فهرست مطالب

  • Volume:1 Issue:1, 2013
  • تاریخ انتشار: 1392/01/26
  • تعداد عناوین: 8
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  • E. Solgi, S.M. Ghasempouri, A. Esmaili Sari Page 1
    Otters at the top of the food chain and feeding largely on fish are likely to be especially vulnerable to the effects of bioaccumulating pollutants. This research reports the first data on mercury levels found in hairs of river otters (Lutra lutra) from Iran. Between June and December 2007, we collected museum and recent collections of river otter hair. These samples were collected from several provinces of three major regions of Iran. The mean of mercury concentration for all samples (recent and museum) was 5.819±1.557 mg/kg with 95% confidence interval for the mean. The concentrations of Total Hg (THg) in hair ranged from 0.293 to 12.382 mg/kg. No significant variation among the sample regions existed. A comparison of THg concentrations between two decades (1986-1996 and 1996-2006) showed that these differences were significant (psignificant difference was found between museum and recent specimens. This study has shown that the river otter has been exposed to THg with increasing trend in two past decades.
    Keywords: Back calculation, Hair, Iran, Mercury, River otter
  • A.R. Ildoromi Page 11
    Study area is located in West of Iran with relatively rough topography. Lithologic units in the region belong from Jurassic and Cretaccous till recent era. The study area of the Alvand mountain region is related to the tectonic zone of the Sanandaj–Sirjan region and the area dominant neo-tectonic regime appears to be compressional-extensional type. One of the identification tools to find out the existence of recent neotectonic activities is tectonic geomorphology evaluation. In this study, we tried to measure the required parameters using topographic maps with scales of 1:50000 utilizing AutoCAD software. In order to identifying the morphologic landform anomalies we use asymmetry factor, transverse topographic symmetry factor and mountain-front sinuosity index. The neotectonic activity of the study area investigated by considering geologic, seismic and remote sensing evidences and with establishing relationship between these evidences and morphologic landforms. Results indicated that tilting occurred around NW-SE axis. There is a remarkable correlation between active mountain front, fault and cleavage identified (from satellite images) and position of earthquake epicenters of study area. Hence all of these evidence indicating the activity of the study area from neotectonic and instability of sub watersheds point of view.
  • A.R. Nafarzadegan, A. Talebi, H. Malekinezhad, N. Emami Page 23
    Rainfall is recognized as one of the main triggering factors of landslides. Researchers have long attempted to determine the amount of precipitation required to trigger slope failures. One of the landslide zones in Iran is Chaharmahal & Bakhtiari province where many landslides cause high casualties in recent decades. It is significant that most of these landslides occur after a rainy period. Thus, determination of rainfall thresholds in this province seems to be necessary as the first step to present an effective landslide warning system. In this research, we tried to introduce some antecedent rainfall thresholds for deep-seated landslides. The antecedent periods considered for the events examined in this study were 5, 10, 15, 20, 25, 28 and 30 days. Since most of landslides occurred by cumulative rainfall for more than 10 days, the results of 5 days and shorter time periods appear not logically connected. We have also established rainfall thresholds for the 15-day antecedent period and 2, 3 and 5 days rainfall events. Results indicate that for 10 to 30 days antecedent periods, mean total rainfall needed to induce landslides varies between about 140 and 280 mm. Finally, we recommend more research on relation between rainfall characteristics and destabilization of different soil classes in the study area (especially clayey-marly deposits).
    Keywords: Antecedent rainfall, Chaharmahal, Bakhtiari, Landslide, Threshold
  • R. Erfanzadeh Page 41
    The effect of soil and phanerogam characteristics on bryophytes composition, richness, abundance and functional groups were investigated in order to understand the factors responsible for bryophytes distribution patterns. Three different sand dunes were selected: untouched, artificial sod-covered and planted by Ammophila. Along 10 transects perpendicular to the shore, a total of 142 permanent relevés, located in three sand dunes, were sampled. In each plot, total cover of vascular herbaceous and bryophytes, and the percentage of litter were estimated. The average of vascular herbaceous height was measured. In each plot, EC, pH, CaCo3, texture and organic matter content of the upper 5 cm layer were also measured. Analyses usingDCA and GLM showed that bryophytes abundance was decreased by EC and phanerogam abundance, while pH increased the species richness of bryophytes. EC increased the relativeabundance of sexual species while decreased the relative abundance of asexual bryophytes species. The relative abundance of colonists increased in planted Ammophila sand dune while the relative abundance of perennial stayers was the highest in untouched sand dune. The successional stage should also be important in distribution pattern of bryophytes.
