排序方式: 共有9条查询结果,搜索用时 0 毫秒
1
1.
Excess lead alters growth, metabolism and translocation of certain nutrients in radish 总被引:4,自引:0,他引:4
To elucidate the deleterious effects of excess lead on radish (Raphanus sativus) cv. Jaunpuri plants were grown in refined sand in complete nutrient solution for 30 days. On the 31st day lead nitrate was superimposed at 0.1 and 0.5mM to radish for 65 days. A set of plants in complete nutrient solution was maintained as control for the same period without lead. Excess Pb at 0.5mM showed growth depression with interveinal chlorosis on young leaves at apex. Excess Pb reduced the fresh and dry weight pronouncedly at d 65. Lead accumulation reduced the concentration of chlorophyll, iron, sulphur (in tops), Hill reaction activity and catalase activity whereas increased the concentration of phosphorus, sulphur (in roots) and activity of peroxidase, acid phosphatase and ribonuclease in leaves of radish. 相似文献
2.
Rehman Muhammad Yasir Abdur Taqi Malik Mumtaz Hussain Imran Nasir Jawad Rizvi Syed Hussain Haider Syed Jabir Hussain 《Environmental science and pollution research international》2020,27(34):42405-42423
Environmental Science and Pollution Research - Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic compounds which are emitted through incomplete combustion of organic materials, fossil fuels,... 相似文献
3.
4.
Rheological Investigation of Wood-Polypropylene Composites in Rotational Plate Rheometer 总被引:1,自引:0,他引:1
Ehsan Soury Amir Hossein Behravesh Ghaus M. Rizvi Nathan Jafarian Jam 《Journal of Polymers and the Environment》2012,20(4):998-1006
In this research work, the rheological properties of Wood-Plastic Composites (WPC) with some selected compositions are investigated. WPC is being recognized as a green composite that, in the past 20?years, has emerged to a commercial product. A study on rheological properties of these materials can give insight into the proper selection of composition and processing condition. Two grades of polypropylene (PP) with two different melt flow indexes (MFI) were selected to prepare WPCs with three different wood contents (50, 60 and 70?% wt.). Four types of rheological experiments were performed utilizing a rotational plate rheometer: (1) strain sweep, (2) frequency sweep, (3) temperature sweep and (4) steady shear rate sweep. The independent variables were chosen as wood content, MFI of polymer (two types), melt temperature, frequency or shear rate, the gap between the plates, and strain percentage. The strain sweep tests specified the linear and non-linear viscoelastic zones of each experiment. The results of frequency sweep experiments indicated that increasing the wood content and frequency and also decreasing the strain percentage and the gap distance, lead to an increase in the storage modulus. Regarding the loss modulus, wood percentage and the gap distance presented positive effects and strain percentage showed a negative effect. The behavior of complex viscosity was almost similar to that of the storage modulus but increasing the frequency caused a decrease in the complex viscosity. In case of temperature sweep experiments, it was observed that the rheological properties exhibit a rapid change near to a temperature of 160?°C. The results also showed that beyond this point, increasing the wood content and also MFI of polypropylene caused an increase in the storage modulus. The results of steady shear rate sweep experiments specified that increasing wood content and also decreasing the MFI of PP, the gap distance and shear rate lead to an increase in both viscosity and shear stress. 相似文献
5.
Ahmad Firoz Uddin Md Meraj Goparaju Laxmi Talukdar Nazimur Rahman Rizvi Javed 《Environment, Development and Sustainability》2021,23(10):15183-15203
Environment, Development and Sustainability - The study utilized the tree covers per cent, agroforestry suitability, present and future (2050) climate, agriculture vulnerability (2050), percentage... 相似文献
6.
Singh RP Tripathi RD Dabas S Rizvi SM Ali MB Sinha SK Gupta DK Mishra S Rai UN 《Chemosphere》2003,52(7):1245-1250
The inhibition of seedling growth and nitrate reductase activity in 5 d old Vigna radiata (L.) Wilczek cv. Pusa Baisakhi in the presence of 1.0 mM lead acetate increased drastically, if NaCl (6 and 12 EC) was also present in the nutrient media along with the metal salt. Correspondingly higher endogenous Na+ levels were accumulated in the roots and leaves of seedlings in presence of the two stresses. On the other hand, the levels of endogenous lead get reduced in presence of NaCl in both the roots and leaves. Roots accumulated more Pb2+ and Na+ than the leaves. The two stresses affect more drastically in the additive or even synergistic manner during the early growth phase of the seedlings. 相似文献
7.
