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علوم محیطی | سال:1391 | دوره:9 | شماره:3

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مرکز اطلاعات علمی SID1
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
Issue Info: 
  • Year: 

    2012
  • Volume: 

    9
  • Issue: 

    3
  • Start Page: 

    1
  • End Page: 

    14
Measures: 
  • Citations: 

    2
  • Views: 

    252
  • Downloads: 

    100
Abstract: 

In this research, the recreational value of the Radio-darya coast of the Chalous coastline was estimated, alongside the measure of visitors' willingness-to-pay (WTP), by using a contingent valuation (CV) method and dichotomous choice (DC) questionnaire. WTP was measured by using a Logit model which parameters were estimated based on the Maximum Likelihood (ML) Model for the year 2009. The results show that 65 percent of investigated individuals will pay for recreational usage of the aforementioned coast. The average WTP is 1169 Rials (about 1 USD) for each visit. Recreational monthly value of this coastal region is more than 37.75 million Rials (about 3230 USD); to be precise, the total annual recreational value of this area is estimated to be about 453 million Rials. Furthermore, the variables of "offer" and "visitors' income" are statistically significant at the level of 1%; so, these two variables are considered as the most important factors affecting visitors' WTP. The next factor influencing their WTP, from the point of view of visitors, is the quality of the coast (coastal neatness and water limpidity) which is significant at the 1% statistical level. Level of education is the next effective factor with significance at the 10% level. Moreover, distance between the coast and place of residence is the next factor affecting WTP negatively at the 10% level.

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Issue Info: 
  • Year: 

    2012
  • Volume: 

    9
  • Issue: 

    3
  • Start Page: 

    111
  • End Page: 

    118
Measures: 
  • Citations: 

    0
  • Views: 

    156
  • Downloads: 

    86
Abstract: 

A field experiment at Qom province was conducted to study the effects of different amounts of nano iron oxide powder and urban solid waste compost coated sulfur (USWCS) on yield and yield components of sunflower plants in a saline-sodic soil, in a randomized complete block design with factorial arrangement with three replications. Treatments were two levels of urban solid waste compost coated sulfur (0 and 15 ton/ha) and two levels of nano iron oxide powder (0 and 20 mg/kg) applied to plots of 4 m2 and sunflower plants were sown.The results showed that the use of nano iron oxide and USWCS increased grain yield by 4 and 22 percent, respectively, compared to the control. The maximum increase in dry matter yield was observed by combined use of 15 (ton/ha) USWCS and 20 (mg/kg) nano iron oxide. Application of nano iron oxide powder significantly increased the plant height, head diameter and 1000 seed weight of sunflower plants. This increasing trend with the use of USWCS was also observed in plant height, head diameter and 1000 seed weight by 8, 18 and 15 percent, respectively, compared to control.

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Issue Info: 
  • Year: 

    2012
  • Volume: 

    9
  • Issue: 

    3
  • Start Page: 

    119
  • End Page: 

    128
Measures: 
  • Citations: 

    1
  • Views: 

    357
  • Downloads: 

    122
Abstract: 

Thermal stress in plants is any temperature increase above the threshold level for a period of time which causes immutable damage in plant growth. At very high temperatures associated severe cellular damage and cell death may occur within a few minutes as a result of disassembling the cell structures. Direct damage from heat stress includes disruption of the protein structure and an increase in fluidity of cell membranes, as well as indirect damage. The result of these disorders is damage to the plants that prevents growth. In the current study, the occurrence time of thermal waves or some climatic phenomena in Qazvin Province were studied over a 25-year period (1982-2007) and an assessment was made of the impact of thermal stress on corn plant growth. The results showed that the highest thermal waves were seen in the months of June, July and August in the years 1985, 2000 and 2001. More heat waves occurred during July in the years 1983, 1995, 1997, 2003 and 2006 while in August more heat waves were experienced in 1983, 1983 and 2005. Over this 25-year period, only on 10 days in June, 63 days in July and 50 days in August did the temperature reach above 38 degrees when corn plant is under stress. In these three months, more negative impact was found in July that caused crop quality reduction or even the death of the plant. When thermal waves increased and rose above than plant endurance threshold, this had a negative impact on production and caused the production rate to reduce or, in some cases, collapse completely.

