Ag, Ta, Ru, and Ir enrichment in surface soil: Evidence for land pollution of heavy metal from atmospheric deposition

No observation has so far been reported that heavy metal elements from atmospheric deposition were accumulated widely in the surface soil layers. In this research, 28 soil profiles from different climate zones and agro-ecosystems in China were studied, and obvious enrichment of Ag, Ta, Ru, and Ir in the surface soils was discovered. It indicates that pollution of heavy metals emitted into the atmosphere from industrial activities is no longer limited to soils in the vicinity of power, metallurgic, metalworking, and machine-making industries, and they may settle down extensively on land besides cities and industrial regions.