A STUDY OF THE ADSORPTION-KINETICS OF ISOPROTURON ON SOIL AND SUBSOIL

The aim of this study is to investigate the mechanisms of adsorption o f isoproturon onto soil and to produce predictive relationships betwee n the adsorption rate constant and the measurable properties of the so il. A batch technique was used to measure the rate of adsorption of is oproturon onto soils down a single soil profile. The major results wer e: (i) simple predictive relationships could not be derived; (ii) use of linear-free energy relationships showed up the differences between different techniques for measuring adsorption rate constants; and (iii ) the linear free energy plot of the data suggested that specific sorb ate-sorbent interactions were an important adsorption mechanism for no n-hydrophobic compounds in a batch methodology. An adsorption mechanis m is proposed that suggests that adsorption of isoproturon to soils is the distribution of the compound between three phases - dissolved in solution, bound to insoluble matter and adsorbed to organic colloids i n suspension. Copyright (C) 1996 Elsevier Science Ltd