Fe–Mn Concretions and Nodules to Sequester Heavy Metals in Soils

Over the last two decades, considerable attention has been paid to the management of metal-contaminated soils. Fe-Mn concretions and nodules can be used to sequester metals by adsorption. Fe-Mn concretions and nodules are discrete bodies with variable compositions formed in the soil system under alternating oxidizing and reducing conditions. This chapter highlights the high adsorption capacity of soil Fe-Mn concretions and nodules for many metal contaminants. The geochemical association of various metals with either Mn or Fe rich phase in Fe-Mn concretions and nodules are a primary environmental procedure that controls the dynamics of these contaminants in the soil system. The formation of Fe-Mn concretions and nodules is the most effi cient and durable process for metal contaminants sequestration in the soils. Since the formation of soil concretions has a potentially benefi cial effect on metals availability, the application of these environmental materials as geochemical reactors to improve the effi ciency of in situ technologies for remediating metal contaminated soils is strongly recommended.