scholarly journals Fast airborne aerosol size and chemistry measurements above Mexico City and Central Mexico during the MILAGRO campaign

2008 ◽  
Vol 8 (14) ◽  
pp. 4027-4048 ◽  
Author(s):  
P. F. DeCarlo ◽  
E. J. Dunlea ◽  
J. R. Kimmel ◽  
A. C. Aiken ◽  
D. Sueper ◽  
...  
Keyword(s):  
Urban Area ◽  
Mexico City ◽  
Atomic Ratio ◽  
Central Mexico ◽  
Strongly Correlated ◽  
Aerosol Mass ◽  
Biogenic Voc ◽  
Strong Source ◽  
The Stability ◽  
Photochemical Age

Abstract. The concentration, size, and composition of non-refractory submicron aerosol (NR-PM1) was measured over Mexico City and central Mexico with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) onboard the NSF/NCAR C-130 aircraft as part of the MILAGRO field campaign. This was the first aircraft deployment of the HR-ToF-AMS. During the campaign the instrument performed very well, and provided 12 s data. The aerosol mass from the AMS correlates strongly with other aerosol measurements on board the aircraft. Organic aerosol (OA) species dominate the NR-PM1 mass. OA correlates strongly with CO and HCN indicating that pollution (mostly secondary OA, SOA) and biomass burning (BB) are the main OA sources. The OA to CO ratio indicates a typical value for aged air of around 80 μg m−3 (STP) ppm−1. This is within the range observed in outflow from the Northeastern US, which could be due to a compensating effect between higher BB but lower biogenic VOC emissions during this study. The O/C atomic ratio for OA is calculated from the HR mass spectra and shows a clear increase with photochemical age, as SOA forms rapidly and quickly overwhelms primary urban OA, consistent with Volkamer et al. (2006) and Kleinman et al. (2008). The stability of the OA/CO while O/C increases with photochemical age implies a net loss of carbon from the OA. BB OA is marked by signals at m/z 60 and 73, and also by a signal enhancement at large m/z indicative of larger molecules or more resistance to fragmentation. The main inorganic components show different spatial patterns and size distributions. Sulfate is regional in nature with clear volcanic and petrochemical/power plant sources, while the urban area is not a major regional source for this species. Nitrate is enhanced significantly in the urban area and immediate outflow, and is strongly correlated with CO indicating a strong urban source. The importance of nitrate decreases with distance from the city likely due to evaporation. BB does not appear to be a strong source of nitrate despite its high emissions of nitrogen oxides, presumably due to low ammonia emissions. NR-chloride often correlates with HCN indicating a fire source, although other sources likely contribute as well. This is the first aircraft study of the regional evolution of aerosol chemistry from a tropical megacity.

scholarly journals Fast airborne aerosol size and chemistry measurements with the high resolution aerosol mass spectrometer during the MILAGRO Campaign

2007 ◽  
Vol 7 (6) ◽  
pp. 18269-18317 ◽  
Author(s):  
P. F. DeCarlo ◽  
E. J. Dunlea ◽  
J. R. Kimmel ◽  
A. C. Aiken ◽  
D. Sueper ◽  
...  
Keyword(s):  
High Resolution ◽  
Urban Area ◽  
Mass Spectrometer ◽  
Atomic Ratio ◽  
Strongly Correlated ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Biogenic Voc ◽  
Strong Source ◽  
The City

Abstract. The concentration, size, and composition of non-refractory submicron aerosol (NR-PM1) was measured over Mexico City and central Mexico with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) onboard the NSF/NCAR C-130 aircraft as part of the MILAGRO field campaign. This was the first aircraft deployment of the HR-ToF-AMS, in which the instrument performed very well, and provided 12 s data. The aerosol mass from the AMS correlates strongly with other aerosol measurements on board the aircraft. Organic aerosol (OA) species dominate the NR-PM1 mass. OA correlates strongly with CO and HCN indicating that pollution (mostly secondary OA, SOA) and biomass burning (BB) are the main OA sources. The OA to CO ratio indicates a typical value for aged air of around 80 μg m−3 (STP) ppm−1. This is within the range observed in outflow from the Northeastern US, which could be due to a compensating effect between higher BB but lower biogenic VOC emissions during this study. The O/C atomic ratio for OA is calculated from the HR mass spectra and shows a clear increase with photochemical age, as SOA forms rapidly and quickly overwhelms primary urban OA, consistent with Volkamer et al. (2006) and Kleinman et al. (2007b). BB OA is marked by signals at m/z 60 and 73, and also by a signal enhancement at large m/z indicative of larger molecules or more resistance to fragmentation. The main inorganic components show different spatial patterns and size distributions. Sulfate is regional in nature with clear volcanic and petrochemical/power plant sources, while the urban area is not a major source for this species. Nitrate is enhanced significantly in the urban area and immediate outflow, and is strongly correlated with CO indicating a strong urban source. The importance of nitrate decreases with distance from the city likely due to evaporation. BB does not appear to be a strong source of nitrate despite its high emissions of nitrogen oxides, presumably due to low ammonia emissions. NR-chloride often correlates with HCN indicating a fire source, although other sources likely contribute as well. This is the first aircraft study of the regional evolution of aerosol chemistry from a tropical megacity.

