Study of the bioavailability of heavy metals from atmospheric deposition on the soil-pakchoi (Brassica chinensis L.) system.

Graphical abstract Highlights • Metals in topsoil originated from atmospheric depositions were higher in bioavailable fractions. • Atmospheric deposition was a key source of metals bioaccumulation in pakchoi. • Foliar uptake from atmospheric deposition was an important pathway of metals in pakchoi. • Health risk of pakchoi consumption may occur due to atmospheric deposition. Abstract The objective of this study was to investigate the bioavailability of heavy metals from atmospheric deposition on the soil-pakchoi (Brassica chinensis L.) system near a smelter. Soil reciprocal translocation experiment was conducted with seven groups of pot culture (filled with soils of gradient levels of heavy metals) in three sites of gradient atmospheric heavy metal depositions. Results showed that the newly deposited heavy metals (Cu and Cd) were preferential retention in topsoil (0–4 cm) and presented as higher bioavailable fractions compared to those in original soils. Atmospheric depositions contributed to 20–85% of shoot Cu and Cd in high deposition site, which were likely resulted not only from the direct transfer of contaminants from atmosphere to foliar but also from the atmosphere-soil-root transfer. However, the 52–62% of Pb in shoot from atmospheric depositions was mainly resulted from foliar direct uptake. The increasing atmospheric heavy metal depositions significantly decreased the photosynthetic parameters of pakchoi. Additionally, the potential health risks associated with the consumption of pakchoi were elevated in high deposition site and the bioaccessibility values were observed up to 56–81%. This study will provide useful reference information for the newly deposited heavy metal dynamics in the surface environment. [ABSTRACT FROM AUTHOR]