Journal of Environmental Studies
Year:2006 | Volume:32 | Issue:39|Papers Count:19

General circulation models (GCMs) are mathematical models (i.e. computer simulations) of atmospheric and oceanic properties and processes that attempt to describe earth's climate system (The global climate system is a consequence of, and a link between, the atmosphere, oceans, the ice sheets (cryosphere), living organisms (biosphere) and the soils, sediments and rocks). Developed in 1960s, they have become the chief tools in analyzing effects of Global climatic change CO2 doubling as one of the most important parameter affecting atmosphere was simulated using the resultant monthly indexes of temperature and precipitation on grid points in Tabriz for a 53-year time period (1952-2003). The resulting Hythergraph and Ambrothermic model of Geophysical Fluid Dynamics Laboratory (GDFL) for Tabriz indicate monthly increases of temperature and precipitation during the CO2 doubling periods. The temperature would increase monthly and seasonally, and the precipitation would decrease on March and increases on April and May. A comparison of the present and simulated Ambrotherrnic, Hyetograph and Xlimagram models applying GDFL model confirm precipitation and temperature changes in Tabriz. Therefore, the results verify climatic changes such as a decrement in the duration and intensity of cold season accompanying freezing days, and decreasing spring and winter precipitation and changing winter precipitation type from snow to rain, as well as, the extension of growth period, and finally the dominance of dry periods.

MTBE is one of the volatile organic compounds in the ambient air. The fuel loss at gas stations and traffic are the main sources of this compound in the air of the city. The studies show 52000 liters of gasoline are lost from the gas station across the city of Tehran. Each station losses approximately 4l5liters per day, which makes the area on and around the gas stations heavily polluted. In current study, MTBE were measured at two gas stations and 20 main cross streets, during summer and winter. The concentration of MTBE in Khavaran gas station in July and August (3.3-10.7 ppm) was higher than December (4.3-6.4 ppm).MTBE concentration in Beheshty gas station at that time (Summer) were 2.2 - 5.5 ppm. The mean concentration of MTBE in ambient air at the 20 measured places across the city was 0.01 -1.2 ppm. This study shows that effect of gas station as a point source of pollution is 30 m from center of gas station.

Distilleries wastewater is an important environmental problem due to its high BOD and COD content, and toxic materials such as phenolic compounds, and low pH. Direct and continuous discharge of this effluent to the soil reduces the quality of soil and destroys agricultural crops. In addition, its discharge to rivers and sea will seriously affect aquatic life. In order to prevent environmental hazards, a number of biological, chemical and physical methods have been introduced for treatment of this wastewater. Chemical and physical methods are based on surface sorption, ion exchange, membrane processes and chemical oxidations. In biological methods, anaerobic processes are more economical than aerobic processes and are more developed more in recent years. Anaerobic lagoons reduce 60-70% of BOD with 1-2 months retention time. Most of anaerobic bioreactor methods are able to reduce wastewater BOD by 80-85% and the remaining 15-20% of BOD can be reduced by aerobic processes. Evaporation of wastewater for production of feedstocks and incineration of wastewater for recovery of potassium are other methods of distillery wastewater treatment used in smaller volumes. These methods can be economic (if technological and production difficulties are not considered) by selling of by-products formed. Distillery wastewater is also used for production of single cell protein, in which selling the by-products can reduce the cost of wastewater treatment.

Application of nitrogen fertilizers have been increased without considering the hannful impacts on soil properties, agricultural products and especially on the environment. As the most common form of nitrogen, nitrate is easily transferred to ground-water resources. Ground-water is the main water supply in arid and semi arid regions, because of good quality and easy availability. The objective of this study was to determine nitrate concentration, distribution and fluctuations in the ground-water around the Zayanderoud River in the arid and semi arid region of Isfahan province. In this way, about 100 functional wells were selected from Baghbahadoran to Varzaneh and the concentration of NO3-N,Cl-, HCO3- K+, Na+, Ca2+,Mg+2, SO2-4,TH and EC were measured monthly from October 1998 to October 2002. The average concentration of NO3-N in Baghbahadoran, Flavarjan, and Varzaneh were 5.5, 17.6 and 6.4 mg/l respectively. The highest value of nitrate nitrogen of 70.8 mg/l (7 times much than standard value of 10 mg/l) was observed in Jalalabad region, one kilometer from Zayanderud River. There was not any significant difference between nitrate nitrogen in drinking water well in Baghmalek village and varzaneh well in the period of sampling but the concentrations were significantly different in Lenjan region (Kaleh Masih, Chamgardan, Zarinshahr, Falavarjan and Dorcheh) with the beginning point and the last point, because of the higher agricultural activities (usually rice). The results also showed that the Nitrate concentration has no correlation with chemical parameters of ground-water.

