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251.
Neha Parkhi Dilip Chate Sachin D. Ghude Sunil Peshin Anoop Mahajan Reka Srinivas Divya Surendran Kaushar Ali Siddhartha Singh Hanumant Trimbake Gufran Beig 《环境科学学报(英文版)》2016,28(5):265-272
A network of air quality and weather monitoring stations was established under the System of Air Quality Forecasting and Research(SAFAR) project in Delhi. We report observations of ozone(O_3), nitrogen oxides(NO_x), carbon monoxide(CO) and particulate matter(PM_2.5and PM_(10)) before, during and after the Diwali in two consecutive years, i.e., November 2010 and October 2011. The Diwali days are characterised by large firework displays throughout India. The observations show that the background concentrations of particulate matter are between 5 and 10 times the permissible limits in Europe and the United States. During the Diwali-2010, the highest observed PM_(10) and PM_2.5mass concentration is as high as2070 μg/m~3 and 1620 μg/m3, respectively(24 hr mean), which was about 20 and 27 times to National Ambient Air Quality Standards(NAAQS). For Diwali-2011, the increase in PM_(10) and PM_2.5mass concentrations was much less with their peaks of 600 and of 390 μg/m~3 respectively, as compared to the background concentrations. Contrary to previous reports,firework display was not found to strongly influence the NO_x, and O_3 mixing ratios, with the increase within the observed variability in the background. CO mixing ratios showed an increase. We show that the large difference in 2010 and 2011 pollutant concentrations is controlled by weather parameters. 相似文献
252.
Abhijit Kar Kousik Mandal Balwinder Singh 《Environmental monitoring and assessment》2013,185(2):1255-1263
Chlorantraniliprole, an anthranilic diamide insecticide with novel mode of action is found effective against several lepidopteran as well as coleopteran, dipteran, and hemipteran pests. The present studies were carried out to study the dissipation pattern of chlorantraniliprole on cauliflower and to suggest suitable waiting period for the safety of consumers. Quick, easy, cheap, effective, rugged, and safe method was used for the extraction and cleanup of samples and the residues of chlorantraniliprole were estimated using high-performance liquid chromatograph (HPLC) and confirmed by liquid chromatograph–mass spectrometer and high-performance thin layer chromatograph. Following three applications of chlorantraniliprole (Coragen 18.5 SC) at recommended dose (9.25 g a.i.?ha?1) and double the recommended dose (18.50 g a.i.?ha?1), the average initial deposits of chlorantraniliprole were observed to be 0.18 and 0.29 mg kg?1, respectively. These deposits were found to be less than the maximum residue limit of 2.0 mg kg?1 prescribed by the Codex Alimentarius Commission. These residues dissipated below the limit of quantification of 0.10 mg kg?1 after 3 and 5 days at recommended and double the recommended dosages, respectively. The half-life value (T 1/2) of chlorantraniliprole was worked out to be 1.36 days following its application at recommended dosages. Hence, the use of this pesticide at recommended dosages does not seem to pose any risk, and a waiting period of 1 day is suggested for safe consumption of cauliflower curds. 相似文献
253.
Environmental Chemistry Letters - Even though moisture in food products is useful for the quality of foods, excess moisture in a package is unfavorable to the quality of the food product and the... 相似文献
254.
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256.
Shashi B. Singh Irani Mukherjee Jaya Maisnam Praveen Kumar Madhuban Gopal Gita Kulshrestha 《Journal of environmental science and health. Part. B》2013,48(4):300-306
Studies were conducted to analyze the residue of commonly used pesticides viz. methyl parathion, chloropyrifos, endosulfan, cypermethrin, fenvalerate, carbendazim, imidacloprid and carbaryl in mango, Dashehari variety, integrated pest management (IPM) and non-IPM samples were collected from the IPM and non-IPM orchards, Lucknow, India. We also present a method for the simultaneous determination of these pesticides in mango samples. Residues of methyl parathion, chloropyriphos, endosulfan, cypermethrin, fenvalerate were extracted from the samples with acetone: cyclohexane: ethyl acetate in the ratio 2:1:1 followed by cleanup using neutral alumina. Analysis was performed by gas chromatography-electron capture detector (GC-ECD) with a megabore column (OV-1). Residues of carbendazim, imidacloprid and carbaryl were extracted with acetone and after cleanup, analysis was performed by high performance liquid chromatography (HPLC) using photo diode array (PDA) detector. Recoveries of all the pesticides ranged between 72.7 – 110.6%, at 0.1 and 1.0 μg g? 1 level of fortification. The residues detected in non-IPM samples of mango were found to be below the prescribed limits of maximum residue limit (MRL) while IPM samples were free from pesticide residues. 相似文献
257.
