Heavy Metals: Definition, Toxicity, and Uptake in Plants

Abstract

This chapter introduces the reader to heavy metals, their availability in soils, and their transfer to plants. While there is a controversy surrounding the terminology of heavy metals, this term encompasses a variety of metals and their compounds that have a negative connotation for health. While some of the metals are essential for living organisms, others are extremely toxic to humans and animals. The cultivation of crops on farmland contaminated with heavy metals from environmental pollution or by irrigation with wastewater leads to accumulation of these metals within plants. Heavy metal uptake in plants varies with the soil type, the plant species, the variety type within the same species, and the location in plant tissue. The highest uptake of heavy metals occurs in leafy vegetables, followed by a moderate level in root vegetables, and the lowest accumulation in legumes. The consumption of plants with high levels of heavy metals can pose deleterious health effects to humans and animals.