Estimation of chlorpyriphos and cypermethrin residues in chilli (Capsicum annuum L.) by gas–liquid chromatography

Dissipation of chlorpyriphos and cypermethrin in chilli was studied following three applications of a combination formulation of Nurelle-D 505 (chlorpyriphos 50 %?+?cypermethrin 5 %) at 1 and 2 L?ha^?1 at an interval of 15 days. Residues of chlorpyriphos and cypermethrin in chilli were estimated by gas–liquid chromatography and confirmed by gas chromatography–mass spectrometry. Half-life periods for chlorpyriphos were found to be 4.43 and 2.01 days, whereas for cypermethrin these values were observed to be 2.51 and 2.64 days at single and double the application rates, respectively. Residues of chlorpyriphos dissipated to more than 80 % after 10 days at both the dosages. However, residues of cypermethrin dissipated to the extent of more than 70 % in 7 days. Soil samples collected after 15 days of the last application did not show the presence of chlorpyriphos and cypermethrin at their respective determination limit of 0.01 mg?kg^?1. The use of chlorpyriphos and cypermethrin mixture at the recommended dosage does not seem to pose any hazards to the consumers, and a waiting period of 1 day is suggested to reduce the risk before consumption of green chilli.     

Assessment of physicochemical characteristics of Ganga Canal water quality in Uttarakhand

Assessment of physicochemical parameters of Ganga Canal water was carried out during 2012–2013 at Haridwar (Uttarakhand) with two different sites, i.e., Bhimgoda Barrage (site 1—control site) and Bahadrabad (site 2—contaminated site), where canal water flows with loads of pollution from highly commercial and industrial areas. During investigation, maximum turbidity (287.72 ± 56.28 JTU), total solids (1167.60 ± 303.90 mg l^?1), free CO₂ (1.88 ± 0.22 mg l^?1), total hardness (60.14 ± 1.13 mg l^?1), pH (7.1 ± 0.13), nitrate (0.048 ± 0.010), nitrite (0.019 ± 0.001), biochemical oxygen demand (2.866 ± 1.098), chemical oxygen demand (6.8 ± 2.61) and phosphate (0.087 ± 0.015), while minimum velocity (1.71 ± 0.19 ms^?1), transparency (0.12 ± 0.08 m) and dissolved oxygen (7.95 ± 0.44 mg l^?1) were recorded in monsoon season at site 2 in comparison with site 1. The mean values of these parameters were compared with WHO and ISI standards and found significant differences (p < 0.05) in the mean values of turbidity, total solids, pH, dissolved oxygen, free CO₂ and total hardness with sampling sites. The turbidity of both the sites 1 and 2 was recorded above the permissible limit. Turbidity of site 2 is much higher than of site 1, so it is counted as more polluted. The values of the studied parameters were more during monsoon season and summer season at site 2 as compared to site 1. The results indicated that most of the physicochemical parameters from Ganga Canal system were within or at periphery in comparison with permissible limit of ISI and WHO for drinking water and therefore may be suitable for domestic purposes, but it requires perceptible consideration due to intense changes in climate and increase in pollution.     

Effect of dehydrogenase,phosphatase and urease activity in cotton soil after applying thiamethoxam as seed treatment

Soil enzymes are indicators of microbial activities in soil and are often considered as an indicator of soil health and fertility. They are very sensitive to the agricultural practices, pH of the soil, nutrients, inhibitors and weather conditions. To understand the effect of an insecticide, thiamethoxam, on different soil enzyme activities, the experiments were conducted at cotton experimental fields of Punjab Agricultural University, Ludhiana. The results here were presented to understand the impact of thiamethoxam on soil enzyme activities. Thiamethoxam was applied as seed treatment to control the pest. Soil from three localities, i.e. soil in which seed was treated with recommended dose at 2.1 g a.i. kg^?1, soil in which seed was treated with four times recommended dose at 8.4 g a.i. kg^?1 and from the control field, were tested for different enzyme activities. Phosphatase and dehydrogenase activities were high in control soil in comparison to control soil while no effect of this insecticide on urease activity. Thiamethoxam had inhibitory effects on dehydrogenase and phosphatase activities. Therefore, it can be attributed that agricultural practices, weather conditions and use of thiamethoxam might be responsible for the different level of enzyme activities in soil.