Chapter 14 - Lead in soils: sources, bioavailability, plant uptake, and remediation

Abstract

Lead (Pb) is a persistent toxic element with no beneficial properties for living beings. Apart from geogenic sources, anthropogenic activities like mining, smelting, paints, Pb-acid battery industries, municipal and industrial dumps and wastewaters, vehicular exhaust, and household dust are responsible for its contamination in soil. Pb bioavailability in soil depends on Pb concentration in the soil, soil type, pH, soil organic matter, Fe- and Mn-oxides, soil flora and fauna, and soil water content. Pb uptake by plants is determined by external/environmental factors, such as soil pH, organic matter and clay contents, and internal/plant factors, such as plant species, plant growth stage, plant root system, production of root exudates, plant metabolites, and transporters. Remediation of Pb-contaminated soils involves in-situ and ex-situ approaches, including physical, chemical, and biological techniques. Physical remediation includes soil replacement, excavation, solidification, vitrification, subsurface barriers, washing and flushing, containment, and thermal treatment. Chemical stabilization, soil washing, and electrokinetics are examples of chemical remediation methods for Pb-contaminated soils. Bioremediation involves processes such as biosorption, bioleaching, and biomembranes using microbes (bacteria, fungi, and algae), plants, or a mix thereof.