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We collected 1 year of aerosol chemical speciation monitor (ACSM) data in Magadino, a village located in the south of the Swiss Alpine region, one of Switzerland's most polluted areas. We analysed the mass spectra of organic aerosol (OA) by positive matrix factorisation (PMF) using Source Finder Professional (SoFi Pro) to retrieve the origins of OA. Therein, we deployed a rolling algorithm, which is closer to the measurement, to account for the temporal changes in the source profiles. As the first-ever application of rolling PMF with multilinear engine (ME-2) analysis on a yearlong dataset that was collected from a rural site, we resolved two primary OA factors (traffic-related hydrocarbon-like OA (HOA) and biomass burning OA (BBOA)), one mass-to-charge ratio (m/z) 58-related OA (58-OA) factor, a less oxidised oxygenated OA (LO-OOA) factor, and a more oxidised oxygenated OA (MO-OOA) factor. HOA showed stable contributions to the total OA through the whole year ranging from 8.1 % to 10.1 %, while the contribution of BBOA showed an apparent seasonal variation with a range of 8.3 %–27.4 % (highest during winter, lowest during summer) and a yearly average of 17.1 %. OOA (sum of LO-OOA and MO-OOA) contributed 71.6 % of the OA mass, varying from 62.5 % (in winter) to 78 % (in spring and summer). The 58-OA factor mainly contained nitrogen-related variables which appeared to be pronounced only after the filament switched. However, since the contribution of this factor was insignificant (2.1 %), we did not attempt to interpolate its potential source in this work. The uncertainties (σ) for the modelled OA factors (i.e. rotational uncertainty and statistical variability in the sources) varied from ±4 % (58-OA) to a maximum of ±40 % (LO-OOA). Considering that BBOA and LO-OOA (showing influences of biomass burning in winter) had significant contributions to the total OA mass, we suggest reducing and controlling biomass-burning-related residential heating as a mitigation strategy for better air quality and lower PM levels in this region or similar locations. In Appendix A, we conduct a head-to-head comparison between the conventional seasonal PMF analysis and the rolling mechanism. We find similar or slightly improved results in terms of mass concentrations, correlations with external tracers, and factor profiles of the constrained POA factors. The rolling results show smaller scaled residuals and enhanced correlations between OOA factors and corresponding inorganic salts compared to those of the seasonal solutions, which was most likely because the rolling PMF analysis can capture the temporal variations in the oxidation processes for OOA components. Specifically, the time-dependent factor profiles of MO-OOA and LO-OOA can well explain the temporal viabilities of two main ions for OOA factors, m/z 44 (CO+2) and m/z 43 (mostly C2H3O+). Therefore, this rolling PMF analysis provides a more realistic source apportionment (SA) solution with time-dependent OA sources. The rolling results also show good agreement with offline Aerodyne aerosol mass spectrometer (AMS) SA results from filter samples, except for in winter. The latter discrepancy is likely because the online measurement can capture the fast oxidation processes of biomass burning sources, in contrast to the 24 h filter samples. This study demonstrates the strengths of the rolling mechanism, provides a comprehensive criterion list for ACSM users to obtain reproducible SA results, and is a role model for similar analyses of such worldwide available data., Atmospheric Chemistry and Physics, 21 (19), ISSN:1680-7375, ISSN:1680-7367

The Po Valley (Italy) is a well-known air quality hotspot characterized by particulate matter (PM) levels well above the limit set by the European Air Quality Directive and by the World Health Organization, especially during the colder season. In the framework of Emilia-Romagna regional project “Supersito”, the southern Po Valley submicron aerosol chemical composition was characterized by means of high-resolution aerosol mass spectroscopy (HR-AMS) with the specific aim of organic aerosol (OA) characterization and source apportionment. Eight intensive observation periods (IOPs) were carried out over 4 years (from 2011 to 2014) at two different sites (Bologna, BO, urban background, and San Pietro Capofiume, SPC, rural background), to characterize the spatial variability and seasonality of the OA sources, with a special focus on the cold season. On the multi-year basis of the study, the AMS observations show that OA accounts for averages of 45±8 % (ranging from 33 % to 58 %) and 46±7 % (ranging from 36 % to 50 %) of the total non-refractory submicron particle mass (PM1-NR) at the urban and rural sites, respectively. Primary organic aerosol (POA) comprises biomass burning (23±13 % of OA) and fossil fuel (12±7 %) contributions with a marked seasonality in concentration. As expected, the biomass burning contribution to POA is more significant at the rural site (urban / rural concentration ratio of 0.67), but it is also an important source of POA at the urban site during the cold season, with contributions ranging from 14 % to 38 % of the total OA mass. Secondary organic aerosol (SOA) contributes to OA mass to a much larger extent than POA at both sites throughout the year (69±16 % and 83±16 % at the urban and rural sites, respectively), with important implications for public health. Within the secondary fraction of OA, the measurements highlight the importance of biomass burning aging products during the cold season, even at the urban background site. This biomass burning SOA fraction represents 14 %–44 % of the total OA mass in the cold season, indicating that in this region a major contribution of combustion sources to PM mass is mediated by environmental conditions and atmospheric reactivity. Among the environmental factors controlling the formation of SOA in the Po Valley, the availability of liquid water in the aerosol was shown to play a key role in the cold season. We estimate that the organic fraction originating from aqueous reactions of biomass burning products (“bb-aqSOA”) represents 21 % (14 %–28 %) and 25 % (14 %–35 %) of the total OA mass and 44 % (32 %–56 %) and 61 % (21 %–100 %) of the SOA mass at the urban and rural sites, respectively.

New Delhi, India is the most polluted megacity in the world and routinely experiences high particulate matter (PM) concentrations. As part of the Delhi Aerosol Supersite Study, we have been measuring PM, concentration and composition in Delhi continuously since January 2017. This paper focuses on autumn, one of the most polluted seasons in Delhi when PM, concentrations steadily increase throughout the season and can exceed 1000 mu g m(-3) during episodic events. Positive matrix factorization on the organic aerosol (OA) spectrum suggests comparable seasonal average contributions from hydrocarbon-like OA (HOA), biomass burning OA (BBOA), and oxidized OA (OOA), with BBOA dominating during episodic events. We demonstrate the influence of regional sources such as agricultural burning during this season through temporal trends of pollutants, PMF factors, meteorology, and nonparametric wind regression analysis. We use inorganic fragment ratios to show the influence of metals during the festival of Diwali. Furthermore, we demonstrate the influence of transitioning meteorology in governing PM, composition through the season. Overall, our analysis provides novel insights into the factors controlling PM, during one of the most polluted seasons in Delhi.

Mit ihrem Buch "Ethnografie urbaner Territorien" bietet Monika STREULE eine Forschungsarbeit, die Anstöße für eine transdisziplinäre Stadtforschung gibt und sich komplexen Verhältnissen widmet. Mit einem Set von ethnografischen und kartografischen Methoden analysiert sie Urbanisierungsprozesse der Megametropole Mexiko-Stadt und regt dazu an, Stadtforschung nicht nur reflektiert und kritisch zu denken, sondern auch innovativ vorzugehen. In diesem Essay findet daher insbesondere eine Auseinandersetzung mit ihren methodischen und methodologischen Herangehensweisen statt., In her book "Ethnography of Urban Territories," Monika STREULE offers useful ideas and advice for transdisciplinary studies that are concerned with the complex conditions most often found in cities. She develops a tool box containing ethnographic and cartographic methods that are used to analyze urbanization processes in the mega metropolis Mexico-City. She encourages us to not only think of urban research more reflectively and critically, but also more innovatively. Therefore, in this article, the methodological approach in general and the used methods in particular will be discussed more thoroughly.

