Spatial and temporal variations in PM10 and PM2.5 across Madrid metropolitan area in 1999–2008

AbstractThis paper presents a summary of the results obtained from the particulate matter (PM) data collected over the 1999–2008 period from representative sites of the Madrid air basin (an urban traffic site, an urban background site and a rural site) which is located in the centre of Spain. A number of PM10 and PM2.5 filters were obtained with high volume samplers and cut-off inlets and chemically analyzed. Pollutants recorded in this area at the Air Quality monitoring stations were also analyzed. The influence of the atmospheric transport scenarios on the levels of PM was investigated by means of atmospheric back-trajectories, satellite imagery and meteorological synoptic charts. Source apportionment studies were performed to characterize the main PM sources whenever was possible. Their contributions to bulk PM levels showed clear spatial patterns, linked to characteristic meteorological scenarios

PM speciation and sources in Mexico during the MILAGRO-2006 Campaign

International audienceLevels of PM10, PM2.5 and PM1 and chemical speciation of PM10 and PM2.5 were measured during the MILAGRO campaign (1st to 31st March 2006, but extended in some cases until 6th April) at four urban, one suburban, two rural background and two rural sites, with different degree of industrial influence, in the Mexico City Metropolitan Area (MCMA) and adjacent regions. PM10 and PM2.5 daily levels varied between 50?56?g/m3 and 24?46?g/m3 at the urban sites, 22?35?g/m3 and 13?25?g/m3 at the rural sites, and 75?g/m3 and 31?g/m3 at the industrial hotspot, lower than those recorded at some Asian mega-cities and similar to those recorded at other Latin American cities. At the urban sites, hourly PM2.5 and PM1 concentrations showed a marked impact of road traffic emissions (at rush hours), with levels of coarse PM remaining elevated during daytime. At the suburban and rural sites different PM daily patterns were registered according to the influence of the pollution plume from MCMA, and also of local soil resuspension. The speciation studies showed that mineral matter accounted for 25?27% of bulk PM10 at the urban sites and a higher proportion (up to 43%) at the suburban and rural sites. This pattern is repeated in PM2.5, with 15% at urban and 28% at suburban and rural sites. Carbonaceous compounds accounted for a significant proportion at the urban and industrial sites (32?46% in PM10, and 51?55% in PM2.5), markedly reduced at the suburban and rural sites (16?23% in PM10, and 30% in PM2.5). The secondary inorganic aerosols accounted for 10?20% of bulk PM10 at urban, suburban, rural and industrial sites, with a higher proportion (40%) at the industrial background site. A relatively high proportion of nitrate in rural sites was present in the coarse fraction. Typically anthropogenic elements (As, Cr, Zn, Cu, Pb, Sn, Sb, Ba, among others) showed considerably high levels at the urban sites; however levels of particulate Hg and crustal trace elements (Rb, Ti, La, Sc, Ga) were generally higher at the suburban site. Principal component analysis identified three major common factors: crustal, regional background and road traffic. Moreover, some specific factors were obtained for each site

Ammonia levels in different kinds of sampling sites in the central Iberian Peninsula

Ponencia presentada en:2nd Iberian Meeting on Aerosol Science and Technology (RICTA 2014) celebrado en Tarragona del 7 al 9 de julio de 2014.Ammonia is the Secondary Inorganic Aerosol (SIC) gaseous precursor which has been studied to a lesser extent in the Madrid Metropolitan Area up to date. A study conducted in the city of Madrid with the aim of characterizing levels of ammonia took place in 2011. These campaigns formed part of a larger study conducted in 6 Spanish cities. A time series of weekly integrated ammonia measurements available at an EMEP rural site (Campisábalos) has been used to obtain information on the ammonia rural background in the region. The results point to traffic and waste treatment plants as the main ammonia sources in Madrid. Relevant seasonal differences have not been observed in the Metropolitan Area. The explanation can be related to the fall in the rural background levels during July 2011, which might conceal urban summer emission increases observed in other cities

Climatic Feedbacks and Desertification: The Mediterranean Model

Abstract Mesometeorological information obtained in several research projects in southern Europe has been used to analyze perceived changes in the western Mediterranean summer storm regime. A procedure was developed to disaggregate daily precipitation data into three main components: frontal precipitation, summer storms, and Mediterranean cyclogenesis. Working hypotheses were derived on the likely processes involved. The results indicate that the precipitation regime in this Mediterranean region is very sensitive to variations in surface airmass temperature and moisture. Land-use perturbations that accumulated over historical time and greatly accelerated in the last 30 yr may have induced changes from an open, monsoon-type regime with frequent summer storms over the mountains inland to one dominated by closed vertical recirculations where feedback mechanisms favor the loss of storms over the coastal mountains and additional heating of the sea surface temperature during summer. This, in turn, favors Mediterranean cyclogenesis and torrential rains in autumn–winter. Because these intense rains and floods can occur anywhere in the basin, perturbations to the hydrological cycle in any part of the basin can propagate to the whole basin and adjacent regions. Furthermore, present levels of air pollutants can produce greenhouse heating, amplifying the perturbations and pushing the system over critical threshold levels. The questions raised are relevant for the new European Union (EU) water policies in southern Europe and for other regions dominated by monsoon-type weather systems

