An odyssey of environmental pollution: the rise, fall and remobilization of industrial lead in Australia

Abstract:

The use of lead in automobile gasoline resulted in more than 240,000 tonnes of lead being emitted to the Australian environment over its 70-year period of use starting in 1932. The consequences of the emissions and subsequent depositions have resulted in marked contamination of urban and peri-urban aerosols, soils, plants and humans. This paper charts these effects and examines the extent of recovery from one of the most pervasive and persistent environmental pollutants. Lead isotopic composition of Adelaide and Sydney aerosol filters show that air lead composition shifts from values that approximate Broken Hill type ores, the predominant lead source used in gasoline (1.04 ²⁰⁶Pb/²⁰⁷Pb and 2.31 ²⁰⁸Pb/²⁰⁷Pb), towards ratios that more closely match local uncontaminated soil and bedrock values (Adelaide ~1.19 ²⁰⁶Pb/²⁰⁷Pb and ~2.50 ²⁰⁸Pb/²⁰⁷Pb; Sydney ~1.15 ²⁰⁶Pb/²⁰⁷Pb and 2.48 ²⁰⁸Pb/²⁰⁷Pb).

Proxy atmospheric measurements from historic wine, lichen and fungi samples extending over 120 years show how both concentration and composition values shifted in the middle to late 20^th century to reflect petrol emissions and then recovered rapidly at the end of the century as leaded gasoline consumption declined. For example, lead in wine from South Australia fell from >100 µg/L in the 1960s and 1970s to < 5 µg/L in the 2010s due to the removal of the primary source of atmospheric lead - gasoline. However, measurement of contemporary surface soils, ash produced from wildfires and air filters demonstrate that the effect of depositions persists and industrial lead and other toxic metals (including arsenic, cadmium and nickel) are subject to frequent remobilization. Predicted increases in wildfires and the generation of lead, arsenic and cadmium toxic particulates warrants greater consideration of the risk for vulnerable populations and firefighters who are most exposed.