INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY (IJEST)
Year:2005 | Volume:1 | Issue:4|Papers Count:12

Kerosene is common adulterant utilized for mixing with diesel. Five fuel-adulterant mixtures in different proportions by volume were prepared and individually tested for density and kinematic viscosity. The mixtures were administered to six light cargo vehicles and the tail pipe exhaust emission was tested for opacity value. No appreciable density variation at different levels of adulteration was observed. Density was within the prescribed value even at higher adulteration. Considerable decrease in kinematic viscosity, a departure from prescribed viscosity, was noted at higher adulteration level. The percent opacity value decreased sharply even at small level of adulteration. The probable amount of kerosene present as an adulterant in diesel dispensed at filling stations in Kathmandu city ranged between 35% and 50%. The observations suggest density test is not a good indicator of diesel adulteration. Kinematic viscosity and opacity value are useful diesel adulteration test parameters. Existing diesel adulteration warrants initiation of strict compliance regulation.

This paper introduces a new structure in neural networks called TD-CMAC, an extension to the conventional Cerebellar Model Arithmetic Computer (CMAC), having reasonable ability in time series prediction. TD-CMAC, the conventional CMAC and a classical neural network model called Multi-Layer Perceptron (MLP) are simulated and evaluated for 1-hour-ahead prediction and 24-hour-ahead prediction of carbon monoxide as one of primary air pollutants. Carbon monoxide data used in this evaluation were recorded and averaged at Villa station in Tehran, Iran from October 3thrd. 2001 to March 14th. 2002 at one-hour intervals. The results show that the errors made by TD-CMAC is fewer than those made by other models.

The adsorption of heavy metals onto treated Azolla filiculoides by H2O2/MgCl2, as a cosmopolitan free-floating waterfern, was investigated from aqueous solutions in the batch biosorption experiments. The maximum uptake capacities of the collected Azolla from rice field at the optimal conditions for Pb, Cd, Cu and Zn ions were approximately 228, 86, 62 and 48 mg/g (dry Azolla), respectively. On the other hand, the maximum uptake capacities of the collected Azolla from the Anzali International Wetland in the north part of Iran at the same conditions for these heavy metals were about 124, 58, 33 and 34 mg/g (dry Azolla), respectively. Such decrease of uptakes is due to the pollution of Anzali International Wetland, which reduces the capacity uptake of metals. The recovery of biosorbed heavy metals from the rice field Azolla was carried out by HCl and NaCl desorbents that the recovery of 64- 86% and 51-72% was occurred, respectively.

Wastewater reclamation and reuse is one of the best alternatives for compensating water shortages. Water supply and environmental conservation can be met through wastewater reclamation. Principally, treated wastewater is a reliable water resource, especially for periodic droughts and in arid areas. This study designed and implemented to investigate the full scale application of effluent for irrigation use. A major objective of this study is to assess on health effects and feasibility of crop irrigation by using stabilization ponds effluent of southern Hovaizeh Wastewater Treatment Plant located in Khuzestan Province. Two experimental plots of about 0.5 ha. were constructed. One of the plots irrigated by stabilization pond effluent and the other irrigated by Nisan River water. Basic parameters in two plots such as type of cultivated crops, amount of fertilizer use and lack of soil contamination have been similar in both. The only difference was the type of water applied for irrigation of agricultural crops. It was shown that high salinity of soil reduced the growth rate of agricultural crops. So, removing salinity from area should be performed before cultivation. Results gained on agricultural crops growth in two studied plots showed the growth rate and quality of crops were increased by using of stabilization pond effluent in comparison with Nissan River water.