In Mexico-City, like in most metropolitan cities, intra-urban residential mobility is the main driving force behind the settlement pattern and reworking of the social division of space. In the colonias populares, illegal settlements which remain an inescapable feature of urban growth, the dull grey aspect of the block-built houses dominates the landscape and poverty is prevalent. However, these characteristics are insufficient to properly grasp these areas, where complex processes of inhabitants’ anchoring are at work. This paper aims to understand the mechanisms of residential anchorage and the relationship between the various forms of anchorage and the socio-spatial changes and developments. Reading the trajectories of the particular places through the prism of the inhabitants’ trajectories gives clues for understanding a certain maturation of the peripheral colonias populares. The analysis of residential mobility, through systematic sources (censuses, detailed samples) and exploratory surveys, can shed light on links between places and the variety of experiences of their inhabitants and contexts. These results, on the one hand, render insufficient the sole approach of studying socio-spatial relegation systematically followed by urban consolidation on and, on the other hand, reveal a socio-spatial stratification that would be poorly represented using the notion of fragmentation., La zona metropolitana del Valle de México, como la mayoría de las metrópolis, está caracterizada por un patrón de poblamiento donde la movilidad residencial intraurbana es el principal impulsor de la reorganización de la división social del espacio. En las colonias populares, construidas ilegalmente y siendo todavía una figura clave de la producción urbana, el color “gris” de los bloques de las casas domina y la pobreza sigue siendo importante. Sin embargo, estas características son insuficientes para entender estos espacios, donde se operan procesos complejos de anclaje de los residentes. El objetivo de este artículo es comprender los mecanismos de anclajes residenciales y las reconfiguraciones socio-espaciales que implican. La lectura de las trayectorias de los espacios a través de las trayectorias de sus habitantes permite acercar una cierta maduración de las colonias populares de la periferia de la metrópoli. A partir del análisis de la movilidad residencial, a través de fuentes sistemáticas (censo, muestras) y de investigaciones exploratorias, ha sido posible aclarar los sistemas de lugares – entre cuales hay vínculos dentro del espacio de vida de los habitantes – y la variedad de las experiencias de los habitantes y de los contextos. Estos resultados ponen en relieve el enfoque obsoleto único en términos de relegación socio-espacial seguida sistemáticamente por consolidación urbana por un lado, y revelan una estratificación socio-espacial mal definida por la noción de fragmentación por otro lado., Mexico est, comme la plupart des métropoles, marquée par une dynamique de peuplement où la mobilité résidentielle intra-urbaine est le principal moteur de la reconfiguration de la division sociale de l’espace. Dans les colonies populaires nées dans l’illégalité et restant encore une figure incontournable de la production urbaine, le « gris » des parpaings des maisons domine et la pauvreté est prégnante ; toutefois, ces caractéristiques sont insuffisantes pour résumer ces espaces, où s’opèrent des processus complexes d’ancrage des habitants. L’objectif de cet article est de comprendre les mécanismes de ces ancrages résidentiels et les recompositions socio-spatiales qu’ils impliquent. Lire la trajectoire des lieux au prisme des trajectoires de leurs habitants donne des clefs pour comprendre une certaine maturation des colonies populaires périphériques. En partant de l’analyse des mobilités résidentielles, à travers des sources systématiques (recensements, fichiers détail) et des enquêtes exploratoires, l’articulation des lieux et la variété des expériences des habitants et des contextes sont mises en lumière, rendant caduque une approche unique en termes de relégation socio-spatiale systématiquement suivie d’une consolidation urbaine d’une part, et révélant une stratification socio-spatiale mal restituée par la notion de fragmentation d’autre part.

Ground level ozone arises primarily from traffic, it is a powerful oxidant and its primary target organ is the lung. Most epidemiological studies reporting the health effects of ozone have estimated individual exposure from measurements obtained from outdoor monitors but surrogates of personal exposure may not adequately reflect personal exposures. Also, the main focus has been on infants and children. Our purpose was to assess associations between urban background ozone and indoor residential ozone levels as well as to investigate the effects of indoor residential ozone on lung function in 51 elderly non-smokers. Indoor ozone was measured passively in homes, while urban background outdoor ozone was monitored continuously at a fixed monitoring station located on the roof of the 20-m high university H.C. Ørsteds campus building in a park area. Lung function was measured at baseline as well as on three consecutive occasions, for each subject. The mean residential ozone levels were 1.33 ppb, and mean outdoor urban background levels were 27 ppb. Outdoor urban background ozone levels were not consistently associated with residential ozone. No significant changes in lung function were detected in association with residential ozone among healthy participants. In this study, we were unable to detect significant changes in lung function in association with increased levels of residential ozone amongst healthy elderly non-smokers.

We show for the first time quantitative online measurements of five nitrated phenol (NP) compounds in ambient air (nitrophenol C6H5NO3, methylnitrophenol C7H7NO3, nitrocatechol C6H5NO4, methylnitrocatechol C7H7NO4, and dinitrophenol C6H4N2O5) measured with a micro-orifice volatilization impactor (MOVI) high-resolution chemical ionization mass spectrometer in Detling, United Kingdom during January-February, 2012. NPs absorb radiation in the near-ultraviolet (UV) range of the electromagnetic spectrum and thus are potential components of poorly characterized light-absorbing organic matter ("brown carbon") which can affect the climate and air quality. Total NP concentrations varied between less than 1 and 98 ng m(-3), with a mean value of 20 ng m(-3). We conclude that NPs measured in Detling have a significant contribution from biomass burning with an estimated emission factor of 0.2 ng (ppb CO)(-1). Particle light absorption measurements by a seven-wavelength aethalometer in the near-UV (370 nm) and literature values of molecular absorption cross sections are used to estimate the contribution of NP to wood burning brown carbon UV light absorption. We show that these five NPs are potentially important contributors to absorption at 370 nm measured by an aethalometer and account for 4 ± 2% of UV light absorption by brown carbon. They can thus affect atmospheric radiative transfer and photochemistry and with that climate and air quality.

Background: There is evidence for adverse effects of outdoor air pollution on lung function of children. Quantitative summaries of the effects of air pollution on lung function, however, are lacking due to large differences among studies. Objectives: We aimed to study the association between residential exposure to air pollution and lung function in five European birth cohorts with a standardized exposure assessment following a common protocol. Methods: As part of the European Study of Cohorts for Air Pollution Effects (ESCAPE) we analyzed data from birth cohort studies situated in Germany, Sweden, the Netherlands, and the United Kingdom that measured lung function at 6–8 years of age (n = 5,921). Annual average exposure to air pollution [nitrogen oxides (NO2, NOx), mass concentrations of particulate matter with diameters < 2.5, < 10, and 2.5–10 μm (PM2.5, PM10, and PMcoarse), and PM2.5 absorbance] at the birth address and current address was estimated by land-use regression models. Associations of lung function with estimated air pollution levels and traffic indicators were estimated for each cohort using linear regression analysis, and then combined by random effects meta-analysis. Results: Estimated levels of NO2, NOx, PM2.5 absorbance, and PM2.5 at the current address, but not at the birth address, were associated with small decreases in lung function. For example, changes in forced expiratory volume in 1 sec (FEV1) ranged from –0.86% (95% CI: –1.48, –0.24%) for a 20-μg/m3 increase in NOx to –1.77% (95% CI: –3.34, –0.18%) for a 5-μg/m3 increase in PM2.5. Conclusions: Exposure to air pollution may result in reduced lung function in schoolchildren. Citation: Gehring U, Gruzieva O, Agius RM, Beelen R, Custovic A, Cyrys J, Eeftens M, Flexeder C, Fuertes E, Heinrich J, Hoffmann B, de Jongste JC, Kerkhof M, Klümper C, Korek M, Mölter A, Schultz ES, Simpson A, Sugiri D, Svartengren M, von Berg A, Wijga AH, Pershagen G, Brunekreef B. 2013. Air pollution exposure and lung function in children: the ESCAPE project. Environ Health Perspect 121:1357–1364; http://dx.doi.org/10.1289/ehp.1306770

We study the combined effects of land surface conditions, atmospheric boundary layer dynamics and chemistry on the diurnal evolution of biogenic secondary organic aerosol in the atmospheric boundary layer, using a model that contains the essentials of all these components. First, we evaluate the model for a case study in Hyytiälä, Finland, and find that it is able to satisfactorily reproduce the observed dynamics and gas-phase chemistry. We show that the exchange of organic aerosol between the free troposphere and the boundary layer (entrainment) must be taken into account in order to explain the observed diurnal cycle in organic aerosol (OA) concentration. An examination of the budgets of organic aerosol and terpene concentrations show that the former is dominated by entrainment, while the latter is mainly driven by emission and chemical transformation. We systematically investigate the role of the land surface, which governs both the surface energy balance partitioning and terpene emissions, and the large-scale atmospheric process of vertical subsidence. Entrainment is especially important for the dilution of organic aerosol concentrations under conditions of dry soils and low terpene emissions. Subsidence suppresses boundary layer growth while enhancing entrainment. Therefore, it influences the relationship between organic aerosol and terpene concentrations. Our findings indicate that the diurnal evolution of secondary organic aerosols (SOA) in the boundary layer is the result of coupled effects of the land surface, dynamics of the atmospheric boundary layer, chemistry, and free troposphere conditions. This has potentially some consequences for the design of both field campaigns and large-scale modeling studies.

