Cadmium (Cd) is known to be toxic to plants and animals and can be transported to both ground and surface water through specific physical mechanisms. The chemical dynamics of Cd and other similar (heavy) metals in the soil environment is controlled by its interactions with both solid and aqueous phases of soil. The concentration of Cd and other metals in soil solution is highly influenced and regulated by processes such as adsorption-desorption, ion exchange, precipitation-dissolution, and soil and solution phase composition. Such processes, in turn, are function of soil properties such as pH, charge density and distribution, thickness of diffuse double layer and the activity of Cd present in solution. This report intends to provide a comprehensive and critical review to the effect of such properties on Cd transport.
Historically, the discover of Cadmium (Cd) goes back to the eighteenth century (1817) by the German scantiest Friedrich Stromeyer who found it as an impurity in zinc carbonate. In the modern world, Cd is used in many industrial, urban, and agricultural applications (, ) and is often found together at sites contaminated with heavy metals. As Cd is a toxic metal to humans  and animals alike, the environmental and soil contamination with Cd is becoming of great concern in the last few decades. Therefore, it is important for chemists, environmental scientists and engineers to understand the chemistry of Cd interactions in soils to understand its bioavailability.
Millions of tonnes of hazardous waste containing CD are generated in the world on yearly basis. Because of the inefficient waste handling techniques and hazardous waste leakage in the past, thousands of sites, especially in industrial world were contaminated by heavy metals, organic compounds and other hazardous materials. The environmental complications of heavy metals from hazardous wastes sites, landfills, and other contaminated sites has become one of the serious environmental issues in the industrial and developing countries in an equal manner. Cadmium in particular, though a naturally occurring, it is potentially a toxic and mobile element present in most soil environments. In contaminated environments Cd can be consumed up by animals and humans. Studies by Nriagu  has shown that that chronic exposure of humans through ingestion and/or inhalation to Cd for a longer period of time may cause severe damage to kidney and lungs, and can lead to other pathological symptoms.
Heavy metals such as Cadmium (Cd) are gradually released into groundwater through the action of abiotic and biotic subsurface processes . In the soil environment, there exist many metal species dissolved in the soil solution. Such metal species are occupying exchange sites on inorganic soil constituents; specifically adsorbed to inorganic soil constituents that exists in insoluble...