Physically Constrained Receptor Modelling of PM10 from Winter Time Krakow

Abstract

Krakow is Poland¿s second largest city and one of the most polluted cities in Europe with regards to particulate matter (PM) and associated compounds, such as benzo(a)pyrene (B(a)P). The study was designed to apportion coal combustion sources in comparison with other main sources for these pollutants PM10 samples were collected in Krakow during typical winter pollution events from 5 sampling sites, all with little different source profiles, industry, traffic, residential, urban background and rural background areas. The receptor samples were chemically analyzed together with PM emissions samples from 20 major sources and the obtained data was subjected to multivariate receptor modeling. 46 individual compounds were included comprising elementary and organic carbon (EC/OC), major anions and cations, trace elements, polyaromatic hydrocarbons and azaarenes. The source apportionment was accomplished by physically constrained positive matrix factorization (CMF). The hybrid receptor model between chemical mass balance and factor analysis with physically meaningful constraints was developed in the early 90ties by Wåhlin (Wåhlin, 1993). Subject for constraints was to gain reduced rotational ambiguity and physically more interpretable factors. In this study, these ideas are developed further by not only constraining ratios of specific elements, but allowing the constraint to be variable within uncertainty limits. The limits for constraints can be obtained from experimental uncertainties of source profiles or expert knowledge about specific elemental ratios, e.g. evaporation or chemical transformation that changes the original source fingerprint from one form to an other. Furthermore, the uncertainties for semivolatile PACs were scaled using temperature corrected subcooled liquid vapor pressures (Fernández et al., 2002). CMF takes advantage of the multi-linear engine ME-2 model tool developed by Paatero,(1999), which facilitate the running of PMF in various constrained modes. The highest primary contributions to the PM10 pollution in the city of Krakow and in particularbackground site Zakopane was from Home heating. In Krakow this source covers 30-50% andin Zakopane to 80-90% of total PM10, which is in agreement with high number of small stoves in Krakow and Zakopane. The second highest primary contribution of PM10 was estimated to come from industrial power generation (coal), 30-40% in Krakow and 5-10% in Zakopane to 80-90%. Traffic and re-suspension was estimated by to be lowest primary source explains to 8-10% in Krakow and less than 2% in Zakopane. The contribution from secondary aerosols was estimated to contribute with 20-21% in Krakow and less than 8-10% in Zakopane.JRC.H.4-Transport and air qualit