Environmental Chemistry and Ecotoxicology of Hazardous Heavy Metals: Environmental Persistence, Toxicity, and Bioaccumulation

Abstract

Heavy metals are well-known environmental pollutants due to their toxicity, persistence in the environment, and bioaccumulative nature. Their natural sources include weathering of metal-bearing rocks and volcanic eruptions, while anthropogenic sources include mining and various industrial and agricultural activities. Mining and industrial processing for extraction of mineral resources and their subsequent applications for industrial, agricultural, and economic development has led to an increase in the mobilization of these elements in the environment and disturbance of their biogeochemical cycles. Contamination of aquatic and terrestrial ecosystems with toxic heavy metals is an environmental problem of public health concern. Being persistent pollutants, heavy metals accumulate in the environment and consequently contaminate the food chains. Accumulation of potentially toxic heavy metals in biota causes a potential health threat to their consumers including humans. This article comprehensively reviews the different aspects of heavy metals as hazardous materials with special focus on their environmental persistence, toxicity for living organisms, and bioaccumulative potential. The bioaccumulation of these elements and its implications for human health are discussed with a special coverage on fish, rice, and tobacco. The article will serve as a valuable educational resource for both undergraduate and graduate students and for researchers in environmental sciences. Environmentally relevant most hazardous heavy metals and metalloids include Cr, Ni, Cu, Zn, Cd, Pb, Hg, and As. The trophic transfer of these elements in aquatic and terrestrial food chains/webs has important implications for wildlife and human health. It is very important to assess and monitor the concentrations of potentially toxic heavy metals and metalloids in different environmental segments and in the resident biota. A comprehensive study of the environmental chemistry and ecotoxicology of hazardous heavy metals and metalloids shows that steps should be taken to minimize the impact of these elements on human health and the environment.

Biosorption of heavy metal polluted soil using bacteria and fungi isolated from soil

“…Heavy metals are natural elements with atomic number greater than 20, characterized by a relatively high density (at least 5 g cm −3 ), and are toxic even at low concentrations [1][2][3]. They are characteristically existing components found in changing variation in the environments and are part of human daily activities, they are also found in important structures and in a range of other artificial mixes [4].…”

“…Heavy metals are generated from both anthropogenic and natural sources and are eventually discharged into the environment [6,7]. The main natural discharge of heavy metals is during volcanic eruptions and weathering of metal-bearing rocks [2]. The discharge of heavy metals through various man-made activities, for example excessive application of chemical fertilizers, wood burning, coal combustion, vehicle exhaust, mining, smelting and incineration [2], has caused a wide spread disruption of the normal biogeochemical cycles of metals causing a larger accumulation of heavy metals in the environment, especially the soil [6][7][8].…”

“…The main natural discharge of heavy metals is during volcanic eruptions and weathering of metal-bearing rocks [2]. The discharge of heavy metals through various man-made activities, for example excessive application of chemical fertilizers, wood burning, coal combustion, vehicle exhaust, mining, smelting and incineration [2], has caused a wide spread disruption of the normal biogeochemical cycles of metals causing a larger accumulation of heavy metals in the environment, especially the soil [6][7][8]. The major heavy metals of concern include lead, cadmium, arsenic, mercury, copper and chromium because of their toxic impact on human health; for instance, environmental exposure to high concentrations of heavy metals has been linked with various cancers and kidney issues [9].…”

Antarctic yeast Cryptococcus laurentii (AL65): biomass and exopolysaccharide production and biosorption of metals

“…The accumulation of heavy metals is traced from the inanimate nature to the plants and animals. In organisms, heavy metals are a prerequisite for obtaining reactive oxygen species (ROS) and cause disturbances in biochemical and physiological processes . Traditional physicochemical purification methods are in some cases inappropriate and expensive .…”

“…In organisms, heavy metals are a prerequisite for obtaining reactive oxygen species (ROS) and cause disturbances in biochemical and physiological processes. 1,2 Traditional physicochemical purification methods are in some cases inappropriate and expensive. 3 Biosorption processes using many biomaterials including fungal biomass, marine algae and bacteria, have been investigated extensively during the past decade for removal of heavy metals because of their lowcost, high-efficiency reduction in the amount of chemical and biological precipitate, regeneration capabilities of some biosorbents and possibilities of metal recovery.…”