PHYSICAL-CHEMICAL CHARACTERISTICS OF HERBICIDES USED FOR MAIZE PRODUCTION IN BIH AS FACTORS OF POTENTIAL HERBICIDE LEACHING IN GROUNDWATER

UDK 631.4:632.954; 633.1:632.954(497.6) The aim of the study is to present the elements which must be considered while determining the risk of the mobility of the herbicides. Herbicides used for maize production have the special eco toxical significance and special risk because some are potentially mobile, they are used on the large surfaces during the rainy period and near rivers. Behaviour of the herbicides in the environment, particularly in the soil is very complex. It does not depend only on the characteristics of the herbicide, but on the many factors of the environment which are very variable. Regardless of this fact, there are experimentally determined physical-chemical indicators for each herbicide that show the possible behaviour of herbicides in the environment. Studied physical-chemical indicators of herbicide behavior are: Distribution Coefficient (Kd); Organic Carbon Partitioning Coefficient (Koc); Time of the Semi-Decomposition (DT50); Water Solubility (S); Groundwater Ubiquity Score (GUS); Henry's Law Constant (Kh), Vapor Pressure (PV) and the Dissociation Constant (pKa). Namely, herbicides, in larger or smaller measure, have “leaching potential“, which is ability to reach the underground water. One of the basic criteria for evaluating the herbicide ability to reach the underground water is related to indicators of mobility and persistency (DT50) herbicides, but neglecting some other criteria in that evaluation such as the amount of applying, characteristics of the soil and the aim of the crop growth. According to the EPA criteria, for the herbicides used in maize production in Bosnia and Herzegovina (BiH), the “trigger“ value will indirectly indicate if the herbicides have large leaching potential.