This clearly indicates
a recent application of a technical grade endosulfan (a mixture
of - and -isomers) to the A5 field compared to other fields.
Endosulfan sulfate accounts the largest proportion of the total
endosulfan residue detected in the A1 and A2 soils (Table 1).
The same thing holds true in soils A3, A4, B1, and B2 (Table 3).
The concentration of endosulfan sulfate was always higher than
the endosulfan isomers, except in the A5 soil, as it is the major
degradation product by soil bacteria.