Endosulfan levels and isomer distribution
Unplanted pots (Un). Pots without plants were established to
determine the influence of watering on the endosulfan dynamics in
soil. An analysis of the total endosulfan concentration (aendosulfan
þ b-endosulfan þ endosulfan sulfate) showed lower
levels of all compounds after 15 and 60 days of soilwatering (Fig.1).
Because the pots were covered with aluminum foil to avoid volatilization,
these results might indicate a decline from endosulfan
degradation to other metabolites not analyzed or from percolation
with the irrigation water.
Additionally, the time dependent decrease was due to a reduction
in the a-isomer at 15 days, followed by a reduction of the b
isomer at 60 days, with a concomitantly increment of the sulfate
metabolite (Fig. 1). These results suggest that endosulfan sulfate is
primarily formed from a-isomer and, as time passed, b isomer
also began to degrade the sulfate metabolite. Moreover, this
behavior is in agreement with the b-endosulfan structure configuration
of chlorines that favors physical (soil adsorption