Abstract:
Organochlorine pesticides, dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH),
are potential chemical pollutants extensively used for agriculture and vector control purposes due to
low cost and high effectiveness. Concentrations of HCH and DDT were determined in 175 surface soil
samples from different agricultural fields, fallow and urban lands of districts Nagaon and Dibrugarh,
Assam, India. The mean concentrations of total HCH and total DDT were 825 ng/g (range: 98–1945 ng/g)
and 903 ng/g (range: 166–2288 ng/g) in district Nagaon while 705 ng/g (range: 178–1701 ng/g) and
757 ng/g (range: 75–2296 ng/g) in district Dibrugarh, respectively. The soils from paddy fields
contained highest amounts of HCH and DDT residues. Total organic carbon was found to be positively
associated with soil HCH and DDT residues. Ratios of DDT/(DDDþDDE) were 1.25 and 1.82 while of a/g
HCH were 2.78 and 2.51 for districts Dibrugarh and Nagaon, respectively. Source identification revealed
that soil residue levels have originated from long past and recent mixed source of technical HCH and
Lindane for HCHs and mainly technical DDT for DDTs. Spatial distribution was also investigated to
identify the areas with higher pesticide loadings in soil.