    Keywords: Bryophyte, Phanerogam cover, Sand dune, Soil characteristics, Restoration management, Succession
  • A. Farajollahi, A. Tavili, B. Gholinejad, J. Darini, H. Pouzesh Page 53
    This research was carried out to investigate allelopathic effect of Peganum harmala on seed germination of Bromus tectorum. Aboveground and underground tissues of Peganum harmala in addition to its seeds were collected from Bijar rangelands. Collected materials of root, leaves, stem, seeds and a complex of mentioned parts were dried and powder. The research was performed at the greenhouse condition. The treatments included 1, 3, 6, 9 and 12 weight percentage of above mentioned powders. Also a control treatment was used, too. A completely randomized design (CRD) was applied for 4 weeks. Germination seeds were counted and recorded daily. Germination properties included: germination percentage, mean germination time, germination speed, inhibitory percentage. At the end of study period, radicle and stem length were measured. Data were analyzed by ANOVA. The results revealed that allelopathic effect of P. harmala resulted in negative effects ongermination properties of Bromus tectorum. The high concentration of P. harmala has strong Allelochemicals inhibitory effects on germination and initial growth characteristics of B. tectorum. It was found that the materials obtained from different tissues of P. harmala had different levels of inhibition on germination properties of B. tectorum, so that seeds were the most inhibitor tissues. The lowest germination percentage and seedling growth resulted from 12gr powder of seeds.
    Keywords: Allelopathy, Bromus tectorum, Germination, Peganum harmala
  • R. Safaeian, Gh. Amin, H. Azarnivand Page 63
    Prangos ferulacea (L.) Lindl. (Umbelliferae family) is a dominant species in the some partial of habitats in Zagros Mountains. According to ethno-botanical studies, this plant is one of the best range plants of Iran. Local ranchers collect green Prangos while it is toxic. They then dry the plant and use it to feed their livestock, especially in winter season. This research done to analyse the changes in the chemical composition of Pr. ferulacea with the effects of time, location and type of secondary metabolisms. Therefore, the ingredients and amounts of the essential oils of Prangos were studied during the growing and flowering stages (in both green/fresh and dried forms) to track such changes. The results showed that the amounts of terpinolene, - phellandrene and bornyl acetate were decreased in the dried form, and some of the harmful components, such as -pinene, -pinene, myrcen and delta-3-carene, were absent, rendering the plant non-toxic. These results confirm the opinion of the ranchers. In the growing stage, the amount of coumarin was significantly less than in the flowering stage, which also supports the conduct of the local ranchers who gather the plants at the most appropriate time.
    Keywords: Chemical compounds, Ethno, botany, Iran, Phytochemistry, Pr. ferulacea (L.) lindl, Zagros
  • A. Kouhpeima, S. Feiznia Page 75
    Today fingerprinting techniques are increasingly adopted as an alternative and more direct and reliable means of assembling sediment source information. One of the principal assumptions of sediment fingerprinting is that potential catchment sediment sources canbe distinguished on the basis of their physical, geochemical and biological properties or fingerprint properties. However, while the source fingerprinting approaches necessarily assume conservative behaviour of the fingerprint properties, some in-stream alteration of these properties during both transport and short-term storage is probably inevitable. This potential limitation must be judged in the context of the problems associated with the use of sediment fingerprinting techniques. Samples of sediment source and reservoir sediment collected during the present study have been used to determine the conservative behavior of fifteen fingerprint properties. Comparison of fingerprinting property concentrations of intensive properties used in fingerprinting indicates there is an increase in content of the N, P, C, Co, Cr, clay minerals (smectite, illite, kaolinite), Low Frequency Magnetic Susceptibility (XLF) and Frequency Dependent Magnetic Susceptibility (XFD) and decrease in clay mineral chlorite and base cations Ca, Mg, Na and K. The results indicate that N, Na and smectite properties have no significant difference in reservoir sediment samples than that in sediment source samples and therefore are useful for fingerprinting investigations in these catchments.
    Keywords: Conservative behavior, Fingerprinting properties, Reservoir sediment, Sediment sources
  • M.S. Lazerjan Page 85
    The relocation of nutrients and water fluxes to the forest floor varies spatially due to artition of rainfall into throughfall and stemflow by tree canopies. In this study, nutrient concentrations of rainfall and stemflow were measured for seven rainfall events in Chaboksar area in the Hyrcanian ecozone of Iran composed of Juglans regia Linn and Cup. Sempervirens L.Var. Fastigiata where such information was absent. In the course of the study, a total of 24 samples were collected, and stemflow samples of these species were analysed in relation to rainfall. The results of this study suggest that the nutrient concentrations in stemflow are mainly influenced by vegetation species. The concentrations of CaCO3, nitrate, calcium, magnesium, sodium, zinc, and chloride, were all higher in the stemflow of cypress tree than that of the walnut tree. The concentration of iron in both stemflow samples was zero. The pH level in the stemflow of Juglans regia Linn and Cup. Sempervirens L. Var. Fastigiata was slightly lower than rainfall pH level. However, in terms of heavy metals, the concentration of lead in cypress stemflow was found to be higher than that in walnut stemflow. Furthermore, a very small amount of copper was detected in the stemflow of cypress tree. Electrical conductivity of cypress stemflow was also higher than that of walnut stemflow.