Soil indicators of antimony pollution from automotive braking

Traffic areas have been the subject of interest due to the high antimony (Sb) concentrations in the topsoils and atmosphere. The release of Sb from brake pad abrasion into two texturally different standard soils was studied through a leaching experiment. The source abrasion was placed 1 cm below the surface of the soil column, which was saturated with water to the constant value (60%-70% of saturation). The soil solution was collected regularly in an identical regime for both investigated soils. For the sandy soil only 4% of the Sb from the source of the abrasion was leached, while the clay soil was able to drain up to 40% of Sb under the same conditions. Sb flow rates exhibited comparable breakthrough profiles for both soils, with the peak of maximum Sb release in the first 3 days and subsequent equilibration of the system over the next 5-15 days. With the repeated saturation, the maximum release shifted by about 10 days, with only half the amount of Sb leached. The clay soil represented a more balanced system in terms of Sb, Fe, and TOC migration, but a much greater contamination risk due to a significantly higher gradient of transported Sb. (C) 2021 Published by Elsevier B.V.