An odyssey of environmental pollution: The rise, fall and remobilisation of industrial lead in Australia

The use of lead as an additive in petrol resulted in more than 240,000 tonnes of lead being emitted to the Australian environment over a 70-year period from 1932, until lead additives in petrol were eliminated in 2002. The consequences of Australia's protracted industrial lead emissions and subsequent depositions caused widespread contamination of urban and peri-urban aerosols, soils, plants, animals, and humans. This paper charts the impact of those lead emissions via environmental archives and proxies and examines the extent of recovery from one of the biosphere's most pervasive and persistent environmental pollutants. The remobilisation of industrial lead is examined by analysis of Sydney air filters that bracket wildfires between 1994 and 2004. Proxy atmospheric measurements of historical wine, lichen and fungi samples extending up to 150 years bp show how both lead concentration and isotopic composition values shifted in the middle to late 20th century to reflect petrol emissions and then recovered rapidly at the end of the century as leaded petrol was phased out. Lead isotopic composition of aerosol filters from Adelaide and Sydney show that air lead composition shifted from values that approximate Broken Hill type ores, the predominant lead source used in petrol (206Pb/207Pb = 1.04; 208Pb/207Pb = 2.32), towards ratios that more closely match local uncontaminated soil and bedrock values in Adelaide (206Pb/207Pb = 1.21; 208Pb/207Pb = 2.52) and Sydney (206Pb/207Pb = 1.14; 208Pb/207Pb = 2.44). However, the recovery from that historic industrial lead contamination is incomplete. Measurements of contemporary surface soils, ash produced from wildfires and aerosols demonstrate legacy industrial lead depositions are declining but are still subject to remobilisation.