PM or particulate matter is a type of contaminant in the atmosphere, considered very harmful for health, ecosystems, climate change, conservation of materials and visibility. Chemist Ms Ainhoa Inza studied the presence of this particulate matter in the Autonomous Community of the Basque Country (CAV-EAE); concretely, the type known as PM10, made up of particles of less than ten micras in diameter. Amongst other things, the researcher compared the concentration of this kind of atmospheric contamination in various areas and periods of the year in the Basque Country and subsequently characterised the main sources of emission of PM10, based on chemical analyses. Her PhD thesis is entitled Study of temporal series and chemical composition of atmospheric particulate matter in different areas of the Basque Country.
To carry out this work, Ms Inza gathered and evaluated series of data on the daily concentration of PM10, apart from other contaminant gaseous species (CO, NOx, SO2 and O3) at various locations within the CAV-EAE. Concretely, she used data registered between 2004 and 2007 from twelve stations belonging to the Air Quality Control and Monitoring Network of the Basque Government's Department of the Environment, Territorial Planning, Agriculture and Fisheries. These stations are representative of four types of Basque environments: regional background, rural-suburban, urban background and urban.
Less than the Iberian Peninsula average
In her thesis Ms Inza concluded that the levels of PM10 increase progressively from the regional background stations to the urban ones, principally due to emissions from road traffic. The difference in PM10 concentrations from one place to another is, moreover, greater in winter than in summer; winter atmospheric stagnation favouring the accumulation of contamination where it is emitted. In summer, on the other hand, the layer of atmospheric mixture (the lower layer of the atmosphere and linked to contamination) is boosted, thus favouring the transport of contaminants from one place to another.
Ms Inza also observed that the PM10 levels studied in the CAV-EAE are generally inferior to those obtained at other stations on the Iberian Peninsula in similar environments. The researcher also showed that, as stipulated in the 2008/50/CE European Directive, the limit value of 40 g/m3 of PM10 annually was not passed in the four years in which these twelve Basque monitoring stations were studied. As regards the norm fixing 35 as the maximum number of times the limit value of 50 g/m3 of PM10 can be passed, it was observed that this has not always been complied with at some urban stations, probably due to the traffic factor. In any case, Ms Inza also explained that the same occurs in similar zones in the Iberian Peninsula and Europe.
Chemical composition, in order to know the sources of emission
An experimental phase was also effected during the research, carried out at a number of locations with different features in the CAV-EAE. In this various techniques were combined which enabled obtaining data about the chemical composition of the PM. Thanks to this information, Ms Inza was able to characterise the main sources of PM10 emission in these notable locations. For example, at the Molinao wharf (Pasaia) it was established that the unloading of scrap metal, mineral material (crustal), marine aerosol, road traffic and secondary regional origin traffic contributed to the PM10 mass. The same ocurred at the Sondika station with industrial 1 source (zinc and lead), industrial 2 source (steelmaking), crustal source, the marine factor, road traffic and regional sulphate.
|Contact: Amaia Portugal|