemical options, preliminary results show high model skill in simulating PM10 when model results are compared to ground measurements in Italy and Croatia. WRF-Chem overestimates PM10 concentrations which is more pronounced when MOZART-GOCART option is applied. Further work will be based on verification of model AOD values with MODIS data and adjusting tuning coefficients to the surface dust emission flux in order to reduce the PM10 values overestimated by model.
A multifaceted approach to atmospheric aerosol analysis is often desirable in field studies where an understanding of technical comparability among different measurement techniques is essential. Herein, we report quantitative intercomparisons of particle-induced X-ray emission (PIXE) and proton elastic scattering analysis (PESA), performed offline under a vacuum, with analysis by aerosol mass spectrometry (AMS) carried out in real-time during the MCMA-2003 Field Campaign in the Mexico City Metropolitan Area. Good agreement was observed for mass concentrations of PIXE-measured sulfur (assuming it was dominated by SO42−) and AMS-measured sulfate during most of the campaign. PESA-measured hydrogen mass was separated into sulfate H and organic H mass fractions, assuming the only major contributions were (NH4)2SO4 and organic compounds. Comparison of the organic H mass with AMS organic aerosol measurements indicates that about 75% of the mass of these species evaporated under a vacuum. However ∼25% of the organics does remain under a vacuum, which is only possible with low-vapor-pressure compounds, and which supports the presence of high-molecular-weight or highly oxidized organics consistent with atmospheric aging. Approximately 10% of the chloride detected by AMS was measured by PIXE, possibly in the form of metal−chloride complexes, while the majority of Cl was likely present as more volatile species including NH4Cl. This is the first comparison of PIXE/PESA and AMS and, to our knowledge, also the first report of PESA hydrogen measurements for urban organic aerosols.
The Sarajevo Canton Winter Field Campaign 2018 (SAFICA) was a project that took place in winter 2017-2018 with an aim to characterize the chemical composition of aerosol in the Sarajevo Canton, Bosnia and Herzegovina (BiH), which has one of the worst air qualities in Europe. This paper presents the first characterization of the metals in PM10 (particulate matter aerodynamic diameters ≤10 μm) from continuous filter samples collected during an extended two-months winter period at the urban background Sarajevo and remote Ivan Sedlo sites. We report the results of 18 metals detected by inductively coupled plasma mass spectrometry (ICP-MS) and electrothermal atomic absorption spectrometry (ETAAS). The average mass concentrations of metals were higher at the Sarajevo site than at Ivan Sedlo and ranged from 0.050 ng/m3 (Co) to 188 ng/m3 (Fe) and from 0.021 ng/m3 (Co) to 61.8 ng/m3 (Fe), respectively. The BenMAP-CE model was used for estimating the annual BiH health (50% decrease in PM2.5 would save 4760+ lives) and economic benefits (costs of $2.29B) of improving the air quality. Additionally, the integrated energy and health assessment with the ExternE model provided an initial estimate of the additional health cost of BiH's energy system.
Abstract. Two Aerodyne Aerosol Mass Spectrometers (Q-AMS) were deployed in Mexico City, during the Mexico City Metropolitan Area field study (MCMA-2003) from 29 March–4 May 2003 to investigate particle concentrations, sources, and processes. We report the use of a particle beam width probe (BWP) in the field to quantify potential losses of particles due to beam broadening inside the AMS caused by particle shape (nonsphericity) and particle size. Data from this probe show that no significant mass of particles was lost due to excessive beam broadening; i.e. the shape- and size-related collection efficiency (Es) of the AMS during this campaign was approximately one. Comparison of the BWP data from MCMA-2003 with other campaigns shows that the same conclusion holds for several other urban, rural and remotes sites. This means that the aerodynamic lens in the AMS is capable of efficiently focusing ambient particles into a well defined beam and onto the AMS vaporizer for particles sampled in a wide variety of environments. All the species measured by the AMS during MCMA-2003 have similar attenuation profiles which suggests that the particles that dominate the mass concentration were internally mixed most of the time. Only for the smaller particles (especially below 300 nm), organic and inorganic species show different attenuation versus particle size which is likely due to partial external mixing of these components. Changes observed in the focusing of the particle beam in time can be attributed, in part, to changes in particle shape (i.e. due to relative humidity) and size of the particles sampled. However, the relationships between composition, atmospheric conditions, and particle shape and size appear to be very complex and are not yet completely understood.
Abstract The role of aqueous multiphase chemistry in the formation of secondary organic aerosol (SOA) remains difficult to quantify. We investigate it here by testing the rapid formation of moderate oxygen‐to‐carbon (O/C) SOA during a case study in Mexico City. A novel laboratory‐based glyoxal‐SOA mechanism is applied to the field data, and explains why less gas‐phase glyoxal mass is observed than predicted. Furthermore, we compare an explicit gas‐phase chemical mechanism for SOA formation from semi‐ and intermediate‐volatility organic compounds (S/IVOCs) with empirical parameterizations of S/IVOC aging. The mechanism representing our current understanding of chemical kinetics of S/IVOC oxidation combined with traditional SOA sources and mixing of background SOA underestimates the observed O/C by a factor of two at noon. Inclusion of glyoxal‐SOA with O/C of 1.5 brings O/C predictions within measurement uncertainty, suggesting that field observations can be reconciled on reasonable time scales using laboratory‐based empirical relationships for aqueous chemistry.
