Atrazine-Soil Organic Matter Interactions

Abstract

Adsorption capacities of Walla Walla silt loam soil for 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) were determined after each extraction with ethyl ether, ethyl alcohol, and hot water. The results suggested that the ether and alcohol-extractable components of the soil organic matter, i.e. fats, oils, waxes, and resins, had a negligible capacity to adsorb atrazine but that hot-water-extractable materials, i.e. polysaccharides, had a small adsorptive capacity. of the compounds chosen to be representative of some soil organic matter components, polysaccharide types had low affinities, a protein and a nucleic acid had intermediate affinities, and humic acid, lignin, and quinizarin had high affinities for atrazine. Comparison of adsorption isotherms of atrazine to lignin and humic acid at 25 and 62 C suggested that a weak chemical bond may contribute to retention of the herbicide by soil organic matter. Nearly quantitative desorption of atrazine from native and calcium saturated soils was affected by repeated water extraction.