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Issue Info: 
  • Year: 

    2012
  • Volume: 

    9
  • Issue: 

    3
  • Start Page: 

    15
  • End Page: 

    26
Measures: 
  • Citations: 

    0
  • Views: 

    119
  • Downloads: 

    85
Abstract: 

The purpose of this study was to determine the efficiency of the USBF process for biological nitrogen removal and achieving the optimal hydraulic retention time according to the maximum nitrogen removal in the system. The synthetic wastewater which was used in this research, was a compound of glucose and urea as a carbon and nitrogen source with the COD/N ratio remaining around 10, while the N concentration based on the sum of nitrite and nitrate ions was approximately 50 mg/L. The investigation was carried out over two phases of start up with inoculation, and the operation at differing hydraulic retention times with flow rates of 0.8, 1, 1.2, 1.4, 1.6, 1.8 and 2 lit per hour. The experimental results showed the increasing efficiency of the system in nitrogen removal with increased flow rates, such that 89.4, 92 and 95.1 percent of the initial phosphorus concentrate in the wastewater was removed at flow rates of 0.8, 0.1 and 0.12, respectively; however, at flow rates of 1.4, 1.6, 1.8 and 2 lit per hour, the mean nitrogen removal efficiency was reduced to 93, 88, 83 and 80 percent, respectively. At the end, the hydraulic retention time for the biological nitrogen removal in this process, was determined at 40 hours in the whole system which is equivalent to 5 hours hydraulic retention time in the clarifier. USBF, as an advanced biological process, had an appropriate removal efficiency for the biological treatment of nitrogen.

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Issue Info: 
  • Year: 

    2012
  • Volume: 

    9
  • Issue: 

    3
  • Start Page: 

    27
  • End Page: 

    40
Measures: 
  • Citations: 

    0
  • Views: 

    342
  • Downloads: 

    117
Abstract: 

The crude oil of various oil reservoirs contain up to 7% sulfur and between 50-95 % of this sulfur is in the form of different thiophenes. The combustion of organosulfur compounds produces sulfur oxides that are the main cause of acidic rain and environmental pollution. The current method for desulfurization is hydrodesulfurization which is too expensive and sulfur does not get completely isolated, therefore, the researchers have focused on biodesulfurization method. Dibenzothiophene (DBT) has been used as a molecule model for validation of microorganisms’ ability in desulfurization. There is no report about chemolithoautotrophic bacteria that desulfurizes the crude oil. The isolated ISA4 bacterium which is used in this study does not break the carbon–carbon bond structure, but only removes the sulfur from the skeleton of DBT. From the industrial viewpoint, this bacterium does not require organic materials as energy and a carbon source for desulfurizing the crude oil. ISA4 Bacterium with 100% query and 99% homology is similar to Klebsiella oxytoca.

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Issue Info: 
  • Year: 

    2012
  • Volume: 

    9
  • Issue: 

    3
  • Start Page: 

    41
  • End Page: 

    58
Measures: 
  • Citations: 

    1
  • Views: 

    215
  • Downloads: 

    85
Abstract: 

Integrated Pest Management (IPM) has been introduced as an appropriate environmental strategy to control pest populations. The purpose of this descriptive correlational study was to determine the factors influencing the knowledge, attitude, skills, and aspirations (KASA) among a sample of orchard farmers participating in IPM training at a farmer field school (FFS). From a total of 130 participants, 97 orchard farmers were randomly selected as the sample size. A researcher-made questionnaire was designed using literature review and informal interviews with FFS participants outside the population. A panel of experts approved the content validity of research instrument. An alpha level of 0.86 showed sufficient reliability of the questionnaire. The results of step-wise regression analysis revealed that participating in FFS, farming experience, yield, trust, and social status affected orchard farmers’ IPM knowledge. Moreover, farmers’ attitudes towards IPM were influenced by knowledge diffusion, creativity, and access to horticultural equipment. In addition, knowledge diffusion, yield, membership in farmer cooperatives, and being creative affected orchard farmers’ skills in IPM. Finally, job satisfaction, age, and knowledge diffusion influenced farmers’ aspirations towards IPM. The result of this study has implications for IPM-FFS policy-makers. Developing FFS sites and actors in the province, conducting orientation classes in IPM for contact farmers, and extending financial support to IPM are all recommended.

