POROUS CUPS FOR PESTICIDES MONITORING IN SOIL SOLUTION - LABORATORY TESTS

In this study, preliminary tests were conducted aiming to validate the use of ceramic porous cup for collecting soil water samples and monit oring pesticides contents, as usually made for nitrates. Interactions between porous cup and pesticides were examined under different experi mental conditions for three herbicides (atrazine, isoproturon, 2,4-D) and one insecticide (carbofuran). The results showed that ceramic was not inert for pesticides : as much as 80% of the applied pesticide cou ld be retained during the flowing of the first tenth milliliters of so lution. Interactions were attributed to sorption and ''screening'' of molecules by the porous walls and were related to the ionic character of pesticides. However, retention was not irreversible, since pesticid es were quickly released by rinsing with distilled water. After these tests, porous ceramic cups could be considered as suitable samplers fo r pesticide determinations in soil solution, contingent on gaining fur ther informations about soil - porous cup - pesticide interactions.