Methods for Determination of Pesticide Adsorption Properties and Examination of Their Mobility in Soil

Abstract

Pesticide destiny in soil depends on a number of factors, as well as on presence and intensity of the processes such as adsorption, degradation, evaporation, rinsing and leaching. Since adsorption processes govern concentration of the free fraction of pesticide molecules, researches in this area are primarily focused on examination of this process, more precisely on determination of adsorption constants and adsorption/desorption isotherms which provide determination of the most responsible soil properties for the retention of the tested pesticides in the soil. Since rinsing across the soil profile is the most frequent and its intensity is indirectly determined by intensity of adsorption processes, determination of adsorption constants of pesticides provides determination of rinsing potential for these substances across the soil profile. Methods for determination of pesticides adsorption properties and examination of their mobility in soil, primarily across the soil profile, are presented in the paper. Special emphasis is placed on the „batch“ method, which is currently the most common, and which was actually proposed by the Organization for Economic Cooperation and Development (OECD).

Sudbina pesticida u zemljištu zavisi od mnoštva faktora, kao i od zastupljenosti i inteziteta procesa, kao što su adsorpcija, degradacija, isparavanje, ispiranje, spiranje, itd. S obzirom da adsorpcioni procesi regulišu koncentraciju slobodne frakcije molekula pesticida, istraživanja u ovoj oblasti su pre svega usmerena na proučavanje ovog procesa, tačnije na određivanje adsorpcionih konstanti i adsorpciono/desorpcionih izotermi koji omogućavaju utvrđivanje karakteristika zemljišta najodgovornijih za zadržavanje ispitivanih pesticida u zemljištu. S obzirom da je od transportnih procesa ispiranje po profilu zemljišta najzastupljenije, i da je njegov intenzitet indirektno određen intenzitetom adsorpcionih procesa, određivanje adsorpcionih konstanti pesticida omogućava i utvrđivanje potencijala ka ispiranju ovih jedinjenja po profilu zemljišta. U ovom radu su predstavljene metode za određivanje adsorpcionih karakteristika pesticida i ispitivanje njihove mobilnosti u zemljištu, pre svega ispiranja po profilu zemljišta. Poseban akcenat je stavljen na „batch“ metodu, koja je danas najviše zastupljena, i koja je između ostalog i predložena od strane Organizacije za ekonomsku saradnju i razvoj (OECD).