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Universidad Politécnica de Cartagena (2010)

Variability of levels and composition in airborne particulate matter in the southeast of the Iberian Peninsula

Negral Álvarez, Luis

Titre : Variability of levels and composition in airborne particulate matter in the southeast of the Iberian Peninsula

VARIABILIDAD DE NIVELES Y COMPOSICIÓN DEL MATERIAL PARTICULADO EN SUSPENSIÓN EN EL SUDESTE DE LA PENÍNSULA IBÉRICA

Auteur : Negral Álvarez, Luis

Université de soutenance : Universidad Politécnica de Cartagena

Grade : Doctor of Philosophy (PhD) 2010

Résumé
The Spanish Law 34/2007 defines air pollution as “the occurrence in atmosphere of materials, substances or energy that cause nuisance, risk or damage to human health, human security, environment and the rest of the of the goods, whatever their natures are”. Particles which are present in the airborne particulate matter (PM) can have either a natural or an anthropogenic origin. Directive 2008/50/EC, conscious that contributions whose origin is natural sources can not be controlled, permits the consideration of the contributions belonging to those sources in those cases in which they are a solid proof for the evaluation of the accomplishment of the limit values. The natural sources of emission which mostly affect PM in the environment in the southeast of the Iberian Peninsula are the dust contributions arriving from the African deserts, the local resuspension of PM and the marine aerosol (Moreno Grau, 1998 ; Querol et al., 2006 ; Negral et al., 2008, 2010). As any source of PM emission has its chemical tracers, it is interesting to look for the tracers which characterize it (Li et al., 2003). Considering these tracers as the main basis, the importance of that source in the PM levels in the environment can be detected and also quantify which its contribution to the time and spatial variability of those levels is, always according to the characteristics of the emission and to the meteorological factors. Objectives : The general search objectives in this thesis are : a) to interpret the variability of PM10 and PM2.5 levels in the environment and that of their majority, minority and trace components. b) to identify and to quantify the contributions of the air masses with African origin to PM10 and PM2.5, as well as those whose origin is in other anthropogenic or natural sources of emission. Material and Methods : Samples from both fractions PM10 and PM2.5 have been taken in three different locations of the city of Cartagena : Bastarreche, Santa Ana and Mompeán. The gravimetric determinations of levels of PM10 and PM2.5 in ambient air have been made, as well as those of the chemical speciation of the samples (ICP-MS, ICP-AES, ionic chromatography, and C, OC and EC elemental analysis). The results from the Network for Air Quality Monitoring in the Region of Murcia have been processed by elaborating the appropriate databases. In order to define the origins of the air masses, there has been a use of geographic information tools together with satellite images and results of atmospheric models. There has been a use of the appropriate methodology for studying the intrusion of air masses originating in the African deserts of Sahara-Sahel. Considering the analysis of the time series of chemical speciation of the two PM fractions obtained in the different places under study, there has been a definition of the contribution of the sources considering the Principal Component Analysis with Multiple Linear Regression (PCA-MLR) and with Positive Matrix Factorization (PMF). Results : The results of the application of the statistical tools which have allowed for the definition of the time and spatial variables studied have been presented. First, this has been made in the case of the gravimetric method and then in those cases of real-time measurements instruments, always comparing the results of both techniques. There has been a collection of the results of those phenomena belonging to the synoptical conditions which have allowed for the arrival of African air masses towards Cartagena since January 1, 2004 to May 31, 2008, together with air mass back-trajectories, aerosol maps, satellite images, and meteorological maps. This analysis has also been extended to the Region of Murcia. A classification of the days under study has been proportioned considering the sectors and the scenarios. For every scenario it has been necessary to obtain the PM10 levels of every sampling station, the concentration of those days exceeding the limit value and the annual average number of days exceeding the legal threshold. The quantification of the mass contribution to the daily and annual average PM10 levels due to the African dust load has been also presented. The results obtained concerning the PM chemical speciation have also been presented and, finally, the same has been made with those related to the application of the reception models through the use of PCA-MLR and PMF. Discussion and conclusions : There has been an identification of a