Distribution characteristics of cadmium and lead in particle size fractions of farmland soils in a lead–zinc mine area in Southwest China

Abstract

Abstract Background Cd and Pb were the main pollution elements in Pb–Zn mining areas. Several studies have focused on heavy metal pollution and risk assessment in the Huize Pb–Zn mining area. In the present study, the soil aggregate composition, chemical properties, contents and chemical fractions of Cd and Pb were analysed in soils at depths of 0–60 cm in the Huize Pb–Zn mining area. Agricultural soils were sampled at depths of 0–20, 20–40 and 40–60 cm surrounding the Pb–Zn mine. The particle size fractions were determined by the aggregate composition of macro-aggregates (0.25–2 mm), micro-aggregates (0.053–0.25 mm), silt (0.002–0.053 mm) and colloid ( 33). Furthermore, there were close correlations between the Cd and Pb fractions and the pH and the phosphorus content and between the exchangeable Pb content and the content of organic matter, cation exchange capacity, and free iron oxide in soil aggregates. Conclusion Cd and Pb existed mainly in the micro-aggregate and colloid and that their chemical fractions were closely related to the chemical properties in soil aggregates of the polluted farmland.

Keywords

• Lead–zinc mine
• Heavy metals
• Chemical fractions
• Soil aggregate
• Soil property