The Kinetic Study of Glyphosate Leachate in Palestinian Soil at Different Concentrations

In recent years, pesticides were used heavily in Palestine, which led to the contamination of soil and water and causing many diseases. As a result of increasing environmental issues many centers were established like Water and Environmental Studies Institute (WESI) at An-Najah National University and Birzeit University and Chemical, Biological, Drugs Analysis Center (CBDA) at An-Najah National University. Many studies focused on the impact of pollutants such as pesticides and oil on soil, humans, animals, plants and the environment in general. The aim of this study was to study glyphosate kinetically in soil columns. Laboratory analyses: Leachate: the samples were analyzed for glyphosate leachate (herbicides moved through the soil), pH and glyphosate were measured. Soil: the soil properties have been tested and classified under two different categories; physical and chemical properties. - Physical analyses are: pH, sieve analysis, hydrometer test. - Chemical analyses are: Kjeldahl nitrogen, calcium carbonate, phosphorus, copper and iron. The results of this study demonstrated that: - Amount of glyphosate in soil decreases with increasing depth of soil, where it is for 0-30cm(11ppm) 30-60cm(6ppm) 60-100cm(2ppm) due to organic content and metal oxides founded in soil that can form stable complexes with glyphosate. - Glyphosate is highly adsorbed to soil due to metal oxides founded in soil where it is for 0-30cm (2000ppm) 30-60cm (1900ppm) 60-100cm (1800ppm). - Doubling the concentration of glyphosate increases the amount glyphosate (contaminant) in leachate where it is for 25x (15.96ppm) 15x (3.91) 5x (3ppm) column. - The amount of glyphosate detected in leachate decreases with increasing time. It takes time for 25x (17days) 15x (13days) 5x (8days) until the inability to detect glyphosate in leachate for concentrations less than 1 ppm. - Glyphosate fit the first order reaction. - Isotherm is in accord with the Freundlich adsorption equation with R value 0.947, k value 0.9949 and n value 1.458 which is higher than one indicates good adsorption to soil (Helby, 1952). - The adsorption isotherms for the soil is of S-type (Giles, 1960), this indicating the easiness of the adsorption, mainly at higher concentrations. - Glyphosate has relatively rapid degradation; where DT50 values of glyphosate was 2, 3 & 3.75 days for 5x, 15x & 25x column respectively. This study and others help to monitor soil erosion; number and amount of pollutants affect soil. Assessing the extent of soil degradation and identifying hot spots, where many steps and mitigation measures could be taken to reduce soil erosion and maintain soil fertility.