Journal of Environmental Studies
Year:2009 | Volume:35 | Issue:49|Papers Count:13

In this paper high order multidimensional positive definite advection transport algorithm (MPDATA) and compact finite difference methods are applied to one (1-D) and two-dimensional (2-D) advection equation. MPDATA methods are designed based on upwind scheme using anti-diffusive velocity that compensates diffusivity of upwind method. In high order compact method one implicit relation between a function and its first derivative is added to the governing equation of flow and this combination increases the accuracy of the method. In the present study, the grid study is carried out at 11,21,41,81, 161,321, and 641 grid points in 1-D case. Also, the number of grid points in 2-D case is 11x11, 21x21, 41x41, 81x81, 161x161 and 321x 321 for MPDA TA method and 11x 11, 21x 21, 41x 41 and 81x 81 for compact scheme. Two important characteristics of numerical schemes are investigated. First, the accuracy of two mentioned methods is compared together. It shows that in 1-D case the accuracy of MPDA TA scheme at 641 grid points is approximately equal to the accuracy of compact method at 161 grid points. In 2-D case this comparison shows that the accuracy of MPDA TA scheme at 321x 321 grid points is approximately equal to the accuracy of compact method at 41x 41 grid points. Second, the comparison of computational cost of two methods shows that the computational cost of compact method is 333 and 306 times of MPDAT A scheme computational cost in 1-D and 2-D cases, respectively.

The CO2 and CH4 as the most important carbon based greenhouse gasses have negative effects on the environment. They have close relationship with soil carbon cycle. For reducing the atmospheric concentration of these gasses, it is possible to fix them into the soil in the form of organic carbon. CO2 is the most abundant greenhouse gas in the atmosphere and its concentration has increased up to 30% after industrial revolution (Houghton et al 1996). Releasing the CO2 from the biosphere includes soil emissions and cutting and burning the forests. Methane is one of the greenhouse gasses with 21 time's green house effect greater than CO2. 20% of global warming in recent years is due to the increase of the atmospheric methane. Reduction is most important process in the soil producing methane that caused by microbial decomposition of organic matter in anaerobic conditions (Bowman, 1990). The increase of CH4 is because of the increase in the rice planting, which is the source of more than 50% of atmospheric CH4 (Ehhalt and Smith, 1978). Methanogenes (bacteria that produce CH4) are anaerobic; therefore, soil moisture condition and irrigation method (rice paddy fields in contrast with alternative irrigated field of wheat) have straight effects on producing methane and emissions from soil. Wheat and rice are two major cereals in Iran that the major difference between them is the time of planting and water efficiency. High irrigating (in rice agriculture) is an effective agent to change carbon condition in soil (Rees et al. 2005).

Heavy metal pollutants are extremely pernicious because they are environmentally persistent and toxic. Nickel is one of the metals that are widely used in alloys, pigments, electroplating processes, electrical contacts, and battery manufacturing. The traditional approaches for removing or recovering metals, such as precipitation, oxidation/reduction, ion exchange, filtration, electrochemical processes,  membrane separations, and evaporation, all exhibit several disadvantages, such as high cost, incomplete removal, low selectivity, high energy consumption, and generation of toxic slurries that are difficult to be eliminated. Biological methods of metal removal, defined as biosorption, have been recommended as cheaper and more effective techniques. Biosorption mainly involves cell surface complexation, ion exchange and micro precipitation. Biological wastewater treatment produces a biological sludge (bios lids), consisting of inert materials and microorganisms. Currently, there are limited reuse/disposal options for bios lids due to high concentrations of heavy metals and the risk of pathogens. Previous research has shown the ability of bios lids to remove metals from the wastewater stream. This study the required bios lid was provided from the waste sludge from Ecbatana's wastewater treatment plant in Tehran. Pretreatment of bios lid included dewatering in 103-104 oC, grinding further the bios lid was grainsized by standard mesh between 50 and 120.

Quantitative prediction of municipal solid waste generation plays an important role in the optimization and programming of municipal solid waste management system. Being aware of generation quantity can be very effective for estimating the amount of investigation in the field of machinery, onsite storage containers, transition stations, disposal capacity and proper organization. There are different ways to estimate the waste generation (WG) rates. The most prominent of these methods are load-count analysis, weight-volume analysis, materials-balance analysis and effective methods such as regression techniques and artificial neural network (ANN) models. Using ANN models in solid waste management systems was reported successfully, because of the high ability of ANN in nonlinear and dynamic problems modeling .However, ANN models may not be able to cope with non-stationary data if preprocessing of the input and/or output data is not performed. One of the very suitable methods for preprocessing of the input and/or output data is wavelet transforms (WT). Recently in the other environmental problems like air pollution, surface water quality, the hybrid model of WT and ANN (WNN model) have been used. The results of these researches have shown the high performance of ANN model.