Detailed comparisons of airborne CH2O measurements acquired by tunable diode laser absorption spectroscopy with steady state box model calculations were carried out using data from the 2006 INTEX-B and MILARGO campaign in order to improve our understanding of hydrocarbon oxidation processing. This study includes comparisons over Mexico (including Mexico City), the Gulf of Mexico, parts of the continental United States near the Gulf coast, as well as the more remote Pacific Ocean, and focuses on comparisons in the boundary layer. Select previous comparisons in other campaigns have highlighted some locations in the boundary layer where steady state box models have tended to underpredict CH2O, suggesting that standard steady state modeling assumptions might be unsuitable under these conditions, and pointing to a possible role for unmeasured hydrocarbons and/or additional primary emission sources of CH2O. Employing an improved instrument, more detailed measurement-model comparisons with better temporal overlap, up-to-date measurement and model precision estimates, up-to-date rate constants, and additional modeling tools based on both Lagrangian and Master Chemical Mechanism (MCM) runs, we have explained much of the disagreement between observed and predicted CH2O as resulting from non-steady-state atmospheric conditions in the vicinity of large pollution sources, and have quantified the disagreement as a function of plume lifetime (processing time). We show that in the near field (within ~4 to 6 h of the source), steady-state models can either over-or-underestimate observations, depending on the predominant non-steady-state influence. In addition, we show that even far field processes (10–40 h) can be influenced by non-steady-state conditions which can be responsible for CH2O model underestimations by ~20%. At the longer processing times in the 10 to 40 h range during Mexico City outflow events, MCM model calculations, using assumptions about initial amounts of high-order NMHCs, further indicate the potential importance of CH2O produced from unmeasured and multi-generation hydrocarbon oxidation compounds, particularly methylglyoxal, 3-hydroxypropanal, and butan-3-one-al.

Fourier Transform Infrared (FTIR) and X-ray Fluorescence (XRF) were used to measure organic functional groups and elements of submicron particles collected during MILAGRO in March 2006 on three platforms: the Mexico City urban area (SIMAT), the high altitude site at 4010 m (Altzomoni), and the NCAR C130 aircraft. Scanning transmission X-ray Microscopy (STXM) and Near-Edge X-ray Absorption Fine Structure (NEXAFS) were applied to single particle organic functional group abundance analysis of particles simultaneously collected at SIMAT and C130. Correlations of elemental concentrations showed different groups of source related elements at SIMAT, Altzomoni, and C130, suggesting different processes affecting the air masses sampled at the three platforms. Cluster analysis resulted in seven distinct Clusters of FTIR spectra, with the last three clusters consisting of spectra collected almost exclusively on the C130 platform, reflecting the variety of sources contributing to C130 samples. Positive Matrix Factorization (PMF) of NEXAFS-STXM spectra identified three main factors representing soot, secondary, and biomass burning type spectra. PMF of FTIR spectra resulted in three fossil fuel combustion type factors, one biomass burning factor, and one mixed or processed factor. The fossil fuel combustion type factors were found to have the largest contributions to OM, while the processed factor has the largest O/C among all factors. Alkane, carboxylic acid, and amine functional groups were mainly associated with combustion related sources, while alcohol groups were likely from atmospheric processing of mixed sources. While the processed factor has the highest O/C, half of the OM and O/C measured could be attributed directly to fossil fuel combustion sources. Both PMF of NEXAFS-STXM spectra and PMF of FTIR spectra indicate that the combustion type factors are more affected by fluctuations in local sources, while the processed factors are more consistent during the sampling period.

International audience; This article aims to observe the social division of Mexico-City space at the lowest available level, the block. Such an analysis, conducted from census data and empirical work seeks to question the dynamic through colonias populares in the outskirts of the city, so often read in terms of urban fragmentation and / or in terms of systematic consolidation. The construction of a typology according poverty indicators highlights the heterogeneity of socio-spatial forms of division. New contextual dimensions emerge and differentiate these neighborhoods, highlighting a plurality of maturation trajectories.; Cet article vise à observer la division sociale de l'espace de Mexico au niveau le plus fin disponible, celui de l'îlot. Une telle analyse, menée à partir des données censitaires et d'un travail empirique, cherche à questionner les dynamiques traversant les colonies populaires périphériques, alors souvent lues sous l'angle de la fragmentation urbaine et/ou sous celui de la consolidation systématique. La construction d'une typologie selon des indicateurs de pauvreté souligne l'hétérogénéité des formes socio-spatiales de division. De nouvelles dimensions contextuelles se dessinent et différencient ces quartiers, mettant en lumière une pluralité des trajectoires de maturation.

International audience; This article studies the social divisions of Mexico-City’s space at the smallest available level, the city block. Such an analysis, based on census data and empirical work, questions the dynamics that undercut the colonias populares in the city’s outskirts, which are often considered in terms of urban fragmentation and/or systematic consolidation. Constructing a typology with poverty indicators highlights the heterogeneity of socio-spatial forms of division. New contextual dimensions emerge and differentiate these neighborhoods, highlighting a plurality of maturation trajectories.; Cet article vise à observer la division sociale de l’espace de Mexico au niveau le plus fin disponible, celui de l’îlot. Une telle analyse, menée à partir des données censitaires et d’un travail empirique, cherche à s’interroger sur les dynamiques traversant les colonias populares périphériques, souvent lues sous l’angle de la fragmentation urbaine et/ou sous celui de la consolidation systématique. La construction d’une typologie selon des indicateurs de pauvreté souligne l’hétérogénéité des formes socio-spatiales de division. De nouvelles dimensions contextuelles se dessinent et différencient ces quartiers, mettant en lumière une pluralité des trajectoires de maturation.

