خيارات البحث
النتائج 31 - 40 من 5,154
Rapid Vulnerability Assessment of Lavizan Urban Forest Park النص الكامل
2018
Darabi, Hassan | Hamedi, roghieh | Ehsani, Amirhoushang | Kafi, Mohsen
Although the vulnerability assessment of forest parks is used to determine the threats they face, a rapid and holistic framework has not been established well. The primary objective of this study is to adopt a framework for rapid assessment of forest parks vulnerability, examined in Lavizan forest park in Tehran (Iran) as the case study. The vulnerability assessment has been conducted, using the evaluation matrix on the basis of landscape and ecological values and threats. In this model, the most important values and threatening factors of the Lavizan forest park have been identified and assessed, based on the intensity of their effect as well as occurrence probability. Finally, this article proposes five strategies to reduce the vulnerability. Results from this research indicate that the most important values have been air purifcation, wildlife, flora and fauna species, environment regulation, mental health, and scientific resources and the most important threats have included reduction of habitat diversity, intensive exploitation of the resources, fire, woodcutting, and reduction of ecological connectivity. Based on these vulnerabilities, the most important strategies propose the use of affordance strategy formulation framework to preserve and enhance ecological and landscape values of the park.
اظهر المزيد [+] اقل [-]Health Risk Assessment of Chromium-Accumulated Fish and Vegetables at Gulshan Lake of Bangladesh: A Case Study النص الكامل
2018
Mohinuzzaman, M. | Saadat, A.H.M. | Mostofa, K.M.G. | Islam, S.M.N. | Hossain, S.M. | Tareq, S.M.
The present study evaluates health risk assessment for inhabitants who are exposed to chromium in fishes and vegetables of the Gulshan Lake. In the fish, chromium concentration has amounted to 2.2 to 149.7 mg/kg, while in vegetables leaf and vegetables stem it has been 5.6 mg/kg and 12.0 mg/kg, respectively. What is more, in sediment it has been 179.5 to 308 mg/kg and in water, 4.0 to 16.9 mg/l. Higher accumulation of chromium (149.7 mg/kg) has been found in a fish species, relatively most affordable for poor people, called Pangas (Pangasius pangasius). Therefore, due to consumption of this fish the resultant non-cancer health hazard indices to people, living nearby Gulshan Lake has been almost 10 times greater than those induced by safe average daily dosages of the respective chemical. Vegetable pathway is still safe in terms of non-carcinogenic health hazard but may be very likely to act as an additive. It is therefore important to immediately take some remedial measures to not only reclaim Gulshan Lake but prevent any further pollution also.
اظهر المزيد [+] اقل [-]Health Risk Assessment of Heavy Metals in Soil from the Iron Mines of Itakpe and Agbaja, Kogi State, Nigeria النص الكامل
2018
Aluko, Tope | Njoku, Kelechi | Adesuyi, Adeola | Akinola, Modupe
The study evaluates associated health risks of heavy metals in the soil to inhabitants of two mining areas of Nigeria. For so doing, it collects and analyses nine homogenous soil samples for their lead, copper, cadmium, zinc, and chromium levels, using AAS. The samples are then used to calculate health risks to adults and children. For adult population in Agbaja community, the calculated hazard quotients fall below one in all considered pathways. Hazard index values for all the pathways are also less than one, taking the following order: Cu>Cr>Pb>Cd>Zn. It is shown that for all considered heavy metals, the adult population in Agbaja mining community was not at any risk of non-carcinogenic effects from these metals. As for the children in Agbaja, the calculated HQ values for Cd and Zn have been less than one in all the pathways, while the HQ values for Pb, Cr, and Cu have significantly surpassed 1, with the ingestion route being the main pathway. The HI values have been in the following order: Cu>Cr>Pb>Cd>Zn, which poses serious non-carcinogenic health risks to the children, living around this community. The carcinogenic risk has been calculated based on Pb, Cd, and Cr, with the former (Pb) proven to be the highest contributor to cancer risk. USEPA considers acceptable cancer risk within the range of 1×10−6 to 1×10−4. Though insignificant in its values, carcinogenic risk for adults in Agbaja (2.95×10-4) and Itakpe (4.71×10-4) and for children in Itakpe (4.47×10-4) have been higher than the acceptable values. Hence, the adults are more at risk, for whom ingestion is the main contributor to excess lifetime cancer risk, followed by dermal pathways. Considering the health hazards, entailed by the accumulation of these heavy metals, on human health, mining sites and areas require to get monitored properly.
اظهر المزيد [+] اقل [-]Chemical Stabilization of Some Heavy Metals in an Artificially Multi-Elements Contaminated Soil, Using Rice Husk Biochar and Coal Fly Ash النص الكامل
2018
Saffari, M.
