Heavy Metals in the Aquatic Ecosystem: Sources, Transport, Toxicity Mechanism, and Mitigation Strategies

Abstract

Any “metal” or “metalloid” element with a density between 3. 5 to 7 g cm−3 is generally termed a “heavy metal” which is poisonous when present in excess amounts as recommended by various government agencies. Heavy metals are hazardous environmental pollutants and are becoming one of the most serious environmental problems because of their persistence, toxicity, non-biodegradability, and ability to be incorporated into the food chain. Over the past century, heavy metals containing industrial effluents have been discharged into the world's rivers and lakes as a result of rapid industrialization, and, consequently, they have accumulated in aquatic animals, marine species, and sediments. These commonly heavy metals include zinc (Zn), nickel (Ni), copper (Cu), cobalt (Co), chromium (Cr), cadmium (Cd), lead (Pb), zinc (Zn), iron (Fe), arsenic (As), selenium (Se), and mercury (Hg). These heavy metals when present in excess amounts can cause negative impacts on animals, plants, and human beings which may damage the photosynthesis activities in plants, can damage water uptake, disrupt the function of the xylem and phloem, it may create obstacles in the transportation of prepared foods in the leaves, whereas in animals and human beings, it may damage the function of the brain, liver, kidney, lungs, sometimes even creates alteration in the blood composition. Hence, heavy metals source, fate, transport, and toxicity needs to be explored widely. In this chapter, we are discussing the presence, fate, transport, toxicity, and remediation technologies for heavy metals. This chapter will provide an overview of heavy metals in the aquatic ecosystem. © 2026 selection and editorial matter, Ravindra Kumar Gautam, Subhash Chandra, and Radha Rani; individual chapters, the contributors.