Esther Richards Reza Rizvi Andrew Chow Hani Naguib 《Journal of Polymers and the Environment》2008,16(4):258-266
One key strategy for increasing the application potential for biodegradable plastics lies in improving the physical and mechanical
characteristics, which can be attained by inducing a cellular morphology in the pure polymer with the aid of a blowing agent,
as well as by blending two or more polymers with the desirable properties. This paper examines the effect that blending two
biodegradable polymers has on the thermal properties and morphology of the resultant foams blown with carbon dioxide (CO2). Polylactic acid (PLA), polyhydroxybutyrate-co-valerate (PHBV) and blends of both were foamed and characterized in terms
of thermal characteristics, relative density, cell size, and foam morphology. The results indicate that although PLA and PHBV
are immiscible, the presence of small quantities of PHBV (25 wt%) could lead to low density foams with finer, more uniform
cells. Furthermore, the crystallinity of PHBV was found to be unaffected by the presence of PLA in the composite, which supports
the immiscibility of PLA and PHBV. 相似文献
8.
Cadmium stress in rice: toxic effects,tolerance mechanisms,and management: a critical review 总被引:5,自引:0,他引:5
Muhammad Rizwan Shafaqat Ali Muhammad Adrees Hina Rizvi Muhammad Zia-ur-Rehman Fakhir Hannan Muhammad Farooq Qayyum Farhan Hafeez Yong Sik Ok 《Environmental science and pollution research international》2016,23(18):17859-17879
Cadmium (Cd) is one of the main pollutants in paddy fields, and its accumulation in rice (Oryza sativa L.) and subsequent transfer to food chain is a global environmental issue. This paper reviews the toxic effects, tolerance mechanisms, and management of Cd in a rice paddy. Cadmium toxicity decreases seed germination, growth, mineral nutrients, photosynthesis, and grain yield. It also causes oxidative stress and genotoxicity in rice. Plant response to Cd toxicity varies with cultivars, growth condition, and duration of Cd exposure. Under Cd stress, stimulation of antioxidant defense system, osmoregulation, ion homeostasis, and over production of signaling molecules are important tolerance mechanisms in rice. Several strategies have been proposed for the management of Cd-contaminated paddy soils. One such approach is the exogenous application of hormones, osmolytes, and signaling molecules. Moreover, Cd uptake and toxicity in rice can be decreased by proper application of essential nutrients such as nitrogen, zinc, iron, and selenium in Cd-contaminated soils. In addition, several inorganic (liming and silicon) and organic (compost and biochar) amendments have been applied in the soils to reduce Cd stress in rice. Selection of low Cd-accumulating rice cultivars, crop rotation, water management, and exogenous application of microbes could be a reasonable approach to alleviate Cd toxicity in rice. To draw a sound conclusion, long-term field trials are still required, including risks and benefit analysis for various management strategies. 相似文献
9.
Olivier R Staudt M Lavoir AV Ormeño E Rizvi SH Baldy V Rivoal A Greff S Lecareux C Fernandez C 《Environmental pollution (Barking, Essex : 1987)》2011,159(4):963-969
Monoterpene emissions of Quercus coccifera L. were repeatedly measured during the two years following the spreading of a sewage sludge compost at rates of 50 Mg ha−1 and 100 Mg ha−1, in a twelve-year-old post-fire Mediterranean shrubland. We also monitored the patterns of change in soil and leaf nutrient content, plant water potential, chlorophyll fluorescence, and plant growth. Compost spreading resulted in weak changes in leaf nutrient content and plant water status, and therefore no significant effect on monoterpene emissions at leaf scale, except during one summer sampling, probably related to advanced leaf maturity with the highest compost rate. However, compost increased plant growth, particularly the leaf biomass. The results suggest that compost spreading in Mediterranean shrublands has no strong short-term effect on Q. coccifera monoterpene emissions at leaf level, but may indirectly increase volatile organic compound fluxes at the stand scale, which may contribute to regional ozone pollution. 相似文献
1