This doctoral thesis explores the recomposition of colonias populares on the outskirts of the metropolitan area of Mexico-City for twenty years. Links between spatial mobility, living spaces of residents in informal settlements and strategies of physical and legal regularization are enlightened though social, demographic and political evolutions. The dynamic and heterogeneous characteristics of colonias populares was examined through two conceptual tools for the study of urban territoriality: the anchorage, as a point of view on the experiences of people; maturation, in order to analyze changes in residential settings. The trajectories of maturation have been understood from the analysis of systematic demographic data and from empirical work in four areas. Once the framework presented, the contexts of maturation were observed in three inputs: social, mobility, and political. Plural trajectories of this maturation were analyzed from the point of view of the anchorage: we tried to understand the pathways leading to the actual visible diversity. We described the residential routes of inhabitants, their urban experiences, more particularly in relation to the resources of the area, the complex dynamics of land and planning regularization and changes in the social division of space. Finally, these neighborhoods are becoming increasingly heterogeneous and "common" compared to the rest of the city, revealing the obsolescence of a single reading in terms of poverty or legal marginality., En esta tesis de doctorado, se analiza la recomposición de las colonias populares de la periferia de la Zona Metropolitana de México desde veinte años. Los vínculos entre la movilidad espacial, los espacios de vida de los residentes de los asentamientos irregulares, y las estrategias de regularización legal y física se examinan a la luz de factores sociales, demográficos y políticos. El rasgo dinámico y diverso de las colonias populares se examinó a través de dos herramientas conceptuales para el estudio de la territorialidad urbana: el anclaje, para tener un punto de vista de las experiencias de los individuos; la maduración, para analizar los cambios en entornos residenciales. Las trayectorias de maduración son entendidas a partir del análisis sistemático de los datos demográficos y del trabajo empírico en cuatro grupos de colonias. Después de la presentación del marco de estudio, se observaron los contextos de la maduración con tres entradas: social, sobre la movilidad, y política. Las trayectorias plurales de esta maduración se analizaron desde el punto de vista del anclaje, tratando de entender las vías que conducen a la diversidad visible hoy. Llegamos a describir a las rutas residenciales de los habitantes, sus experiencias urbanas, particularmente en relación con los recursos de la zona, la dinámica compleja de la regularización del suelo y de la planificación, y los cambios en la división social del espacio. Al final, estas colonias son cada vez más heterogéneas y "triviales" en comparación con el resto de la ciudad, dejando al descubierto la obsolescencia de una sola lectura en términos de pobreza o marginalidad., Cette thèse étudie les recompositions des colonies populaires périphériques de la zone métropolitaine de Mexico depuis vingt ans. Les liens entre les mobilités spatiales, les espaces de vie des habitants dans des quartiers illégaux à l’origine, et les stratégies de régularisation physique et juridique sont interrogés au regard des évolutions sociales, démographiques et politiques. Le caractère dynamique et divers des colonies populaires a été examiné à travers deux outils conceptuels de l’étude des territorialités urbaines : l’ancrage, point de vue sur les expériences des individus ; la maturation, pour analyser les changements des contextes résidentiels. Les trajectoires de maturation ont été comprises à partir de l’analyse de données sociodémographiques systématiques et d’un travail empirique dans quatre quartiers.Une fois le cadre de travail présenté, les contextes de la maturation ont été observés selon trois entrées : sociale, relative aux mobilités, et politico-juridique. Les trajectoires plurielles de cette maturation ont ensuite été analysées du point de vue de l’ancrage, en tentant de comprendre les chemins ayant conduit à la diversité visible aujourd’hui : il s’est agi de décrire les itinéraires résidentiels des habitants, leurs expériences citadines, en particulier par rapport aux ressources de la proximité, les dynamiques de régularisation foncière et urbanistique dans leur complexité et les évolutions de la division sociale de l’espace. Au final, ces quartiers deviennent de plus en plus hétérogènes et « banals » par rapport au reste de la ville, révélant l’obsolescence d’une lecture unique en termes de pauvreté ou de marginalité juridique.

This doctoral thesis explores the recomposition of colonias populares on the outskirts of the metropolitan area of Mexico-City for twenty years. Links between spatial mobility, living spaces of residents in informal settlements and strategies of physical and legal regularization are enlightened though social, demographic and political evolutions. The dynamic and heterogeneous characteristics of colonias populares was examined through two conceptual tools for the study of urban territoriality: the anchorage, as a point of view on the experiences of people; maturation, in order to analyze changes in residential settings. The trajectories of maturation have been understood from the analysis of systematic demographic data and from empirical work in four areas. Once the framework presented, the contexts of maturation were observed in three inputs: social, mobility, and political. Plural trajectories of this maturation were analyzed from the point of view of the anchorage: we tried to understand the pathways leading to the actual visible diversity. We described the residential routes of inhabitants, their urban experiences, more particularly in relation to the resources of the area, the complex dynamics of land and planning regularization and changes in the social division of space. Finally, these neighborhoods are becoming increasingly heterogeneous and "common" compared to the rest of the city, revealing the obsolescence of a single reading in terms of poverty or legal marginality.; En esta tesis de doctorado, se analiza la recomposición de las colonias populares de la periferia de la Zona Metropolitana de México desde veinte años. Los vínculos entre la movilidad espacial, los espacios de vida de los residentes de los asentamientos irregulares, y las estrategias de regularización legal y física se examinan a la luz de factores sociales, demográficos y políticos. El rasgo dinámico y diverso de las colonias populares se examinó a través de dos herramientas conceptuales para el estudio de la territorialidad urbana: el anclaje, para tener un punto de vista de las experiencias de los individuos; la maduración, para analizar los cambios en entornos residenciales. Las trayectorias de maduración son entendidas a partir del análisis sistemático de los datos demográficos y del trabajo empírico en cuatro grupos de colonias. Después de la presentación del marco de estudio, se observaron los contextos de la maduración con tres entradas: social, sobre la movilidad, y política. Las trayectorias plurales de esta maduración se analizaron desde el punto de vista del anclaje, tratando de entender las vías que conducen a la diversidad visible hoy. Llegamos a describir a las rutas residenciales de los habitantes, sus experiencias urbanas, particularmente en relación con los recursos de la zona, la dinámica compleja de la regularización del suelo y de la planificación, y los cambios en la división social del espacio. Al final, estas colonias son cada vez más heterogéneas y "triviales" en comparación con el resto de la ciudad, dejando al descubierto la obsolescencia de una sola lectura en términos de pobreza o marginalidad.; Cette thèse étudie les recompositions des colonies populaires périphériques de la zone métropolitaine de Mexico depuis vingt ans. Les liens entre les mobilités spatiales, les espaces de vie des habitants dans des quartiers illégaux à l’origine, et les stratégies de régularisation physique et juridique sont interrogés au regard des évolutions sociales, démographiques et politiques. Le caractère dynamique et divers des colonies populaires a été examiné à travers deux outils conceptuels de l’étude des territorialités urbaines : l’ancrage, point de vue sur les expériences des individus ; la maturation, pour analyser les changements des contextes résidentiels. Les trajectoires de maturation ont été comprises à partir de l’analyse de données sociodémographiques systématiques et d’un travail empirique dans quatre quartiers. Une fois le cadre de travail présenté, les contextes de la maturation ont été observés selon trois entrées : sociale, relative aux mobilités, et politico-juridique. Les trajectoires plurielles de cette maturation ont ensuite été analysées du point de vue de l’ancrage, en tentant de comprendre les chemins ayant conduit à la diversité visible aujourd’hui : il s’est agi de décrire les itinéraires résidentiels des habitants, leurs expériences citadines, en particulier par rapport aux ressources de la proximité, les dynamiques de régularisation foncière et urbanistique dans leur complexité et les évolutions de la division sociale de l’espace. Au final, ces quartiers deviennent de plus en plus hétérogènes et « banals » par rapport au reste de la ville, révélant l’obsolescence d’une lecture unique en termes de pauvreté ou de marginalité juridique.

The performance of the Weather Research and Forecasting regional model with chemistry (WRF-Chem) in simulating the spatial and temporal variations in aerosol mass, composition, and size over California is quantified using the extensive meteorological, trace gas, and aerosol measurements collected during the California Nexus of Air Quality and Climate Experiment (CalNex) and the Carbonaceous Aerosol and Radiative Effects Study (CARES) conducted during May and June of 2010. The overall objective of the field campaigns was to obtain data needed to better understand processes that affect both climate and air quality, including emission assessments, transport and chemical aging of aerosols, aerosol radiative effects. Simulations were performed that examined the sensitivity of aerosol concentrations to anthropogenic emissions and to long-range transport of aerosols into the domain obtained from a global model. The configuration of WRF-Chem used in this study is shown to reproduce the overall synoptic conditions, thermally driven circulations, and boundary layer structure observed in region that controls the transport and mixing of trace gases and aerosols. Reducing the default emissions inventory by 50% led to an overall improvement in many simulated trace gases and black carbon aerosol at most sites and along most aircraft flight paths; however, simulated organic aerosol was closer to observed when there were no adjustments to the primary organic aerosol emissions. We found that sulfate was better simulated over northern California whereas nitrate was better simulated over southern California. While the overall spatial and temporal variability of aerosols and their precursors were simulated reasonably well, we show cases where the local transport of some aerosol plumes were either too slow or too fast, which adversely affects the statistics quantifying the differences between observed and simulated quantities. Comparisons with lidar and in situ measurements indicate that long-range transport of aerosols from the global model was likely too high in the free troposphere even though their concentrations were relatively low. This bias led to an over-prediction in aerosol optical depth by as much as a factor of 2 that offset the under-predictions of boundary-layer extinction resulting primarily from local emissions. Lowering the boundary conditions of aerosol concentrations by 50% greatly reduced the bias in simulated aerosol optical depth for all regions of California. This study shows that quantifying regional-scale variations in aerosol radiative forcing and determining the relative role of emissions from local and distant sources is challenging during `clean' conditions and that a wide array of measurements are needed to ensure model predictions are correct for the right reasons. In this regard, the combined CalNex and CARES data sets are an ideal test bed that can be used to evaluate aerosol models in great detail and develop improved treatments for aerosol processes.

