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81.
In relation to fluoride in ground water, dental fluorosis is studied in seven villages, viz., Nasipur, Vabanandapur, and Deshnabagram
under Nalhati I block and Kamdebpur, Chalk Atla, Nowapara, and Junitpur under Rampurhat II block, of Birbhum district, West
Bengal, India. Water samples (N = 70) were collected from the tube wells of the mentioned villages in the months of December 2010 to February 2011 and analyzed
for fluoride and other water parameters. The study result revealed that the fluoride levels of almost all the water samples
(95.7%) were higher than 1.5 mg/L, with mean values of 3.15 and 3.83 mg/L in Nalhati I block and Rampurhat II block, respectively.
Dental fluorosis of 490 respondents was visually determined by a competent dentist using Dean’s index (DI) and the tooth surface
index of fluorosis (TSIF). According to the DI, the percentage of severely affected respondents was lowest in Chalk Atla (0%)
and highest in Deshnabagram (50%). The percentage of severely affected respondents was lowest in Kamdebpur and Chalk Atla
(0%) and highest in Nowapara (20%) according to the TSIF score. The age group 10–20 years showed the highest percentage of
severe DI (40.8%) and the age group 21–30 years showed the highest percentage of severe TSIF (22.51%) compared to the other
age groups in the study. The positive relationship between the fluoride level in water and the severity of dental fluorosis
has been proved statistically. The high mean score of dental fluorosis indicates that dental fluorosis is endemic throughout
the study area. 相似文献
82.
Nickitas Georgas Srinivasan Rangarajan Kevin J. Farley Sarath Chandra K. Jagupilla 《Journal of the American Water Resources Association》2009,45(3):715-733
Abstract: The Generalized Watershed Loading Functions (GWLF) model and its ArcView interface (AVGWLF) were used to estimate and examine the components of the total nitrogen (TN) nonpoint source (NPS) load generated within New York and Connecticut (CT) watersheds surrounding Long Island Sound (LIS, the Sound). The majority of data used as model inputs were generally available from online sources, and the work involved an overall calibration to streamflow and TN data in accordance with generic guidelines recommended in the GWLF manual. The GWLF model performance for three calibration and two validation watersheds in CT was compared with results of a detailed model, Hydrological Simulation Program in Fortran, developed in a previous study. The results of the application illustrate the usefulness of the relatively simpler, less parameter‐intensive GWLF model in performing exploratory loading analysis in preparation for adaptive nutrient management in the LIS watersheds. The presented methodology is valuable for identification of priority watersheds for NPS pollution reduction and also for planning‐level evaluation of best management practices to achieve the desired reductions. It is estimated that ground‐water base flow may be the largest pathway for NPS TN to the Sound, contributing about 54% of the total NPS TN load, a finding with significant implications for LIS total maximum daily load reduction scenarios. In addition to ground water, septic systems are estimated to contribute about 17% of the total load, with the remaining TN load being mostly runoff from urban (17%), agricultural (5%), and low impact (e.g., forest) areas (6%). 相似文献
83.
Aniza K. Verma Avanish K. Srivastava Beer Singh Dilip Shah Smriti Shrivastava Chandra Kant P. Shinde 《Chemosphere》2013,90(8):2254-2260
1-(4-Chlorophenyl))-N-hydroxymethanimine and cyclohexyl-N-hydroxymethanimine were synthesized and a well-established oxime, i.e., 2-[(hydroxyimino)methyl]-1-methylpyridinium chloride was purchased. Thereafter; all were loaded over Al2O3 using incipient wetness technique. The prepared systems were characterized using surface area analyzer, scanning electron microscope, energy dispersive X-ray spectrophotometer, Fourier transform infrared spectrophotometer and thermogravimetric analyzer. Kinetics of the degradation of sarin (GB) and simulant, i.e. diethylchlorophosphate (DEClP) was studied over synthesized oxime impregnated Al2O3 and results were compared with well reported oxime impregnated Al2O3. Kinetics of reaction was found to be following the pseudo first order reaction kinetics. The order of reactivity of the prepared systems was found to be cyclohexyl-N-hydroxymethanimine/Al2O3 > 1-(4-chlorophenyl)-N-hydroxymethanimine/Al2O3 > 2-[(hydroxyimino)methyl]-1-methylpyridinium chloride/Al2O3 > Al2O3. From the reaction kinetics it was observed that the reaction with DEClP was faster than with GB. Cyclohexyl-N-hydroxymethanimine/Al2O3 was found to be the most reactive system with half-life of 0.94 and 15 h for DEClP and GB respectively. 相似文献
84.
