Md. Wasim Aktar

Impact assessment of pesticide residues in fish of Ganga river around Kolkata in West Bengal

An investigation was conducted from 2001 to 2005 for determining the residual concentration of five pesticides, viz., total-HCH, total-DDT, total-Endosulfan, Dimethoate and Malathion in fish samples collected from various points of the river Ganga. Fish samples were analyzed for pesticide residues using standard laboratory procedures by GC method. It was found that total-HCH concentration remains above the MRL values for maximum number of times in comparison to four other pesticides. The pesticide contamination to fish may be due to indiscriminate discharge of polluted and untreated sewage-sludge to the river. The pesticide contents in some places are alarming. Thus proper care, maintenance, treatment and disposal of sewage water and sludge are most vital and should be the prime thrust for the nation.

Impact assessment of various parameters polluting Ganga water in Kolkata Region: a study for quality evaluation and environmental implication.

The quality of sewage-sludge samples obtained in Kolkata region was evaluated. Both sewage water and sludge components were analyzed for a number of physico-chemical, microbiological parameters using standard laboratory procedures, some heavy metals by AAS method and pesticide contents by GC method. Some of the physical and chemical constituents of the samples are within the allowable levels while the rest are not. The samples are rich in nutrients and have suitable pH for agricultural uses. In terms of Electrical Conductivity and Sodium Adsorption Ratio, sewage water is not suitable for irrigation. Fecal and coliform bacterial population is high in all samples. Pesticide and heavy metals in some places are alarming. So sewage-sludge produced in Kolkata cannot be used for agricultural purpose without any treatment. Thus proper care, maintenance, treatment and disposal of sewage water and sludge are most vital and should be the prime thrust for the nation.

Degradation dynamics and dissipation kinetics of an imidazole fungicide (Prochloraz) in aqueous medium of varying pH

Degradation dynamics and dissipation kinetics of an imidazole fungicide (Prochloraz) in aqueous medium of varying pH Laboratory degradation studies were performed in water at pH 4.0, 7.0 and 9.2 using Prochloraz (450 EC) formulation at the concentration of 1.0 (T1) and 2.0 (T2) μg/mL. Water samples collected on 0 (2 h), 3, 7, 15, 30, 45, 60 and 90 days after treatments were processed for residue analysis of Prochloraz by HPLC-UV detector. In 60 days, dissipation was 89.1-90.5% at pH 4.0, 84.1-88.2% at pH 7.0, and 92.4-93.8% at pH 9.2 in both treatments. The results indicate that at pH 7.0 the degradation of Prochloraz was much slower as compared to other two. Between pH 4.0 and 9.2 the degradation of compound is little faster at pH 9.2. The half-life periods observed were 18.35 and 19.17 days at pH 4.0, 22.6 and 25.1 days at pH 7.0 and 15.8 and 16.6 days at pH 9.2 at T1 and T2 doses respectively.

Vertical migration of some herbicides through undisturbed and homogenized soil columns

Vertical migration of some herbicides through undisturbed and homogenized soil columns A laboratory experiment was conducted by using three herbicides, two from dinitroaniline group and one from thiocarbamate group to know their degree of downward movement (leachability) through soil columns and their contribution in ground water contamination. Soil columns were loaded with Pendimethalin, Benthiocarb and Oryzalin at doses of 10.0, 10.0 and 7.7 kg/ha, respectively. After 30 days soil samples were analyzed from each segments (i.e. 0-6, 6-12, 12-18, 18-24 and 24-30 cm) for Benthiocarb and Pendimethalin by GLC equipped with Ni63 electron capture detector (ECD) and for Oryzalin by HPLC coupled with UV-VIS detector. The results obtained in the present study reveal that the residues of the three herbicides under investigation were predominantly confined to the upper soil layer (0-6 cm). Comparatively, low mobility of these herbicides in soils could be due to strong adsorption of these chemical to soil colloids.

An Improved Commercial Method for Determination of Nicotine in Tobacco

A high-pressure thin-layer chromatography (HPTLC) method for quantitative analysis of nicotine in Nicotiana sp. was developed using a methanol extract of leaves and stems and TLC plates (silica gel 60 GF254) with spot visualization under ultraviolet (UV) light. Scanning at 235 nm in the absorption-reflection mode produced linear calibration curves in the range of 2 to 25 μg, with a correlation coefficient of 0.991. The average recovery rate was 95% (CV % 1.35). From the present study, the lower limit of detection was 0.08 μg spot−1 for the nicotine. The validity of the method was confirmed by comparing the UV spectra of the tobacco plant samples with standards within the same Rf window.