A greenhouse experiment has been planned for this study to delineate the benefits of two types of rice husk biochars (namely B300 and B600 which are prepared at 300°C and 600°C, respectvely) and coal fly ash (CFA), as soil amendments, for decreasing the amount of some heavy metals (like Pb, Cd, Ni, Cr, and Cu) as well as mobility and phytoavailability in an artificially-calcareous multi-element-contaminated soil. The effect of soil amendment on heavy metals’ availability has been evaluated via sequential extraction experiment and phytoavailability of the plant. According to the results, among the studied amendments, B600 has had the highest positive effect on both dry matter yield in corn and heavy metals’ availability reduction in post-harvest soil samples (with the exception of Cr), compared to CFA and B300, due to the increasing specific surface area, CEC, and pH that promote heavy metals’ sorption in the soil through surface complexation and ion exchange mechanisms. Evaluation of heavy metals’ chemical forms in post-harvest soil samples indicates that addition of amendments has significantly decreased mobility factor of heavy metals (with the exception of Cr in CFA-amended soils). In general, application of three soil amendments to this polluted soil has considerable effect on the reduction of heavy metals’ availability and phytoavailability. However, among the studied amendments, B600 and CFA have had the maximum and minimum effect on heavy metals’ availability reduction, respectively.
اظهر المزيد [+] اقل [-]Industrial waste disposal alternatives in the process of aromatic compounds in petrochemical industry (case study: Nouri petrochemical complex, Asaluyeh, Iran النص الكامل
2018
Heidari, L. | Jalili Ghazizade, M. | Salemi, A.
Application of aromatic compounds has dramatically increased as raw materials in various industries and different factories have been established to produce aromatic compounds. The current research aims at characterizing industrial waste generation in aromatics production process in petrochemical industries and determining the best feasible alternative for waste disposal. For this purpose, the world’s biggest aromatic producer, i.e. Nouri Petrochemical Complex (NPC), located in Asaluyeh, Iran, has been selected as case study. Firstly, different waste streams, generated during aromatics production, have been determined through a specific checklist. Spent industrial soil, catalyst, spent sieve, and Normal-Formyl-Morpholine (NFM) solvent are the most important identified wastes in NPC, with the former being the most generated waste in NPC with a rate of 600 tons per year. Afterwards, the mentioned waste has been sampled and important physicochemical specification such as heavy metals and organic compounds has been measured. Ni, Cu, and As are remarkable trace heavy metals, observed in all kinds of generated waste. In the next step, industrial waste classification and coding has been done, based on different guidelines. Finally different feasible alternatives like material recovery, sanitary landfill, and incineration have been compared, based on conventional economic, technical, and environmental indices. The best feasible waste disposal methods are the extraction of heavy metals from spent catalysts, recycling of spent molecular sieves and spent industrial soil as additives to building materials, and recovery of thermal energy by incineration of spent NFM solvent.
اظهر المزيد [+] اقل [-]Facile Synthesis of Zn-TiO2 Nanostructure, Using Green Tea as an Eco-Friendly Reducing Agent for Photodegradation of Organic Pollutants in Water النص الكامل
2018
tavakoli, F. | Badiei, A.
The present study synthesizes Zn-TiO2 photocatalyst via a simple and economic green rout, in which Green Tea is applied as a green reducing agent due to the presence of polyphenols Molecules. Polyphenol molecules in green tea act as a reductant, thus changing Zn2+ to metallic Zn. The by-produced nanocmposites are characterized by using XRD, FESEM, EDS, and DRS. Zn-TiO2 photocatalyst possesses great efficient charge separation properties. In order to investigate the presence of Zn, different weight ratio of Zn to TiO2 (viz. 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, and 50 wt%) have been synthesized and their performance in Acid Orange 7 (AO7) photodegradation, compared with pure TiO2. According to the results, the compound with 25 wt% Zn shows 97% degradation of AO7 as a model pollutant. Also, it has been shown that after three tests with EDTA, benzoic acid, and under Ar gas, photodegradation of AO7 with Zn-TiO2 photocatalyst mainly depends on photogenerated holes.
اظهر المزيد [+] اقل [-]Two-dimensional advection-dispersion equation with depth- dependent variable source concentration النص الكامل
2018
Chatterjee, Ayan | Singh, Mritunjay
The present work solves two-dimensional Advection-Dispersion Equation (ADE) in a semi-infinite domain. A variable source concentration is regarded as the monotonic decreasing function at the source boundary (x=0). Depth-dependent variables are considered to incorporate real life situations in this modeling study, with zero flux condition assumed to occur at the exit boundary of the domain, i.e. its semi-infinite part. Without losing any generality, one can consider that the aquifer is initially contamination-free. Thus, the current study explores variations of two-dimensional contaminant concentration with depth throughout the domain, showing them graphically. Non-point source problem, i.e. the line source problem, can be discussed by solving two-dimensional depth-dependent variable source problem, as x=0 is a 2D line. A new transformation has been used to transform the time-dependent ADE to one with constant coefficients, with Matlab (pdetool) being employed in order to solve the problem, numerically, using finite element method.
