نشریه علوم محیطی
سال نهم شماره 3 (پیاپی 35، بهار 1391)

In this research, recreational value of Radio-darya of Chalous was estimated, besides the measure of visitor's willingness-to-pay (WTP) by using contingent valuation (CV) method and dichotomous choice (DC) questionnaire. WTP was measured by using Logit model whose parameters was estimated based on Maximum Likelihood (ML) Model. The results show that 65 percent of investigated individuals will to pay for recreational usage of mentioned coast. The average of WTP is 1169 Rial (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, total annual recreational value of this area is estimated about 453 million Rials. Furthermore, the variables of offer amount and visitor's income are statistically significant at the level of 1%; so, these 2 variables are considered as the most important factors affecting visitor's WTP.The next factor influencing their WTP, in the view of visitors, is the quality of coast (coast neatness and water limpidity) which is significant in 1% statistical level. Level of education is the next effective factor with significance at 10% level. Moreover, the distance between coast and habitation place is the next factor affecting WTP negatively at 10% level.

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.

The crude oil of various oil reservoirs have up to 7% sulfur and between 50 - 95 % of the sulfur are 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 doesn’t break carbon – carbon bond structure and only remove the sulfur from the skeleton of DBT. From the industrial view, this bacterium does not need organic materials as energy and carbon source for desulfurizing the crude oil. ISA4 Bacterium with 100% query and 99% homology is similar to Klebsiella oxytoca.

Integrated Pest Management (IPM) was introduced as an appropriate environmental strategy to control pest population. The purpose of this descriptive correlational study was to determine factors influencing knowledge, attitude, skills, and aspirations (KASA) among a sample of orchard farmers participating in IPM training in farmer field school (FFS). From a total of 130 participants, 97 orchard farmers were randomly selected of sample size. A researcher-made questionnaire was designed using literature review and informal interview 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. 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’ attitude towards IPM was 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 in IPM. The result of this study has implications for IPM-FFS policy-makers. Developing FFS sites actors the province, conducting orientation classes in IPM for contact farmers, and extending financial support to IPM is recommended.

In order to study the effect of residual in some of sulfonylurea herbicides on sunflower and cotton, two randomized complete block design was 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) that all of the herbicides were used at three doses, and no-herbicide control. Soil was sprayed with the herbicides and the treated soils were transferred to the greenhouse after four months, therefore, sunflower and cotton were planted in the pots included the soils. Length and dry weight of different plant organs (root, stem and leaf) and total dry weight were measured at four-leaf stage. The results showed that the treatments had negative effects on the most of measured characters in sunflower and sulfosulfuron+ metsulfuron methyl and chlorsulfuron at 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% in comparison of control, respectively. Whereas, height and root length of cotton had been just affected of the herbicides and sulfosulfuron+metsulfuron methyl and chlorsulfuron at highest dose had the most negative effects on height and root length of cotton. In attention to the gotten results, we can conclude that sunflower is probably the more sensitive than cotton into sulfonylurea herbicides residual.

For identifying sources of groundwater salinization in Lenjanat Plain, samples were seasonally collected from groundwater, surface water and industrial wastewater. 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 μS/cm. Chloride ion as an indicator of groundwater salinization, highly correlated with EC and elements Mg، Ca، Br and Sr. Certain ratios, 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 borders) to 4492 (the center of plain). These data confirm the reported Cl/Br ratios for groundwater affecting by the dissolution of evaporation deposits but overlap with range of Cl/Br ratios for domestic sewage effluent groundwater.

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

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.

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.