In this research, the Shefa-rud river sediments have been chemically analyzed to determine elemental matrix, heavy metals concentrations and pollution intensity. Though comparison of geochemical results with the world's standards have been a common practice since 1971 but the research results show that use of mean of the metals concentrations of the earth's crust and world sediments are not suitable means to estimate the pollution load in the study area. Heavy metals concentrations of Shefa-rud river bed sediments are under control by the geology of study area and as a matter of fact, limestone units have a greater significant role than the other units. As limestone contains lesser concentrations of heavy metals, it is evident that the obtained concentrations are much lower than various world average sediment metal concentrations. Besides, natural organic materials have been effective in elemental absorption and formation of organic metal bond. In continuation of present research, Al, Ca, and LOI were used as the indices of lithogenous, biogenic and organic sources, respectively to find out the sources of Mn, Fe, Ni, Cu, Zn, Pb and Co. Though Fe and Mn have direct link with lithogenous index but we propose the same source for other studied metals. It is believed that organics and biogenic materials are land derived. Thus cluster analysis is indicative of lithogenous source for heavy metals in the study area, and fortunately no evidence of Shefa-rud river bed sediment elemental pollution has been observed. "Muller" geochemical Index (Igeo) is a proof to this fact, and the index output calculations demonstrate unpolluted class for Mn-Pb-Ni-Cu-Zn-Fe in the sediments.

Wastewater is the main point-source pollutant on a global scale. Between 90 and 95% of the sewage produced in the world is released into the environment without any treatment. Development of petrochemical industry in IRAN, construction of new plants and up gradation of existing units, has lead to generate more wastewater of higher strength. Some kinds of aerobic and anaerobic processes are applied for treatment of this type of wastewater. Performances during startup of a anaerobic hybrid reactor (UASB/Filter) treating petrochemical wastewater at mesophilic condition were investigated. The reactor was seeded with flocculent sludge from a UASB plant treating dairy wastewater. The reactor was run for 5 months without adaptation but it was unsuccessful. Hence the adaptation of sludge considered in 2 stage operation. At the first stage, the synthetic wastewater made from dry milk was fed to the reactor. After 65 days, the performance of reactor was 77.8 percent at OLR=2.0 kg/m3 day and HRT=18 hrs. Then in stage 2, The COD part of feed related to petrochemical wastewater increased step by step at 10 percent increments (increased COD mass of petrochemical wastewater by 10% per cycle) and injected to reactor completely from petrochemical wastewater. After 30 weeks, a COD removal of 70.3% was obtained at OLR=2.0 kg/m3 day and HRT=18 hrs.

Heat island and urbanization effects of Tehran have been studied using time series of long term (about 40 years) weather records. This investigation shows a significant increase in minimum temperatures compared with maximum temperatures. The greatest trend for the mean temperature has occurred in November. Comparisons of time series of temperature for Tehran and Varamin in this period show that the rate of annual minimum temperature increases in Tehran was four times lager than that of Varamin (S.Tehran). Although a decrease rate of maximum temperature seems to be observed in both stations. The highest trend of mean monthly minimum temperature in Tehran and Varamin were 4.64°C and 2.12°C respectively, which were occurred in November. This indicates that the artificial and anthropogenic increases of temperature leading to urban heat island in Tehran have been significant in this period. This study also indicates that drainage of cold air from northern mountains over Tehran (Mehrabad) has also been weakened due to the increase in built-up area. The wind decreasing trend intensifies urban heat island effect.