scholarly journals Investigation of the sources and processing of organic aerosol over the Central Mexican Plateau from aircraft measurements during MILAGRO

2010 ◽  
Vol 10 (12) ◽  
pp. 5257-5280 ◽  
Author(s):  
P. F. DeCarlo ◽  
I. M. Ulbrich ◽  
J. Crounse ◽  
B. de Foy ◽  
E. J. Dunlea ◽  
...  
Keyword(s):  
Mexico City ◽  
Biomass Burning ◽  
Forest Fires ◽  
Organic Aerosol ◽  
Impact Factors ◽  
Fire Intensity ◽  
High Time Resolution ◽  
Strongly Correlated ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass

Abstract. Organic aerosol (OA) represents approximately half of the submicron aerosol in Mexico City and the Central Mexican Plateau. This study uses the high time resolution measurements performed onboard the NCAR/NSF C-130 aircraft during the MILAGRO/MIRAGE-Mex field campaign in March 2006 to investigate the sources and chemical processing of the OA in this region. An examination of the OA/ΔCO ratio evolution as a function of photochemical age shows distinct behavior in the presence or absence of substantial open biomass burning (BB) influence, with the latter being consistent with other studies in polluted areas. In addition, we present results from Positive Matrix Factorization (PMF) analysis of 12-s High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) OA spectra. Four components were resolved. Three of the components contain substantial organic oxygen and are termed semivolatile oxygenated OA (SV-OOA), low-volatility OOA (LV-OOA), and biomass burning OA (BBOA). A reduced "hydrocarbon-like OA" (HOA) component is also resolved. LV-OOA is highly oxygenated (atomic O/C~1) and is aged organic aerosol linked to regional airmasses, with likely contributions from pollution, biomass burning, and other sources. SV-OOA is strongly correlated with ammonium nitrate, Ox, and the Mexico City Basin. We interpret SV-OOA as secondary OA which is nearly all (>90%) anthropogenic in origin. In the absence of biomass burning it represents the largest fraction of OA over the Mexico City basin, consistent with other studies in this region. BBOA is identified as arising from biomass burning sources due to a strong correlation with HCN, and the elevated contribution of the ion C2H4O2+ (m/z 60, a marker for levoglucosan and other primary BB species). WRF-FLEXPART calculated fire impact factors (FIF) show good correlation with BBOA mass concentrations within the basin, but show location offsets in the far field due to model transport errors. This component is small or absent when forest fires are suppressed by precipitation. Since PMF factors represent organic species grouped by chemical similarity, additional postprocessing is needed to more directly apportion OA amounts to sources, which is done here based on correlations to different tracers. The postprocessed AMS results are similar to those from an independent source apportionment based on multiple linear regression with gas-phase tracers. During a flight with very high forest fire intensity near the basin OA arising from open BB represents ~66% of the OA mass in the basin and contributes similarly to OA mass in the outflow. Aging and SOA formation of BB emissions is estimated to add OA mass equivalent to about ~32–42% of the primary BBOA over several hours to a day.

scholarly journals Investigation of the sources and processing of organic aerosol over the Central Mexican Plateau from aircraft measurements during MILAGRO

2010 ◽  
Vol 10 (2) ◽  
pp. 2445-2502 ◽  
Author(s):  
P. F. DeCarlo ◽  
I. M. Ulbrich ◽  
J. Crounse ◽  
B. de Foy ◽  
E. J. Dunlea ◽  
...  
Keyword(s):  
Mexico City ◽  
Biomass Burning ◽  
Forest Fires ◽  
Organic Aerosol ◽  
Impact Factors ◽  
Fire Intensity ◽  
High Time Resolution ◽  
Strongly Correlated ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass

