Environmental Pollutants: Metal(loid)s and Radionuclides

Abstract

AbstractAnthropic inputs of toxic metals into the environment pose a serious environmental and human health risk globally. Whereas some metals such as copper, manganese, nickel, and zinc are essential in regulating biological processes in living organisms, many metal(loid)s such as arsenic, cadmium, chromium, mercury, and germanium are toxic even at low concentrations. Moreover, some metals and metal(loid)s such as uranium, strontium, and cesium have radioactive properties and, as such, are classified as radionuclides. Metal(loid)s and radionuclides are nonbiodegradable persistent pollutants which originate from agricultural, domestic, and industrial effluents; hence, they pose a threat to the environment. Since humans constitute the highest trophic level, and toxic metals are biomagnified along the food chain, humans have a higher likelihood of suffering serious health problems. For instance, metal(loid)s and radionuclides can potentially cause cancer, damage of vital organs, nausea, and vomiting. A number of chemical and physical removal methods have been explored, but their limitations, such as the generation of secondary pollution, the intricate subsequent processing, and the high cost, make them inefficient. In view of this, microbial bioremediation, specifically the application of bacteria, has attracted attention owing to the feasibility and efficiency of the technique in removing toxic metals from aquatic systems. Bacteria remove metal(loid)s and radionuclides through adsorption, biosorption, efflux, and general resistance mechanisms. This chapter discusses various sources of toxic metal(loid)s and radionuclides, their occurrence, and bioremediation of contaminated aquatic systems.KeywordsBacteriaBiopolymersBioremediationRadioisotopesToxicityWastewater