细化搜索
结果 671-680 的 61,240
Evaluation of the status of heavy metal pollution in surface water and sediments of the Nil River (North Eastern Algeria)
2017
Krika, Abderrezak | Krika, Fouad
Water and sediment samples were collected from six different stations, located along the Nil River between February and June 2015. Concentrations of cadmium, lead, zinc, and copper were determined. The extent of the sediment pollution was assessed, using the multiple pollution indices, namely contamination factor (CF), pollution load index (PLI), and the geoaccumulation index (Igeo). The results showed that the level of metals in water samples exceeded background concentrations for Cd and Pb, and the average values for those elements were higher than those of Zn and Cu, ranked as the following: Pb (0.58)> Zn (0.38)> Cd (0.32)> Cu (0.061). For sedimentary samples, the results showed that Zn and Pb concentrations were greater than the concentrations of Cu and Cd, exceeding the background values (except for Cu). The concentration of the tested heavy metals decreased to the following order: Zn (96.2)> Pb (61.5)> Cu (38.83)> Cd (2.34). The Igeo values revealed that Cd (2.87) and Pb (1.61) had accumulated significantly in the Nil River. Contamination factor (CF) confirmed that the sedimentary samples were moderate to very high in terms of Cd, Pb, and Zn contamination. The Pollution Load Index (PLI) values were above one (>1), indicating an advanced decline of the sediment quality. Also, the results showed that the stations, located at the middle portion of the river (S3, S4, and S5) have higher levels of metals than the other stations (S1, S2, and S6). The assessment of heavy metals' levels in water and sedimentary samples indicated that river water and the sediments in the study area were strongly impacted by agricultural activities and domestic waste water.
显示更多 [+] 显示较少 [-]Identification of the sources of dust storms in the City of Ahvaz by HYSPLIT
2017
Broomandi, Parya | Dabir, Bahram | Bonakdarpour, Babak | Rashidi, Yousef
Dust particles have dangerous impacts on human health, the environment, and the economy. Recently dust storms, originating from Arabian countries, have increased remarkably, affecting western and central parts of Iran.HYSPLIT model and the mean monthly maps of AAI (Absorbing Aerosol Index), surface skin temperature, and top soil layer moisture from OMI (Ozone Measurement Instrument) have been used to study the origins and trajectories of suspended particles of dust storms from wind erosion during the warm period in 2010.According to HYSPLIT Model, during their move from their source areas to the downwind ones, dust particles could arrive at city of Ahvaz in different directions: (a) NW-SE (the dust particles are transported from north western region of Iraq and eastern Syria), (b) W-E (the dust particles are transported from central parts of Iraq to the south western and western parts of Iran). Also, inspecting dust emission potential with the aerosol index data from Ozone Measurement Instrument (OMI) shows a persistent intense dust activity in north western parts of Iraq and eastern Syria, hitting South-West of Iran, especially the city of Ahvaz. As a result, the main origins of dust particles in the city of Ahvaz include north west Iraq as well as east Syria.
显示更多 [+] 显示较少 [-]Investigation of effective parameters on the performance of NF membrane in simultaneous removal of Cr (VI) and Cu from contaminated water
2017
Aghaei, Fatemeh | Jalilzadeh Yengejeh, Reza
The present study investigates an NF process for removal of copper and hexavalent chromium, studying the effect of pH (5, 7, 9) as well as contaminants' concentration (50, 500, 5000 µg/L) at a constant pressure of 8 bar; with the recovery rate, regulated at 75±2%. To determine the main factors, affecting the system performance, and evaluate the interaction effects among the factors, the experiment is designed via RSM Method. The chrome shows a higher rejection, compared with Copper, all over the range of investigated factors. As Copper concentration grows, Cu removal efficiency drops while, the Cr (VI) removal efficiency ascends. Also by increasing chrome concentration, the Cu removal efficiency decreases, while Cr (VI) removal efficiency increases. Results show that with an increase in pH, the Cu removal drops and Cr removal is increased. The pH is the main parameter, influencing the removal rate. It has been found that the maximum removal efficiency is up to 99% and 73% for Cr (VI) and Cu, respectively. There is an adequate agreement between real data and that obtained from the models (R2 was found to be 0.9889 and 0.9664, for Cu and Cr (VI) rejection, respectively).
