ABSTRACT
484Heavy metals, which are the stable metals or metalloids whose density is greater than 4.5 g/cm3, include, among others, lead, copper, nickel, cadmium, platinum, zinc, mercury, antimony, arsenic, beryllium, chromium, cobalt, molybdenum, selenium, silver, tellurium, thallium, tin, titanium, uranium, and vanadium. These metals are stable and cannot be degraded or destroyed, and therefore accumulate in the environment. This chapter explores the sources of three metals, namely selenium, nickel, and beryllium, including man-made sources such as industrial point sources and natural sources. Such anthropogenic activities release Se, Ni, and Be into the environment: air, soil, and water, where they not only affect water quality but also enter the food chain where they accumulate in organisms such as fish, making it unfit for human consumption and reducing the growth of some plants. For instance, in high concentrations, heavy metals cause adverse effects on health such as the deterioration of the immune system, nervous system, and metabolic activities. This chapter discusses the various toxic effects of selenium, nickel, and beryllium in man and other animals with specific reference to well-studied aquatic fish and birds.
In order to mitigate the environment of Se, Ni, and Be pollution, a number of processes and methods have been developed to either remove or reduce the levels to acceptable standards. This chapter explains some of the processes that are currently being used to mitigate the environment of the three metal pollutants. Finally, the standards and regulatory role of the U.S. Environmental Protection Agency (USEPA) are highlighted.
