The PhD student Rosa Lara will defend her thesis titled "Suspended and settleable particulate matter in the western area of the conurbation of Gijón"
The PhD student Rosa Lara, from the EGAR group, will defend her thesis on 18 January at 12:00h in Sala de Proyectos at Escuela Politécnica de Gijón.
Title: Suspended and settleable particulate matter in the western area of the conurbation of Gijón
Directors: Xavier Querol and Luis Negral
Thesis Committee: Stella Moreno, Andrés Alastuey, Jesús de la Rosa, Beatriz Suárez-Peña and Leonor Castrillón
Abstract:
Air pollution is one of the leading causes of premature deaths in Europe. Above all autonomous communities in Spain, Asturias is one of the latest to comply with the PM10 limit values established by state regulations. One of the areas of particular concern is identified in the western area of the conurbation of Gijón, which is noted for the persistence of significant levels of suspended and settleable particulate matter. This is an area of intense industrial activity, in which an integrated steel plant, a port with the state’s largest bulk solid traffic, coal and mineral stockyards, a cement plant, and a coal-fired power plant exist, among others. The high levels of PM recorded in the area, together with the presence of sources of fugitive PM emissions and the persistence of high levels of atmospheric deposition in the area, highlight the need to deepen knowledge of the characterization of these pollutants, as well as the identification and quantification of their principal sources.
Regarding the study of PM, a sampling campaign was carried out between May 2019 and September 2020 employing a high-volume collector equipped with a selective PM10 head. 447 24-h samples were collected. A representative part of the samples (32%) was chemically characterized. For the study of atmospheric deposition, a sampling campaign was carried out between December 2019 and June 2020, employing a self-designed and self-built collector located in five different sites to obtain representative samples attending to the spatial variability. Rainy days were avoided to collect the samples in the best conditions for the dispersion of settleable particulate matter. 150 24-h samples (30 per location) of dry atmospheric deposition (DSPM) were collected and chemically characterized.
Mobility and industrial activity restrictions, derived from the COVID-19 pandemic, occurred during both sampling campaigns, subsequently leading to the possibility of analysing their impact on PM10 and DSPM levels. During strict confinement, there was an increase of 9.1% in the PM10 concentration, mainly due to the increase in secondary inorganic aerosol, favoured by meteorological conditions. In DSPM, significant reductions (>74%) in sites closest to the industrial activity. However, these reductions should be taken with caution because of the variation in the wind dynamics of the compared periods.
The assessment of source apportionment for PM10 and DSPM was carried out by using the PMF multivariate receptor model. Regarding PM10, eight contribution sources were identified: “Biomass burning”, “Iron and steel combustion”, “Secondary nitrate”, “Secondary sulfate”, “Sinter”, “Fugitive from iron and steel resuspension”, “Local diffuse” (mixture of resuspension of abrasion products from brakes and wheels, and industrial metals deposited on the road surface) and “Marine aerosol”. Regarding DSPM, two sources were identified in the stations that presented higher levels of DSPM: “Sinter/Steelmaking” and “Resuspension of contaminated crustal”. The other two stations also presented a factor associated with marine aerosol and, in the more rural one, a factor associated with biomass burning was detected.
Future air quality policies should consider measures to reduce anthropogenic emissions of PM10 and DSPM with the aim of reducing their impact in industrialized urban/suburban areas. The results also highlight the need to take environmental action on the secondary PM precursor gases to reduce PM10 and PM2.5 levels efficiently.