显示更多 [+] 显示较少 [-]Characterization of tannery effluents of Hazaribagh area, Dhaka, Bangladesh
2017
Kabir, Mohammad | A. N. M, Fakhruddin | M. A.Z, Chowdhury | Z., Fardous | Islam, Rashedul
The present investigation characterizes tannery effluents by determining water quality parameters and some selected trace metallic constituents in order to measure the magnitude of environmental pollution. Effluents and sediments have also been used to isolate chromium-resistant bacteria, collected from Hazaribagh area, Dhaka, claimed to be increasing Cr (VI)-enriched environments, and utilized to reduce Cr (VI). The pH, TDS, DO, and EC values of all investigated samples have been within the range of 4.35 to 9.74, 290 to 9,200 mg/L, 1.5 to 4.90 mg/L, and 587 to 19,000 µs/cm, respectively. The concentrations of trace metallic constituents have been determined by means of Atomic Absorption Spectrophotometer (AAS), giving the following ranges: Cr: 14.282 to 6,769.554 mg/L; Cd: 1.546 to 2.214 mg/L; Pb: 18.808 to 32.026 mg/L; Cu: 1.522 to 2.578 mg/L; Zn: 0.682 to 8.688 mg/L; Fe: 1.37 to 108.556 mg/L; and Mn: 3.494 to 17.17 mg/L. The order of trace metallic constituents in the effluent samples was Cr > Fe > Pb > Mn > Zn > Cd > Cu. The water quality parameters and metallic constituents’ concentration were higher than that of standard permissible limits in all the examined samples. The average number of Cr (VI)-resistant bacteria in the sediment samples with glucose (0.5%, w/v) supplementation was 2.35× 103 CFU/gm at 24h. One of the representative isolate was able to tolerate up to 400 mg/L of K2Cr2O7 as Cr (VI). The bacteria, isolated in the present study, can be used as eco-friendly biological agents for the remediation and/or detoxification of chromium (Cr) pollution from the chromium contaminated environments.
显示更多 [+] 显示较少 [-]Risk assessment of exposure to released BTEX in district 12 of Tehran municipality for employees or shopkeepers and gas station customers
2017
Faraji, Afsaneh | Nabibidhendi, Gholamreza | Pardakhti, Alireza
Owing to environmentally-destructive impact of aromatic hydrocarbons, such as benzene, benzene ethyl, toluene, and xylenes or BTEXs, these materials are classified as hazardous pollutants in the air. This study studies cancer and non-cancer risk in District 12 of Tehran Municipality, through these components for two groups of employees or storekeepers and gas station customers. By measuring pollutant concentrations along with doing related calculations, the areas and gas stations of the study area with the highest risk have been found. Results show that Station 7, located in Zone 4, is one of the most dangerous spots in terms of cancer and non-cancer risk to employees or storekeepers in the area. Additionally, there is no risk of non-cancerous disease for the customers, using these stations, during their lifetime. Finally, the study proposes some solutions for making appropriate decisions, concerning the sustainable management plan.
显示更多 [+] 显示较少 [-]Synoptic approach to forecasting and statistical downscaling of climate parameters (Case study: Golestan Province)
2017
Ghanghermeh, Abdolazim | Roshan, Gholamreza | Nasrabadi, Touraj
The present study attempts to introduce a method of statistical downscaling with a synoptic view. The precipitation data of Golestan Province has been used for the years 1971 to 2010. Employing multivariable regression, this study models the precipitation gauges in the station scale, by making use of 26 predicting components of model HadCM3, on the basis of two A2 and B2 scenarios. However, the minimum predicting components for precipitation in station scale included 26 components for one grid to 390 atmosphere circulation components for the 15 suggested grids. Nevertheless, results indicate minimum error, related to the precipitation models, based on projecting components of the studies of 15 grids. By applying this selected method, the precipitation gauges for 2020 to 2040 has been simulated. General results of the precipitation changes for the yearly decennial average of Golestan Province indicates additive stream of this component, based on both A2 and B2 scenarios. Yet this yearly decennial addition of precipitation go with seasonal and annual changes, i.e. getting drier in summer as well as its subsequent increase in draught issue on one hand, and increased centralization of precipitations in the winter and lack of its proper distribution during year on the other. As a result, changes in local patterns of precipitations throughout the province is promising for maximum increase of precipitation for the farthest southwest area of Golestan, greatly potential for decreasing precipitation of sub eastern area.
显示更多 [+] 显示较少 [-]Polycyclic aromatic hydrocarbons in air from industrial areas in Lagos and Ogun states, Nigeria
2017
Salaudeen, Ibrahim | Sonibare, Oluwadayo | Sojinu, Samuel | Ekundayo, Olusegun
There is currently scarce information on the occurrence and distributions of Polycyclic Aromatic Hydrocarbons (PAHs) in the air from industrial estates in Nigeria. Hence, the present study aims to evaluate the extent and sources of pollution of polycyclic aromatic hydrocarbons in the air from some industrial estates in Lagos and Ogun States, Nigeria. Ten air samples have been collected from the industrial estates in Lagos (Ogba and Ilupeju) and ten from Ogun (Agbara and Ota) between October and November, 2014, using low volume air sampler. Also five further air samples have been collected from Epe town, located in the outskirts of Lagos, where there are no industrial activities to serve as control. The concentrations and distributions of 20 target Polycyclic Aromatic Hydrocarbons (PAHs) in the air samples have been determined by gas chromatography-mass spectrometry. The concentration of ∑20PAHs ranged from 89.20 to 96.48 ng/m3 (with an average of 92.84 ng/m3) and 72.52 to 142.91 ng/m3 (with an average of 107.72 ng/m3) in the air samples from Lagos and Ogun industrial estates, respectively. The air from the control site has a total ∑20PAHs concentration of 19.55 ng/m3 (9.78 ng/m3 in average). When compared with global data, these values show that the air samples have been moderately polluted. PAHs in most air samples are mainly from pyrolytic sources, which may have resulted from diesel fuel combustion and high vehicular emissions, typical of industrial activities in the area.
