JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY
Year:2008 | Volume:10 | Issue:1 (36)|Papers Count:16

Methyl Tertiary-Butyl Ether (MTBE) is added to gasoline to increase its octane number and efficiency. The U.S. EPA has categorized this compound as a hazardous material with high cancer risk to human health. RCRA has also listed MTBE as a dangerous material.The main source of soil contamination by MTBE in the environment occurs through its production and leaching from USTs. Modified clays are a type of bentonite clays that have been tailored structurally to absorb hydrocarbons. In this study, free swell test and absorption analysis were carried out to investigate the efficiency of modified clays in removing MTBE from liquid wastes. The results of the study showed that the volume of the clays increased from 2 cm3 to 11.95 cm3 (a 497% increase). There was also a noticeable decrease in MTBE concentration for all the absorption isotherm samples due to the removal of MTBE from liquid solutions, thus denoting the efficiency of modified clays in absorbing this compound.

Application of organotin compounds are limited by international regulations. Unfortunately, in spite of these international regulations, they have been used in Iran unofficially. The extensive application of these compounds has caused negative environmental effects on aquatic organisms and marine ecosystem. Therefore, it is very important to determine their quantity in marine ecosystem.In this research, a fish species native to the Persian Gulf, Scatophagus argus, was used to determine the amount of accumulation and accumulation threshold of tributyltin chloride through food. The food, contained tributyltin chloride with 4 different concentrations (0.0, 0.00264, 0.0264 and 0.0528 mgml-1), was given to the fish throughout the period of experiment. Three fish were taken after 7, 14, 21 days of experiment. Tributyltin chloride was detected by GC-ECD in 4 steps. These steps were extraction, clean-up, concentration and detection. During the 21 days of experiment, different amounts of accumulation were observed at aquarium bioassay at different sampling times. Also, the accumulation threshold of this compound (0.0264 mgml-1) was determined by GC-ECD system with the detection limit of 0.1 ngg-1.

Synthetic dyes are among the substances that pollute the ecosystems such as the soil, surface water, and underground water, and affect living organisms when industrial effluents are released in the environment. The most common synthetic dyes are Azo dyes, among which are the reactive dyes that can cause a lot of problems due to their high solubility in water and low degradability.In this study, one gram negative bacilli (Shewanella putrefaciens) with a high capacity in decolorization of azoic dyes, especially reactive black 5, is isolated from among 15 microbial strains in Tehran textile effluents.The results of the study showed that, in the presence of external energy and carbon source, this strain could decolorize the dye in a shorter period of time. An 18-20h pure culture of Shewanella putrefaciens decolorized more than 80% of the dye during 12 hours under aerobic conditions in broth and the figure reached 100% after 24 hours. Decolorization in Saline Basal Medium during 48 h was 85%, when the dye was regarded as the sole source of carbon and energy. The conditions for the gram negative bacilli (Shewanella putrefaciens) that had the best effect on decolorization were as follows: a temperature of 30°C, the pH of 6-6.5, 150 rpm shaker speed, and 200 ppm (mg/l) concentration of dye. Decolorization took place better in the presence of yeast extract as nitrogen source and sucrose as carbon source. Moreover, the culture showed a better decolorization activity in the logarithmic phase of growth.Since the Shewanella putrefaciens do its decolorization activity in a short period of time even in an autotrophic pathway, it is thus this strain that can have a valuable role in biodegradation of dye compounds in textile effluents.

This research aimed at investigating the intensity of the mineral pollution of Shirood River located in the west of Mazandaran Province (7 Kilometers from Tonekabon) through environmental geochemical studies and by compiling pollution intensity indexes for the maintenance of sustainable development. To this end, seven sediment samples were collected from different parts of the river and the total concentration of such elements as copper (Cu), zinc (Zn), plumb (Pb), vanadium (V), nickel (Ni), manganese (Mn), and iron (Fe) was measured by atomic absorption. To estimate the pollution intensity in the mentioned river, the researchers used the geochemical index (Igeo) and the enrichment factor (EF), compared the two indexes, quantified the EF index, and equated it with Igeo.The results of the study show that the pollution intensity of the mentioned elements in two stations– mouth of the river and Soleiman Abad (up river)– are as follows: the amounts of Iron and manganese are normal, which indicates too weak an absorption (without pollution) in the environment; vanadium and nickel are in the weak absorption class (without pollution to very slight pollution); elements such as copper, zinc, and plumb are in the medium absorption class (very slight pollution to slight pollution) and intensive absorption class (much pollution to severe pollution). Therefore, the results of the study also show that by combining the above-mentioned indexes, it is possible to develop a sustainable development index for the recognition of environmental pollutions.