اظهر المزيد [+] اقل [-]Spatio-temporal variability of aerosol characteristics in Iran using remotely sensed datasets النص الكامل
2018
Rezaei, Mohammad | Farajzadeh, Manuchehr | Ghavidel, Yousef | Alam, Khan
The present study is the first attempt to examine temporal and spatial characteristics of aerosol properties and classify their modes over Iran. The data used in this study include the records of Aerosol Optical Depth (AOD) and Angstrom Exponent (AE) from MODerate Resolution Imaging Spectroradiometer (MODIS) and Aerosol Index (AI) from the Ozone Monitoring Instrument (OMI), obtained from 2005 to 2015. The high concentration of AOD and AI values (representing high-high cluster) have been observed in the southwest and east regions, while their low concentrations (representing low-low cluster) have been found in the high mountainous areas. Based on AE values, Iran has been divided into three distinct regions, including fine, mixture, and coarse aerosol modes in each season. Results show that the maximum/minimum area under fine aerosols mode has occurred in the autumn, covering an area of 84.15% and in the spring, covering an area of 40.5%. In the case of coarse mode, the maximum/minimum area has been found in the spring, covered area=53.5% / in the Autumn covered area=12. 5%. The different aerosol modes regions strongly coincide with the topographical structure. To analyze the relation between aerosol properties and topography, Aerosol Properties Index (API) has been developed by combining OMI and MODIS datasets. API is a simple indicator, capable of showing the degree of aerosol coarseness in each pixel. There is a negative correlation between API and topography over the studied region, meaning that aerosol concentrations are high in the lowlands, but low in the highlands. However, this relation differs in various geographic regions, as Geographically Weighted Regression (GWR) model shows a higher determination coefficient in all seasons, in comparison to Ordinary Least Squares (OLS).
اظهر المزيد [+] اقل [-]Arsenic Health Risk Assessment through Groundwater Drinking (Case Study: Qaleeh Shahin Agricultural Region, Kermanshah Province, Iran) النص الكامل
2018
Sobhanardakani, Soheil
Groundwater resources make up an important portion of potable and irrigation water in Iran, making it important to monitor toxic elements of pollutants in these resources in order to protect the inhabitants' health. The current study has been carried out to assess the health risks, caused by trivalent inorganic arsenic-polluted groundwater in Qaleeh Shahin Plain, an important agricultural region in Kermanshah Province. For this purpose, in total 20 groundwater wells have been chosen randomly. The samples have been filtered (0.45 μm) and preserved with HNO3 to a pH level lower than 2, then to be taken in acid-washed polyethylene bottles and kept at a temperature of 4 °C for further analysis. Finally, As(III) concentration has been determined, using ICP-OES with three replications. Results have shown that mean content of As (ppb) in groundwater samples were 6.0 ± 3.0 for winter and 9.0 ± 6.0 for summer in 2014. Also, according to the results, the computed values of the hazard quotient (HQ) and target risk (TR) of groundwater samples were below 1 and less than 10E-06, respectively; therefore, non-carcinogenic effect (chronic risk) and carcinogenic exposure are not likely for the inhabitants of this study area. However, due to over and long-term use of agricultural inputs in the study area, it is recommended to have some paramount consideration for better management and care of using agricultural inputs, especially chemical fertilizers, arsenical pesticides, or herbicides, and for treatment of As-polluted groundwater with proper removal methods prior to preparation of drinking water.
اظهر المزيد [+] اقل [-]Soundscapes of Urban Parks in and around Bhubaneswar and Puri, Odisha, India: A Comparative Study النص الكامل
2018
Swain, Bijay | Goswami, Shreerup
Anthropogenic noise is debatably one of the most common threats to national parks' resources. Park visitors and workers generally suffer from adverse effects of noise from on- and off-road vehicles. The parks, studied here, are located in strictly urban areas, surrounded by streets with intense vehicle traffic. This study assesses the soundscape of urban parks in two cities of Odisha State, on the basis of acoustic field measurements and interviews. Noise descriptors in and around three different parks in Bhubaneswar and Puri cities have been measured and analyzed. A field experiment has been conducted with 330 participants in three parks, representing urban natural environment. The questionnaire comprised identification of the interviewee, characteristics of the user's profile in terms of his/her use of the park, and aspects of individual’s perception of the soundscape and environmental quality of the park. Positive correlation has been established among the noise levels of these three parks. The present study reveals that the acoustic sound levels of all the investigated parks are more than 50 dB (A) [permissible limit, established by Central Pollution Control Board (CPCB) for green parks]. Considering the urban elements and acoustical characteristics, it can be concluded that all the parks are affected by several factors such as urban planning, land use, main traffic routes, type of public transportation, and its internal sounds.
اظهر المزيد [+] اقل [-]