Spatial and temporal trends in δ66Zn and 206Pb/207Pb isotope ratios along a rural transect downwind from the Upper Silesian industrial area: Role of legacy vs. present-day pollution. (1st July 2023) - Prechova, Eva
Abstract: Transect sampling is an under-exploited tool in isotope studies of atmospheric pollution. Few studies have combined Zn and Pb isotope ratios to investigate whether atmospheric pollution at a receptor site is dominated by a different anthropogenic source of each of these toxic elements. It has been also unclear whether pollution abatement strategies in Central Europe have already resulted in regionally well-mixed background isotope signature of atmospheric Zn and Pb. Zinc and lead isotope ratios were determined in snow collected along a rural transect downwind from the Upper Silesian industrial area (southern Poland). Spatial and temporal gradients in δ 66 Zn and 206 Pb/ 207 Pb ratios at four sites were compared with those of ore and coal collected in eight Czech and Polish mining districts situated at distances of up to 500 km. Snow pollution was extremely high 8 km from Olkusz in 2011 (1670 μg Zn L −1 ; 240 μg Pb L −1 ), sharply decreased between 2011 and 2018, and remained low in 2019–2021. Snow pollution was lower at sites situated 28–68 km from Olkusz. Across study sites, mean δ 66 Zn and 206 Pb/ 207 Pb ratios of snow were −0.13‰ and 1.155, respectively. With an increasing distance from Olkusz, the δ 66 Zn values first increased and then decreased, while the 206 Pb/ 207 Pb ratios first decreased and then increased. The δ 66 Zn values in snow plotted closer to those of Upper Silesian ores (−0.20‰) than to the δ 66 Zn values of Upper Silesian stone coal (0.52‰), showing predominance of smelter-derived over power-plant derived Zn pollution. The 206 Pb/ 207 Pb ratios of Upper Silesian coal (1.171) and Upper Silesian ores (1.180) were higher compared to those of snow. A 206 Pb/ 207 Pb vs. 208 Pb/ 207 Pb plot identified legacy pollution from leaded gasoline as the low-radiogenic mixing end-member. Across the transect sites, only the last sampling campaign exhibited a high degree of isotope homogenization for both Zn and Pb. Graphical abstract: Image 1 Highlights: Zn and Pb isotope ratios were studied in mid-winter snow at 4 rural sites in 4 years. At greater distances from pollution sources, δ 66 Zn first increased and then decreased. Along the same downwind gradient, 206 Pb/ 207 Pb first decreased and then increased. Ore-derived Zn dominated over coal-burning derived Zn.. In addition to mostly coal-derived Pb, legacy alkyl-Pb was detected.