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Результаты 431-440 из 62,157
Evaluation of natural radioactivity of soil samples from different regions of Wassit governorate
2017
Najam, Laith | Karim, Mahmood | Hameed, Taghreed
The present paper measures natural radioactivity in different areas of Wassit governorate, using (HPGe) detector. Gamma spectrum analysis for each sample along with caululated specific activity show that the average concentrations of U-238, Th-232, and K-40 have been 19.420±4.7 Bq/kg, 18.487±5.05 Bq/kg, and 204.266±46.9 Bq/kg respectively, which is lower than the worldwide average value. While the average value of Radium equivalent, absorbed dose, indoor and outdoor annual effective dose, activity index, and internal and external hazard index for each sample have been found to be 85.182 Bq/kg, 39.962 nGy/h, 0.196 mSv/y, 0.049 mSv/y, 0.374, 0.313, 0.309, and 0.230 respectively, all of them are lower than the permissibility limit value.
Показать больше [+] Меньше [-]Tropospheric Ozone Pollution in Some Major Cities of West Africa and its Relationship with Atmospheric Circulations
2017
Oluleye, Ayodeji | Ochei, M.
This study utilizes a decade long (2005-2014) monthly data of Total Column Tropospheric Ozone (TCTO) in Dubson units to evaluate the spatial and temporal trend of LAO over some major cities of West Africa, namely Lagos, Accra, Niamey, Abuja, Bamako, Dakar, Agadez, Conakry, Kano, and Ouagadougou which are either capital cites or major commercial hubs, where the population ranges from 0.09 million (Agadez, Niger) to over 9 million (Kano and Lagos, Nigeria). The mean (long term average) of TCTO in Lagos (Nigeria) was 34.4±0.6 DU (α=5%) for the entire period, being the highest in all major cities of this study. The lowest TCTO, 30.4±0.5 DU (α=5%), occurred in Bamako (Mali). It was also observed that the concentrations of TCTO vary seasonally. The seasonal changes in TCTO was investigated by categorizing months of the year to very dry months of December, January, and February (DJF), onset of rainy season months of March, April, and May (MAM), wet season months of June, July, and August (JJA), and end of rainy season months of September, October, and November (SON). Seasonal mean of TCTO is higher in all cities, close to the coast during DJF, and cities, north of latitude 12o N, during MAM, compared to rest of the seasons. Elevated TCTO concentrations can be attributed to transport mixing, due to the flow direction of well-known wind regime over the study area. This was established from the analysis of correlation coefficient between the mean of zonal, meridional winds, vertical wind speeds and divergence, and TCTO over region.
Показать больше [+] Меньше [-]A review on enhancement techniques of electrokinetic soil remediation
2017
Jamshidi-Zanjani, Ahmad | Khodadadi Darban, Ahmad
During the last decade, the expansion of urbanization and industrial activities caused serious environmental problems such as soil pollution. Novel technologies are required to remediate soil contamination with toxic contaminants, including heavy metals and organic pollutants. In recent years, there have been increasing attempts to improve soil remediation efficiency. Electrokinetic (EK) is an emerging remediation technology for mixed contaminants, especially in low hydraulic conductivity soils. During EK remediation process, an electric field is applied to the specimen to remove the contaminants from soil by means of electro-osmotic (EO), electro-migration (EM), and electrophoresis (EP) processes. The usual EK technique may have no suitable removal efficiency or contaminants migration. Thus, enhancement techniques or their combination with other technologies are required to overcome EK limitations, increasing its efficiency. The present study reviews seven main enhancement techniques combined with EK; they include using surfactant, chelants, complexing agents, soil pH control, bioremediation, permeable reactive barriers, and ultrasonication. It should be mentioned that, selecting the suitable combination technique highly depends on the soil type and the kind of contaminant.
Показать больше [+] Меньше [-]Assessment of surface water pollution in urban and industrial areas of Savar Upazila, Bangladesh
2017
Anny, Fahima | Kabir, Mohammad | Bodrud-Doza, Md.
The present study has been conducted to determine the surface water quality of urban area in Savar, Dhaka, Bangladesh by determining some water quality parameters (Transparency, Temperature, pH, EC, Eh, DO, TSS, TDS, TS, BOD5, COD, TOC, Cl-, Br-, SO4-2, NO3-, NO2-, PO4-3, TP, HCO3- and Total alkalinity) as well as the status of phytoplankton’s community in the water from two lakes (Tiger Lake and AERE Lake) and one canal (Karnapara Canal). It has been shown that, with exception of BOD and COD, all water quality parameters of AERE Lake in the present study are within the acceptable limits, recommended by local and international standards. Among water quality parameters of Tiger Lake and Karnapara Canal, the concentration of transparency, temperature, EC, DO, TSS, TDS, BOD, COD, TOC, NO2-, and TP exceed the acceptable limits. Organic Pollution Index (OPI) demonstrate that the water bodies are severely polluted by organic matters. R mode Cluster Analysis (CA) suggests that common sources of water quality parameters are industrial, agricultural, and natural. The Principle Component Analysis/Factor Analysis (PCA/FA) identifies two dominant factors, responsible for data structure, explaining 100% of total variance in the data set. The PCA agrees with CA, suggesting that multiple anthropogenic and natural sources are responsible for the water quality parameters. The present study reflects the actual scenario of surface water quality of Savar urban area, thus helping the policy planers and makers of the People’s Republic of Bangladesh to take proper management and abatement strategies for the management of sustainable water resource in Bangladesh.