显示更多 [+] 显示较少 [-]Modeling environmental indicators for land leveling, using Artificial Neural Networks and Adaptive Neuron-Fuzzy Inference System
2017
Alzoubi, Isham | Delavar, Mahmoud R. | Mirzaei, Farhad | Nadjar Arrabi, Babak
Land leveling is one of the most important steps in soil preparation and cultivation. Although land leveling with machines requires considerable amount of energy, it delivers a suitable surface slope with minimal soil deterioration as well as damage to plants and other organisms in the soil. Notwithstanding, in recent years researchers have tried to reduce fossil fuel consumption and its deleterious side effects, using new techniques such as Artificial Neural Networks (ANNs) and Adaptive Neuron-Fuzzy Inference System (Fuzzy shell-clustering algorithm) models that will lead to a noticeable improvement in the environment. The present research investigates the effects of various soil properties such as Embankment Volume, Soil Compressibility Factor, Specific Gravity, Moisture Content, Slope, Sand Percent, and Soil Swelling Index in energy consumption. The study consists of 90 samples, collected from three different regions. The grid size has been set on 20 m * 20 m from a farmland in Karaj Province, Iran. The aim is to determine the best linear model, using ANNs and ANFIS model to predict environmental indicatorsand find the best model for land leveling in terms of its output (i.e. Labor Energy, Fuel energy, Total Machinery Cost, and Total Machinery Energy). Results show that ANFIS can successfully predict labor energy, fuel energy, total machinery cost, and total machinery energy. All ANFIS-based models have R2 values above 0.995 and MSE values below 0.002 with higher accuracy in prediction, given their higher R2 value and lower RMSE value.
显示更多 [+] 显示较少 [-]Evaluation of visual pollution in urban squares, using SWOT, AHP, and QSPM techniques (Case study: Tehran squares of Enghelab and Vanak)
2017
Allahyari, Hadis | Nasehi, Saeedeh | Salehi, Esmail | Zebardast, Lobat
Visual pollution, observed in urban areas, makes human beings suffer indirectly from mental distress and illnesses in long term. We are daily confronted with a variety of advertisement pictures in city squares and review them in our minds. But we may not be aware of the fact that such a visual scramble leads to mind distraction, decreasing mental concentration. The present study applies the techniques of SWOT and QSPM to identify and introduce the most influential factors, related to visual pollution, in internal and external environment of Tehran, comparing the rate of visual pollution in both Vanak and Enghelab squares. Accordingly, in SWOT matrix, strengths, weaknesses, threats, and opportunities in these squares have been investigated and, using Expert Choice, AHP method has been applied to weight them. SWOT as an analytic instrument can be used for evaluation purposes in QSPM system. Finally, using the Quantitative Strategic Planning Matrix (QSPM), the selected strategies have been prioritized. The results of the study indicate that Vanak Square has an invasive strategy and Enghelab Square, a conservative strategy. Aided by QSPM matrix, the study has offered eight prioritization strategies, introducing the best possible strategy for these squares. Regarding visual pollution, Vanak Square has a better position than Enghelab square.
显示更多 [+] 显示较少 [-]Assessment of levels and health risk of heavy metals (Pb, Cd, Cr, and Cu) in commercial hen’s eggs from the city of Hamedan
2017
Sobhan Ardakani, Soheil
Increasing consumption of chicken products in Iran makes it very important to analyze their residual heavy metal contents; therefore, the present study has been conducted to determine Pb, Cd, Cr, and Cu in commercial hen eggs, marketed in the city of Hamedan in 2016. In this descriptive study, a sum of 27 samples of hen eggs has been collected from the Hamedan City's market. After preparation and processing the samples in the laboratory, the concentration of metals has been determined in mixed albumen and yolk, using inductively coupled plasma-optical emission spectrometry. Also, all statistical analyses have been conducted, using the SPSS statistical package (version 20) with the results showing that the mean concentrations (mg/kg) of Pb, Cd, Cr, and Cu in the samples have been 0.29±0.16, 0.18±0.04, 0.31±0.03, and 2.81±1.56, respectively. Also, the mean contents of Cd and Cr have surpassed the maximum permissible levels (MPL), established by WHO/FAO. The computed health risk index values show that there is no potential risk for adults and children through egg consumption at the current rate in the study area.According to the results, considering the mean contents of Cd and Cr observed in egg samples have been higher than the MPL; therefore, it is recommended to pay serious attention to pollutants discharge in the environment and monitor chemical residue, especially heavy metals, in the foodstuff.
显示更多 [+] 显示较少 [-]