Phytoremediation of Heavy Metals from the Biosphere Perspective and Solutions

Abstract

In the past 50 years, a number of environmental problems have emerged due to industrialization, urbanization, increased use of chemicals in agriculture, vehicular emissions, etc. Agents like pesticides, volatile organic compounds, harmful gases, heavy metals, persistent organic compounds, etc. are responsible for most of the problems inside living organisms. About 60% of known elements are heavy metals having densities of higher than 5 g/cm3. These generally have a higher atomic number and atomic mass, and form compounds and complexes at different oxidation states. There are around 82 heavy metals and at least 20 are classified as toxic. Heavy metals that have a poisonous impact on humans and other living beings are lead, nickel, copper, mercury, chromium, cadmium, zinc, and arsenic. They enter the food chain, get into the process of bioaccumulation and biomagnification, and affect living organisms. Heavy metals are a prominent cause of various health-related problems among living beings at different levels and concentrations. Heavy metals are introduced into environmental components, i.e. air, water, and soil through emissions and effluents from different industries, mining activities, smelting, agricultural waste, vehicular emissions, etc. Toxic heavy metals are the cause of concern because once they get released into the environment, they persist for a long time and pose a severe threat to humankind. Many techniques associated with heavy metal elimination from environmental components like air and water systems have appeared and these conventional methods involve chemical precipitation, membrane filtration, adsorption, ion exchange, etc. Phytoremediation has emerged as a prospective method for the removal of heavy metals from water. It is an effective and inexpensive treatment that uses plant physiology and metabolism for the efficient removal of a variety of contaminants. In this chapter, phytoremediation for the removal of heavy metals is considered due to advantages like cost-effectiveness, eco-friendliness, and the use of solar energy, and requiring minimum investment and low maintenance. This method does not produce persistent and harmful by-products.