TEMPORAL AND SPATIAL VARIABILITY OF ATMOSPHERIC PARTICLE NUMBER SIZE DISTRIBUTIONS ACROSS SPAIN

This study synthesizes for the first time results from simultaneous aerosol measurements performed at seven diverse locations distributed all over the Spanish geography. The observations were carried out during two field campaigns in 2012–2013, one-month each and during different seasons. These field campaigns were performed in the framework of the Spanish Network of DMAs (REDMAAS) activities. Measurement sites were grouped as polluted sites (urban background) and clean sites (rural background and high-altitude sites). Seasonal differences were more important at polluted sites, mainly related to meteorology and aerosol sources. Higher total particle concentrations were found during the cold period, driven mainly by Aitken-mode particles (traffic-related aerosol particles).This work has been financed by the Ministry of Science and Innovation (CGL2011-15008-E, CGL2010-1777, CGL2011-27020, CGL2014-52877-R, CGL2010-11095-E, CGL2012-39623-C02-01, CGL2014-55230-R & PI15/0051

Variability of carbonaceous aerosols in remote, rural, urban and industrial environments in Spain: implications for air quality policy

We interpret here the variability of levels of carbonaceous aerosols based on a 12 yr database from 78 monitoring stations across Spain specially compiled for this article. Data did not evidence any spatial trends of carbonaceous aerosols across the country. Conversely, results show marked differences in average concentrations from the cleanest, most remote sites (around 1 μg m-3 of non-mineral carbon (nmC), mostly made of organic carbon (OC) with very little elemental carbon (EC), around 0.1 μg m-3; OC/EC Combining double low line 12-15), to the highly polluted major cities (8-10 μg m-3 of nmC; 3-4 μg m-3 of EC; 4-5 μg m-3 of OC; OC/EC Combining double low line 1-2). Thus, urban (and very specific industrial) pollution was found to markedly increase levels of carbonaceous aerosols in Spain, with much lower impact of biomass burning and of biogenic emissions. Correlations between yearly averaged OC/EC and EC concentrations adjust very well to a potential equation (OC Combining double low line 3.37 EC0.326, R2 Combining double low line 0.8). A similar equation is obtained when including average concentrations obtained at other European sites (OC Combining double low line 3.60EC0.491, R2 Combining double low line 0.7). A clear seasonal variability in OC and EC concentrations was detected. Both OC and EC concentrations were higher during winter at the traffic and urban sites, but OC increased during the warmer months at the rural sites. Hourly equivalent black carbon (EBC) concentrations at urban sites accurately depict road traffic contributions, varying with distance from road, traffic volume and density, mixing-layer height and wind speed. Weekday urban rush-hour EBC peaks are mimicked by concentrations of primary gaseous emissions from road traffic, whereas a single midday peak is characteristic of remote and rural sites. Decreasing annual trends for carbonaceous aerosols were observed between 1999 and 2011 at a large number of stations, probably reflecting the impact of the EURO4 and EURO5 standards in reducing the diesel PM emissions. This has resulted in some cases in an increasing trend for NO2/(OC+ EC) ratios as these standards have been much less effective for the abatement of NOx exhaust emissions in passenger diesel cars. This study concludes that EC, EBC, and especially nmC and OC+ EC are very good candidates for new air quality standards since they cover both emission impact and health-related issues.This study was supported by the Ministry of Agriculture, Food and the Environment of Spain, the Ministry of Economy and Competitivity (MINECO) of Spain and FEDER funds under the projects VAMOS (CGL2010-19464/CLI), PRISMA (CGL2012-39623-C02-01), GRACCIE (CSD 200700067), POLLINDUST (CGL2011-26259) and UHU (CGL201128025); and by AGAUR-Generalitat de Catalunya (2009 SGR 00008) and LIFE+ AIRUSE (LIFE11-ENV/ES/000584). The Montseny site forms part of the ACTRIS network (European Union Seventh Framework Programme (FP7/2007-2013) project no. 262254), formerly EUSAAR (EUSAAR R113-CT-2006-026140). Funding was also received for the Andaluc´ıa sites from projects 2007-RNM027329 and 2011-RNM7800 (Department of Innovation Science and Enterprise, Andalusia Autonomous Government) M. C. Minguillón was funded by the JAE-Doc CSIC programme, co-funded by the European Social Fund (ESF).publishe

Study of aerosol hygroscopic events over the Cabauw experimental site for atmospheric research (CESAR) using the multi-wavelength Raman lidar Caeli