Nath BN Khadge NH Nabar S Raghukumar C Ingole BS Valsangkar AB Sharma R Srinivas K 《Environmental monitoring and assessment》2012,184(5):2829-2844
An area of 0.6 km(2) in the manganese nodule field of the Central Indian Basin was physically disturbed and sediments discharged in the near bottom waters to simulate seabed mining and study its impact on benthic ecosystem. An estimated 2 to 3 tonnes of sedimentary organic carbon (C(org)) was resuspended into the water column during a 9-day experiment. The majority of the sediment cores from within the disturbed area and areas towards the south showed a ~30% increase in C(org) content as well as an increase in carbon burial rates after disturbance, though with a reduction in carbon/phosphorus ratios. High specific surface area (SSA~25 m(2) g(-1)) and low C(org)/SSA ratios (mostly <0.5) are typical of deep-sea sediments. The increased C(org) values were probably due to the organic matter from dead biota and the migration and redeposition of fine-grained, organic-rich particles. Spatial distribution patterns of C(org) contents of cores taken before and after disturbance were used to infer the direction of plume migration and re-sedimentation. A positive relationship was observed between total and labile C(org) and macrobenthos density and total bacterial numbers prior to disturbance, whereas a negative relationship was seen after disturbance owing to drastic reduction in the density of macrofauna and bacteria. Overall decrease in labile organic matter, benthic biota and redistribution of organic matter suggest that the commercial mining of manganese nodules may have a significant immediate negative effect on the benthic ecosystem inducing changes in benthic community structure. 相似文献
85.
Amal Chandra Das Hemanta Nayek Arunabha Chakravarty 《Environmental monitoring and assessment》2012,184(12):7453-7459
An experiment was conducted under laboratory conditions to investigate the effect of two systemic herbicides, viz. pendimethalin (a dinitroaniline) and quizalofop (an arylphenoxy propionic acid) at their recommended field application rates (1.0?kg and 50?g active ingredient per hectare, respectively), either separately or in a combination, on growth and activities of phosphate-solubilizing microorganisms in relation to their effects on biochemical transformations and availability of organic carbon, total and available phosphorus in a Typic Haplustept soil of West Bengal, India. Application of herbicides, in general, significantly stimulated the growth and activities of phosphate-solubilizing microorganisms which increased microbial biomass resulting in higher accumulation of oxidizable organic carbon, total and available phosphorus in soil as compared to untreated control. The combined application of both the herbicides highly stimulated the proliferations of phosphate-solubilizing microorganisms, while pendimethalin alone significantly accentuated phosphate-solubilizing capacities 36.4% as compared to untreated control and retained highest amount of total phosphorus due to greater microbial activities in soil. The separate application of quizalofop also manifested an induced effect on the proliferations of phosphate-solubilizing microorganisms and accounted significant amounts of organic carbon and available phosphorus in the soil system. The results of the present study thus indicated that the cited herbicides at their field application rates can be safely used to eradicate weeds in the crop fields. 相似文献
86.
The monthly maximum of the 24-h average time-series data of ambient air quality-sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)) and suspended particulate matter (SPM) concentration monitored at the six National Ambient Air Quality Monitoring (NAAQM) stations in Delhi, was analysed using Box-Jenkins modelling approach (Box et al. 1994). Univariate linear stochastic models were developed to examine the degree of prediction possible for situations where only the past record of pollutant data are available. In all, 18 models were developed, three for each station for each of the respective pollutant. The model evaluation statistics suggest that considerably satisfactory real-time forecasts of pollution concentrations can be generated using the Box-Jenkins approach. The developed models can be used to provide short-term, real-time forecasts of extreme air pollution concentrations for the Air Quality Control Region (AQCR) of Delhi City, India. 相似文献
87.
