Source Apportionment of PM10 and Associated Air Toxics Using Chemical Analysis and Receptor Modelling in Highly Polluted Areas: Overview of Results from the Po Valley Italy and Krakow, Poland

Abstract

¿The Lombardy Region (RL) is located in the Po Valley and with its more than 9 million residents it is Italy¿s most densely inhabited area and one of the most polluted areas in Europe with regard to PM and photochemical smog. The EU air quality limit for PM10 of 50 µg m-3 (24 hours average) is exceeded up to 180 days per year and the limit of 40 µg m-3 (yearly average) is in breach for most urban / urban-background areas. In many cities in the new EU member-states, where coal combustion is a major energy source, such as Krakow, the situation is similar or even worse. With the aim of identifying efficient abatement strategies for the Lombardy Region, Italy the EU Joint Research Centre has embarked on a major integrated air quality project focused on particulate matter pollution to be carried out over a 5 years period (2006-2010). An overview is given of the results obtained in the first phase of the project and comparisons are made to a recent project carried out during winter 2005 in Krakow, Poland. In total 700 (RL) + 150 (Krakow) PM10 samples were collected and analyzed chemically for the regulated air toxics and source marker compounds including PAHs, higher linear alkanes, levoglucosan, K and Rb (wood combustion); Ca, Al, Fe, Mg, K, Ti, Ce, and Sr (soil/dust re- suspension); Na (road salt); Fe, Cu, Sn, Sb, and Mo (break-ware); V(fuel oil); Ce, Rh, Pt, and Pd (vehicle exhaust catalysts); Zn (tire-ware/tire combustion); Fe, Mn, Cr (railroad steel abrasion). In order to complete the chemical characterization the most significant cations and anions were also determined. Quantitative source apportionment was achieved by positive/constrained matrix factorization (PMF/CMF) and chemical mass balance modeling (CMB). During the studied pollution episodes in Krakow (Jan.-Feb. 2005) the European air quality limits were exceeded with up to a factor 8 for PM10 and up to a factor 200 for B(a)P, which is typical during winter for regions like Krakow. The major culprit for the extreme pollution levels resulted from CMB and CMF calculations to be residential heating by coal combustion in small stoves and boilers (>50% for PM10 and >90% B(a)P), whereas road transport (<10% for PM10 and <3% for B(a)P), and industry (4-15% for PM10 and <6% for B(a)P) played a lesser role. The inorganic secondary aerosol component of PM10 amounted to around 30%, which for a large part may be attributed to the industrial emission of the precursors SO2 and NOX. During the Lombardy Region study period (Feb. 2007), the PM10 concentrations were in the range of 21 to 209 µg m-3 and displayed a high degree of synchronism caused by typical winter meteorological conditions with very weak, cyclic winds, temperature inversions and shallow mixed boundary layers. The EU 24h limit was exceeded in the vast majority of days all over the region. The associated air toxics B(a)P, Pb, Ni, Cd and As did not exceed their respective EU limits with the exception of B(a)P in Sondrio. The secondary aerosol components NH4NO3 and (NH4)2SO4 contributed with 30-45% of the mass and it is evident that abatement strategies in RL for PM10 must include the reduction of emissions of gaseous precursors. At all sites, vehicle emissions and the related re-suspension of road-dust/soil were the main contributors, amounting to 31-41% of the total PM10 mass. Wood-burning was estimated by CMB with rater high uncertainties. It contributed with 10-18% of the total PM10 mass in the Po valley and with 27% in Sondrio (situated in the Valtelline valley). Minor specific sources were revealed for Sondrio (combustion of fuel oil, 7%), Brescia (cement production, 3%) and sodium chloride was found to contribute with around 2%, which may derive form long-transported sea-salt, or more likely may derive from road de-freezing agents.JRC.H.4-Transport and air qualit