Crilley 2014_Identification of the sources of primary organic aerosols a...

162                                                                                  L.R. Crilley et al. / Environmental Pollution 191 (2014) 158e165


                                                                                         % of Species                  Concentration of species
                                                              1000                                                                                              100
                                                                      Biomass Burning                                                                           90
                                                              100                                                                                               80
                                                                10                                                                                              70
                                                                                                                                                                60
                                                                1                                                                                               50
                                                                                                                                                                40
                                                               0.1                                                                                              30
                                                              0.01                                                                                              20
                                                                                                                                                                10
                                                             0.001                                                                                              0




                                                              100                                                                                                100
                                                                     Cooking                                                                                     90
                                                                10                                                                                               80
                                                                                                                                                                 70
                                                                1                                                                                                60
                                                                                                                                                                 50
                                                               0.1                                                                                               40
                                                                                                                                                                 30
                          Concentration of Species, ng m-3




                                                                                                                                                                       % of Species total
                                                              0.01                                                                                               20
                                                                                                                                                                 10
                                                             0.001                                                                                               0



                                                             1000                                                                                               100
                                                                     Vehicle Emissions                                                                          90
                                                              100                                                                                               80
                                                                                                                                                                70
                                                              10                                                                                                60
                                                                                                                                                                50
                                                                1                                                                                               40
                                                                                                                                                                30
                                                              0.1                                                                                               20
                                                                                                                                                                10
                                                             0.01                                                                                               0




                                                             1000                                                                                                100
                                                                     Plant Wax                                                                                   90
                                                              100                                                                                                80
                                                                                                                                                                 70
                                                              10                                                                                                 60
                                                                                                                                                                 50
                                                                1                                                                                                40
                                                                                                                                                                 30
                                                              0.1                                                                                                20
                                                                                                                                                                 10
                                                             0.01                                                                                                0




Fig. 3. Source factor profiles from the positive matrix factorization (PMF) analysis using EPA-PMF3.0 model. Bars represent mass concentration while the squares indicate the
percentage contribution.



et al., 1998). DHAA is also a constituent of vehicle tires, indicating                                                  All of these seasonal differences were statistically significant
the presence of another possible source at the schools (Rogge et al.,                                                   (p < 0.05). The higher concentrations of the biomass burning
1993b; Sheya, 2002). As levoglucosan was generally the most                                                             tracers, levoglucosan and mannosan in winter is expected in Bris-
abundant compound detected at most of the schools (Table 3), it                                                         bane due to the influence of prescribed burning of bushland sur-
indicates that biomass burning was a significant source. Schools                                                         rounding the city during the winter to reduce the risk of summer
sampled in the summer generally had a lower concentration than                                                          bushfires. Prescribed burning typically occurs during JulyeAugust,
the schools sampled in winter, with the averages of 27.6  22.4 and                                                     which was when the highest concentration of levoglucosan and
94.6  60.3 ng m3 for summer and winter, respectively. By com-                                                         mannosan were observed (Table 3). The levoglucosan detected at
parison, using the same analytical technique, the mean levogluco-                                                       the schools sampled in the summer are likely to be from a different
san concentrations were higher in Augsburg, Germany compared to                                                         wood burning source as unlike at the schools sampled in winter
the current study at 112  84 and 337  174 ng m3 for summer and                                                       (Table 3), these schools recorded concentrations of DHAA above the
winter, respectively (Pietrogrande et al., 2011). The lower concen-                                                     detection limit. DHAA is emitted only from softwood combustion
trations in the current study are likely to be due to the warmer                                                        (specifically pine) unlike levoglucosan that is emitted by combus-
climate in Brisbane and the resulting low levels of domestic wood                                                       tion of all forms of cellulose containing materials (Pietrogrande
burning for heating.                                                                                                    et al., 2011; Robinson et al., 2006a; Rogge et al., 1998). This sug-
   Distinct seasonal trends were observed between the schools                                                           gests that in the summer there is a different source of biomass
sampled in summer and winter in the concentrations and distri-                                                          burning, possibly related to domestic wood burning such as from
butions of the biomass burning tracers. Schools sampled in winter                                                       barbeques, which in Brisbane predominantly use pine. In the pre-
recorded higher concentrations of levoglucosan and mannosan,                                                            vious section, higher contributions from vehicle emission at schools
compared to schools sampled in summer, whereas the schools                                                              sampled in summer were observed and another possible source of
sampled in summer had higher concentrations of DHAA (Table 3).                                                          DHAA is tire wear (Rogge et al., 1993b; Sheya, 2002). Thus, traffic