نشریه علوم و تکنولوژی محیط زیست
سال چهاردهم شماره 3 (پیاپی 54، پاییز 1391)

Nitrification is the microbial oxidation of ammonium to nitrate in the soil which results nitrate loss and water resource contamination. Nitrification inhibitors basically evolved to improve nitrogen use efficiency of crops particularly in vegetable production systems. They also aimed to reduce nitrate accumulation and oxalate problems in fresh leafy vegetables, as well as less ground water nitrate content. The effectiveness of two types of chloride salts were compared to 3, 4-dimethylpyrazole phosphate (DMPP), as a standard synthetic nitrification inhibitor, in pot experiment under controlled conditions. Results showed that DMPP strongly inhibited nitrification during the whole period of experiment (7 weeks). On the other hand, chloride in forms of ammonium chloride and potassium chloride, significantly inhibited nitrification compared to control at all sampling dates. Inhibitory effects of chloride were positively correlated to chloride concentrations, in which higher concentration (500 mg/kg soil) showed more effective inhibition compared to less concentration (250 or 100 mg/kg soil). The results also indicated that apart from commercial nitrification inhibitors, chloride also can retard nitrification in soil. Therefore, where chloride is not a soil problem, chloride forms of nitrogen fertilizers could significantly increase nitrogen use efficiency.

Acceptance of a worldwide sustainable development strategy result is the need to design the relevant comprehensive measures. Furthermore, the inevitable complication in economical, social and environmental interactions and their effects on the society needs efficient urban system models. The current study, utilizing a dynamics system model, presents an approach to simulate cause and effect relationships between transportation and those parts of the society that usually considered in sustainable development studies. A management scheme for Mashhad is suggested to improve environmental indicators by evaluating the forecasted 15 scenarios during the years 2009 to 2029.In this evaluation, increasing cost of energy contents and limitation for single occupancy vehicles, have the most environmental effects as well as the ability to minimize the growth of environmental measures during 20 years.

This research was conducted to determine levels of heavy metals pollution in air near nuclear power plant I Tehran-Iran. Concentration of heavy metal (lead & cadmium) has been measured and analyzed in different seasons. Air sampling was done by HI-VI (High Volume Sampler) in different seasons. The preparation of heavy metal samples were determined by atomic absorption spectrophotometry. The results were analyzed by Spss software. Results showed average concentration of Pb and Cd was 0.41, 0.04 μ g/m3 respectively in the second half of the year that were below than the standards (1.5, 0.15 g/m3μ). The results confirm that the concentration of heavy metals (lead and cadmium) depends on the circumstances especially precipitation and air turbulence which were reduced during precipitation, also in inversion situation concentration of heavy metals increases because of being lower than international standard even in inversion situation.

An appropriate disinfectant in water and wastewater applications must have acceptable effect on different kind of micro-organisms especially in minor concentrations which should contain ignorable toxicity on human and animals and its environmental side effects must be very low. Studies related to finding non-chlorinated disinfectants which have same effects of chlorine and not contain its adverse by-products are continued in recent years. Hydrogen peroxide solution with stabilized formulation and oligo-dynamic amounts of silver ion (trade mark: Nanosil) recently become a popular disinfectant for fruits, vegetables, surfaces, medical instruments and disinfections. This study was based on determining removal efficiency of fecal coliforms from samples taken from Qom wastewater treatment plant effluents after exposing with hydrogen peroxide-silver ion complex. Disinfectant efficiency was studied in six concentrations. Contact time for all concentrations was one hour. Sample size was 12 and sampling was daily. Results reveal that in concentration; 80mg/l, disinfectant achieves 2.1 logarithmic removals of fecal coliforms. In concentration; 480mg/l, fecal coliforms logarithmic removal was 5.3. In CT value 5800(mg/l). Min and more, the fecal coliforms effluent standard for surface water discharge and agriculture irrigation was achieved (Iranian environmental protection agency act).Use of hydrogen peroxide-silver ion complex as a water and wastewater disinfectant, has various benefits such as; dont remain hazardous by products, measurable residual amount an but because of its oxidation nature when contact the organic materials in wastewater and microbial harboring in suspended solids content of effluent, its application in wastewater effluent is more costly than other usual disinfectants.

