Laboratory dust generation and size-dependent characterization of metal and metalloid-contaminated mine tailings deposits

•A laboratory dust fractionator was developed for the production of respirable dust.•The size-dependent distribution of arsenic and lead in mine tailings dust is reported.•Metal and metalloid contaminants are enriched in particles smaller than 10μm.•Lead isotope signatures show spread of mine tailings particles onto surrounding soils. The particle size distribution of mine tailings material has a major impact on the atmospheric transport of metal and metalloid contaminants by dust. Implications to human health should be assessed through a holistic size-resolved characterization involving multidisciplinary research, which requires large uniform samples of dust that are difficult to collect using conventional atmospheric sampling instruments. To address this limitation, we designed a laboratory dust generation and fractionation system capable of producing several grams of dust from bulk materials. The equipment was utilized in the characterization of tailings deposits from the arsenic and lead-contaminated Iron King Superfund site in Dewey-Humboldt, Arizona. Results show that metal and metalloid contaminants are more concentrated in particles of