Abstract:
Groundwater Quality analyses carried out .for pesticide residues in Ludhiana and Muktsar districts of Punjab have shown persistence of Organo-Chlorine pesticides of BHC (Lindane), Heptachlor, Heptachlor Epoxide, Endosulfan I, 4,4 - DDT, Methoxychlor and OrgnanoPhosphorous pesticides of Methyl Parathion, Dimethoate and Malathion. It has been found that generally the presence of organo-chlorine pesticide residues in groundwater in Muktsar district are about 6-8 times higher than Ludhiana district during pre-monsoon of 2003. The use of pesticides depends mostly on crops grown in the area. The cotton crop grown over large part of Muktsar district is contributing for elevated pesticide residues persistence in groundwater whereas their persistence is found to be low due to predominantly paddy grown areas in Ludhiana district. Further, shallow ground water table condition in the Muktsar district also adds to the problem as pesticides leach fast to the shallow water table compared to the prevalent deep water table in Ludhiana. Paddy crop requires more irrigation water compared to cotton crop and thereby more dilution of pesticide residues could be expected while leaching to groundwater table.
The post monsoon sampling during 2003 also indicated persistence of pesticide residues in Muktsar district with slight decline in their concentrations with respect to pre-monsoon values. Whereas in the case of groundwater in Ludhiana district, elevated concentrations of pesticide residues have been found during post monsoon sampling. One reason could be that deep water table in Ludhiana and shallow water table in Muktsar play a vital role in pesticide migration and its persistence as it is dependent on travel times taken by them in the sandy loam soils. The above database has been utilized to develop a PESTAN (Pesticide transport) model to verify possibility of their migration under two scenarios of shallow and deep water table conditions.