The study was conducted for the investigation of amount of radioactivity in the barren and cultivated soil of Bio saline Research Station in Pakka Anna, established by Nuclear Institute for Agriculture and Biology (NIAB) in 1990, 34 km. away from the city of Faisalabad, in the Punjab province of Pakistan. The studies were done on an area of about 100 hectares of two types of virgin and fertilized saline soils. The technique of gamma ray spectrometry was applied using HPGe (high purity germanium) gamma ray detector and a PC based MCA. Activity concentration levels due to 40K, 137Cs, 226Ra and 232Th were measured in 250 saline soil samples collected at a spacing of about 4 hectares at the depth level of 0–25 cm. with a step of 5 cm. depth. Activity concentrations ranges of the concerned radionuclides for both of the soils were as follows: 40K, for virgin and cultivated saline soil was 500-610.2 and Bqkg-1 560.2-635.6 respectively; 137Cs, 3.57-3.63 and 1.98-5.15 Bqkg-1 238U, 26.3-31.6 and 30.3-38.7 Bq.kg-1, and 232Th, 50.6-55.3 and 50.6-64.0 Bqkg-1 respectively. The absorbed dose rate in air lies in the region 63--73 nGyh-1 and 68--83 nGyh-1 for virgin and fertilized soils respectively. This indicates that this region lies in the area of higher radiation background, while comparing with the worlds’ average. The slightly higher value of dose in the fertilized farm may be due to the use of fertilizers for cultivation. Before the radiometric measurements, chemical analysis for concentration of Na, Ca and Mg was also carried out along with the measurement of electrical conductivity and pH of the soil samples.

Crude oil and water samples were collected from selected Iranian oil reservoirs. Experimental works were carried out in laboratory conditions. The samples have been grown on PYG medium and incubated at 30-80 0C. Thirty-six mesophile and thermophile bacterial strains have been isolated. All the isolates were able to grow at aerobic condition. Batch growth kinetic studies were carried out in a 500 ml. shake flask. Out of 36 isolated strains from 24 crude oil and water samples, 35 strains were gram positive rod. Shaped spore forming bacteria and one strain was coccid form. Eight out to 35 bacillus species were capable of producing surfactant. Production of biosurfactant was found to be cell growth associated. The ability of surfactant producing bacteria indicated by reduction of surface tension (ST) and interfacial tension (IFT) of the supernatant. Eight strains obtained the IFT reduction in crude oil, hexadecane, sucrose, glucose, fructose and mannose medium as a sole source of carbon and energy at 40 0C by 15-30 mN/m. Results showed that all the bacteria are producing more surfactant when glucose is the carbon source. Further screening of biosurfactant producer showed that three of the isolated strains resulted the maximum ST and IFT. Effect of temperature on these three isolates investigated at 30-80 0C, above 50 0C surfactant production was dramatically reduced. The isolated strains had the capacity to produce the surfactant at 3-5% NaCl a wide rang of pH (6.5-8.5).

With long-term use of sewage waste, heavy metals can accumulate to phytotoxic levels and resulted in reduced plant growth and/or enhanced metal concentrations in plants, as a result food chain. If these metals penetrate too rapidly in a particular soil, especially with high water table, they can pollute ground water supplies. The aim of this research is prevention of movement of waste water-borne heavy metals in soils of southern parts of Tehran. These waste waters are used for irrigation of agricultural lands at southern regions since many years ago. For this purpose, 6 soil samples from southern parts of Tehran city and 2 ones from Zanjan city without lime and organic matter were selected. In laboratory, sorption capacities of the soils for Ni, Cd and Pb were compared with those of calcite, Na-bentonite, zeolite, illite and hematite amendments. The method was carried out by equilibration of known quantities of these adsorbents and soils with solutions containing these elements. The results showed that among the 5 amendments, calcite and Na-bentonite had the greatest sorption percentages of the 3 elements and illite had the least one. The retention capacity of calcite and Na-bentonite for Cd was highest in all 8 soils. However, retention capacities of these 2 minerals for Pb and Ni were higher than those of loamy soils without lime and organic matter and also sandy soils. Because of abundance and low price of calcite, this amendment is preferred to Na-bentonite. Therefore, calcite is recommended for adding to soils with low sorption capacity of Ni, Cd and Pb.

One of the undesirable characteristics of some groundwater sources is hardness, which has some adverse effects on water pipes, boilers and soap consumption. Therefore several treatment processes have been introduced to remove or reduce the hardness from hard waters. One of the new innovations in this regard is crystallization process. Hardness can be removed from hard waters by growth of calcium carbonate crystals in a fluidized bed reactor called pellet reactor. The design, setting up, starts up and reaching optimal condition for calcium carbonate crystallization process in a pellet reactor which has been initially seeded with sand as a crystal citation can be a successful solution for treatment of hard waters. The chemistry of pellet softening process is essentially the same as conventional softening process, instead of precipitation of calcium carbonate which does not have any useful consumption and must be removed once in a while some how, crystallization process in a fluidized bed reactor produces pure solid grain of calcite. These pellets can be used in some industries and are in fact an economic commodity. For this purpose a pilot was set up as a crystallization reactor and water with total hardness ranging from 150 up to 500 mg/l as CaCO3 was fed to the system with a flow rate of 24 l/hr. To remove hardness, caustic and soda, lime milk was fed to the system separately at first stage at then together. The formation of CaCO3 crystals on the surface of sands represented the reduction of hardness. An analysis is made for the characteristics of a softed water resulted from the use of caustic soda, lime milk or both as regent.