This study examined whether awareness of tobacco control policies was associated with social unacceptability of smoking and whether social unacceptability had an effect on smoking cessation in three European countries. Representative samples (n = 3865) of adult smokers in France, the Netherlands and Germany were used from two survey waves of the longitudinal International Tobacco Control Europe Surveys. Associations were examined of aspects of social unacceptability of smoking (i.e. feeling uncomfortable, important people disapproval and societal disapproval) with tobacco policy awareness (i.e. awareness of warning labels, anti-tobacco information and smoking restrictions at work) and smoking cessation. Only the positive association of awareness of anti-tobacco information with feeling uncomfortable about smoking was significant in each of the three countries. Important people disapproval predicted whether smokers attempted to quit, although this did not reach significance in the French and German samples in multivariate analyses. Our findings suggest that anti-tobacco information campaigns about the dangers of second-hand smoke in France and about smoking cessation in the Netherlands and Germany might have reduced the social acceptability of smoking in these countries. However, campaigns that influence the perceived disapproval of smoking by important people may be needed to ultimately increase attempts to quit smoking.

Decesari, S. ... et. al.-- 24 pages, 15 figures, 4 tables, the supplement related to this article is available online https://doi.org/10.5194/acp-14-12109-2014-supplement, The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterised by a less dense urbanisation. We present here the results obtained at a background site in the Po Valley, Italy, in summer 2009. For the first time in Europe, six state-of-the-art spectrometric techniques were used in parallel: aerosol time-of-flight mass spectrometer (ATOFMS), two aerosol mass spectrometers (high-resolution time-of-flight aerosol mass spectrometer - HR-ToF-AMS and soot particle aerosol mass spectrometer - SP-AMS), thermal desorption aerosol gas chromatography (TAG), chemical ionisation mass spectrometry (CIMS) and (offline) proton nuclear magnetic resonance (1H-NMR) spectroscopy. The results indicate that, under high-pressure conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC), secondary semivolatile compounds such as ammonium nitrate and amines and a class of monocarboxylic acids which correspond to the AMS cooking organic aerosol (COA) already identified in urban areas. In daytime, the entrainment of aged air masses in the mixing layer is responsible for the accumulation of low-volatility oxygenated organic aerosol (LV-OOA) and also for the recycling of non-volatile primary species such as black carbon. According to organic aerosol source apportionment, anthropogenic aerosols accumulating in the lower layers overnight accounted for 38% of organic aerosol mass on average, another 21% was accounted for by aerosols recirculated in residual layers but still originating in northern Italy, while a substantial fraction (41 %) was due to the most aged aerosols imported from transalpine areas. The different meteorological regimes also affected the BC mixing state: in periods of enhanced stagnation and recirculation of pollutants, the number fraction of the BC-containing particles determined by ATOFMS was 75% of the total, while in the days of enhanced ventilation of the planetary boundary layer (PBL), such fraction was significantly lower (50 %) because of the relative greater influence of non-BC-containing aerosol local sources in the Po Valley. Overall, a full internal mixing between BC and the nonrefractory aerosol chemical components was not observed during the experiment in this environment. © Author(s) 2014, This work was funded by European integrated project on aerosol cloud climate and air quality interactions (no. 036833-2, EUCAARI). The ERA-Interim data were kindly provided by Silvio Davolio (CNR-ISAC). Data analysis was co-funded by the project PEGASOS (EC FP7-ENV-2010-265148) and by the project SUPERSITO of Region Emilia-Romagna. ACCENTC is also gratefully acknowledged. Finally, Emanuela Finessi (CNR-ISAC, now at University of York) is also gratefully acknowledged for the precious work in aerosol filter collection in the field. Manuel Dall’Osto and Roy M. Harrison thank the UK National Centre for Atmospheric Science for financial support

WOS: 000334006700023, PubMed ID: 24561926, Respiratory health effects of ambient air pollution were studied in 605 school children 9 to 13 years in Eskisehir, Turkey. Each child performed a fractional exhaled nitric oxide (FENO) measurement and a lung function test (LFT). Self-reported respiratory tract complaints (having cold, complaints of throat, runny nose and shortness of breath/wheezing) in the last 7 days and on the day of testing were also recorded. As acute health outcomes were investigated, weekly average ambient concentrations of ozone (O-3), nitrogen dioxide (NO2) and sulfur dioxide (SO2) were determined by passive sampling in the school playgrounds simultaneously with the health survey. Effects of air pollution on respiratory tract complaints and exhaled NO/lung function were estimated by multivariate logistic regression and multivariate linear mixed effects models, respectively. Upper respiratory tract complaints were significantly (p < 0.05) associated with weekly average O-3 concentrations during the health survey (adjusted odds ratios (OR) of 1.21 and 1.28 for a 10 mu g m(-3) increment for having cold and a runny nose on day of testing, respectively). FEN levels were significantly (p < 0.05) increased in children with various upper respiratory tract complaints (ratio in FEN varied between 1.16 and 1.40). No significant change in FEN levels was detected in association with any of the measured pollutants (p >= 0.05). Lung function was not associated with upper respiratory tract complaints and FEN levels. Peak Expiratory Flow (PEF) levels were negatively associated with weekly average O-3 levels for children without upper respiratory tract complaints. In summary, elevated levels of air pollutants increased respiratory tract complaints in children, MATRA [9S0635.01]; Dutch Ministry of Foreign Affairs, This study was part of the MATRA project no: 9S0635.01 "Together Towards Clean Air in Eskisehir and Iskenderun, Turkey" financed by the Dutch Ministry of Foreign Affairs.

