Airborne heavy metals deposition and contamination to water resources

Abstract

Heavy metals are group of metals or metalloids with higher atomic weight, density, and toxicity. These metals occur in a natural background geochemical composition in Earth’s crust, atmosphere and water. But in the past few decades, due to increased anthropogenic activities and emissions, the background level of heavy metals has changed considerably, which has overwhelmed the natural biogeochemical cycling processes of the metals across the Earth’s system. Most of the metals exist in ionic or inorganic form which cannot be further disintegrated like organics and thus persist, accumulate, and get transported from one sphere to another in the interlinked environmental system. They are highly undesirable and of paramount concern because of their toxicity, even at a low concentration, except for some essential metals. Mining, smelting, and refining of metals, industrial processes (electroplating, coating, galvanizing, paint, and spray), coal-based power plant, agriculture activities, and open metallurgical processes are some potential anthropogenic sources of heavy metal emission to atmosphere. Once the metals or metalloids bound particle or vapor emitted to the surrounding atmosphere their fate come under the purview of prevailing meteorology and wind circulation. Their natures of nondegradability add another moment to persist longer in the atmosphere and thus get long-range transported far away from the source region. That eventually scavenged through wet or dry depositional processes over open lands, water bodies and on plant leaves. In aquatic system via physiochemical and biological processes, they get metabolized into ingestible form which may then be taken up by plants and lower living organisms. This chapter will present an overview of in-land emission sources of heavy metals, their advection in the free troposphere and eventually their deposition to aquatic body. © 2023 Elsevier Inc. All rights reserved.