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21.
The study of heavy metals’ redistribution between different fractions allows to know their bioavailability and mobility in soils. Soil samples were collected from a lead mine in Hamadan provinces, NW Iran. In a factorial experiment soil was treated with cow, sheep and poultry manures (20?g?kg?1 soil) separately and incubated near field capacity at 10°C and 37°C. An untreated soil (as control) was also incubated at the same temperatures. After 0 and 120 days, a sequential extraction scheme was used to fractionate Pb of incubated samples into soluble-exchangeable (Sol-Exch), organic matter associated (AOM), carbonates associated (ACar), and residual (Res) forms. Soil Pb in Sol-Exch and AOM fractions were increased by manure application significantly. The AOM and ACar forms of Pb were higher in soils treated with the manures and incubated in lower temperature. In contrast, the Sol-Exch and Res chemical forms of Pb were higher in the soils incubated at 37°C. These results may be related to the higher calcium carbonate dissolution and organic matter decomposition because of better biological activity in the soils incubated in higher temperature. The increase of the Res fraction (stable form) in this condition may resulted in lower toxicity and mobility in soil environment. 相似文献
22.
Yousef Mohammadian Ali Akbar Saboor Yaraghi Hossein Kakooei Mohammad Hajaghazadeh 《毒物与环境化学》2013,95(6):1037-1047
Carbon nanotubes (CNTs) have found numerous applications in various industries. Recently, adverse effects of these materials on human and animal cells in vitro have been reported. In the present study, the cytotoxicity of single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), and chrysotile asbestos in human lung epithelial cells has been studied using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The cells were exposed for 6 h and 24 h to between 0.97 and 1500 μg mL?1 of CNTs and chrysotile fibers prepared in two culture media containing 5% serum and 0.5% dimethylsulfoxide. Dose–response curves were obtained to determine the nonobservable adverse effect concentration and the half-maximum inhibitory concentration (IC50). The way of dispersion affects the cytotoxicity of CNTs. For MWCNT, the toxicological indexes were lower than for SWCNT. Chrysotile fibers were even less cytotoxic than CNTs. Therefore, workplace control measures are recommended as priority for occupational and environmental conditions. 相似文献
23.
Ali Akbar Safari Sinegani Hossein Mirahamdi Araki 《Environmental Chemistry Letters》2010,8(2):129-137
Sorption of metal ions by soil and clay minerals is a complex process involving different mechanisms, and controlled by different
variables that can interact. The aim of this work was to study the retention mechanisms of Pb ions on different soil samples.
Surface soils were sampled from Guilan and Hamadan provinces in north and northwest of Iran with temperate and semiarid climates.
The adsorption isotherms of Pb on the soils have been studied at 15, 27 and 37°C. The adsorption data for different soils
were fitted into Langmuir and Freundlich models. Temperate soil samples had higher clay content, cation exchange capacity,
dichromate (oxidable) organic carbon, total Kjeldahl-nitrogen, biological activity, amorphous and crystalline Fe and Al, but
semiarid soil samples had higher sand content, pH, equivalent calcium carbonate, available P and K. Lead adsorption data obtained
from semiarid soils against those obtained from temperate soils were better fitted in both Langmuir and Freundlich models.
Langmuir constants Q
0 for Pb adsorption in semiarid soils were considerably lower than those for Pb adsorption in temperate soils. However, the
binding energy (K
L) of Pb and Freundlich constant n were higher for data of semiarid soils. The effect of temperature on the Pb adsorption was positive especially in temperate
soils; however, soil properties had higher effects on Pb adsorption. 相似文献
24.
Mohammad Behbahani Fatemeh Najafi Saman Bagheri Majid Kalate Bojdi Parmoon Ghareh Hassanlou Akbar Bagheri 《Environmental monitoring and assessment》2014,186(4):2609-2618
A simple, rapid, and efficient sample pretreatment technique, based on solvent-based de-emulsification dispersive liquid–liquid microextraction (SD-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for simultaneous preconcentration and trace detection of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) in water and urine samples. Some parameters such as acidity of solution, the amount of salt, type, and volume of extraction solvents, type of disperser/de-emulsifier solvent, and its volume were investigated and optimized. Under optimum extraction conditions, the limits of detections (LODs) of this method for MCPA and 2,4-D were 0.2 and 0.6 μg L?1 (based on 3Sb/m) in water and 0.4 and 1.6 μg L?1 in urine, respectively. Furthermore, dynamic linear range of this method for MCPA and 2,4-D was 1–300 and 2–400 μg L?1, repectively. Finally, the applicability of the proposed method was evaluated by extraction and determination of the herbicides in urine and different water samples. 相似文献
25.
M. Ishaq F. Akbar Jan Murad Ali Khan I. Ihsanullah I. Ahmad M. Shakirullah Roohullah 《Environmental monitoring and assessment》2013,185(2):1483-1494
The purpose of the present study was to find out the sources of mercury and arsenic pollution of water in the industrial area of Peshawar, the capital of Khyber Pakhtunkhwa, Pakistan. Samples of effluents, mud, and water were collected from the target area (industrial area of Peshawar), the area of water supply source, and from the less polluted area, the Lower Dir district, as the control. Hg was determined by the cold vapor generation technique, while arsenic was determined using the electrothermal atomic absorption technique. Data of the water from the industrial area were compared with that of the source area, control area, as well as with the WHO and some international drinking water quality standards. The results show that some parameters, i.e., TDS, DO, pH, and hardness, were more than the permissible limits. Textile and glass industries were found to be the major sources of Hg and As pollution. Downstream dilution of these contaminants was also observed. 相似文献
26.