The main causes of oil pollution in the oceans are extraction of oil, transportation with ballast water release, tanker accidents and also war-related incidents. The spills are particularly destructive for local wildlife and plant life when they get close to shorelines. They also damage boats, fishing gear and harbor installations and greatly diminish the value of the shore as recreational resources. Many, methods have been used to remove oil spills from water including physical removal of crude oil, chemical remediation of the spills using dispersants and so-called "sinking agents," and, in some cases, intentionally burning floating petroleum slicks. Using chemical dispersants as an oil spill countermeasure is the most frequently employed clean-up method because such liquids can be readily applied to large oil spills also this method is generally more cost-effective than physical remediation methods. On the other hand the exclusive property of these dispersants to make oil spills dispersed into water will enhance the biodegradability of crude oil due to the increased exposed surface of the spills to such agents. Nevertheless, II surfactant compositions are efficient in dispersing spilled oil products and many of the effective ones the drawbacks of being toxic and/or not biodegradable. Persian Gulf is recognized as the world's largest source of fossil fuels and thus enshrining its importance as the world's most strategic waterway. The result of extensive marine traffic is a high risk of oil pollution, both intentional and accidental. To diminish risk ore environmental pollution, use of highly biocompatible dispersants has been recommended. In this paper, we study biodegradability and the impacts of three dispersants; Pars I, Pars2 (produced by Iranian lore Oil Company) and Gamlen on degradation of crude oil in Siri Island water. Biodegradability of Gamlen and its effects on dispersing of oil had been already studied and it is being used in Persian Gulf " Here, we present the most dispersing, effective and biodegradable component for dispersion of crude Siri Island water.

The study of regional variations and the anthropogenic contamination by trace toxic elements of soils is very important for environmental planning and monitoring in urban areas. As urban areas are densely populated the environmental quality of urban soils is closely related to human health. Urban soils act as sink for heavy, metals and other pollutants. The possible sources of pollution in urban soils include vehicle emissions industrial wastes, the atmospheric deposition of dust and aerosol, and others. In this investigation, concentrations of some major (AI, Fe, Mg, Ca, Na, K) and potentially toxic trace elements (As, Bi, Cd,  Cr, Cu, Hg, Mn, Mo, Ni, Pb, Rb, S, Sb, Se, Sn, Sr, Th, Ti, U, V, W& Zn ) were studied in the urban environment of Kerman city. Kerman city is located in Kerman province of Iran. The area has a semiarid I arid climate. The temperature mostly varies between _8° C in winter to 37° C in summer on average. Kerman lowland areas are composed of Cretaceous limestone that covered by Quaternary deposits (alluvial evaporative and aeolian sediments). At present study, 37 samples were collected and analyzed by ICP-N for 29 elements. These concentrations were compared with environmental investigation limits. Due to assessing mineral contents, 5 aeolian and evaporative sediment samples were analyzed by XRD technique Geochemical maps of some trace elements (Cu, Ni, Pb & Zn) were produced, using GIS technology.

The frequency of which the humanistic and environmental disasters occur in chemical processes has induced experts to probabilistic approaches to gauge the frequency and consequences of such mishaps. Studies show that AHP has been used both independently and in sync with other methods to assess risks in different situations. Studying the proper places for major investments, Neil et al. used GIS to implement the AHP. Incorporating the professional system, the researchers determined appropriate physical, environmental, and geographical criteria for a place in order to be judged suitable for investment. Next, on the basis of the specified parameters, AHP was conducted to distinguish a place in order to consider a place worthy of investment (Neil et al. 2004). A study of risk assessments conducted on the basis of automatic and computerized method, as a tool for rapid risk assessment in petroleum refinery, shows that the method can be used to assess mishaps such as fires, the explosion and seeping of toxic materials from different units of refineries. TORAP enables users to concentrate on possible mishaps and predict the nature and intensity of the outcomes (Khan & Abbasi 2000). In Switzerland, risk assessments associated with natural disasters were conducted taking into consideration three stages: phenomenon mapping, intensity mapping using modeling expert systems and hazard mapping. So, catchments were classified on the basis of their sensitivity to erosion, and a special geomorphologic map was made on the scale of the catchments. The cartographic and non-cartographic data were also synthesized simultaneously. Utilizing this method, researchers have been able to devise warning strategies on the scale of catchments (Theler et al. 2006).There are more than seventy risk assessment methods all over the world, which fall into one of the two categories, qualitative and quantitative (Mathews & Karydas 1997).The objective of this article is to simulate a number of major risks in Asalouyeh and determine the cumulative risk assessment method was incorporated The following research hypothesis was put forth: the semi-quantitative risk assessment method, which enjoys the attributes of both qualitative and quantitative methods, facilitates risk management in the risky zone of Asalouyeh. Located in southeastern Bushehr province, the coastal area of Asalouyeh was selected as the site for the construction of land facilities and the development of South Pars gas fields.

