10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Particulate matter in the Northwest of the Iberian Peninsula: A one-year study
Fernanda Oduber, Carlos Blanco-Alegre, Ana Isabel Calvo, Amaya Castro, Roberto Fraile, Teresa Nunes, CÉLIA ALVES, University of Aveiro
Abstract Number: 248 Working Group: Source Apportionment
Abstract Humans and the environment are exposed to a complex mixture of several atmospheric contaminants, including particulate matter (PM). The study of the PM composition and its temporal variation allows determining the potential emission sources and, therefore, to establish mitigation measures. Researches on the spatial and temporal variation of chemical characteristics of PM in the northwest of the Iberian Peninsula are scarce.
The present study was carried out in León city, located in the northwest of the Iberian Peninsula (42° 36′ N, 05º 35′ W and 838 m above sea level), between 9th March 2016 and 14th March 2017. PM10 sampling was carried out on the roof of the Faculty of Veterinary (University of León). Two different devices were used: a) a low volume sampler (TECORA, ECHOPM) operated with 47 mm diameter teflon filters and b) a high volume sampler (CAV-A/Mb) equipped with 150 mm diameter quartz filters. Quartz filters were used to determine PM10 by gravimetry, and organic and elemental carbon (OC and EC) by a thermo-optical method. Teflon filters were used for the analysis of water soluble ions (ionic chromatography). Furthermore, an automatic weather station located in the sampling site recorded temperature, wind speed and direction, relative humidity and precipitation data. Likely due to the seasonality of sources and meteorological processes, well-defined temporal differences were observed in PM10 concentrations and chemical composition. Monthly and seasonal variations were studied in detail. During the sampling period, the mean temperature and relative humidity were 12 ºC and 64%, respectively. Summer (July-September) was the season with less precipitation and higher mean temperature (21.3 mm and 20 ºC, respectively), whereas spring (April-June) was the rainiest season (223.2 mm). The PM10 daily limit value (50 µg/m3, Directive 2008/50/EC) was only exceeded on 23rd February 2017 (60.4 µg/m3), coinciding with a Saharan dust intrusion episode. The lowest PM10 value (2.0 µg/m3) was observed in summer, after a precipitation event. Winter (January-March) was characterized by high PM10, OC, EC and NO3- mean concentrations (20.6 ± 9.3, 3.0 ± 1.5, 1.0 ± 0.5, and 1.7 ± 1.8 µg/m3, respectively). These results may be due to the contribution of fossil fuel-based heating systems. The lowest PM10 and OC mean concentrations were observed in spring (11.8 ± 6.1, 1.8 ± 1.0 µg/m3, respectively). The decrease in the particulate matter levels during spring can be associated with the intense precipitation in this period. Summer was characterized by low EC and NO3- concentrations (0.6 ± 0.3 and 0.5 ± 0.3 µg/m3, respectively) and high Ca2+ and SO42- mean values (0.3 ± 0.2 and 1.6 ± 1.1 µg/m3, respectively). The presence of high levels of ions, such as Ca2+ and SO42-, can be attributed to different episodes of African dust intrusions that reached the Peninsula [1, 2].
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