Sparse vegetation gives rise to increased overland water flow, soil erosion, water pollution and decreased soil fertility. Golestan Province has witnessed a relatively extensive forest clearing during recent years causing intensified flooding. We used ETM+ land sat imagery to classify forest cover of the Golestan Province using Max like classification and assessed its accuracy.Land uses and land covers were distinguished on the color composite images of the area and used as training sites for image classification that included all six bands of the imagery. We also used an ISO-Cluster unsupervised classification to derive 100 clusters for purifying initial training sites. Accuracy assessment was implemented through test set pixels that were randomized and set aside from the training set pixels. We also used a LISS III imagery to assess the accuracy of the classification. Our assessment proved the classification to be of high accuracy.

Azo as a member of chromo-gen group has different efficiency in different industries such as mutation potential and carcinogenesis. Some kinds of chromo-gen are known in primary studies. Azo chromo-gen can cause undesirable color to water and also these colors have mutation and carcinogenesis potential in human and can produce poisonous side product in environmental water. The aim of this investigation is usage of iron, element to subject an effective method to remove azo dye acid yellow 36 of water solution. This experiment fulfills in the scale of laboratory. In this experiment synthetic solution made from color and efficiency of iron powder is considered in removing the yellow 36 acid color of water solution and effects of different parameters during the contact time. Effect of iron powder is considered in efficiency of removal by iron powder. Results of experiments show that PH solution is more effective in access to more removal. From the results of the experiment it can be concluded that the time of contact of Iron in the acidy solution as an important factor through access to more color is more effective. Increasing the contact time of iron powder in the solution, decreases the time of discoloration. Results of experiments show that pH have more important role on efficient color removing and Slight pH can be more efficient to remove the color. Increasing pH from 3 to 11 with iron powder 3.33 g/l and contact time of 100 minute, removal time is decreased from about 94.84% to 16.94%. This method is recommended to remove Azo dyes from environmental water as it is simple and efficient.

Biological treatment is known as most effective method of organic matter elimination in municipal solid wastes. These include aerobic ad anaerobic compost. Presently anaerobic method is well known as a suitable technique for energy production. The methane production by anaerobic method is useful for energy production as well as direct fuel and also mechanical functions. Thus, present investigation is carried out in the light f greenhouse gas reduction, environmental protection and reduction of municipal waste management costs. In this research methane production from municipal waste was carried out at laboratory scale. Initially we used wastewater from dairy factory that contains high BOD. The methane production was examined at medium (about 35) and high (about 65) temperatures. All relevant parameters such as humidity, pH, load factor and efficiency were measured. The results show that methane production is more evident at lower temperatures. About 0.21 to 0.65m3 of methane can be produced from each kilogram of waste.

Estuaries are considered as important zones for the occurrence of environmental, biological and geochemical processes. Elements are carried to the sea through rivers and estuaries are pathways for this transmission. In estuaries dissolved elements of river water ooze out of dissolved phase due to several estuarine processes such as flocculation.In the present investigation, for the first time of flocculation Zn, Cu, Pb, Ni and Mn during mixing of a filtered sample (0.45µm) from Persian Gulf water with a filtered water sample taken from the Minab river in 9 different salinity proportions is studied. For the first time flocculation of elements in relation to redox potential (Eh) is investigated and the results indicated that elemental flocculation during estuarine mixing is not controlled by (Eh). The flocculation trend of studied metals is Cu (83.3%)> Ni (82.9)> Zn (75.2%)> Mn (69.4%) > Pb (38%). Flocculation rate varies considerably from one metal to another. Highest flocculation of metals occurs between salinities of 3.3‰ to 11.4‰. Statistical analysis indicate that flocculation of metals (except for Pb) is governed by dissolved organic carbon whose source is teri-genous in the area of study. The amount of metal flocculation is about 30.5, 6.6, 25.3, 10.4 and 36.5 ton/yr for Zn, Pb, Ni, Cu and Mn, respectively, as a result of mixing of Minab river water with the Persian Gulf water. Therefore estuarine processes can be considered as effective mechanisms in clean up of colloidal metals that are anthrop pogenically entered into the fresh water ecosystem.

