Fate and distribution of C-14-atrazine in a tropical oxisol

The herbicide atrazine is the most commonly detected pesticide in groundwat er world-wide. A new microcosm test-system was used to determine the fate o f C-14-atrazine in a Brazilian oxisol. C-14 Ring-labelled atrazine was appl ied in a mixture with the commercial product Gesaprim 500 (Novartis) at a r ate of 3 kg ha(-1). During two months, about 1% of the initially applied am ount was lost by volatilization. The mineralization of the pesticide, measu red directly using (CO2)-C-14 evolved from the applied pesticide, was betwe en 0.09% and 0.16%, whereas less than 0.2% was leached. The distribution of radioactivity in the soil profile showed that most of the radioactivity re mained in the top soil down to a 3 cm depth. The radioactivity in the upper 3 cm of the column was adsorbed perferably in fulvic acid (FA) and humin f ractions. (C) 1999 Elsevier Science Ltd. All rights reserved.