Appraisal of salinity and fluoride in a semi-arid region of India using statistical and multivariate techniques 总被引:1,自引:0,他引:1
Suman Mor Surender Singh Poonam Yadav Versha Rani Pushpa Rani Monika Sheoran Gurmeet Singh Khaiwal Ravindra 《Environmental geochemistry and health》2009,31(6):643-655
Various physico-chemical parameters, including fluoride (F−), were analyzed to understand the hydro-geochemistry of an aquifer in a semi-arid region of India. Furthermore, the quality
of the shallow and deep aquifer (using tube well and hand pumps) was also investigated for their best ecological use including
drinking, domestic, agricultural and other activities. Different multivariate techniques were applied to understand the groundwater
chemistry of the aquifer. Findings of the correlation matrix were strengthened by the factor analysis, and this shows that
salinity is mainly caused by magnesium salts as compared to calcium salts in the aquifer. The problem of salinization seems
mainly compounded by the contamination of the shallow aquifers by the recharging water. High factor loading of total alkalinity
and bicarbonates indicates that total alkalinity was mainly due to carbonates and bicarbonates of sodium. The concentration
of F− was found more in the deep aquifer than the shallow aquifer. Further, only a few groundwater samples lie below the permissible
limit of F−, and this indicates a risk of dental caries in the populace of the study area. The present study indicates that regular monitoring
of groundwater is an important step to avoid human health risks and to assess its quality for various ecological purposes. 相似文献
258.
Nandita Singh Lena Q. Ma Joseph C. Vu Anshita Raj 《Environmental pollution (Barking, Essex : 1987)》2009,157(8-9):2300-2305
This study investigated the effects of arsenic on the in vitro activities of the enzymes (nitrate reductase and nitrite reductase) involved in nitrate metabolism in the roots, rhizomes, and fronds of four-month old Pteris vittata (arsenic – hyperaccumulator) and Pteris ensiformis (non-arsenic--hyperaccumulator) plants. The arsenic treatments (0, 150, and 300 μM as sodium arsenate) in hydroponics had adverse effects on the root and frond dry weights, and this effect was more evident in P. ensiformis than in P. vittata. Nitrate reductase and nitrite reductase activities of arsenate-treated plants were reduced more in P. ensiformis than in P. vittata. This effect was accompanied by similar decreases in tissue NO3? concentrations. Therefore, this decrease is interpreted as being indirect, i.e., the consequence of the reduced NO3? uptake and translocation in the plants. The study shows the difference in the tolerance level of the two Pteris species with varying sensitivity to arsenic. 相似文献
259.
Kunwar P. Singh Shikha Gupta Premanjali Rai 《Environmental science and pollution research international》2014,21(9):6001-6015
Groundwater hydrochemistry of an urban industrial region in Indo-Gangetic plains of north India was investigated. Groundwater samples were collected both from the industrial and non-industrial areas of Kanpur. The hydrochemical data were analyzed using various water quality indices and nonparametric statistical methods. Principal components analysis (PCA) was performed to identify the factors responsible for groundwater contamination. Ensemble learning-based decision treeboost (DTB) models were constructed to develop discriminating and regression functions to differentiate the groundwater hydrochemistry of the three different areas, to identify the responsible factors, and to predict the groundwater quality using selected measured variables. The results indicated non-normal distribution and wide variability of water quality variables in all the study areas, suggesting for nonhomogenous distribution of sources in the region. PCA results showed contaminants of industrial origin dominating in the region. DBT classification model identified pH, redox potential, total-Cr, and λ 254 as the discriminating variables in water quality of the three areas with the average accuracy of 99.51 % in complete data. The regression model predicted the groundwater chemical oxygen demand values exhibiting high correlation with measured values (0.962 in training; 0.918 in test) and the respective low root mean-squared error of 2.24 and 2.01 in training and test arrays. The statistical and chemometric approaches used here suggest that groundwater hydrochemistry differs in the three areas and is dominated by different variables. The proposed methods can be used as effective tools in groundwater management. 相似文献
260.
Exploring correlation between redox potential and other edaphic factors in field and laboratory conditions in relation to methane efflux. 总被引:1,自引:0,他引:1
S N Singh 《Environment international》2001,27(4):265-274
Methane is primarily a biogenic gas, which is implicated in global warming. Although its production in the anoxic conditions is regulated by several edaphic factors, aquatic macrophytes also influence methane emission by providing aerenchyma to act as chimney for CH4 transport from the sediment to troposphere, by releasing root exudates to the sediment to serve as substrate for methanogenic bacteria and by transporting atmospheric O2 to rhizosphere, which stimulates CH4 consumption. Among the edaphic factors, redox potential (Eh) is the most important, which largely determines the action of methanogenic bacteria. Hence, a study was undertaken first to find out the correlation between CH4 emission and edaphic factors in the field conditions and then to understand the relationship between Eh and other edaphic factors. The field studies revealed that natural wetlands were the major source of CH4 emission, and the vegetation plays an important role in CH4 emission from the water bodies. However, it was very difficult to establish a strong relationship between the CH4 emission and the edaphic factors in the field conditions due to other limiting factors and their constant fluctuations. In this connection, the laboratory experiments exhibited that soil temperature, pH, moisture regime and incubation period were negatively correlated with Eh, which determines the initiation of methanogenic process. However, organic carbon and the water regime over the soil surface did not show any impact on Eh in this study. 相似文献