Review of Electro Kinetic Techniques in Controlling Nitrate Contamination in Different Soils

Contamination of surface and ground water has become a major problem related to different agricultural and irrigation practices. Nitrate; one of the principal plant fertilizers, is the chemical having the greatest effect on such practices. Nitrates are highly soluble in water with low retention by soils. Best Management Practices have been developed to guide fertilizer use and minimize nitrogen losses, but they do not address control of nitrate movement from the crop root zone. Electro kinetics, an in-situ soil remediation technique, has shown to be an effective method for controlling nitrate movement and retaining it near the root zone for further removal. Laboratory studies found that the electro-kinetic process effectively concentrated and retained nitrate close to the anode in sandy soils using either horizontal or vertical soil columns. The effectiveness of the used technique depended on the initial nitrate concentration, the degree of saturation of the soil and the amount of applied electricity (current and duration). It was also shown that the effectiveness of the electro-kinetic process in retaining nitrate close to the anode is highly affected by the percentage of clay in soil. For the same amount of electricity, the loamy soils showed considerably slight migration of nitrate to the anode while the clay soil showed no migration of nitrate. This paper aims at reviewing the different electro kinetic techniques used to control the movement of nitrate in different soils, summarizing the important results and evaluating the effectiveness of such techniques with each type of soil.