In the recent years, special attention has been devoted to the loss of biodiversity, because it is among the most serious environmental problems. There has been a revival of the debate about the effects of economic growth on environment quality (Antoci et al., 2005; Asafu-Adjaye, 2003). In this context, the environmental Kuznets curve (EKC) has been proposed to explain the dependence of environmental quality on the level of economic growth (Jha and Murthy, 2003). A typical feature of the EKC is the inverted U shape, which suggests that level of biodiversity loss or pollution reaches a maximum level with respect to economic rate, after which it begins to decrease. Thus, the existence of such a relationship would lend support to the view that as the countries grow, they experience a better and cleaner environment. This paper aim to contribute to this literature by estimating an Eke relationship for developed and developing countries and examining the relationship between biodiversity and economic growth using indicators of species diversity and income per capita as proxies for biodiversity and economic growth, respectively. Also, we investigated the effects of agricultural value added as a percentage of GDP, trade freedom index, exchange rate, population, percentage of land developed for agriculture, percentage of protected land area and climate variables on biodiversity and offer some suggestions for policy…

Urban storm runoff is typically highly polluted by pathogenic, organic and inorganic substances that are a public health threat. There are many types of artificial treatment mechanisms of urban storm runoff. Infiltration systems have been used in urbanizing areas to decrease discharges of storm water to surface waters, and to help preserve ground water recharge. In order to protect the groundwater resources and achieve the desired water quality management goals, such systems must be carefully designed using sufficient site specification information. An important prerequisite for infiltration is a sufficient permeability and percolation rate of the top layer of the ground, measured as hydraulic conductivity. However, high hydraulic conductivity does not provide enough contact time for soils to remove dissolved pollutions like heavy metals. Heavy metals maybe a problem when infiltrating urban runoff especially using a rapid infiltration system..

In the sector of electricity production, the existence of investment resources limitation and environmental criteria are the main factors that influence this process. The reduction of costs and the destructive impacts on environment have been always mentioned by specialists. Consequently, the importance of the environmental protection and the electric-energy production lead to focus on geothermal power plants. Obviously, in our country the issue of required resources for investment surpasses the environmental factors. Here, the main question is that in the current situation of our country, the replacement of fossil fuel power plants with geothermal power plants is possible or not and can we hope that it would be possible in future? Also, this research endeavors to do an economic evaluation on the above mentioned subject in Iran taking into consideration the high costs of electricity production by geothermal power plants and the situation of electricity production costs and social costs.

A city can be considered to posses many ecosystems made by human. The difference between the cities and other ecosystems is human dominance on them. Anthropogenic effects cause significant variations on flora, biocoenose and urban biotopes. Moreover, human disturbances change the succession process from natural systems to anthropogenic systems in urban area. Hemeroby is used to evaluate the value of anthropogenic effects. Likewise, hemeroby degrees show the response of each urban plant to different anthropogenic effects for investigation on flora and vegetation in urban areas and to protect their natural biotopes, a new division of biological science, urban ecology, was constructed. Urban ecology was suggested first by Park et al.

Nowadays, developing green spaces are on rise due to the fact that the population, urban structures and human needs for social, physical and emotional balance are also increasing. In Iran, paying attention to green spaces has risen along with the appearance of industries around the cities. In Isfahan city, green space planning has received significant attention from years ago which have been manifested through complexes such as Char Bagh, Bagh Karan, Hezar Jerib garden, Chelsotun garden, etc. However, in spite of the high amount of the green space per capita, the need for paying attention to these places has risen due to the factories and industrial units causing the environmental pollutions. Moreover, parks and green spaces spatial distribution in urban zones has not been carried out fairly; therefore, unequal distribution in different zones can be seen vividly. …