Antimony (Sb) is considered to be a toxic semimetal with potential carcinogenic effect on human health. Due to abrasion during the braking process, the application of Sb in brake linings causes a diffuse contamination of local hotspots in urban areas, particularly on roadsides. Both the spatial distribution of total Sb (inverse aqua regia digestion) and geochemical fraction of Sb in roadside soils along a minor travelled road (approx. 9,000 vehicles per day) in Cologne (Germany) were studied. Therefor five transects perpendicular to the road at intervals of 10 m were conducted with depth of 0-5, 5-10, 10-20, and 20-30 cm at seven distances up to 10 m. Total Sb ranged between 0.513 and 6.18 g kg–1 with clear trends of decreasing contents with depth and distance to road. A chemical sequential extraction procedure originally designed for arsenic was applied and yielded reliable and reproducible data for geochemically fractions. Three patterns revealed: i) specifically sorbed Sb (F2, 0.05 mol l–1 (NH4)H2P2O4) was only detected within 1 m distance to the road and decreased with depth, ii) Sb associated with poorly-crystalline oxides of Fe and Al (F3, 0.2 mol l–1 (NH4)2-oxalate buffer; pH 3.25) decreased with distance to road while iii) contents of Sb bounded to well-crystalline Fe and Al oxides (F4, 0.2 mol l–1 (NH4)2-oxalate buffer + 0.1 M ascorbic acid; pH 3.25) and Sb present in the residual fraction (F5, aqua regia) remained relatively constant for each depth. As soil characteristics of the samples did not differ significantly, changes in geochemical fractions were attributed to traffic related input of Sb.

Distribution of antimony in roadside soils

253rd National Meeting (2017)

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