Ambient wintertime background urban aerosol in Cork city, Ireland, was characterized using aerosol mass spectrometry. During the three-week measurement study in 2009, 93% of the ca. 1 350 000 single particles characterized by an Aerosol Time-of-Flight Mass Spectrometer (TSI ATOFMS) were classified into five organic-rich particle types, internally mixed to different proportions with elemental carbon (EC), sulphate and nitrate, while the remaining 7% was predominantly inorganic in nature. Non-refractory PM1 aerosol was characterized using a High Resolution Time-of-Flight Aerosol Mass Spectrometer (Aerodyne HR-ToF-AMS) and was also found to comprise organic aerosol as the most abundant species (62 %), followed by nitrate (15 %), sulphate (9 %) and ammonium (9 %), and chloride (5 %). Positive matrix factorization (PMF) was applied to the HR-ToF-AMS organic matrix, and a five-factor solution was found to describe the variance in the data well. Specifically, "hydrocarbon-like" organic aerosol (HOA) comprised 20% of the mass, "low-volatility" oxygenated organic aerosol (LV-OOA) comprised 18 %, "biomass burning" organic aerosol (BBOA) comprised 23 %, non-wood solid-fuel combustion "peat and coal" organic aerosol (PCOA) comprised 21 %, and finally a species type characterized by primary m/z peaks at 41 and 55, similar to previously reported "cooking" organic aerosol (COA), but possessing different diurnal variations to what would be expected for cooking activities, contributed 18 %. Correlations between the different particle types obtained by the two aerosol mass spectrometers are also discussed. Despite wood, coal and peat being minor fuel types used for domestic space heating in urban areas, their relatively low combustion efficiencies result in a significant contribution to PM1 aerosol mass (44% and 28% of the total organic aerosol mass and non-refractory total PM1, respectively).Ambient wintertime background urban aerosol in Cork city, Ireland, was characterized using aerosol mass spectrometry. During the three-week measurement study in 2009, 93% of the ca. 1 350 000 single particles characterized by an Aerosol Time-of-Flight Mass Spectrometer (TSI ATOFMS) were classified into five organic-rich particle types, internally mixed to different proportions with elemental carbon (EC), sulphate and nitrate, while the remaining 7% was predominantly inorganic in nature. Non-refractory PM1 aerosol was characterized using a High Resolution Time-of-Flight Aerosol Mass Spectrometer (Aerodyne HR-ToF-AMS) and was also found to comprise organic aerosol as the most abundant species (62 %), followed by nitrate (15 %), sulphate (9 %) and ammonium (9 %), and chloride (5 %). Positive matrix factorization (PMF) was applied to the HR-ToF-AMS organic matrix, and a five-factor solution was found to describe the variance in the data well. Specifically, "hydrocarbon-like" organic aerosol (HOA) comprised 20% of the mass, "low-volatility" oxygenated organic aerosol (LV-OOA) comprised 18 %, "biomass burning" organic aerosol (BBOA) comprised 23 %, non-wood solid-fuel combustion "peat and coal" organic aerosol (PCOA) comprised 21 %, and finally a species type characterized by primary m/z peaks at 41 and 55, similar to previously reported "cooking" organic aerosol (COA), but possessing different diurnal variations to what would be expected for cooking activities, contributed 18 %. Correlations between the different particle types obtained by the two aerosol mass spectrometers are also discussed. Despite wood, coal and peat being minor fuel types used for domestic space heating in urban areas, their relatively low combustion efficiencies result in a significant contribution to PM1 aerosol mass (44% and 28% of the total organic aerosol mass and non-refractory total PM1, respectively).

International audience; Processus vieux d'un demi-siècle, la régularisation des quartiers illégaux périphériques de Mexico demande à être interrogée sous l'angle d'une de ses principales composantes : les organisations sociales. Au sein de ce processus, les collectifs d'habitants jouent effectivement un rôle à la fois primordial et paradoxal. L'appréhension de la régularisation du point de vue des habitants et des autorités dans quatre quartiers permet, d'une part, d'identifier ces mécanismes et les acteurs de l'action collective locale, d'autre part, d'interpréter la diversité des degrés et des rythmes des améliorations en fonction des rapports de pouvoir en place. Un paradoxe semble se dégager : si d'un côté, les habitants s'ancrent dans leur quartier et prennent en main leur espace de manière autonome, d'un autre côté, l'État trouve dans cet ancrage le moyen d'un « rattrapage » du processus d'urbanisation et d'une assise relative de son autorité. Mots-clefs : organisation sociale, régularisation, quartiers illégaux, Mexico The role of social organizations in the regularization process of the illegal settlements on the outskirts of Mexico City. Abstract: Since half a century, the regularization process of illegal settlements in the outskirts of Mexico City is a very important dimension in the growing of the city. It needs to be questioned in terms of its main dimensions: social organizations. The mechanisms of this progressive integration involve inhabitants groups who do play both a critical and paradoxical role. Monitoring regularization with locals and authorities in four areas allows us on one hand, to identify these mechanisms and actors of the local collective action, on the other hand, interpret the diversity of levels and rhythms of the improvements in terms of power relations. A paradox seems to emerge: if on one hand, people are rooted in their neighborhood and take control of their space autonomously, on the other hand, the State uses this anchoring in order to lead to a "catch up" and potential better base of the authority.

We evaluate predictions from the Community Multiscale Air Quality (CMAQ version 4.7.1) model against a suite of airborne and ground-based meteorological measurements, gas- and aerosol-phase inorganic measurements, and black carbon (BC) measurements over Southern California during the CalNex field campaign in May/June 2010. Ground-based measurements are from the CalNex Pasadena ground site, and airborne measurements took place onboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Navy Twin Otter and the NOAA WP-3D aircraft. BC predictions are in general agreement with observations at the Pasadena ground site and onboard the WP-3D, but are consistently overpredicted when compared to Twin Otter measurements. Adjustments to predicted inorganic mass concentrations, based on predicted aerosol size distributions and the AMS transmission efficiency, are shown to be significant. Owing to recent shipping emission reductions, the dominant source of sulfate in the L.A. Basin may now be long-range transport. Sensitivity studies suggest that severely underestimated ammonia emissions, and not the exclusion of crustal species (Ca2 +, K+, and Mg2 +), are the single largest contributor to measurement/model disagreement in the eastern part of the L.A. Basin. Despite overstated NOx emissions, total nitrate concentrations are underpredicted, which suggests a missing source of HNO 3 and/or overprediction of deposition rates. Adding gas-phase NH 3 measurements and size-resolved measurements, up to 10 μm, of nitrate and various cations (e.g. Na+, Ca2 +, K +) to routine monitoring stations in the L.A. Basin would greatly facilitate interpreting day-to-day fluctuations in fine and coarse inorganic aerosol. Key pointsWe measured inorganic gas- and aerosol-phase species during CalNexWe compare ground-based and airborne measurements to CMAQ predictionsMeasure/model agreement varies depending on the species and location © 2012. American Geophysical Union. All Rights Reserved.

To evaluate the success of vehicle emissions regulations, trends in both fleet-wide average emissions as well as high-emitter emissions are needed, but it is challenging to capture the full spread of vehicle emission factors (EFs) with chassis dynamometer or tunnel studies, and remote sensing studies cannot evaluate particulate compounds. We developed an alternative method that links real-time on-road pollutant measurements from a mobile platform with real-time traffic data, and allows efficient calculation of both the average and the spread of EFs for light-duty gasoline-powered vehicles (LDG) and heavy-duty diesel-powered vehicles (HDD). This is the first study in California to report EFs under a full range of real-world driving conditions on multiple freeways. Fleet average LDG EFs were in agreement with most recent studies and an order of magnitude lower than observed HDD EFs. HDD EFs reflected the relatively rapid decreases in diesel emissions that have recently occurred in Los Angeles/California, and on I-710, a primary route used for goods movement and a focus of additional truck fleet turnover incentives, HDD EFs were often lower than on other freeways. When freeway emission rates (ER) were quantified as the product of EF and vehicle miles traveled (VMT) per time per mile of freeway, despite a two- to three-fold difference in HDD fractions between freeways, ERs were found to be generally similar in magnitude. Higher LDG VMT on low HDD fraction freeways largely offset the difference. Therefore, the conventional assumption that freeways with the highest HDD fractions are significantly worse sources of total emissions in Los Angeles may no longer be~true.

L’évolution actuelle de la métropole mexicaine est moins à suivre en termes de croissance urbaine qu’en termes de redistribution interne de sa population. Les mobilités résidentielles alimentent des phénomènes de recompositions socio-spatiales importants ; ce mouvement qualifié de transition urbaine est étudié grâce aux données des recensements de population. Considéré dans le cadre de la Zone Métropolitaine de la Vallée de Mexico (ZMVM), Mexico compte plus de 19,2 millions d’habitants. Sur la période 1995-2000, la croissance continue par apports de la croissance naturelle (environ 1,8 million de personnes supplémentaires). Le solde migratoire est, lui, négatif : la ville perd davantage qu’elle n’attire et voit le départ d'environ 800 000 personnes. Parallèlement, la mobilité interne (changements de résidence) est, elle, très forte puisqu’on enregistre environ 1,4 million de mouvements sur la même période ; cela concerne donc 8 % de la population. L’article insiste sur l’amplification et la complexification des trajectoires de migrants à l’intérieur de la métropole ; cela permet de proposer une lecture de l’expansion urbaine comme processus de redistribution de la population. The current evolution of the Mexican metropolis requires an approach examining the population redistribution into the urban area, further than a growth rate study. Residential movements are shaping deep socio-spatial changes. The urban transition process is enlightened by population census data. Considered into the metropolitan area limits (ZMVM), 19.2 million people are living in Mexico City. During the period 1995-2000, the city was still growing, thanks to the natural growth (plus 1.8 million people). There was a negative net migration : the city was more pushing people than pulling and 800 000 people left the metropolitan area. In the same time, inner mobility was very important and the census registered 1.4 million residential changes during this period (8 per cent of the total population). This paper focuses on the development of more and more expanded and complex migrants’ trajectories into the area. This hypothesis lets enlighten the urban development as populating dynamics of migrations into the city.

