AbstractCadmium (Cd) is known to be toxic to plants and animals and can be transported to ground and surface waters by specific physical mechanisms. The chemical dynamics of Cd and other similar (heavy) metals in the soil environment is controlled by its interactions with soil solid and aqueous phases. The concentration of Cd and other metals in soil solution is strongly influenced and regulated by processes such as adsorption-desorption, ion exchange, precipitation-dissolution, and phase composition of soil and the solution. Such processes in turn depend on soil properties such as pH, density and charge distribution, the thickness of the diffuse double layer and the activity of Cd present in solution. This report aims to provide a comprehensive and critical review of the effect of these properties on the transport of Cd.1. IntroductionHistorically, the discovery of Cadmium (Cd) dates back to the 18th century (1817) by the rare German Friedrich Stromeyer who found it as an impurity in zinc carbonate. In the modern world, cadmium is used in many industrial, urban and agricultural applications ([1], [2]) and is often found together at sites contaminated with heavy metals. As cadmium is a metal toxic to humans [3] and animals, contamination of the environment and soil with cadmium has become a great concern in recent decades. Therefore, it is important for chemists, environmental scientists, and engineers to understand the chemistry of Cd interactions in soils in order to understand its bioavailability. Millions of tons of hazardous waste containing CD are generated each year worldwide. Due to inefficient waste treatment techniques and hazardous waste leaks in the past, thousands of sites, are...... middle of paper ......in terms of two basic mechanisms: specific adsorption, which is characterized by more selective and less reversible reactions, including chemisorbed inner sphere complexes, and nonspecific adsorption (or ion exchange), which involves rather weak and less selective outer sphere complexes [14]. It is established that specific adsorption results in strong and irreversible binding of heavy metal ions with organic matter and minerals with variable charge, while nonspecific adsorption is an electrostatic phenomenon in which cations from pore water are exchanged for cations close to the surface. Cation exchange is a type of outer-sphere complexation with only weak covalent bonding between metals and charged soil surfaces. The process is naturally reversible and occurs relatively quickly as it is typical of diffusion-controlled reactions and electrostatic in nature.. [14].