Abstract. Organic aerosol (OA) represents approximately half of the submicron aerosol in Mexico City and the Central Mexican Plateau. This study uses the high time resolution measurements performed onboard the NCAR/NSF C-130 aircraft during the MILAGRO/MIRAGE-Mex field campaign in March 2006 to investigate the sources and chemical processing of the OA in this region. An examination of the OA/ΔCO ratio evolution as a function of photochemical age shows distinct behavior in the presence or absence of substantial open biomass burning (BB) influence, with the latter being consistent with other studies in polluted areas. In addition, we present results from Positive Matrix Factorization (PMF) analysis of 12-s High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) OA spectra. Four components were resolved. Three of the components contain substantial organic oxygen and are termed semivolatile oxygenated OA (SV-OOA), low-volatility OOA (LV-OOA), and biomass burning OA (BBOA). A reduced "hydrocarbon-like OA" (HOA) component is also resolved. LV-OOA is highly oxygenated (atomic O/C~1) and is aged organic aerosol linked to regional airmasses, with likely contributions from pollution, biomass burning, and other sources. SV-OOA is strongly correlated with ammonium nitrate, Ox, and the Mexico City Basin. We interpret SV-OOA as secondary OA which is nearly all (>90%) anthropogenic in origin. In the absence of biomass burning it represents the largest fraction of OA over the Mexico City basin, consistent with other studies in this region. BBOA is identified as arising from biomass burning sources due to a strong correlation with HCN, and the elevated contribution of the ion C2H4O2+ (m/z 60, a marker for levoglucosan and other primary BB species). WRF-FLEXPART calculated fire impact factors (FIF) show good correlation with BBOA mass concentrations within the basin, but show location offsets in the far field due to model transport errors. This component is small or absent when forest fires are suppressed by precipitation. Since PMF factors represent organic species grouped by chemical similarity, and this study spans a very large and continuous range of OA ages, additional postprocessing is needed to more directly apportion OA amounts to sources, which is done here based on correlations and regressions to key tracers. The postprocessed AMS results are similar to those from an independent source apportionment based on multiple linear regression with gas-phase tracers. During a flight with very high forest fire intensity near the basin OA arising from open BB represents ~66% of the OA mass in the basin and contributes similarly OA mass in the outflow. Aging and SOA formation of BB emissions is estimated to add OA mass equivalent to about ~32–42% of the primary BBOA over several hours to a day.

scholarly journals Estimating the Rainwater Potential per Household in an Urban Area: Case Study in Central Mexico

Water ◽  
2015 ◽  
Vol 7 (12) ◽  
pp. 4622-4637 ◽  
Author(s):  
Liliana Lizárraga-Mendiola ◽  
Gabriela Vázquez-Rodríguez ◽  
Alberto Blanco-Piñón ◽  
Yamile Rangel-Martínez ◽  
María González-Sandoval
Keyword(s):  
Urban Area ◽  
Central Mexico

Sentinel-1 InSAR survey to constrain subsidence-induced surface faulting and quantify its induced risk in major cities of central Mexico

2021 ◽  
Author(s):  
Francesca Cigna ◽  
Deodato Tapete
Keyword(s):  
Risk Assessment ◽  
Mexico City ◽  
Land Subsidence ◽  
Groundwater Resources ◽  
Urban Infrastructure ◽  
Capital City ◽  
Transport Infrastructure ◽  
Central Mexico ◽  
Groundwater Exploitation ◽  
Persistent Scatterers