Показать больше [+] Меньше [-]Physico-chemical and bacteriological characterization of surface water in Djendjen River (North Eastern Algeria)
2017
Krika, Abderrezak | Krika, Fouad
Djendjen River is one of the largest rivers in the region of Jijel (Algeria). Human activities such as urban discharges, industrial, agricultural, and livestock have significant effects on the quality of water. The present study attempts to evaluate the quality of water along the banks of the Djendjen River at different sampling sites, using physico-chemical and bacteriological methods. The collected samples are analyzed per standard method parameters and measured in situ. The mean values of the physico-chemical parameters of the river water samples are consistently lower than the levels, certified by the Algerian standard (exept for pH and PO43-). The total and fecal coliform surpasses the Algerian standard limits (0 cfu/ 100 ml) at all sites, signifying that without treatment the water is unsuitable for human consumption. Results reveal that water quality of the Djendjen River is generally affected by the anthropogenic activities, taking place along its banks. The moderate organic pollution (OPI= 2-2.6) and high faecal contamination (MQI=3-3.25) of water in the study area has adverse impacts on the environment and public health, which requires a combined treatment (biological and physicochemical).
Показать больше [+] Меньше [-]Evaluation of Faryab spring hydrochemistry in Hormozgan Province, Southern Iran
2017
Asadpour, Gholamabbas
With a mean precipitation rate, much lower than that of the world, Iran is among the countries that face severe water challenges. The present study has dealt with the evaluation of hydrochemistry of Faryab spring water in Hormozgan Province, Iran. Four different composite water samples have been analyzed to detect major anions, cations, total dissolved solids, electrical conductivity, pH, and sodium absorption ratio. The dominant water type was detected as sodium-chloride, with remarkable high concentration of sodium and chloride ions that makes it unfit for drinking purposes. Regarding irrigation use, high values of electrical conductivity (29989 to 31983 µS/cm) and sodium absorption ratio (SAR) (58.1 to 61) indicate a very high risk level for salinity and sodium alkali hazards, respectively. Abundance of secondary minerals such as halite and gypsum is considered to be the main reason for remarkably-high TDS values. Intensity of salt domes within the area would also facilitate solution/dissolution process of Na+ and Cl- into water column.
Показать больше [+] Меньше [-]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.
Показать больше [+] Меньше [-]Effect of organic amendment on organic metabolites in root knot nematode (Meloidogyne Incognita) infested spinach
2017
Gupta, Shalini
The Nematodes are roundworms that are found in every environment of the earth. While some species are harmful parasites, others play a vital role in nutrient cycle and medical research. Nematode infestation in the fields is poly-specific; however, depending on the agro-climatic conditions, one or two species are dominant over the rest. The present studies attempts to observe and control the root knot infestation on spinach (Spinacea oleracea), which belong to Chenopodiaceous family and is extensively cultivated in India for its nutritious leaves. Various organic metabolites have been estimated in root knot nematode infested spinach, including chlorophyll, total carbohydrates, and total free amino acids. Spinach plants, infested with root knot nematode, have been treated with peels of lemon, which proved beneficial in terms of increased chlorophyll content. Altered total carbohydrate and total free amino acid content have been found with S/4 of lemon-peel-treated spinach plants. It has been found that the infested spinach shows 137.5% carbohydrate content over the normal plants. The kaghzi neemboo amended spinach contains lower carbohydrate than normal-control. Rate of carbohydrate contents has been found to be inversely proportional to the rate of extracts concentrations as S/4, S/2, and S show 92.5%, 55%, and 37.5% increase over normal-control spinach. The bio-amendment of citrus aurantifolia, (kaghzi neemboo) helps controlling root knot nematodes, which is more beneficial than using chemicals to control the same, as the chemical fertilizer causes pollution, exerting negative impacts on flora and fauna.
Показать больше [+] Меньше [-]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).
Показать больше [+] Меньше [-]Phytoremediation potential of heavy metals by two native pasture plants (Eucalyptus grandis and ailanthus altissima) assisted with AMF and fibrous minerals in contaminated mining regions
2017
Abbaslou, Hakime | Bakhtiari, Somayeh
The current study assesses the effect of fibrous clay minerals’ amendments and arbuscular mycorrhiza incubation on heavy metal uptake and translocation in Eucalyptus grandis and Ailanthus altissima plants. For doing so, Eucalyptus and ailanthus trees have been grown in a soil sample, contaminated with heavy metal iron ore mining and collected from southern Iran. The area under study is arid, with the majority of trees being ailanthus and eucalyptus. Amounts of Cd, Pb, Zn, Cu, and Mn have initially been at toxic levels which declined after cultivation. Fibrous clay minerals have been added to soils as a natural adsorbent to adsorb heavy metals like Pb, Cd, Zn, and Mn. Accumulation of the elements in the roots and shoots has been in the following order: Cu>Zn>Mn>Cd>Pb>Fe. The organ metal concentrations have not statistically translocated from roots to shoots of plants, except for Zn and Cu whose concentrations have been significantly higher in roots. Eucalyptus is well capable of extracting elements from contaminated soils, compared to ailanthus, particularly in case of Cu and Cd. The percentage of mycorrhizal colonization proves to be more in pots with ailanthus plants grown in contaminated soil, suggesting enhanced effect of high metal concentrations on plant infection by G. mosseae. AMF assists soil remediation by enhancing the growth and retention of toxic elements by ailanthus, while no substantial change has been observed between inoculated and non-inoculated eucalyptus plants by AFM, regarding translocation of elements to plants. The possibility of increasing metal accumulation in roots is interesting for phytoremediation purposes, since most high-producing biomass plants, such as eucalyptus, retain heavy metals in roots.
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