time and spatial variability for those species under study. The biggest values for the crustal species in PM10 have been registered in Santa Ana. In the case of those species indicating industrial activities, their levels in PM10 have been higher in Bastarreche. Concerning PM2.5, there are no data in the case of Bastarreche and the highest levels of the species studied, except for those related to the total mass, have appeared in Mompeán. The events which are linked to a lower load of PM10 in the Region of Murcia correspond to those called Northern Atlantic, Northwestern Atlantic and Western Atlantic, and in these situations the increase in the levels of atmospheric pollutants is due to the activies which are characteristic in that area. Southwestern Atlantic is a common origin of dust outbreaks. The contribution which has a natural origin and a local character also appears within the Regional events, in which the anthropogenic contribution can also be noticed. The typical weak Mediterranean gradient of pressure, for which there is an African advection reaching the Region of Murcia, allows for the definition of a fifth (new) scenario, which means up to 21% of the days with dust outbreak which have been studied in this memory, and consequently, they have to be considered in order to assess the air quality in the area. It has been revealed the amount of crustal species from exogenous sources and the importance of indigenous sources, such as wheeled traffic, for the carbonaceous fraction. The African dust contribution to the PM10 annual mean is considered between 4 and 6 μg/m3. In the period between January 1, 2004 and May 31, 2005, there have been 562 days with dust outbreak. It is mentioned the possibility of using as a regional background sampling station for the Region of Murcia, the one located in Caravaca de la Cruz. A decrease in PM10 levels can be observed as a consequence of changing the sampling station from Bastarreche to Mompeán. The latter is a sampling station without breach of the limits, neither in the cases of PM10 and PM2.5 nor in those ones of metals subject to regulation. The differences found in PM10, between the real-time measurements of the Network for Air Quality Monitoring in the Region of Murcia and the gravimetric data, have made it necessary a detailed study of the causes which have provoked this incidence. The factors extracted by PCA-MLR, together with its average contributions to the total mass of PM10 and PM2.5 are associated to the following sources : a) PM10 in Bastarreche : Mineral or crustal 25.0% ; Traffic 19.0% ; Secondary 17.0% ; Local zinc metallurgical industry 3.0% ; Marine 3.0% ; and shipyard 2.0%. b) PM10 in Santa Ana : Mineral or crustal 30.0% ; Traffic 26.0% ; Secondary 22.0% ; Industrial from Cartagena 12.0% ; and Marine 5.0%. c) PM2.5 in Santa Ana : Traffic 40.0% ; Industrial from Cartagena 27.0% ; Mineral or crustal 9.0% ; Marine 2.0% ; and Local zinc metallurgical industry 0.0%. The factors extracted by PMF, together with its average contributions to the total mass of PM10 and PM2.5 are associated to the following sources : a) PM10 in Bastarreche : Traffic 22.0% ; Secondary SO4 2- 19.0% ; Secondary NO3 - 16.1% ; Marine 16.0% ; Power station and local influence 8.2% ; Refinery 7.7% ; Dust outbreaks and other mineral contributions 6.4% ; and Local zinc metallurgical industry 4.5%. b) PM10 in Santa Ana : Secondary NO3 - 26.0% ; Traffic 16.0% ; Dust outbreaks and other mineral contributions 15.6% ; Marine 13.9% ; Secondary SO4 2- 9.8% ; Refinery 8.4% ; Power station and local influence 8.1% ; and Local zinc metallurgical industry 2.0%. c) PM10 in Mompeán : Secondary NO3 - 34.5% ; Secondary SO4 2- 15.4% ; Marine 12.5% ; Traffic 11.1% ; Dust outbreaks and other mineral contributions 11.0% ; Refinery 8.1% ; Power station and local influence 7.4% ; and Local zinc metallurgical industry 0.0%. d) PM2.5 in Santa Ana : Secondary NO3 - 27.2% ; Secondary SO4 2- 26.5% ; Marinem 14.6% ; Traffic 7.3% ; Influence of Construction 7.0% ; Refinery 6.2% ; Dust outbreaks and other mineral contributions 5.8% ; and Local zinc metallurgical industry 5.3%. e) PM2.5 in Mompeán : Secondary SO4 2- 26.4% ; Secondary NO3 - 26.1% ; Dust outbreaks and other mineral contributions 13.1% ; Power station and local influence 9.5% ; Marine 8.1% ; Refinery 6.5% ; Local zinc metallurgical industry 6.2% ; and Traffic 4.0%. It is remarkable that the two receptor models are complementary. They have allowed for a coherent vision of the contributions to airborne particulate matter either with natural or anthropogenic origin. In the medium term, the plans for the environmental management of Cartagena´s inner city will have to focus their attention on the traffic, as that is likely to become the most relevant anthropogenic source

Mots clés : Contaminación atmosférica ; Polvo africano ; Material particulado suspensión ; Sudeste Península Ibérica ; Airborne particulate ; Southeast of the Iberian Peninsula ; Dust outbreaks

Présentation (TESEO)

Page publiée le 23 juin 2013, mise à jour le 11 février 2019