Revealing long-term anthropogenic influence on PM10 through lead isotope signatures in a post-mining region

This study investigated long-term anthropogenic contributions to airborne particulate matter (PM 10 ) in the Upper Meža Valley, Slovenia, a region historically affected by ore mining, smelting, and, more recently, secondary Pb production. PM 10 samples collected at five locations in the summer and autumn of 2018 and at one location in the spring and summer of 2021 were analysed for elemental composition and Pb isotope ratios to identify and quantify pollution sources. Elevated concentrations of Pb, Zn, Cd, and As were observed across all sites, with minimal temporal variations. Enrichment factor (EF) analysis indicated lower EF values for Zn and As, suggesting a primarily crustal origin. Conversely, higher EF values for Cd and Pb pointed to mixed crustal and anthropogenic sources. The proportion of PM 10 samples with high Pb enrichment increased from 9.09 % in 2018 to 20.5 % in 2021, indicating a rising influence of anthropogenic emissions. This study represents the first application of Pb isotope composition and a two-endmember mixing model for detailed source apportionment of PM 10 in the region. The Pb isotope ratios of PM 10 samples fell between local geogenic background and known anthropogenic sources, with anthropogenic contributions accounting for 55.8 % to 69.3 % of total Pb in PM 10 . These findings have important implications for local environmental management, as they can support targeted mitigation strategies, which are critical for public health protection. • Investigation of PM 10 sources using elemental and Pb isotope data • Temporal variations in PTEs concentrations and Pb isotopes observed • Anthropogenic Pb contributed 55.8%-69.3% to PM 10 highlighting human activity impact • Study highlights the need to address historical and current sources of Pb pollution