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61.
The depletion of the ozone layer and enhancement of solar radiation may exert an adverse influence on the ecosystem. Phototoxicity of sludge and polycyclic aromatic hydrocarbons (PAHs) under ultraviolet radiation (UVR) to seedling was studied. Seeds of wheat (Triticum aestivum) were planted in sludge and PAHs (anthracene (An), benzo(a)pyrene (BaP) and pyrene (Py)) with and without UVR. Toxicity of sludge increased in the presence of UVR in wheat. UVB radiation was found to be more hazardous than UVA radiation. Results demonstrated that An, BaP and Py induced phototoxicity at various concentrations (1–10?µg/mL) under UVA (1.5?mW/cm2) or UVB (1.08?J/cm2) exposure. The pattern of phototoxicity was An?>?Py?>?BaP to shoot length, root length, and fresh weight; chlorophyll, protein content, enzyme activity of catalase and α-amylase were reduced while the activity of superoxide dismutase and starch was enhanced. Reduction in seedling growth and biochemical parameters may be related to less photosynthesis, less nutritional uptake, and distortion of root cap. Thus, the synergistic effect may be due to alterations in photosynthesis, phytohormones, or nutritional uptake. 相似文献
62.
Purpose
The purpose of this study is the development of a suitable process for the disinfection of drinking water by evaluating bactericidal efficacy of silver ions from silver electrodes.Methods
A prototype of a silver ioniser with silver electrodes and control unit has been fabricated. Silver ions from silver electrodes in water samples were estimated with an atomic absorption spectrophotometer. A fresh culture of Escherichia coli (1.75?×?103 c.f.u./ml) was exposed to 1, 2, 5, 10 and 20?ppb of silver ions in 100?ml of autoclaved tap water for 60?min. The effect of different pH and temperatures on bactericidal efficacy was observed at constant silver ion concentration (5?ppb) and contact time of 30?min.Results
The maximum bactericidal activity (100%) was observed at 20?ppb of silver ion concentration indicating total disinfection after 20?min while minimum bactericidal activity (25%) was observed after 10?min at 01?ppb of silver ions. Likewise, 100% bactericidal activity was noticed with 2, 5 and 10?ppb of silver ions after 60, 50 and 40?min, respectively. Bactericidal activity at pH?5, 6, 7, 8 and 9 was observed at 79.9%, 79.8%, 80.5%, 100% and 100%, respectively, whereas it was 80.4%, 88.3%, 100%, 100% and 100% at 10°C, 20°C, 30°C, 40°C and 50°C, respectively.Conclusion
The findings of this study revealed that very low concentrations of silver ions at pH?8?C9 and temperature >20°C have bactericidal efficacy for total disinfection of drinking water. Silver ionisation is suitable for water disinfection and an appropriate alternative to chlorination which forms carcinogenic disinfection by-products. 相似文献63.
The authors have developed the Activity Accounting Technique for predicting far field noise levels due to operation of specific set of mining machinery. The technique is based on the breaking down of the mining operations into a number of activities and establishing their duration and average location. By estimating the noise levels due to these activities, the overall noise field near a surface mine can be predicted. Experiments were undertaken at a quarry to validate the model developed based on this technique. Results of these experiments are discussed in this paper. The Activity Accounting Technique has the scope of elaborate application for prediction of environmental noise near mining sites. In a system where the activities involved and their duration can be estimated one can develop a noise quality prediction model based on near field spectrum of the sound pressure levels due to the activities. However, this method will be more useful if an acoustic database can be evolved for all the possible activities for different alternative equipment system. 相似文献
64.
Kumar Ankur Singh Prakhar Agarwal Tarun Joshi Manish Semwal Poonam Singh Kuldeep Pathak Parmanad Prakash Ramola Rakesh Chand 《Environmental science and pollution research international》2020,27(32):40229-40243
Environmental Science and Pollution Research - Regional averages of radon, thoron, and associated decay product concentration are reported to be higher than their respective global averages in... 相似文献
65.
Manoj Patowary Rajakumar Ananthakrishnan Khanindra Pathak 《Environmental science and pollution research international》2017,24(22):18063-18072
Development of efficient techniques to combat the harmful effects of oil spill is an emerging field, where fabrication of new sorbents for selective removal of oil has become a hot topic for environmental scientists. The present study reports the preparation of superhydrophobic/oleophilic magnetic titania nanotubes via a facile hydrothermal method, followed by the treatment with octadecylamine, as potential magnetically driven sorbent for selective removal of oil from water surface. The magnetic nature (superparamagnetism at 300 K) of the nanotubes enabled magnetic removal of the oil-sorbed material from water surface. Wettability test of the material depicted a static water contact angle of 166 ± 1°, indicating its superhydrophobic character. Oil uptake experiments and contact angle measurements revealed its superoleophilicity with maximum oil sorption capacity >1.5 g/g for a variety of oils. In addition to the ease of magnetic removal, the nanotubes possess sufficient buoyancy, high selectivity, and quick rate of oil uptake and is more than five times reusable. 相似文献
66.
Vikram S. Negi Ravi Pathak K. Chandra Sekar R.S. Rawal I.D. Bhatt S.K. Nandi 《Journal of Environmental Planning and Management》2018,61(10):1722-1743
Ethnobotanical knowledge plays a significant role in plant diversity conservation and the curing of various ailments in remote rural areas of the Indian Himalayan Region (IHR). A total of 53 plant species from 27 families have been documented from the Byans valley and are used traditionally for the treatment of various diseases. Valley inhabitants have maintained a symbiotic relationship between natural resources and their cultural belief system by developing sacred forests/groves which conserve the region's plant diversity pool. Information on sacred natural sites and traditional beliefs was documented in order to understand the environmental and conservationist implications of these rules and practices. The study provides comprehensive information about eroding traditional knowledge and biodiversity conservation practices. This study could be a pilot to strengthen the conservation practices and sustainable utilization of frequently used bioresources by understanding the traditional knowledge system and conservation ethics of tribal communities in the Himalayan region. 相似文献
67.
