Baseline characterisation of source contributions to daily-integrated PM2.5 observations at Cape Grim using Radon-222

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dc.contributor.authorCrawford, Jen_AU
dc.contributor.authorChambers, SDen_AU
dc.contributor.authorCohen, DDen_AU
dc.contributor.authorWilliams, AGen_AU
dc.contributor.authorAtanacio, AJen_AU
dc.date.accessioned2020-11-03T03:51:12Zen_AU
dc.date.available2020-11-03T03:51:12Zen_AU
dc.date.issued2018-08-20en_AU
dc.date.statistics2020-10-29en_AU
dc.description.abstractWe discuss 15 years (2000–2015) of daily-integrated PM2.5 samples from the Cape Grim Station. Ion beam analysis and positive matrix factorisation are used to identify six source-type fingerprints: fresh sea salt (57%); secondary sulfate (14%); smoke (13%); aged sea salt (12%); soil dust (2.4%); and industrial metals (1.5%). An existing hourly radon-only baseline selection technique is modified for use with the daily-integrated observations. Results were not significantly different for days on which >20 hours were below the baseline radon threshold compared with days when all 24 hours satisfied the baseline criteria. This relaxed daily baseline criteria increased the number of samples for analysis by almost a factor of two. Two radon baseline thresholds were tested: historic (100 mBq m−3), and revised (50 mBq m−3). Median aerosol concentrations were similar for both radon thresholds, but maximum values were higher for the 100 mBq m−3 threshold. Back trajectories indicated more interaction with southern Australia and the Antarctic coastline for air masses selected with the 100 mBq m−3 threshold. Radon-only baseline selection using the 50 mBq m−3 threshold was more selective of minimal terrestrial influence than a similar recent study using wind direction and back trajectories. The ratio of concentrations between terrestrial and baseline days for the primary sources soil, smoke and industrial metals was 3.4, 2.6, and 5.5, respectively. Seasonal cycles of soil dust had a summer maximum and winter minimum. Seasonal cycles of smoke were of similar amplitude for terrestrial and baseline events, but of completely different shape: peaking in autumn and spring for terrestrial events, compared to summer for baseline conditions. Seasonal cycles of industrial metals had a summer maximum and winter minimum. A significant fraction of the Cape Grim baseline smoke and industrial metal contributions appeared to be derived from long-term transport (>3 weeks since last terrestrial influence). Crown Copyright © 2018 Published by Elsevier Ltd.en_AU
dc.identifier.citationCrawford, J., Chambers, S. D., Cohen, D. D., Williams, A. G., & Atanacio, A. (2018). Baseline characterisation of source contributions to daily-integrated PM2. 5 observations at Cape Grim using Radon-222. Environmental Pollution, 243, 37-48. doi:10.1016/j.envpol.2018.08.043en_AU
dc.identifier.issn0269-7491en_AU
dc.identifier.journaltitleEnvironmental Pollutionen_AU
dc.identifier.pagination37-48en_AU
dc.identifier.urihttps://doi.org/10.1016/j.envpol.2018.08.043en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/9958en_AU
dc.identifier.volume243en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectAerosolsen_AU
dc.subjectRadonen_AU
dc.subjectTasmaniaen_AU
dc.subjectParticulatesen_AU
dc.subjectIon beamsen_AU
dc.subjectFactorizationen_AU
dc.titleBaseline characterisation of source contributions to daily-integrated PM2.5 observations at Cape Grim using Radon-222en_AU
dc.typeJournal Articleen_AU
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