Due to the toxicity of cadmium and its bioaccumulation property, it has drawn significant attention. The aim of this study was to investigate cadmium elimination by used soil the wastes of vegetable-oil industries, after being prepared by heating in a vacuum furnace. The absorbent prepared in this way was capable of absorbing metal ions such as cadmium in aqueous environment. Also, how to improve the performance of the absorbent was studied, and the optimal conditions in terms of influent concentration, pH, and absorption value were determined. The best efficiency and absorption capacity were investigated for both organic and inorganic salts of cadmium (cadmium acetate and cadmium solfate) as well. Isotherm curves were developed for Langmiear B.E.T and Frondlich which indicated that cadmium absorption by this absorbent follows Langmiear equation (R= 0.98). Meanwhile, the highest absorption that occurred for cadmium sulphate was 0.1234 mg/g; the efficiency for 10 mg/l of influent concentration was 68.2 per cent when 3.5 g/l of absorbent was applied. An increasing in pH and retention time resulted in higher absorption by the absorbent.

Electricity production has a lot of advantages for the country, but it also has certain harms and unwanted damages such as environmental destruction. In investigations on electricity generation technologies and their environmental impacts, special attention should be paid to social costs. In this paper, the social costs of SO2 emission have been calculated for Shahid Rajaii Power Plant.The fossil fuels used in Shahid Rajai Power Plant are natural gas, fuel oil, and gas oil. Having one combined cycle unit and one steam unit, the power plant has a capacity of 2000 MW. The combined cycle unit includes 6 gas turbines and 3 steam units, and the other one has 4 steam units.To calculate the social costs, the private and external costs were computed separately for each unit of the power plant. The private costs pertain to maintenance, fuel, and investment. The fuel cost was computed for each steam and combined cycle unit in terms of subsidized and FOB prices. The private costs were about 257.652 and 534.371 Rls/KWh. The SO2 emission was compared with the international standard of ambient air in the four seasons and in two conditions: normal and maximum load. The external costs were about, 262.096 and 421.226 Rls/KWh.Finally, the social costs were obtained from 8 scenarios in two seasons as the sum of private and external costs. The results show that in comparison with the other units, the social costs of the steam unit are considerable, which is due to the high consumption of fuel oil.

Regarding the importance of parks in urban areas, issues such as health, safety and environment are important elements which should be considered in the fields of planning, operation, management, and maintenance before the occurrence of accidents and undesirable effects and in order to meet the needs of park users in particular and of citizens in general. The aim of this research is to determine and consider factors affecting the optimal health, safety and environmental management of urban parks and to provide managerial solutions for the improvement of the present situation.To this end, first the effective factors in health, safety and environmental management of urban parks were determined through library and field studies. Then, two types of questionnaires were used to obtain the opinions of the people in charge and those going to parks regarding health, safety and environmental state of some parks in district No. 5 of Tehran municipality and the results were analyzed using statistical software.The results indicate that the desirability rate of health indices in the parks under study (58.9%) is less than that of safety indices (%59.2%) and more than that of environmental indices (46.1%). Also, indices such as appropriate health state in the staff rooms of the parks, information state and installation of warning signs while spraying poisons in parks, and the state of accomplished measures to reduce noise pollution in parks had the least desirability rates in the areas of health, safety, and environment (35%, 3.3% and 28.3%, respectively) in the parks under study.

