Radiocarbon determination of woodsmoke contribution to air particulate matter in Launceston, Tasmania

The radiocarbon (14C) content of ambient air particulate matter (PM) collected in Launceston (Australia) through routine state government PM10 sampling has been measured by accelerator mass spectrometry (AMS) to determine the contribution of woodsmoke to wintertime air pollution. For AMS sample preparation a modified combustion method was required for determination of the non-carbonate carbon fraction of PM collected on borosilicate filter media to minimise the effects of the filter melting during combustion to CO2. Negligible differences in the radiocarbon content of atmospheric aerosols were observed for samples using different filter media, particle-size fraction, sample storage, and sample combustion conditions. 14C analyses revealed that contemporary carbon sources contribute 97–99% of the total non-carbonate carbon mass of wintertime ambient PM, supporting the conclusion that woodsmoke is the main contributor to Launceston air pollution. Conversely, fossil carbon sources were found to contribute a relatively constant 1.0±0.7 μg C m−3 throughout the year, characteristic of transport-related emissions.