Equal to international efforts for more attention to the capacity of the earth and preservation of the resources which is the best of sustainable development, Islamic Republic of Iran try to pay its proportion of these efforts too. Emprises like establishing national committee of the sustainable development due to the Rio De Janeiro summit, interpolating the environmental consideration in the Laws of Economic, Social and Cultural Development Plans, and performing projects with cooperation of international towards preserving environment proofs these claims.Despite of accomplishing all these emprises in different fields for achieving goals of the agenda 21 and approaching sustainable development we could state that there still are some shortages and incompetency in different fields specially in politics and laws. So considering the available incompetency and also preferences and necessities which is caused by the circumstances of the country, we could present some proposals such as utilizing management implements alike logical and economical tools as means of planning and management, promoting public co-operations and training environment to preserve of resources for sustainable development in Iran, active attendance in local and international environment co-operations and also codify and implement local agenda 21 that they are challenging for achieving the goals of the agenda 21 and approaching sustainable development.

This research evaluates the meteorological drought spells by multi-dimensional comparison of fourmeteorological drought indices supported with 35 years rainfall data (1967-2001) series records for 22 rain gauge stations in a cold semi-arid region located in west of Iran. Drought indices include: Percent of Normal Precipitation Index (PNPI), Z Standard Index (Z), Rainfall Anomaly Index (RAI) and Standard Precipitation Index (SPI). After calculation of drought indices for the desire time scale, they were evaluated and compared using correlation relations. Using Cluster Analysis technique, the drought status in the region was classified into different categories. The criteria were the statistical ones based on the succession of dry, normal and wet years. It was found that both Z and RAI indices were statistically similar and gave almost similar results in drought evaluations. By correlation, all indices of PNPI-Z, PNPI-RAI and Z-RAI in all stations indicated high reciprocal correlations in addition to Z-RAI which showed similar results explaining drought conditions. Finally, from the correlation relationships and the output den do-grams, RAI and Z were respectively identified as the best indices for meteorological drought evaluations in the region, due to more relevance to the reality than the rest. These indices showed that four droughts have occurred during years of 1967-1968, 1976-77, 1983-84, 1988-89, 1996-97 and 1998-99. Despite the common use of SPI in monitoring the meteorological drought in Iran, this index is not recommended for cold semi-arid climate conditions.

Today, theoretical sciences are practiced through experimental and practical activities. In other words, sciences such as physics and biology, which are derived from nature, have turned into fundamental bases for the study of other subjects such as arts and architecture.Taking architectural ideas out of natural features is being widely used in modern architect's works (such as the Fractal and Revolutionary ideas), so a need arises here to find some media to generalize scientific details in different fields and apply them to the details in architecture.To find these intermediaries, the involved process is moving from instances to the generalities to reflect them in architectural instances of expressing natural features directly in the architectural forms which must be avoided and instead we should observe general rules of nature and then reflect them in the architecture. The process of 'from slight to whole and from whole to slight' or the so-called 'architectural creativity' will result in prominent and lasting works in our provided architecture that they are derived from natural observations. The subject-matter has been dealt with in this article. The article consists three major parts as fallows.• A study of religious, mystical and functional aspects, as well as the philosophy of nature. • Looking for some principles governing natural phenomenon which could be useful in generating forms. • A study of natural forms for architects and designers.

One of the results of contemporary modernity is a strong presence of media in daily life. Scholars see this process from different aspects and the issue which is widely accepted by them is the deep influence of media on people.This influence and experience which is a mediated experience, due to its fast nature and mass information, cannot be a deep experience and it reduces the direct effect of environment.This issue which can shape the relationship between the human and environment in the area of architecture is very important and at the first stage training about it is very vital. Contemporary architecture has a global view and challenges such as tradition and modernity in Iran and the education system of it contains a lot of compulsory and fundamental differences with the past. Because of fastness, easiness, low costing and attraction of media big majority of students use it and get influenced by it. So because of the mentioned reasons this question is asked "What is the role of media in architecture education and environmental experiment for students?" Based on the above isuues a research was done amongst 250 students of Tehran and Islamic Azad university of Tehran in the year of 85-86. The results showed that major part of their architectural knowledge is gained via media which is not deep enough. This recognition is weak as there is no deep knowledge about philosophy of architecture and its related cultural and social issues which causes a weak and inefficient environmental experiment.