The UPV/EHU researcher Iratxe Uria has developed a standardised protocol based on known models of air quality management to identify sources of pollution and to quantify the impact that these sources have on ambient levels. What is more, the protocol has been validated with data on volatile organic compounds obtained in the Lower Cadagua area.
A method for locating and quantifying pollution sources is designed
Researchers of the UPV/EHU-University of the Basque Country have produced a protocol to locate sources of volatile organic compounds and to quantify the pollution they cause
First publication date: 24/07/2015
Having available quantitative, reliable information about sources of pollutants is essential when it comes to implementing efficient strategies designed to cut pollution and to evaluate the results arising out of the control measures applied. Iratxe Uria, the researcher in the Department of Chemical Engineering and the Environment of the UPV/EHU's Advanced School of Engineering, has developed and validated a standardised protocol to locate and apportion sources of volatile organic compounds (VOCs) based on the application of receptor modelling. These models are mathematical techniques widely used in managing air quality in order to identify pollution sources and to quantify what impact these sources have on ambient pollution levels.
By applying this protocol at two air quality measuring stations in the Lower Cadagua area, similar sources were resolved relating mainly to the emissions coming from the coking plant, road traffic, the use of solvents and the vegetation. By applying the protocol, the percentages of VOCs coming from the sources identified at both stations were accurately identified. In view of the fact that the protocol has produced very good results in an area with a complex orography and meteorology, it has turned out to be a valid protocol that can be used anywhere else.
The protocol was specified on the basis of the methodologies most used right now to apportion sources, for the most widespread situation in which detailed information is not available about the emission sources or about the concentration of their emissions. Once the protocol had been obtained, it was validated using real data: it was applied to ambient VOC data obtained at two sampling points located in an area of the Lower Cadagua during measuring campaigns within the project entitled "Evaluation of air quality and apportioning of emission sources of organic compounds in the Lower Cadagua area," funded by the Government of the Basque Autonomous Community (region).
VOCs coming from the coking plant and road traffic
VOCs are organic compounds that are in a gaseous state at ambient temperature. They can be harmful to health because they are precursors of ozone and contaminating particles: some are carcinogenic and others are toxic (they cause dizziness, nausea, etc.). Even so, most VOCs are not regulated but it is important to measure their ambient levels. The high number and range of VOC sources present in the Lower Cadagua area at the time of the study (resulting from the operating of a coking plant, a coal tar distillation plant, an oil refinery, motorways with a lot of traffic, densely populated urban areas, etc.), and the complexity of the topography and meteorology meant that this area was an ideal experimental field to specify and test the protocol being studied.
The measurements were taken at the air quality station that the Government of the Basque Autonomous Community had in the Zorroza district, and in Zubileta, too, with a mobile unit equipped by the Government of the Basque Autonomous Community. In Zorroza, measurements were taken every hour non-stop over the course of one year, whereas in Zubileta the procedure was followed for more than a year and a half. At the same time, hourly data on conventional pollutants and meteorological parameters at these stations were gathered to be subsequently used to identify the sources of pollution.
Using these data, a qualitative and quantitative analysis was made. It became patently clear that the concentrations of pollutants recorded at the two stations were strongly influenced by the prevailing meteorology in the area and by the emissions of industrial provenance coming from the Cadagua valley. High concentrations of ethane, ethylene, benzene and napthalene were found. They were very likely caused by the coking plant located there and which was subsequently closed down. Road traffic was also identified as a probable major source of VOCs in Zorroza and in Zubileta, while other lesser sources appeared to be related to solvent use; evidence of the impact of the oil refinery emissions at the station in Zorroza even emerged. These results coincided perfectly with the results obtained by means of the use of the protocol designed by the researcher.
Additional information
Iratxe Uria (Bilbo, 1985) is a chemical engineer, has a Master's in Environmental Engineering and a doctorate in Environmental Engineering. She wrote up her PhD thesis Development and application of a protocol for source apportionment of ambient volatile organic compounds in urban/industrial areas, at the Department of Chemical Engineering and the Environment of the UPV/EHU's Advanced School of Engineering in Bilbao, and her PhD supervisor was Marino Navazo-Muñoz.
References:
I. Uria-Tellaetxe, D. C. Carslaw (2014). "Conditional bivariate probability function for source identification". Environmental Modelling & Software, 59 1-9.
J. D. Ramón, M. Navazo, L. Alonso, N. Durana, M. C. Gómez, I. Uria (2013). "Determinación de Fuentes de Contaminantes Atmosféricos en un Área de Fondo Rural Mediante los Modelos Umnix – Pmf Aplicados a Medidas Horarias de 64 COVs Durante 3 Años". Revista Ambiental Aire, Agua, Suelo. Vol.4, 2. ISSN 1900-9178.