This article presents a study of aerosol optical and microphysical properties under different relative humidity (RH) but well mixed layer conditions using optical and microphysical aerosol properties from multi-wavelength (MW) Raman lidar and in-situ aerosol observations collected at the Cabauw Experimental Site for Atmospheric Research (CESAR). Two hygroscopic events are described through 3 backscatter (β) and 2 extinction (α) coefficients which in turn provide intensive parameters such as the backscatter-related Ångström exponent (åβ) and the lidar ratio (LR). Along with it, profiles of RH were inferred from Raman lidar observations and therefore, as a result of varying humidity conditions, a shift on the aerosol optical properties can be described. Thus, it is observed that as RH increases, aerosols uptake water vapour, augment their size and consequently the åβ diminishes whereas the LR increases. The enhancement factor based on the backscatter coefficient at 532 nm, which characterizes the aerosol from hygroscopic standpoint, is also estimated. Finally, microphysical properties that are necessary for aerosol radiative forcing estimates - such as volume, effective radii, refractive index and size distribution, all vertically resolved - are retrieved using the inversion with regularization. Using this method, two hygroscopic events are described in detail. © 2015 Elsevier Ltd

Comparison of temporal features of sulphate and nitrate at urban and rural sites in Spain and the UK

A seasonal comparison of aerosol secondary inorganic component (SIC) patterns on annual, weekly and daily timescales has been performed at urban Madrid and London and at rural sites in the central Iberian Peninsula and south-eastern UK alongside data for precursor gases. A database from winter 2004 to summer 2011 has been analysed. Results show the dominant processes affecting the formation and evolution of nitrate (NO3-) and sulphate (SO42-) in both regions. In Madrid, photochemistry dominates formation of nitrate, which is mostly locally-generated. Strong thermal decomposition results in very low concentrations in summer. In contrast, in London high nocturnal values suggest the importance of heterogeneous formation processes as well as nitrate condensation at lower temperatures. The seasonal nitrate maximum in the UK is found in late winter-early spring, when the region typically receives the highest input of pollutants transported from mainland Europe. Daily evolution of nitrate in both cities is heavily influenced by meteorological factors. Seasonal sulphate patterns show no obvious trend, except at the Spanish rural site in summer where photochemical formation was apparent. In Madrid, daily SO and sulphate patterns exhibiting maximum concentrations at noon were found in winter. In previous studies this phenomenon was observed for SO in London, where it was explained by the entrainment of pollutants from aloft into the mixing layer. SIC weekend reductions were investigated at the urban background sites of Madrid and London, and in both cities statistically significant fine nitrate reductions of around 20% are found in summer. These values are consistent with the annual reductions observed by researchers in the US. Weekend sulphate reductions occurred in winter, reflecting a clear impact of anthropogenic sulphate in urban environments, in spite of the large reductions in sulphur emissions in Europe in the last decade. Ratios of nitrate and sulphate to oxidant gases and to one another have been calculated for Madrid, and are consistent with a contribution of local formation to sulphate in winter, while in summer a regional background unrelated to urban SO is observed. The strong differences in the behaviour seen in London and Madrid (and the rural sites) emphasises the need to study cities individually and not to extrapolate conclusions drawn in one city to others in different climate/topographic situations

Evaluation of aerosol sources at European high altitude background sites with trajectory statistical methods

International audienceThis study has investigated the influence of synoptic weather patterns and long-range transport episodes on the concentrations of several compounds related to different aerosol sources (EC, OC, SO42−, Ca2+, Na+, K+, 210Pb, levoglucosan and dicarboxylic acids) registered in PM10 or PM2.5 aerosol samples collected at three remote background sites in central Europe. Air mass back-trajectories arriving at these sites have been analysed by statistical methods. Firstly, air mass back-trajectories have been grouped into clusters. Each cluster corresponds to specific meteorological scenarios, which were extracted and discussed. Finally, redistributed concentration fields have been computed to identify the main potential source regions of the different key aerosol components. A marked seasonal pattern is observed in the occurrence of the different clusters, with fast westerly and northerly Atlantic flows during winter and weak circulation flows in summer. Spring and fall were characterised by advection of moderate flows from northeastern and eastern Europe. Significant inter-cluster differences were observed for concentrations of receptor aerosol components, with the highest concentrations of EC, OC, SO42−, K+ and 210Pb associated with local and mesoscale aerosol sources located over central Europe related to enhanced photochemical processes. Emissions produced by fossil fuel and biomass burning processes from the Baltic countries, Byelorussia, western regions of Russia and Kazakhstan in spring and fall also contribute to elevated levels of EC, OC, SO42−, K+ and 210Pb. In the summer period long-range transport episodes of mineral dust from North-African deserts were also frequently detected, which caused elevated concentrations of coarse Ca2+ at sites. The baseline aerosol concentrations in central Europe at the high altitude background sites were registered in winter, with the exception of coarse Na+. While the relatively high concentrations of Na+ can be explained by sea salt advected from the Atlantic, the low levels of other aerosol components are caused by efficient aerosol scavenging associated to advections of Atlantic air masses, as well as lower emissions of these species over the Atlantic compared to those over the European continent and very limited vertical air mass exchange over the continent