Copper, Pb, Zn, Ni, Co, Mn, AI, Ca, magnetic susceptibility and loss on ignition of sediments from two cores near Mangalore along the western continental shelf of India have been studied. The sediments have high Al and organic matter contents due to the high sedimentation rate and their proximity to river mouths. Down-core variations of elements indicate a decrease of lithogenous component during probably the past few centuries. While abundance of calcareous shells in some zones has lead to the dilution of most of the metals, it appears that Pb and Mn are associated with this phase. Copper, Zn and Fe are associated with organic matter and detrital particles, whereas Ni and Co are predominantly associated with the insoluble fraction. Oxides/hydroxides of Fe and Mn are absent because of the reducing conditions and the high terrigenous influx. Geochemically, Mn and Fe are present in different phases of sediments (in the insoluble fraction and organic matter respectively). The Fe content of one of the cores is positively correlated with magnetic susceptibility.

One of the most important pollutants of groudwaters is nitrate. Different human activities including the application of chemical fertilizers in agriculture, causes the emission of nitrate into groudwaters. In this paper, the dynamic effect of soil moisture on carbon and nitrogen cycles has been analyzed by presenting a connection between soil moisture sample and nonlinear differential equations. At present, wide researches are carried out on modeling soil moisture control in solution flows contain nitrate. In order to do so, separation of energy conservation law equations is carried out by a particular method. The mathematical model governing the nitrate containing current in non-isotropic environment has been presented in the form of combined equations. Equation for distribution in multiple environments and Darcy rule has been considered in this model. Then, using finite volume method, separation of flows contain nitrate in porous media is carried out. The current flux is obtained from central difference approximations or upwind approximation. Mashad plain has been considered for case study at this research. Carrying out calibration operation, the measured results have been contrasted with numerical results of finite volume method. After testing the model, it is possible to foresee the way of nitrate changes in other nodes of calculation network. Using these forecasts, the quality of drinking water for several next years is determined. Carrying out numerical modeling by finite volume method, it is found out that the quality of drinking water of Mashad plain would be suitable for the next ten years.

A cross-sectional survey was conducted through Tehran city and a field study was conducted to prepare main and accessory drainage channels map. Three main drainage channels were identified for this research and some sampling stations were chosen. Three stations selected in south of Tehran. The reason for selecting these stations is that all urban surface runoff completely pass through these points and samples taken from these points are representative of all kinds of pollutants that transit from city surface. Another Three stations were selected in center and further three stations were selected at north of Tehran. Surface runoff flow in three main channels, from north to south of Tehran, converge at south of Rey city and finally end up to Ghom Salt lake. The stations were chosen at three trajectories, Sorkhe Hesar, Emad Avard, Kan. At each month two samples were prepared from nine different stations. After collection of samples with respect to standard methods, they were dissolved in nitric acid and then analyzed by atomic absorption device. The results show that the concentrations of pollutants increased from north to south. For instance, Zinc had most concentration with monthly average of 0.98 mg/l and Nickel had the lowest amount with 0.02 mg/l in southern stations. Average concentration of Zn, Pb, Cd, Cu and Ni were: 0.638, 0.097, 0.04 and 0.035 mg/l respectively. Total average concentrations of heavy metals at three main channels were of 0.177, 0.176 and 0.145 mg/l. Emad Avard was the most polluted channel.

Nature based tourism (NBT) as an effective instrument for sustainable use of biodiversity is an interesting issue to be studied in order to evaluate response the of international community to the interaction between developmental and environmental pillars of sustainable development. Various international endeavours have been carried out with considerable outcomes to address NBT in different forms and manifestations. As a result, the international community has attained many successful achievements and valuable experiences. There is an urgent need for an internationally accepted instrument to address the existing gaps and overlaps appropriately. Such an instrument should respond to lake of adequate environmental and developmental rules and regulations at international scale. Careful study of major international environmental and developmental achievements related to NBT could provide the international community with an appropriate legal framework to address such an environmentally fragile, economically viable, and a culturally sensitive issue.