<p>Several major cities in central Mexico suffer from aquifer depletion and land subsidence driven by overexploitation of groundwater resources to address increasing water demands for domestic, industrial and agricultural use. Ground settlement often combines with surface faulting, fracturing and cracking, causing damage to urban infrastructure, including private properties and public buildings, as well as transport infrastructure and utility networks. These impacts are very common and induce significant economic loss, thus representing a key topic of concern for inhabitants, authorities and stakeholders. This work provides an Interferometric Synthetic Aperture Radar (InSAR) 2014-2020 survey based on parallel processing of Sentinel-1 IW big data stacks within ESA’s Geohazards Exploitation Platform (GEP), using hosted on-demand services based on multi-temporal InSAR methods including Small BAseline Subset (SBAS) and Persistent Scatterers Interferometry (PSI). Surface faulting hazard is constrained based on differential settlement observations and the estimation of angular distortions that are produced on urban structures. The assessment of the E-W deformation field and computation of horizontal strain also allows the identification of hogging (tensile strain or extension) and sagging (compression) zones, where building cracks are more likely to develop at the highest and lowest elevations, respectively. Sentinel-1 observations agree with in-situ observations, static GPS surveying and continuous GNSS monitoring data. The distribution of field surveyed faults and fissures compared with maps of angular distortions and strain also enables the identification of areas with potentially yet-unmapped and incipient ground discontinuities. A methodology to embed such information into the process of surface faulting risk assessment for urban infrastructure is proposed and demonstrated for the Metropolitan Area of Mexico City [1], one of the fastest sinking cities globally (up to 40 cm/year subsidence rates), and the state of Aguascalientes [2], where a structurally-controlled fast subsidence process (over 10 cm/year rates) affects the namesake valley and capital city. The value of this research lies in the demonstration that InSAR data and their derived parameters are not only essential to constrain the deformation processes, but can also serve as a direct input into risk assessment to quantify (at least, as a lower bound) the percentage of properties and population at risk, and monitor how this percentage may change as land subsidence evolves.</p><p>[1] Cigna F., Tapete D. 2021. Present-day land subsidence rates, surface faulting hazard and risk in Mexico City with 2014–2020 Sentinel-1 IW InSAR. <em>Remote Sens. Environ.</em> 253, 1-19, doi:10.1016/j.rse.2020.112161</p><p>[2] Cigna F., Tapete D. 2021. Satellite InSAR survey of structurally-controlled land subsidence due to groundwater exploitation in the Aguascalientes Valley, Mexico. <em>Remote Sens. Environ.</em> 254, 1-23, doi:10.1016/j.rse.2020.112254</p>

scholarly journals Particulate organic nitrates observed in an oil and natural gas production region during wintertime

2015 ◽  
Vol 15 (16) ◽  
pp. 9313-9325 ◽  
Author(s):  
L. Lee ◽  
P. J. Wooldridge ◽  
J. deGouw ◽  
S. S. Brown ◽  
T. S. Bates ◽  
...  
Keyword(s):  
Field Measurements ◽  
Atomic Ratio ◽  
Gas Production ◽  
Heterogeneous Reactions ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Production Region ◽  
Aerosol Mass ◽  
Oil And Natural Gas ◽  
Aerosol Volume

Abstract. Organic nitrates in both gas and condensed (aerosol) phases were measured during the Uintah Basin Winter Ozone Study from January to February in 2012. A high degree of correlation between total aerosol volume at diameters less than 500 nm and the particulate organic nitrate concentration indicates that organic nitrates are a consistent, if not dominant, fraction of fine aerosol mass. In contrast, a similar correlation with sub-2.5 μm aerosol volume is weaker. The C : N atomic ratio inferred from field measurements of PM2.5 and particulate organic nitrate is 34 : 1. Calculations constrained by the observations indicate that both condensation of gas-phase nitrates and heterogeneous reactions of NO3 / N2O5 are responsible for introducing organic nitrate functionality into the aerosol and that the source molecules are alkanes. Extrapolating the results to urban aerosol suggests organic nitrate production from alkanes may be a major secondary organic aerosol source.

scholarly journals Morphometric Differences in Testicular Tissue of Tadarida brasiliensis Bats from the Urban Area of Mexico City During Summer, Autumn, and Winter

2013 ◽  
Vol 31 (3) ◽  
pp. 932-936
Author(s):  
Juan J Pérez-Rivero ◽  
Emilio Rendon-Franco ◽  
Mario Pérez-Martínez ◽  
Alejandro Ávalos-Rodríguez ◽  
Rafael Ávila-Flores
Keyword(s):  
Urban Area ◽  
Mexico City ◽  
Testicular Tissue ◽  
Tadarida Brasiliensis ◽  
Autumn And Winter

scholarly journals Mexico City aerosol analysis during MILAGRO using high resolution aerosol mass spectrometry at the urban supersite (T0) – Part 1: Fine particle composition and organic source apportionment

