Quantification of manganese species in particulate matter collected in an urban area nearby a manganese alloy plant

Abstract

A sequential extraction test was used to evaluate the manganese (Mn) species in PM10 samples collected in an urban area impacted by a Mn alloy plant, where the annual guideline value for Mn in air according to the World Health Organization (WHO) is frequently exceeded (i.e. > 150 ng m−3). The average Mn level in this campaign was 208.6 ng m−3, reaching maximum daily values up to 1138.9 ng m−3. Manganese species were dominated by water-soluble Mn (49.9%), followed by metallic Mn (Mn0) and Mn2+ (27.1%), insoluble Mn (14.6%), and Mn3+ and Mn4+(8.8%). This study reveals, on one hand, the higher fraction of water-soluble Mn species present in atmospheric aerosols in comparison with aerosols collected in work environments of the Mn alloy industry, which is attributed to the reaction between emitted Mn oxides and gaseous pollutants (SO2, NO2 and HCl) during transport in the atmosphere. On the other hand, there was a non-negligible fraction of more toxic species (Mn3+ and Mn4+), which are more potent than Mn2+ to induce reactive oxygen species.