Source apportionment of air pollutants in the Greater Auckland Region of New Zealand using receptor models and elemental levels in the lichen, Parmotrema reticulatum

Özet

Some lichen species can provide environmental archives of atmospheric deposition of potentiallyharmful elements that can be investigated as records of environmental change. The use of lichens for airquality assessment in New Zealand has not been widely explored, despite their widespread applicationaround the world. Due to this lack of attention, there is no lichen species that has been formally validatedfor use locally as an air pollution biomonitor although some species have been identified as beingpotentially useful. The most promising of these is Parmotrema reticulatum. This study assessed theperformance of the lichen, P. reticulatum, as a biomonitor of elemental air pollutants by examining theextent to which its elemental composition can provide a meaningful pollution source apportionmentmodeling in Auckland's central business district (CBD). Using the elemental content in transplanted P.reticulatum, principal component analysis, cluster analysis and positive matrix factorisation receptormodels, the major elemental air pollutants in Auckland's CBD were determined. Five sources explained74.4% of the total variance contained in the lichen dataset. These sources represent elemental contributions from motor vehicles, port activities, biomass burning, marine aerosol and roadside dust or crustalmatter. Motor vehicles, Auckland port activities, Biomass burning and marine aerosol were found toaccount for 11.8%, 39.8%, 10.2% and 6.9% of the overall elemental concentrations respectively. Emissionsfrom roadside dust accounted for 5.6% of the overall elemental concentrations in the lichen data. Evidence from this study suggests that P. reticulatum elemental content be used to model pollution sources