The first observations regarding the adverse effects of exposure to VDTs go back to the years following 1970. Most complaints about the negative effects of EMFs emitted by VDTs include: visual disorders, skin rashes and itching, adverse effect on the reproductive system, spontaneous abortion, low birth weight, and pregnancy disorders among VDT users. To assess the adverse effects of EMFs emitted by VDTs, 97 VDT users who spent more than 4 hours a day in front of VDTs were studied in the present research. Also, a questionnaire was used to obtain the required information.The results of the study showed that there was no significant relationship between the prevalence and intensity of the above-mentioned disorders on the one hand and the exposure to EMFs emitted by VDTs on the other. The results also revealed that, in certain cases, an increase in the exposure time would lead to menstrual disorders among VDT users. OR=1/199 (DI %95: 0/998-1/44). Moreover, the findings showed that an increase in the daily exposure to VDTs aggravated the users’ visual disorders. OR=1/244 (DI %95:1/507-1/027). These findings confirm the results of some of the studies conducted previously on the issue.

This paper aimed at investigating the items and values affecting the Persian Garden as a special place in line with environmental and cultural values. To this end, first the origins of the Iranian ancient culture and its impact on the structure of the Persian Garden were studied. Secondly, the Islamic cultural aspect was investigated as a factor of commitment for providing the similarities between Iranian cultural aspect before and after Islam. Based on historical evidence, besides the Islamic aspects, Iranian knowledge and technique have had a supplementary role in designing the Persian Garden. Despite minor differences in the appearance, the design principles of the Persian Garden have remained unchanged throughout history and can be used by landscape architects in future.

Following the experimental method of Thompson and Atchley, laser Doppler anemometry (LDA) was used to investigate the effects of a thermo-acoustically induced axial temperature gradient and of fluid inertia on the acoustic streaming generated in a cylindrical standing-wave resonator filled with air driven sinusoid ally at a frequency of 308 Hz. The axial component of Lagrangian streaming velocity was measured along the resonator axis and across the diameter at acoustic-velocity amplitudes of 2.7, 4.3, 6.1, and 8.6 m/s at the velocity antinodes. The magnitude of the axial temperature gradient along the resonator wall varied between approximately 0 and 8 K/m by repeating measurements with the resonator surrounded by a water jacket, suspended within an air-filled tank, or wrapped in foam insulation.The results of the study indicate that there is a significant correlation between the temperature gradient and the behavior of the streaming: as the magnitude of the temperature gradient increases, the magnitude of the streaming decreases, and the shape of the streaming cell becomes increasingly distorted. Therefore, the observed steady-state streaming velocities are not in agreement with any available theory.

To identify and estimate the population of fishes in Namroud river (between Namroud Bridge and Tehran Gezel Breeding Center), a period of sampling was done in June, 2004, using an electro shocker. Sampling was done in one phase and in a zigzag over a length of 600 meters, and 43 fishes were hunted altogether.The results showed that the fishes were of 6 types:Alburnoides bipunctatus (Bloch, 1782), Capoeta aculeata (Valencienns, 1844), Capoeta damascina (Valencienns, 1842), Leuciscus cephalus (Linnaeus, 1758), Nemacheilus bergianus ( Derzhavin, 1934) and Oncorhynchus mykiss (Walbaum, 1792).The population estimation of each species was done based on their ratios in the sample.Considering the obtained species, type of river bed, and temperature and speed of water, it seems that the region under study should be considered as a Sub Mountain Zone according to Holcik-Hensel classification. Such regions have Barbel, Grayling, and Trout. These kinds of fishes are not only native to the region, but they have also come via the exit canal of Tehran Gezel Breeding Center and have survived due to suitable environmental conditions.

The study was conducted on secondary school teachers to study their environmental awareness with respect to their residential background, subject specialization and teaching experience in India and Iran. One thousand and four teachers were selected through the stratified random sampling technique from 103 secondary schools of Mysore city (India) and Tehran city (Iran). Subjects consisted of 505 male and 499 female. They were assessed using the Environmental Awareness Test (EAT) (Shabina Jinaraja, 1999). Results revealed that there are significant differences between them in environmental awareness across and within two groups with regard to their subject specialization (science and arts). Also in overall lengths of teaching experience is not a factor, which can affect teacher's environmental awareness.