Monitoring the effects of chelating agents and electrical fields on active forms of Pb and Zn in contaminated soil 总被引:2,自引:0,他引:2
Iman Tahmasbian Ali Akbar Safari Sinegani 《Environmental monitoring and assessment》2013,185(11):8847-8860
The application of electrical fields and chelating agents is an innovative hybrid technology used for the decontamination of soil polluted by heavy metals. The effects of four center-oriented electrical fields and chelating agents on active fractions of lead and zinc were investigated in this pot experiment. Ethylenediaminetetraacetic acid (EDTA) as a synthetic chelator and cow manure extract (CME) and poultry manure extract (PME) as natural chelators were applied to the pots (2 g kg?1) 30 days after the first irrigation. Two weeks later, four center-oriented electrical fields were applied in each pot (in three levels of 0, 10, and 30 V) for 1 h each day for 14 days. The soil near the cathode and anodes was collected and analyzed as cathodic and anodic soil, respectively. Results indicated that the soluble–exchangeable fraction of lead and zinc were decreased in the cathodic soil, while the carbonate-bound fractions were increased. In the anodic soil, however, the opposite result was observed. EDTA enhanced the soluble–exchangeable form of the metals in both anodic and cathodic soils. Furthermore, the amounts of carbonate-bound heavy metals were increased by the application of CME in both soils. The organic-bound fraction of the metals was increased by the application of natural chelators, while electrical fields had no significant impacts on this fraction. 相似文献
27.
Faranak Pishgar Homayon Ahmad Panahi Ali Akbar Khodaparast Haghi Vahid Mottaghitalab Amir Hesam Hasani 《Journal of Polymers and the Environment》2016,24(2):176-184
In this research, a novel thermosensitive nanosphere polymer (TNP) was synthesized by copolymerization of N-isopropylacrylamide with 3-allyloxy-1,2-propanediol for the removal of diazinon from water. The characterization of the synthesized adsorbent has been performed by Fourier transform infrared spectrometer, scanning electron microscopy and elemental analysis. Batch adsorption method was performed to investigate the influences of various parameters like pH, temperature and contact time on the adsorption of diazinon. The equilibrium adsorption data of diazinon by TNP was studied by Langmuir, Freundlich, Temkin and Redlich–Peterson model. According to equilibrium adsorption results, the Langmuir, Freundlich and Temkin constants were evaluated to be 0.912 (L/mg), 7.916 (mg/g) (L/mg)1/n and 2.494 respectively at pH 7 and room temperature. Based on Redlich–Peterson model analysis, the equilibrium data for the adsorption of diazinon was conformed well to the Langmuir isotherm model. This method was successfully applied for removal of diazinon from environmental samples. Moreover, in reusing of TNP, the sorption capacity was maintained without any significant change after 10 cycles of sorption–desorption process. 相似文献
28.
Cut-off grade strategy (COGS) is a concept that directly influences the financial, technical, economical, and environmental issues in relation to the exploitation of a mineral resource. Despite the simple definition of cut-off grade, the COGS problem is one of the complex and complicated problems in the mine planning process. From the optimization point of view, the COGS with an objective of maximizing the present value of future cash flows is a non-linear and a non-convex problem that even in its deterministic form can be solved using approximate optimization methods. This optimization problem will also be more complex and complicated under uncertainty conditions. This paper proposes an uncertainty based multi-criteria ranking system to investigate the problem of COGS selection considering metal price and geological uncertainties. The proposed system aims at selection of the best COGS among technically feasible alternative COGSs under uncertainty circumstances. Our developed system is based on integrating metal price and geological uncertainties as well as operating flexibility to close the mine early. We incorporate this operating flexibility into the proposed system using a Monte Carlo based real options (RO) valuation model. For this purpose, in addition to the expected value, other risk criteria are considered to rank the alternatives. These risk criteria include abilities of strategies in producing extra profits, minimizing losses, and achieving the predefined goals of the production. In this study, the technically possible COGSs are generated using the Lane comprehensive algorithm. To demonstrate the effectiveness of the proposed system, we utilize data of an Iranian gold mine. Results show that the proposed system outperforms conventional methods in the sense that it shows significantly lower average mis-ranking than the other methods and also selects a strategy with a higher value. The sensitivity analysis of the proposed system relative to the gold price shows that the system is highly dependent on the parameters of the stochastic process used to model the evolution of the metal price. Therefore, special consideration should be given in estimating stochastic process parameters. 相似文献
29.
Muhammad Farooq Saleem Khan Jing Wu Cheng Cheng Mona Akbar Chuanyang Liu Bo Liu Jian Shen Yu Xin 《Frontiers of Environmental Science & Engineering》2020,14(3):42
30.
Zhong Ruoyu Ren Xuedi Akbar Muhammad Waqas Zia Zeenat Sroufe Robert 《Environmental science and pollution research international》2022,29(31):46898-46915
Environmental Science and Pollution Research - The previous studies focused on environmental issues, identifying their root causes, urging prompt action to reduce environmental degradation. In this... 相似文献