MODELING HEAVY-METAL (CADMIUM) UPTAKE BY SOIL-PLANT ROOT-SYSTEM

Among various toxic substances that contaminate plants and enter the f ood chain, thereby posing health problems to human beings, heavy metal s are particularly severe in their action. The behavior of heavy metal present in sewage sludge and industrial wastes that are used in agric ultural practices has been the center of much attention during the las t decade. Among these heavy metals, cadmium has been identified as the most critical metal due to its human toxicity. The presence of cadmiu m and its accumulation in the plant root Zone also results in decrease d crop yield. This study develops a methodology to simulate the transp ort of cadmium in soil water and its uptake by plant roots. The transi ent unsaturated water flow equation with a root extraction term in cou pled with mass transport equation and mass balance of solute concentra tion. The model takes into account the root growth with time. The macr oscopic root-soil water flow and solute (cadmium) movement model yield s a set of partial differential equations that can be solved using num erical techniques for a given set of initial and boundary conditions.