Sea salt aerosol can significantly affect the air quality. Sea salt can cause enhanced concentrations of particulate matter and change particle chemical composition, in particular in coastal areas, and therefore should be accounted for in air quality modelling. We have used an EMEP Unified model to calculate sea salt concentrations and depositions over Europe, focusing on studying the effects of uncertainties in sea salt production and lifetime on calculation results. Model calculations of sea salt have been compared with EMEP observations of sodium concentrations in air and precipitation for a four year period, from 2004 to 2007, including size (fine/coarse) resolved EMEP intensive measurements in 2006 and 2007. In the presented calculations, sodium air concentrations are between 8% and 46% overestimated, whereas concentrations in precipitation are systematically underestimated by 65–70% for years 2004–2007. A series of model tests have been performed to investigate the reasons for this underestimation, but further studies are needed. The model is found to reproduce the spatial distribution of Na+ in air and precipitation over Europe fairly well, and to capture most of sea salt episodes. The paper presents the main findings from a series of tests in which we compare several different sea spray source functions and also look at the effects of meteorological input and the efficiency of removal processes on calculated sea salt concentrations. Finally, sea salt calculations with the EMEP model have been compared with results from the SILAM model and observations for 2007. While the models produce quite close results for Na+ at the majority of 26 measurement sites, discrepancies in terms of bias and temporal correlation are also found. Those differences are believed to occur due to differences in the representation of source function and size distribution of sea salt aerosol, different meteorology used for model runs and the different models' resolution. This study contributes to getting a better insight on uncertainties associated with sea salt calculations and thus facilitates further improvement of aerosol modelling on both regional and global scales.

The present paper deals with the multiple scattering by randomly distributed elastodynamic systems at the surface of a horizontally layered elastic halfspace due to an incident plane wave. Instead of solving this problem for a particular configuration of the system, multiple scattering theory is used to compute the ensemble response statistics. The Dyson equation is used to calculate the mean field, while the nonstationary second order statistics are obtained by means of the Bethe-Salpeter equation. This allows for the determination of the mean square response of the system in the time and frequency domains. This model is used to study multiple scattering between buildings under seismic excitation. The influence of multiple scattering on the seismic site response is verified. Furthermore, the influence of the footprint and the damping of the buildings are investigated. The results are compared to results of a coupled finite element/boundary element solution for a group of buildings. (c) 2009 Acoustical Society of America. [DOI: 10.1121/1.3086290] ispartof: Journal of the acoustical society of america vol:125 issue:4 pages:2041-2052 ispartof: location:United States status: published

Conflicts over water will become more and more widespread in forecoming years. This is not only true for international conflicts but as well for conflicts inbetween nations, for example between major cities and their countryside. Mexico-City as one of the largests cities of the world is highly dependend on water sources from outside its own territory to maintain its function as developing motor of the whole country. Therefore it is an extremely interesting case in this context. This is especially true as the city does not only depend on the countryside for drinking water but also for sending its wastewater and rainwater into the countryside to prevent the flodding of its territory. This does not only contradict all that is known about sustainable use of resources, it leads to a highly critical dependence between the water-sending countryside, the city itself and the wastewater-receiving countryside as well. This interdependence is not easily corrected for a diverse set of reasons that have to do with political, structural, institutional and cultural developments since the early 19th century. The thesis analyzes these reasons in the context of conflicts between the city and its countryside and tries to evaluate the future development. For the political and structural development of ecological matters it also draws a short parallel between Mexico and middle and eastern European states. In difference to other publications the work does not only evaluate the strategic behaviour of administrative and organized civil actors in this context, but concentrates on the opinion and strategies of the immediately affected parts of society. For this reason the work includes an empirical study that is interview based and evaluates the strategic position of all three actor-groups. Doing so it can be shown, that the situation of water distribution between Mexico-City and the surrounding countryside is much more critical as the low number of open conflicts at the moment state. Rather the different stakeholders for diverse strategic reasons decide against open conflicts, but for the permanent decline of water availability show tendencies to change their behaviour in the near future. Furthermore the thesis shows how the human-initiated transformation of the ecological environment and the human systems to deal with political and structural changes contradict and lead to a constant decline of the water resources. The core of the theoretical background is build on a combination of Scharpf's Actor Centered Institutionalism and Ostrom's considerations on comon pool resources. It is supplemented by works that especially focus on the different actor groups analysed.

Taking advantage of a large displacement-release experiment on a two-story reinforced concrete building located in Bagnoli (Naples, Italy), we performed free-field measurements using 3D seismometers, accelerometers, and a 100-m-long vertical array. The ground motion was noticeable: near the building, the acceleration exceeded 5% g. At each measurement point, it was possible to recognize two source terms, due to the tested building and to the reaction structure. The two sources generated different wave trains. High-frequency accelerations propagated as Rayleigh waves, whereas 1-2 Hz waves carrying most of the displacement propagated only as body waves. The experiment lends further support to the hypothesis that buildings are able to modify substantially the free-field ground motion in their proximity: the peak ground acceleration we observed is the 20% of the ground acceleration required to produce a displacement on the building equal to the one imposed during the release test. We recognize, however, the difficulty of a realistic modeling of wave propagation in the topmost layer of a densely urbanized area.

When a seismic wavefield impinges on the foundation of a building, the building vibrates and generates waves in the subsoil. In a city, different buildings interact with each other through the scattered waves. The detailed description of the wave propagation in this coupled city - soil system is a complex problem. Instead of solving this problem for a particular city configuration, a statistical description of the city is applied and the limit of a city of infinite size is considered. This leads to a model of the coupled city - soil system, where the buildings are modelled as resonant scatterers that are uniformly distributed at the surface of a deterministic, horizontally layered elastic half-space that represents the soil. The equations that govern the interaction between the city and the soil now become a set of stochastic equations. Based on these equations, the Dyson and Bethe - Salpeter for the configurationally averaged field and field correlation are formulated. The solution of the single scatterer problem is used to obtain an approximate solution of these equations that allows us to quantify the change of the mean site response through the presence of the city and the ratio of the coherent and incoherent response. Furthermore, the influence of the city on the duration of the seismic records is estimated by the approximate solution of the non-stationary Bethe - Salpeter equation. The results obtained for the configurationally averaged field quantities are validated by means of results for the seismic response of a deterministic model of a city quarter of Mexico City.

