Assessment of the impact of pesticide usage in groundwater aquifer of an agriculturally dominated area in North West India

Groundwater pollution due to several anthropogenic activities has been a worldwide problem, one such activity being injudicious pesticide usage in agriculture. Assessment of pesticide impact on groundwater is a prerequisite step towards the formulation of regulatory policies related to the pesticides' application. The present study deals with assessment of the impact of pesticide usage in the groundwater aquifer of an agriculturally dominated area in North West India. The relationship between the pesticide usage and its impact on the quality of groundwater has been established by employing a model named Pesticide Impact Rating Index (PIRI). For illustration, seven farms lying in Nakodar tehsil of Punjab state in India were considered. Based on the frequency of usage of various pesticides in the study area, four pesticides namely atrazine, chlorophyrifos, phorate and monocrotophos were selected for detailed analysis. Groundwater samples were collected and analyzed for observed values of pesticide residues. The observed residues were compared with the PIRI model estimates and results showed that though the observed values were higher corresponding to the estimated values, the ratio seemed to be fluctuating within a consistent range. Therefore multiplicative correction factors were introduced for the model estimates so as to predict realistic pesticide residues in an area.