Systematic study of wood mouse (Genus: Apodemus) was carried out using morphological and morphometric dental and cranial characters in eight specimens from Noor region (Altitude: -26 m) in Mazindaran Province. According to present study, this is the first record of wood mouse (A.hyrcanicus) in Noor region. The skin is black brown in ventral side, which obviously is different from the other species of Apodemus in Iran. V shaped Fronto-parietal suture with frequency of %88, curved posterior edge of palatine (frequency: %77), developed and wide Angular process, massive bulla, absence of Cingulums in lower M/2 (frequency: %87.5), Absence of C1 Cingulum in lower M/2 (frequency: %100), largeness of length and width of lower Molars, and largeness of length and width of upper M2/ are the Key discriminating characters. The geographic distribution of Apodemus hyrcanicus, which is native to the hyrcanian region, stretch from deciduous lowland forest of eastern Caucasus in the west to the easternmost limit of hyrcanian forest in the southern coast of the Caspian Sea in Iran.

Nematodes are one of those biological organisms that because of their abundance in surface water and their resistance to disinfection are of great importance in control of water treatment processes. Because of lack of information about efficiency of nematodes removal in direct filtration process, this subject has been examined under various conditions in this research with regard to size of filter media, filtration rate, injection rate of coagulant and activity or inactivity of nematodes, by using a pilot plant consisting of raw water unit, coagulation and flocculation units as well as two parallel single and triple media filter. Based on results obtained, the average efficiency for removal of active nematodes by single and triple media Filters has been 68.8 and 73.9 percent respectively. Based on microscopic survey, the mobility of nematodes has been the main reason for low rate efficiency. By making nematodes inactive, prior to entering the filter, the average efficiency for removal of nematodes in single and triple media filters increased by 93.7 and 95.8 percent respectively. Hence, this is strongly recommended.

The soil studies are necessary for all of investigation of natural resources. One of the common soils studying method in natural resources is Geology method. This method was applied in Hasanjoon sub-catchments of Taleghan drainage basing which is located in 50°37' to 50°50' longitude and 36°7' to 36°20' latitude, and having considerable geological variation. First, the map of geology units with photo logy and field checks using geographic information system, (scale 1:20000) was prepared. Then 60 profiles and soil samples were analyzed physically and chemically and pH, Ec, %OM, %caco3, %silt, %sand and clay were determined. Results of statistical test showed that, geology method is proper appropriate for primary study, because geology units are significantly different together. It is necessary to separate faces from litho logy for soil science study, because geology units are not homogenous and the profiles located at material have significant difference (except pH). Therefore for overall investigation and at identification stage, geology method can be useful, but for common soil science in natural resources, this method only is suitable to evaluate pH.

Siahkuh protected area is managed by the Dept. Environment of Yazd province since 2001. This region (199512 ha) contains a flat plain covering about (65%) with altitude 950-2050m. A study was conducted to determine vegetation and wildlife biota as well as limiting factors. Major limiting factors are: climatic limits (precipitation equal 48 mm/year), length of aridity season, land resources limitations salinity, high ground water table, soil depth inaducey, erosion and sedimentation, land drainage problem) and lack of water resources. Other factors are mine exploitation and hunting. In these harsh ecological conditions, xerophytes vegetation and aridity resistance wildlife are living. 47 species of plants belong to 43 genera and 25 families were identified. Major plant families are Chenopodiaceae with 9 taxa, Compositae and Umbelifera with 4 taxa, and Polygonaceae with 3 taxa. Based on Red Data List 4 taxa in Lower Risk (LR) include: Hyssopus angustifolius, Zataria multiflora, Salsola yazdiani and Acantholimon Scolpus. Later two taxa are endemic. According to existing frequency, biological forms are Phanerophytes, Hemichryptophytes, Therophytes and Geophytes with 41, 21, 17, 15 and 6 percent respectively. 19 species of mammals were identified in this area. Based on IUCN, Cites categories, and Dept. of Environment 8 taxa are protected including: Vulpes cana. Acinonyx jubatus venaticus and Jaculus blanfordi. 35 birds species were identified which 11 taxa including Podoces pleskei and Chlamydotis undulata which are protected. Also 10 species of reptiles were identified which belong to Orders Ophidia, Testudinitae and Sauria there are 2 protected taxa which include Vatanus griseus caspius and Testudo graeca.