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Issue Info: 
  • Year: 

    2012
  • Volume: 

    9
  • Issue: 

    3
  • Start Page: 

    59
  • End Page: 

    70
Measures: 
  • Citations: 

    0
  • Views: 

    193
  • Downloads: 

    81
Abstract: 

In order to study the effect on sunflower and cotton of the residue of some sulfonylurea herbicides, two randomized complete block design studies were conducted with ten treatments in four replications for both of plants. Treatments included: sulfosulfuron (Apirus), idosulfuron + mesosulfuron (Chevalier), chlorsulfuron (Megaton), sulfosulfuron + metsulfuron methyl (Total), idosulfuron + mesosulfuron + mefenpyr (Atlantis) where all of the herbicides were used in three doses, with a no-herbicide control. Soil was sprayed with the herbicides and the treated soils were transferred to the greenhouse after four months, and sunflower and cotton were planted in pots containing these soils. The length and dry weight of different plant organs (root, stem and leaf) and total dry weight were measured at the four-leaf stage. The results showed that the treatments had negative effects on most of the measured characteristics in sunflower and sulfosulfuron + metsulfuron methyl and chlorsulfuron at the highest dose (44 and 22.5 g ai ha-1, respectively) had the most harmful effects on the sunflower and reduced dry weight by 82.97% and 70.31%, respectively, in comparison with the control. Only the height and root length of cotton had been affected of the herbicides and sulfosulfuron + metsulfuron methyl and chlorsulfuron at the highest dose had the greatest negative effects on the height and root length of cotton. In attention to the results obtained, we can conclude that sunflower is probably more sensitive than cotton towards sulfonylurea herbicide residue.

Yearly Impact:  

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Issue Info: 
  • Year: 

    2012
  • Volume: 

    9
  • Issue: 

    3
  • Start Page: 

    71
  • End Page: 

    92
Measures: 
  • Citations: 

    0
  • Views: 

    553
  • Downloads: 

    168
Abstract: 

The results of field and laboratory measurements show a gradual increase in major (Na, Ca, Cl, SO4) and minor (Li, Br, Sr, I, Ba, F, Si) elements through groundwater flow direction. Electrical conductivity varies between 561 and 11390 mS/cm. The chloride ion, as an indicator of groundwater salinization, is highly correlated with EC and the elements Mg, Ca, Br and Sr. Certain ratios, the saturation index and geochemical graphs indicate that both the dissolution of evaporation deposits (halite and gypsum) and cation exchange are the most important processes affecting the chemical composition of groundwater. Mass ratios of conservative elements Cl/Br for groundwater samples in Lenjanat plain range from 329 (at the borders) to 4492 (center of the plain). These data confirm the reported Cl/Br ratios for groundwater affected by the dissolution of evaporation deposits but overlap with range of Cl/Br ratios for domestic sewage effluent groundwater.

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Issue Info: 
  • Year: 

    2012
  • Volume: 

    9
  • Issue: 

    3
  • Start Page: 

    93
  • End Page: 

    110
Measures: 
  • Citations: 

    0
  • Views: 

    193
  • Downloads: 

    95
Abstract: 

In the present study depositional temperature, diagenetic type and major climatic changes are investigated using oxygen and carbon stable isotopes. For this purpose, a sediment core (140 cm long) of 12 Km distance from the coast (near Langroud city), was collected from the southern Caspian Sea. A sedimentation rate of 0.9 cm/year was obtained based on a 210Pb and 137Cs isotope study of the sediment core. The depositional temperature and diagenetic type were obtained based on Mass Spectrometry analysis of sediment samples. The oxygencarbon isotope study indicates a very low depth of burial diagenesis. Water temperature based on the heaviest oxygen isotope value with least alteration, shows around 21oC during sedimentation, (120 years ago) while CTD results during sampling show the same result, so it seems that there have been no major climatic changes in the study area.

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مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID