After entering the environment, the heavy metals are transported and may by transformed into other chemicals. Transport can occur within a compartment or between compartments. Transformation processes in the environment involve photo degradation or chemical degradation or biodegradation. Heavy metals may also be transformed within organisms and this is called biotransformation. The examples of heavy metals conducted are mercury, cadmium , and lead. They will be considered and described as the examples of environmentally important and influential elements as follows: