Trends analysis of PM source contributions and chemical tracers in NE Spain during 2004–2014: A multi-exponential approach

Abstract

In this work for the first time data from two twin stations (Barcelona, urban background, and Montseny, regional background), located in NE of Spain, were used to study the trends of the concentrations of different chemical species in PM10 and PM2.5 along with the trends of the PM10 source contributions from Positive Matrix Factorization (PMF) model. Eleven years of chemical data (2004–2014) were used for this study. Trends of both specie concentrations and source contributions were studied using the Mann-Kendall test for linear trends and a new approach based on multi-exponential fit of the data. Despite the fact that different PM fractions (PM1, PM2.5, PM10) showed linear decreasing trends at both stations, the contributions of specific sources of pollutants and the related chemical tracers showed exponential (single or double) decreasing trends. The different types of trends observed reflected the different effectiveness and/or time of implementation of the measures taken to reduce the concentrations of atmospheric pollutants (i.e. those implemented in the Industrial Emission Directives and in the Large Combustion Plants Directive). Moreover, the trends of the contributions from specific sources such as those related with industrial activities and with primary energy consumption mirrored the effect of the financial crisis in Spain from 2008. The sources that showed statistically significant downward trends at both Barcelona (BCN) and Montseny (MSY) during 2004–2014 were Ammonium sulfate, Ammonium nitrate, and V-Ni bearing source. The contributions from these sources decreased exponentially during the considered period indicating that the observed decrease was not gradual and consistent over time. Moreover, statistically significant decreasing trends were observed for the contributions to PM from the Industrial/Traffic source at MSY (mixed metallurgy and road traffic) and from the Industrial (metallurgy mainly) source at BCN. These sources were clearly linked with anthropogenic activities and the observed decreasing trends confirmed the effectiveness of pollution control measures implemented at EU or regional/local levels. The general trends observed for the calculated PMF source contributions well reflected the trends observed for the chemical tracers of these pollutant sources. ; This work was supported by the MINECO (Spanish Ministry of Economy and Competitiveness), the MAGRAMA (Spanish Ministry of Agriculture, Food and Environment), the Generalitat de Catalunya (AGAUR 2014 SGR33 and the DGQA) and FEDER funds under the PRISMA project (CGL2012‐39623‐ C02/00). The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 654109 and previously from the European Union Seventh Framework Programme (FP7/2007‐2013) under grant agreement n° 262254. NO2 map analyses and visualizations used in this paper were produced with the Giovanni online data system, developed and maintained by the NASA GES DISC. The authors would like to express their gratitude to D. C. Carslaw and K. Ropkins for providing the Openair software used in this paper (Carslaw and Ropkins, 2012; Carslaw, 2012). ; Peer reviewed