V. Gianelle

Benzo(a)pyrene air concentrations and emission inventory in Lombardy region, Italy

Three years of particle phase B(a)P air concentration measurements in 13 sites in Lombardy (Italy) and a detailed emission inventory at the municipal scale for the whole region were used to infer the contribution of different sources to B(a)P atmospheric levels. The analyses of the weekly and monthly profiles of B(a)P concentrations, the cluster analysis and the comparison between the B(a)P/PM10 ratios in ambient air and in the emissions allowed identifying wood burning in small residential appliances as the key source for all the sites, except for those located in Milan. The highest values of the average B(a)P concentrations were not found in the wider urban areas, where in general the highest PM10 levels were registered. Regarding the seasonal variability, a marked reduction of both B(a)P concentrations and B(a)P/PM10 ratios was observed in the summer season. The cluster analysis of PM10 and B(a)P concentrations showed that the two pollutants tend to have a separate pattern; moreover the cluster analysis of B(a)P/PM10 ratios showed that the trend of this ratio split the stations depending on their location: plain area, piedmont and valley zones, and mountain sites. The dominance of the wood combustion highlighted by the emission inventory, originating from the residential sector and from pizzerias in the city of Milan, is consistent with the findings of other studies based on a source apportionment approach or air quality modeling, although some patterns of ambient B(a)P concentrations in one site were not adequately explained by the emission sources included in the emission inventory.

Spatial and temporal variability of carbonaceous aerosols: Assessing the impact of biomass burning in the urban environment.

Biomass burning (BB) is a significant source of atmospheric particles in many parts of the world. Whereas many studies have demonstrated the importance of BB emissions in central and northern Europe, especially in rural areas, its impact in urban air quality of southern European countries has been sparsely investigated. In this study, highly time resolved multi-wavelength absorption coefficients together with levoglucosan (BB tracer) mass concentrations were combined to apportion carbonaceous aerosol sources. The Aethalometer model takes advantage of the different spectral behavior of BB and fossil fuel (FF) combustion aerosols. The model was found to be more sensitive to the assumed value of the aerosol Ångström exponent (AAE) for FF (AAEff) than to the AAE for BB (AAEbb). As result of various sensitivity tests the model was optimized with AAEff=1.1 and AAEbb=2. The Aethalometer model and levoglucosan tracer estimates were in good agreement. The Aethalometer model was further applied to data from three sites in Granada urban area to evaluate the spatial variation of CMff and CMbb (carbonaceous matter from FF or BB origin, respectively) concentrations within the city. The results showed that CMbb was lower in the city centre while it has an unexpected profound impact on the CM levels measured in the suburbs (about 40%). Analysis of BB tracers with respect to wind speed suggested that BB was dominated by sources outside the city, to the west in a rural area. Distinguishing whether it corresponds to agricultural waste burning or with biomass burning for domestic heating was not possible. This study also shows that although traffic restrictions measures contribute to reduce carbonaceous concentrations, the extent of the reduction is very local. Other sources such as BB, which can contribute to CM as much as traffic emissions, should be targeted to reduce air pollution.

Determination of Local Source Profile for Soil Dust, Brake Dust and Biomass Burning Sources

.Via E. Fermi 2749, Ispra (VA) 21020, Italy Knowledge on the main emission sources and their relative importance is essential for policy makers to define effective pollution reduction strategies. Such knowledge can be gained by receptor modeling using e.g. the chemical mass balance model (CMB). For a successful application of CMB all important sources must be known and information must be available on representative emission profiles. Speciation profiles of emission sources can be found in literature and extensive databases are available (U.S. E.P.A., 2002). However, it is preferable to use profiles representing the actual sources present in the area whenever is possible. For the Lombardy region, previous studies have demonstrated the importance of soil and fugitive dust, biomass burning and brake lining dust (Regione Lombardia, ARPA Lombardia, Fondazione Lombardia per l’Ambiente, 2008; AA.VV., 2006). The goal of this work is to report our methodology used to determine ‘local’ source profiles of soil dust, domestic wood burning and brake lining dust, to be used for example in the CMB applications. To investigate the model sensitivity, simulations were carried out for several sites with different local and no-local profiles.

Emissions from the combustion of eucalypt and pine chips in a fluidized bed reactor.

Interest in renewable energy sources has increased in recent years due to environmental concerns about global warming and air pollution, reduced costs and improved efficiency of technologies. Under the European Union (EU) energy directive, biomass is a suitable renewable source. The aim of this study was to experimentally quantify and characterize the emission of particulate matter (PM2.5) resulting from the combustion of two biomass fuels (chipped residual biomass from pine and eucalypt), in a pilot-scale bubbling fluidized bed (BFB) combustor under distinct operating conditions. The variables evaluated were the stoichiometry and, in the case of eucalypt, the leaching of the fuel. The CO and PM2.5 emission factors were lower when the stoichiometry used in the experiments was higher (0.33±0.1 g CO/kg and 16.8±1.0 mg PM2.5/kg, dry gases). The treatment of the fuel by leaching before its combustion has shown to promote higher PM2.5 emissions (55.2±2.5 mg/kg, as burned). Organic and elemental carbon represented 3.1 to 30 wt.% of the particle mass, while carbonate (CO3(2-)) accounted for between 2.3 and 8.5 wt.%. The particulate mass was mainly composed of inorganic matter (71% to 86% of the PM2.5 mass). Compared to residential stoves, BFB combustion generated very high mass fractions of inorganic elements. Chloride was the water soluble ion in higher concentration in the PM2.5 emitted by the combustion of eucalypt, while calcium was the dominant water soluble ion in the case of pine.

Case Studies of Source Apportionment and Suggested Measures at Southern European Cities

This chapter reports the results of the PM10 and PM2.5 source apportionment at 3 urban background sites (Barcelona, Florence and Milan, BCN-UB, FI-UB, MLN-UB) 1 suburban background site (Athens, ATH-SUB) and 1 traffic site (Porto, POR-TR). Road traffic (sum of vehicle exhaust, non-exhaust and traffic-related secondary nitrate) is the most important source of PM10 (23–38% at all sites) and PM2.5 (22–39%, except for ATH-SUB and BCN-UB). The second most important source of PM10 (20–26%) is secondary sulphate/OC at BCN-UB, FI-UB and ATH-SUB, while it represents 10–14% in MLN-UB and POR-TR. The relative importance of this source is higher in PM2.5 (19–37% at SUB-UB sites). Biomass burning contributions vary widely from 14–24% of PM10 in POR-TR, MLN-UB and FI-UB, 7% in ATH-SUB to <2% in BCN-UB. In PM2.5, BB is the second most important source in MLN-UB (21%) and in POR-TR (18%). This large variability is due to the degree of penetration of biomass for residential heating. Other significant sources are local dust, industries (metallurgy), remaining secondary nitrate (from industries, shipping and power generation), sea salt and Saharan dust. The same analysis is performed for exceedances days. Based on the above, a priority list of measures to improve PM levels is proposed for each city.