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491.
492.
Deepak Singh Rajawat Abhishek Kardam Shalini Srivastava Soami Piara Satsangee 《Environmental science and pollution research international》2013,20(5):3068-3076
In recent years, increasing awareness of the environmental impact of heavy metals has prompted a demand for monitoring and decontaminating industrial wastes prior to discharging into natural water bodies. This paper describes the preparation and electrochemical application of carbon paste electrode modified with nanocellulosic fibers for the determination of cadmium and lead in water samples using anodic stripping voltammetry. First, cadmium and lead were adsorbed on the carbon paste electrode surface at open circuit potential, followed by anodic stripping voltammetric scan from -1 to 0 V. Different factors affecting sensitivity and precision of the electrode, including accumulating solvent, pH of the accumulating solvent, accumulation time, supporting electrolyte, and scan rate were investigated. The proposed method was also applied to the determination of Cd (II) and Pb (II) in the presence of other interfering metal ions and cetyl trimethyl ammonium bromide, sodium dodecyl sulfate, and Triton X-100 as a representative of cationic, anionic, and neutral surfactants. Linear calibration curves were obtained in the concentration ranges of 150–650 μg?L?1 and 80–300 μg?L?1, respectively, for cadmium and lead at an accumulated time of 10 min with limits of detection 88 and 33 μg?L?1. Optimized working conditions are defined as acetate buffer of pH?5 as accumulating solvent, hydrochloric acid as supporting electrolyte, and scan rate 50 mV/s. This technique does not use mercury and therefore has a positive environmental benefit. The method is reasonably sensitive and selective and has been successfully applied to the determination of trace amounts of Cd (II) and Pb (II) in water samples. 相似文献
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Ajay Batish Tejinder P Singh 《International journal of occupational safety and ergonomics》2008,14(2):223-235
This paper describes an assessment tool for analysing material handling tasks and its application for material handling tasks prevalent in engine bearing industry. After a close observation of material handling tasks spread over many days, a list of tasks and parameters/variables affecting those tasks was made. Ergonomic conditions present in these tasks and their deficiencies were then identified and on the basis of the relationships between the tasks and their affinities, categories were developed. Using the data of those categories and various conditions and parameters, an assessment tool called MHAC (material handling assessment chart) was developed. 相似文献
496.
Vishnu Vardhan Kanuri Rita Saha Shiv Pratap Raghuvanshi Ashwani Kumar Singh Bipasha D. Chakraborty V. Kiran Kumar 《Chemistry and Ecology》2020,36(1):30-47
ABSTRACTTo understand the temporal variations of the physicochemical characteristics of the Bhagirathi-Hooghly River (BHR), three locations representing three districts of West Bengal were selected. The material fluxes from 34 drains during pre-monsoon season was quantified. The analysis of variance (ANOVA) revealed that no significant spatial variations were observed for the physicochemical parameters, whereas seasonal variations were significant. The mean discharge was found to be highest (247.2?×?103?m3?d?1) in the midstream drains. Highest mean concentrations of dissolved oxygen (DO) (7.35?mg?L?1) and nitrate (0.81?mg?L ?1) were observed during the post-monsoon season followed by the monsoon and pre-monsoon. According to the BIS, WHO and the European standard of water quality (pH, 6.5–8.5; Nitrate, 0–2.5?mg?L?1;DO, ≥5?mg?L?1), the results of the respective parameters revealed the BHR system is maintained at high to good water quality, meaning that the BHR system is slightly altered from its pristine environment. The mean concentrations of biological and chemical oxygen demands were found to be high during the monsoon season, revealing that a large quantity of refractory organic matter is transported to the eastern Bay of Bengal from the Ganges. 相似文献
497.
The critical loads concept is used by the UN-ECEConvention on Long Range Transboundary Air Pollution(CLRTAP) for setting pollution reduction targets.Increasing numbers of countries are adopting the SimpleMass Balance equation (SMB) to calculate critical loads ofacidifying S and N for forest soils. The equation is madeup of a series of mass balances each of which is used tocalculate a leaching flux. The assumptions in the SMBequation were investigated by testing its ability topredict current sulphur load and by comparing each of thecalculated leaching fluxes to measured rates. It was notpossible to predict current sulphur load at our sites usingthe SMB equation. The leaching tests demonstrated that,primarily due to its steady state assumptions, the SMBequation generates critical loads that are theoretical longterm estimates of risk, and are untestable. Thesimplifying assumptions sometimes lead to illogicalresults. Some of these can be improved by adding a final,simple but dynamic, calculation step to determine theexpected time until effects are observed. Theacceptability of combining annual average data, which bestapproximates steady state, with a biological indicator isquestionable. It is not possible to test critical loadscalculated using the SMB equation when applied with all ofits assumptions but it is possible to test its fundamentalapproach using non steady state data. 相似文献
498.
Jitendra Pandey Usha Pandey Anand V. Singh Deepa Jaiswal Ekabal Siddiqui Kavita Verma 《Chemistry and Ecology》2018,34(5):422-438
We investigated the possible drivers of the N:P stoichiometric shift and its relationship with micro-algal production of transparent exopolymeric particles (TEP) along a 35?km gradient of the Ganga River. The objective was to evaluate if the trade-off between N:P stoichiometry and production of TEP helps in maintaining water quality of the river. Mesocosm experiments were conducted to examine N:P-TEP linkages and its role in turbidity removal. In situ measurements did not show Si to be a limiting nutrient (N:Si?1.3). The TEP production increased with decreasing N:P ratio and peaked at N:P::6:1 with dominance of Aulacosira granulata and Fragilaria intermedia. Settling efficiency, turbidity removal and sedimentation of TEP, biogenic silica (BSi) and biomass all increased with decreasing N:P ratio proportionately to the amount of TEP produced in the mesocosm. The study demonstrates that trade-off between N:P stoichiometry and the production of TEP generates feedback to buffer the ecological impacts of nutrient pollution. 相似文献
499.
Madhura Lavanya Singh Shalini Kanchi Suvardhan Sabela Myalowenkosi Bisetty Krishna Inamuddin 《Environmental Chemistry Letters》2019,17(1):65-121
Environmental Chemistry Letters - Water contamination by pollutants has become one of the most critical health problem worldwide. In the current era, the supply of high-quality drinking water to... 相似文献
500.
Forest structure and regeneration along the altitudinal gradient in the Binsar Wildlife Sanctuary,Uttarakhand Himalaya,India 总被引:1,自引:0,他引:1
Forest structure and regeneration were studied along the altitudinal gradient in the Binsar Wildlife Sanctuary of Uttarakhand
Himalaya in India. Stratified random sampling of tree species was done by placing minimum 15 quadrats of 10 × 10 m at each
aspect and altitude. The results reveal that along the altitudinal gradient there were three types of forest communities in
the Sanctuary viz., chir pine (Pinus roxburghii), oakchir pine (Quercus leucotrichophora and Pinus roxburghii) and oak (Quercus floribunda and Quercus leucotrichophora). Rhododendron arboreum, Cornus macrophylla and Lyonia ovalifolia were main associates of these forest communities. The oak forests had larger shrub population as compared to chir pine. Myrsine africana was the most dominant shrub across the altitudinal gradient, whereas few shrub species were restricted to a certain altitudinal
range. The regeneration of chir pine was best at lower altitude on south and east aspects, which indicates that it mostly
regenerates on warm and dry slopes. In general, the regeneration potential in most of the tree species declines with the altitude.
The density of saplings and seedlings also represented the dominant species at each altitudinal range, which indicates the
cyclic regeneration of forests in the Sanctuary area. 相似文献