Banff National Park has the potential for large-scale connectivity. However, conservation of the area depends on the resolution of problems arising from the historical development of the park. The study area for this project, centered in the town of Banff, represents a conflict zone between human use and valued ecosystem components in the park. This project would provide a scientific basis for the modification of human use in the area through an assessment of the relative human use capabilities of biophysical parameters. It would consider 'Ground Cover Index' and 'Habitat Effectiveness', respectively, as the standard indicators of local and regional ecosystems, using 20 key independent indicators of GCI. The study area has been divided into a total of 715 homogeneous units that are distributed over the study area and form a total, 36532 units. One hundred and ninety-one sampling units have been randomly selected from these populations that include 54 homogeneous units. Attribute data are collected for each sampling unit. The data was analyzed using multiple regressions. The total of 8 independent variables was statistically significant. The synthesis was an "Ecological Human Use Capability Spectrum Characterizing Model". By testing the reliability of model in the Sisangan Forest Park and Golestan National Park, a framework of design developed for Caspian Region of Iran. Model will add scientific credibility to management decisions over the definition of the Limits of Acceptable Change at local and regional levels. It will also assist managers to model the local Recreation Opportunity Spectrum in Natural Parks and protected areas.

The wetlands are dynamic ecosystems, having greater biodiversity and special botanicecologica l structure. These ecosystems are always changing under the influence of natural and human factors by passing through healthy threshold and destruction. One of the approved regulations of Ramsar convention and AGENDA 21 about wise use of wetlands and immigrant birds, for member countries is the measurement of ecological characteristics and sustaining the biodiversity in order to evaluate the environmental consequences in wetlands. To understand the effects of socio-economical activities of human societies around wetlands on vegetation structure of these ecosystems, the present research has been carried out in 7 indicator wetlands in northern Iran, located in southern coast of Caspian sea during 1995-2005. The evaluation of the changes in relative density of observed plants on water surface has been done by Distance Method and the statistical analysis has been carried out by using the ANOVA with SPSS9 software. Based in the results of the research, the following plant species: Azolla filiculoides, Nympha alba, Phragmites australis, Nelumbiym nuciferum, Juncus articulatus, Scirpus maritimus and Utricularia neglecta are the increasing species and the following plant species: Lemna minor, Butomus umbelatus, Sparganium erectum, Salvinia natans and Iris pseudacorus are the decreasing species in northern Iran's wetlands. Considering the growth rate, propagation and morphological characteristics of increasing species, these plants decrease the penetration of light into the water with their continuous canopy cover, interfere in the food chain, decrease the diversity of fauna and flora and finally by accumulation in the wetland bed, create the phenomenon of eutrophication and the death of these aquatic ecosystems.

In urban design literature, character is the synonym of physical identity and encompasses the physical features, which makes a city unique, different and distinguished. Urban morphology that concentrates on the physical aspects of urban areas provides the necessary framework for studying the character of cities. It is the organized survey of form, shape, map, structure and functions of urban fabric and its evolution during the time. The concept of urban tissue is an applied method, which has been formed in the realm of this approach, meaning street and block arrangement. The method which is the combination of Italian and German schools of urban morphology was developed by Karl Kropf. Main structure theory provides a comprehensive approach to urban fabric and could be used as a complement for urban tissue method to express the interrelationships of different components to shape the entire city. It is suggested in this paper that in order to develop a method for the analysis of urban character, the urban tissue method should be combined with main structure theory. The combined method provides a comprehensive tool for the study of the character of cities. The method could be used for the selection of an urban zone which encompasses the most important physical features of the city. Studying the selected zone will lead to acquirement of a general knowledge about the physical character of the entire city.