2009 ◽  
Vol 9 (2) ◽  
pp. 8377-8427 ◽  
Author(s):  
A. C. Aiken ◽  
D. Salcedo ◽  
M. J. Cubison ◽  
J. A. Huffman ◽  
P. F. DeCarlo ◽  
...  
Keyword(s):  
High Resolution ◽  
Mexico City ◽  
Biomass Burning ◽  
Emissions Inventory ◽  
Secondary Sources ◽  
Diurnal Cycles ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry ◽  
Order Of Magnitude ◽  
Primary Emissions

Abstract. Submicron aerosol was analyzed during the MILAGRO field campaign in March 2006 at the T0 urban supersite in Mexico City with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and complementary instrumentation. Mass concentrations, diurnal cycles, and size distributions of inorganic and organic species are similar to results from the CENICA supersite in April 2003 with organic aerosol (OA) comprising about half of the fine PM mass. Positive Matrix Factorization (PMF) analysis of the high resolution OA spectra identified three major components: chemically-reduced urban primary emissions (hydrocarbon-like OA, HOA), oxygenated OA (OOA, mostly secondary OA or SOA), and biomass burning OA (BBOA) that correlates with levoglucosan and acetonitrile. BBOA includes several very large plumes from regional fires and likely also some refuse burning. A fourth OA component is a small local nitrogen-containing reduced OA component (LOA) which accounts for 9% of the OA mass but one third of the organic nitrogen, likely as amines. OOA accounts for almost half of the OA on average, consistent with previous observations. OA apportionment results from PMF-AMS are compared to the PM2.5 chemical mass balance of organic molecular markers (CMB-OMM, from GC/MS analysis of filters). Results from both methods are overall consistent. Both assign the major components of OA to primary urban, biomass burning/woodsmoke, and secondary sources at similar magnitudes. The 2006 Mexico City emissions inventory underestimates the urban primary PM2.5 emissions by a factor of ~4, and it is ~16 times lower than afternoon concentrations when secondary species are included. Additionally, the forest fire contribution is underestimated by at least an order-of-magnitude in the inventory.

scholarly journals Characterization of ambient aerosols in Mexico City during the MCMA-2003 campaign with Aerosol Mass Spectrometry – Part I: quantification, shape-related collection efficiency, and comparison with collocated instruments

2005 ◽  
Vol 5 (3) ◽  
pp. 4143-4182 ◽  
Author(s):  
D. Salcedo ◽  
K. Dzepina ◽  
T. B. Onasch ◽  
M. R. Canagaratna ◽  
Q. Zhang ◽  
...  
Keyword(s):  
Mexico City ◽  
Mass Concentration ◽  
Collection Efficiency ◽  
Beam Width ◽  
Soil Mass ◽  
Emission Spectrometry ◽  
Ambient Aerosols ◽  
Pixe Analysis ◽  
Aerosol Mass ◽  
Beam Broadening

Abstract. An Aerodyne Aerosol Mass Spectrometer (AMS) was deployed at the CENICA Supersite, while another was deployed in the Aerodyne Mobile Laboratory (AML) during the Mexico City Metropolitan Area field study (MCMA-2003) from 31 March–4 May 2003 to investigate particle concentrations, sources, and processes. This is the first of a series of papers reporting the AMS results from this campaign. The AMS provides real time information on mass concentration and composition of the non-refractory species in particulate matter less than 1 µm (NR-PM1) with high time and size-resolution. For the first time, we report field results from a beam width probe, which was used to study the shape and mixing state of the particles and to quantify potential losses of irregular particles due to beam broadening inside the AMS. Data from this probe show that no significant amount of irregular particles was lost due to excessive beam broadening. A comparison of the CENICA and AML AMSs measurements is presented, being the first published intercomparison between two quadrupole AMSs. The speciation, and mass concentrations reported by the two AMSs compared relatively well. The differences found are likely due to the different inlets used in both instruments. In order to account for the refractory material in the aerosol, we also present measurements of Black Carbon (BC) using an aethalometer and an estimate of the aerosol soil component obtained from Proton-Induced X-ray Emission Spectrometry (PIXE) analysis of impactor substrates. Comparisons of AMS + BC + soil mass concentration with other collocated particle instruments (a LASAIR Optical Particle Counter, a Tapered Element Oscillating Microbalance (TEOM) and a DustTrak Aerosol Monitor) are also presented. The comparisons show that the AMS + BC + soil mass concentration during MCMA-2003 is a good approximation to the total PM2.5 mass concentration.

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