Method Development, Validation, Monitoring, Seasonal Effect and Risk Assessment of Multiclass Multi Pesticide Residues in Surface and Ground Water of New Alluvial Zone in Eastern India

Abstract A liquid-liquid extraction (LLE) method consisting gas chromatography-mass spectrometric (GC-MS) determination of thirty six pesticides in environmental waters was standardized. The method was validated as per SANTE/11813/2017 guidelines. Effect of three seasons namely summer, monsoon and winter on monitoring of pesticide residues in environmental waters (river, pond and tube well) of rural area was studied and subsequently risk assessment was evaluated. Within two districts (Nadia and North 24paraganas) of new alluvial zone in eastern India, six different places were chosen for sampling of river water. On the contrary, six different ponds and tubewells as well were considered for sampling. 144 samples of 2 liter each (48 each of river, pond and tubewell water) of each district irrespective of seasons were analyzed during the study period. Each water sample (750 ml) was extracted with ethylacetate:dichloromethane (8:2). The total residue was reconstituted in acetone (1 ml) and analysed in GC-MS after proper filtration with 0.22 μm nylon syringe filter. Average percent recovery ranged from 77.84 to 118.15. Irrespective of seasons, maximum total organochlorine (OC) and organophosphorous (OP) pesticide residues were dominated respectively in river and pond water. Irrespective of types of environmental waters, monsoon (July to October) showed presence of total maximum pesticide residues. Risk Quotient (RQ) [acute and chronic] was calculated respectively in pond and river water. Only Seven water samples of tubewell were contaminated with butachlor and chlorpyriphos, although in non-significant average amount (< 0.1ngml-1), irrespective of seasons and thus safe for consumption.