Biodegradable polymers are the need of the day. Due to their natural spontaneous degradation such materials are becoming the
subject of intensive research. Poly(5-hydroxylevulinic acid) (PHLA) is a biodegradable polymer obtained from biomass resources.
In the present study, one dimensional isolated chain model is used for quantitative characterization of FTIR spectra by vibrational
dynamics giving potential energy distribution and dispersion curves for PHLA. The predicted values of heat capacity calculated
in the range 10–500 K, via density-of-states are being reported. 相似文献
68.
Tara Sankar Pathak Jung-Ho Yun Se-Jong Lee Dae-Jin Baek Ki-Jung Paeng 《Journal of Polymers and the Environment》2010,18(1):45-56
Alginates, extracted from algae are linear unbranched polymers containing β-(1→4)-linked d-mannuronic acid (M) and α-(1→4)-linked l-guluronic acid (G) residues. The conversion of alginic acid into the metal alginate is confirmed using FTIR spectroscopy.
Asymmetric and symmetric stretching of free carboxyl group present in metal alginate occurs almost at the same position in
various solvent compositions. Total intrusion volume of metal alginate prepared in propanol (0.0742 mL/g) is greater compared
to those in ethanol (0.0648 mL/g) and methanol (0.0393 mL/g) as solvent. Surface morphology as well as porosity and pore size
distribution of metal alginate are greatly influenced by solvent. It can be seen from thermal analysis results that calcium
alginate prepared using different solvent compositions started decomposing at 100 °C, but rapid degradation started around
200 °C. The results showed a stepwise weight loss during thermal sweep, indicating different types of reactions during degradation.
First and second step of rapid degradation was situated around 200–300 and 300–550 °C, respectively; whereas the final step
is situated around 550–650 °C. The trend of degradation was similar for all the solvents, although the amount of final residue
varied from one solvent to another. At the same time, lower thermal stability was also observed with higher heating rates.
Additionally, a kinetic analysis was performed to fit with TGA data, where the entire degradation process has been considered
as three consecutive first order reactions. 相似文献
69.
Ebrayi KN Pathak H Kalra N Bhatia A Jain N 《Environmental monitoring and assessment》2007,131(1-3):451-465
Nitrogen is the most widely used fertilizer nutrient, and it is a universally deficient nutrient too, which often severely
restricts the growth and yield of crops. To improve N fertilizer management, soil–plant system models can be applied to simulate
adequate N supply for both, optimal crop growth and minimal N losses. The likely impact of climate change on the cereal production
is of paramount importance in the planning strategies to meet the future growing needs on sustainable grounds. In this scenario
models are the effective tools to foresee the probable impacts and for choosing appropriate land use options. The study reported
in this thesis, employs field experiments and use of simulation tools to understand the dynamics of soil N balance and relate
growth and yield of rice under varying nitrogen inputs. The InfoCrop model was used in this study, which was calibrated with
the historic data sets, and subsequently validated with the field experiment conducted at IARI Farm, New Delhi. Simulated
results matched well with the observed values in terms of growth and yield of rice and seasonal nitrogen uptake. The components
of soil nitrogen balance differed among varying nitrogen level treatments, which was also captured by use of InfoCrop. The
model was then taken to climate change impact analysis. The results clearly revealed that when temperature increased, the
soil N losses, like denitrification, volatilization, N2O emission increased, whereas grain and biomass yields decreased. The
further scope of the study is to validate the study in contrasting agroenvironments. 相似文献
70.
Bhatia A Pathak H Jain N Singh PK Tomer R 《Environmental monitoring and assessment》2012,184(5):3095-3107
Conventional blanket application of nitrogen (N) fertilizer results in more loss of N from soil system and emission of nitrous
oxide, a greenhouse gas (GHG). The leaf color chart (LCC) can be used for real-time N management and synchronizing N application
with crop demand to reduce GHG emission. A 1-year study was carried out to evaluate the impact of conventional and LCC-based
urea application on emission of nitrous oxide, methane, and carbon dioxide in a rice–wheat system of the Indo-Gangetic Plains
of India. Treatments consisted of LCC scores of ≤4 and 5 for rice and wheat and were compared with conventional fixed-time
N splitting schedule. The LCC-based urea application reduced nitrous oxide emission in rice and wheat. Application of 120 kg
N per hectare at LCC ≤ 4 decreased nitrous oxide emission by 16% and methane by 11% over the conventional split application
of urea in rice. However, application of N at LCC ≤ 5 increased nitrous oxide emission by 11% over the LCC ≤ 4 treatment in
rice. Wheat reduction of nitrous oxide at LCC ≤ 4 was 18% as compared to the conventional method. Application of LCC-based
N did not affect carbon dioxide emission from soil in rice and wheat. The global warming potential (GWP) were 12,395 and 13,692 kg CO2 ha−1 in LCC ≤ 4 and conventional urea application, respectively. Total carbon fixed in conventional urea application in rice–wheat
system was 4.89 Mg C ha−1 and it increased to 5.54 Mg C ha−1 in LCC-based urea application (LCC ≤ 4). The study showed that LCC-based urea application can reduce GWP of a rice–wheat
system by 10.5%. 相似文献