This doctoral thesis explores the recomposition of colonias populares on the outskirts of the metropolitan area of Mexico-City for twenty years. Links between spatial mobility, living spaces of residents in informal settlements and strategies of physical and legal regularization are enlightened though social, demographic and political evolutions. The dynamic and heterogeneous characteristics of colonias populares was examined through two conceptual tools for the study of urban territoriality: the anchorage, as a point of view on the experiences of people; maturation, in order to analyze changes in residential settings. The trajectories of maturation have been understood from the analysis of systematic demographic data and from empirical work in four areas. Once the framework presented, the contexts of maturation were observed in three inputs: social, mobility, and political. Plural trajectories of this maturation were analyzed from the point of view of the anchorage: we tried to understand the pathways leading to the actual visible diversity. We described the residential routes of inhabitants, their urban experiences, more particularly in relation to the resources of the area, the complex dynamics of land and planning regularization and changes in the social division of space. Finally, these neighborhoods are becoming increasingly heterogeneous and "common" compared to the rest of the city, revealing the obsolescence of a single reading in terms of poverty or legal marginality.; En esta tesis de doctorado, se analiza la recomposición de las colonias populares de la periferia de la Zona Metropolitana de México desde veinte años. Los vínculos entre la movilidad espacial, los espacios de vida de los residentes de los asentamientos irregulares, y las estrategias de regularización legal y física se examinan a la luz de factores sociales, demográficos y políticos. El rasgo dinámico y diverso de las colonias populares se examinó a través de dos herramientas conceptuales para el estudio de la territorialidad urbana: el anclaje, para tener un punto de vista de las experiencias de los individuos; la maduración, para analizar los cambios en entornos residenciales. Las trayectorias de maduración son entendidas a partir del análisis sistemático de los datos demográficos y del trabajo empírico en cuatro grupos de colonias. Después de la presentación del marco de estudio, se observaron los contextos de la maduración con tres entradas: social, sobre la movilidad, y política. Las trayectorias plurales de esta maduración se analizaron desde el punto de vista del anclaje, tratando de entender las vías que conducen a la diversidad visible hoy. Llegamos a describir a las rutas residenciales de los habitantes, sus experiencias urbanas, particularmente en relación con los recursos de la zona, la dinámica compleja de la regularización del suelo y de la planificación, y los cambios en la división social del espacio. Al final, estas colonias son cada vez más heterogéneas y "triviales" en comparación con el resto de la ciudad, dejando al descubierto la obsolescencia de una sola lectura en términos de pobreza o marginalidad.; Cette thèse étudie les recompositions des colonies populaires périphériques de la zone métropolitaine de Mexico depuis vingt ans. Les liens entre les mobilités spatiales, les espaces de vie des habitants dans des quartiers illégaux à l’origine, et les stratégies de régularisation physique et juridique sont interrogés au regard des évolutions sociales, démographiques et politiques. Le caractère dynamique et divers des colonies populaires a été examiné à travers deux outils conceptuels de l’étude des territorialités urbaines : l’ancrage, point de vue sur les expériences des individus ; la maturation, pour analyser les changements des contextes résidentiels. Les trajectoires de maturation ont été comprises à partir de l’analyse de données sociodémographiques systématiques et d’un travail empirique dans quatre quartiers.Une fois le cadre de travail présenté, les contextes de la maturation ont été observés selon trois entrées : sociale, relative aux mobilités, et politico-juridique. Les trajectoires plurielles de cette maturation ont ensuite été analysées du point de vue de l’ancrage, en tentant de comprendre les chemins ayant conduit à la diversité visible aujourd’hui : il s’est agi de décrire les itinéraires résidentiels des habitants, leurs expériences citadines, en particulier par rapport aux ressources de la proximité, les dynamiques de régularisation foncière et urbanistique dans leur complexité et les évolutions de la division sociale de l’espace. Au final, ces quartiers deviennent de plus en plus hétérogènes et « banals » par rapport au reste de la ville, révélant l’obsolescence d’une lecture unique en termes de pauvreté ou de marginalité juridique.

Single particles were collected from an aircraft platform as part of the Intercontinental Chemical Transport Experiment – Phase B (INTEX-B) conducted over the eastern Pacific and western North America. Single particle spectra were obtained using scanning transmission X-ray microscopy-near edge X-ray absorption fine structure spectroscopy (STXM-NEXAFS). Bulk submicron particles were also collected and organic functional group and elemental concentrations were quantified with Fourier transform infrared (FTIR) spectroscopy and X-ray fluorescence (XRF). Single particle spectra were classified into metaclasses associated with different sources and atmospheric processing. Particles with spectra indicative of secondary organic aerosol production and combustion sources were found at several locations and a range of altitudes. At lower altitudes, particles with spectra resembling soil dust and biomass burning fingerprints were commonly observed. The types of particle spectra most commonly observed aloft were similar to those observed during a previous study over the northwestern Pacific, indicating that long-range transport may have been an important particle source. Single particle spectra provided evidence that condensation and surface-limited oxidation contributed to particle growth. Organic mass (OM) concentrations ranged from 1 to 7 μg m−3 and averaged 2.4–4.1 μg m−3. Alkane functional groups were the largest fraction of OM, averaging 1.9–2.1 μg m−3 or 50–76% of OM, followed by alcohol functional groups (0.35–0.39 μg m−3, 9–14%). Organic and elemental concentrations are compared within and among geographical air mass regions: "Pacific" free troposphere, "Continental" free troposphere, "Seattle" metropolitan region, and the California "Central Valley". OM concentrations were highest and most variable in the Central Valley (3.5±2 μg m−3). Oxygen-to-carbon ratios were relatively constant in the Central Valley but variable for the Continental air masses. Overall, the OM concentrations showed greater variability within air mass categories as compared to averages among them, suggesting sampled air mass regions included a variety of sources and processing of organic aerosol.

In-situ airborne measurements of trace gases, aerosol size distributions, chemistry and optical properties were conducted over Mexico and the Eastern North Pacific during MILAGRO and INTEX-B. Heterogeneous reactions between secondary aerosol precursor gases and mineral dust lead to sequestration of sulfur, nitrogen and chlorine in the supermicrometer particulate size range. Simultaneous measurements of aerosol size distributions and weak-acid soluble calcium result in an estimate of 11 wt% of CaCO3 for Asian dust. During transport across the North Pacific, ~5–30% of the CaCO3 is converted to CaSO4 or Ca(NO3)2 with an additional ~4% consumed through reactions with HCl. The 1996 to 2008 record from the Mauna Loa Observatory confirm these findings, indicating that, on average, 19% of the CaCO3 has reacted to form CaSO4 and 7% has reacted to form Ca(NO3)2 and ~2% has reacted with HCl. In the nitrogen-oxide rich boundary layer near Mexico City up to 30% of the CaCO3 has reacted to form Ca(NO3)2 while an additional 8% has reacted with HCl. These heterogeneous reactions can result in a ~3% increase in dust solubility which has an insignificant effect on their optical properties compared to their variability in-situ. However, competition between supermicrometer dust and submicrometer primary aerosol for condensing secondary aerosol species led to a 25% smaller number median diameter for the accumulation mode aerosol. A 10–25% reduction of accumulation mode number median diameter results in a 30–70% reduction in submicrometer light scattering at relative humidities in the 80–95% range. At 80% RH submicrometer light scattering is only reduced ~3% due to a higher mass fraction of hydrophobic refractory components in the dust-affected accumulation mode aerosol. Thus reducing the geometric mean diameter of the submicrometer aerosol has a much larger effect on aerosol optical properties than changes to the hygroscopic:hydrophobic mass fractions of the accumulation mode aerosol. In the presence of dust, nitric acid concentrations are reduced to y as a fraction of total nitrogen (NOy plus particulate nitrate), is reduced from >85% to 60–80% in the presence of dust. These observations support previous model studies which predict irreversible sequestration of reactive nitrogen species through heterogeneous reactions with mineral dust during long-range transport.

Submicron atmospheric aerosol particles were collected during the Megacity Initiative: Local and Global Research Observation (MILAGRO) in March 2006 at three platforms located in the Mexico City urban area (at the Mexico City Atmospheric Monitoring System building – SIMAT), at about 60 km south-east of the metropolitan area (Altzomoni in the Cortes Pass), and on board the NCAR C130 aircraft. Organic functional group and elemental composition were measured by FTIR and XRF. The average organic mass (OM) concentration, calculated as the sum of organic functional group concentrations, was 9.9 μg m−3 at SIMAT, 6.6 μg m−3 at Altzomoni, and 5.7 μg m−3 on the C130. Aliphatic saturated C-C-H and carboxylic acid COOH groups dominated OM (more than 60%) at the ground sites. On the C130, a non-acid carbonyl C=O, carboxylic acid COOH, and amine NH2 groups were observed in concentrations above detection limit only outside the Mexico City basin. From the elemental composition of SIMAT samples, we estimated the upper bound of average contribution of biomass burning to the organic carbon (OC) as 33–39%. The average OM/OC ratio was 1.8 at SIMAT, 2.0 at Altzomoni, and 1.6–1.8 on the C130. On the aircraft, higher OM/OC ratios were measured outside of the Mexico City basin, north of the urban area, along the city outflow direction. The average carboxylic acid to aliphatic saturated ratio at SIMAT reflected a local increase of oxidized functional group concentration in aged particles.