Sumit Sharma Navin Chandra Kothiyal 《Environmental science and pollution research international》2013,20(12):8986-8995
In this study, a natural adsorbent (activated dry flowers (ADF)) was prepared from plant-derived waste biomass by chemical activation and employed for chromium (VI) removal from aqueous medium using experimental batch technique. Experiments were carried out as function of adsorbent dosage, pH, and contact time. The maximum chromium (Vl) removal was observed at initial pH 3 (~94 % removal). The equilibrium data was fitted well to Langmuir isotherm. The adsorption capacity of ADF was found to be 4.40 (mg chromium (Vl)/g) which was comparable to the adsorption capacity of some other adsorbents documented. Among various kinetic models applied, pseudo second-order model was found to explain the kinetics of chromium (VI) adsorption most effectively (R 2 >0.99). Thermodynamic parameters such as ΔG, ΔS, and ΔH shows that adsorption process was spontaneous and endothermic at all the concentration ranges studied. Desorption of chromium (Vl) with 2 N NaOH was effective (~71 %) and, hence, there exists the possibility of recycling the ADF. The major advantages of using ADF as an adsorbent are due to its effectiveness in reducing the concentration of chromium (Vl) to very low levels. It requires little processing and is reversible as well as eco-friendly in contrast to traditional methods. 相似文献
88.
Arachis hypogaea hulls, an agricultural waste, were used to prepare activated carbon by chemical activation with zinc chloride under four different activation atmospheres. The most important parameter in chemical activation was found to be the chemical ratio (activating agent/precursor). Carbonization temperature and time are the other two important variables, which had significant effect on the pore structure of carbon. The maximum Brunquer-Emmett-Teller (BET) surface area and micropore volume of the activated carbon was found to be 418 m(2)/g and 0.28 cm(3)/g, respectively. The activated carbon developed shows substantial capability to adsorb phenol from aqueous solutions. The kinetic data were fitted to the models of intraparticle diffusion, pseudo-second-order, and Lagergren, and followed more closely the pseudo-second-order chemisorption model. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models. Solution pH has significant effect on adsorption and the maximum uptake of phenol was reported at pH 3.5. 相似文献
89.
Activated carbon from Ceiba pentandra hulls, an agricultural waste, as an adsorbent in the removal of lead and zinc from aqueous solutions 总被引:2,自引:0,他引:2
The ability of low-cost activated carbon prepared from Ceiba pentandra hulls, an agricultural waste material, for the removal of lead and zinc from aqueous solutions has been investigated. In the batch tests experimental parameters were studied, including solution pH, contact time, adsorbent dose and initial metal ions concentration. The adsorbent exhibited good sorption potential at pH 6.0. Maximum removal of lead (99.5%) and of zinc (99.1%) with 10 g/l of sorbent was observed at 50 mg/L sorbate concentration. Removals of about 60-70% occurred in 10 min, and equilibrium was attained at around 50 min for both metals. The functional groups (CO, SO,-OH) present on the carbon surface were responsible for the adsorption of metal ions. The adsorption parameters were analysed using both the Freundlich and Langmuir models. The data are better fitted by the Freundlich isotherm as compared to Langmuir model, and the adsorption capacities for lead and zinc were 25.5 and 24.1 mg/g, respectively. Kinetics of adsorption obeyed a second order rate equation and the rate constant was found to be 2.71 x 10(-2) and 2.08 x 10(-2) g/mg/min for lead and zinc, respectively. The desorption studies were carried out using dilute HCl, and the effect of HCl concentration on desorption was studied. Maximum desorptions of 85% for lead and 78% for zinc were attained with 0.15 M HCl. 相似文献
90.
Ananga M Chandra Suhana Ghosh Rauf Iqbal Nachiketa Sadhu 《International journal of occupational safety and ergonomics》2007,13(3):271-278
An ergonomic assessment of the involvement of static muscular forces like back strength, grip strength and pinch strength in different occupations was made. A study was conducted on 45 normal adult males (15 subjects per group) which included video display terminal (VDT) operators, industrial workers and safety inspectors. Their maximum back strength, handgrip strength and pinch strength were measured with dynamometers. The observed values of back strength were significantly lower in VDT operators while significantly higher in safety inspectors and moderate in industrial workers. The values of grip strength and pinch strength of all sample groups were more or less similar. The findings clearly indicate that static muscular strength varies significantly in different occupations. Heavy static muscular load might lead to an accumulation of metabolic waste and toxins on the back resulting in lower back strength in VDT operators and industrial workers. 相似文献