Atmospherically deposited trace metals from bulk mineral concentrate port operations

Although metal exposures in the environment have declined over the last two decades, certain activities and locations still present a risk of harm to human health. This study examines environmental dust metal and metalloid hazards (arsenic, cadmium, lead and nickel) associated with bulk mineral transport, loading and unloading port operations in public locations and children's playgrounds in the inner city of Townsville, northern Queensland. The mean increase in lead on post-play hand wipes (965μg/m²/day) across all sites was more than 10-times the mean pre-play loadings (95μg/m²/day). Maximum loading values after a 10-minute play period were 3012μg/m², more than seven times the goal of 400μg/m² used by the Government of Western Australia (2011). Maximum daily nickel post-play hand loadings (404μg/m²) were more than 26 times above the German Federal Immission Control Act 2002 annual benchmark of 15μg/m²/day. Repeat sampling over the 5-day study period showed that hands and surfaces were re-contaminated daily from the deposition of metal-rich atmospheric dusts. Lead isotopic composition analysis of dust wipes (²⁰⁸Pb/²⁰⁷Pb and ²⁰⁶Pb/²⁰⁷Pb) showed that surface dust lead was similar to Mount Isa type ores, which are exported through the Port of Townsville. While dust metal contaminant loadings are lower than other mining and smelting towns in Australia, they exceeded national and international benchmarks for environmental quality. The lessons from this study are clear - even where operations are considered acceptable by managing authorities, targeted assessment and monitoring can be used to evaluate whether current management practices are truly best practice. Reassessment can identify opportunities for improvement and maximum environmental and human health protection.