Fig. 1. Concentrations of tracer (bromide), acetochlor, and its degradates, ethanesulfonic acid (ESA) and oxanilic acid (OA), in a calcisol on (a) Day 7 for 46 mm of total rainfall, (b) Day 21 for 95 mm of total rainfall, (c) Day 56 for 184 mm of total rainfall, and (d) Day 344 and 1103 mm of total rainfall, after application. Average and standard deviation for 16 individual samples for bromide. Pesticide concentrations measured with a composite sample made up of 16 individual samples.