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Vegetation composition differentiation and species-environment relationships in the northern part of Isfahan Province, Iran

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Journal of Arid Land 2017年第2期9卷 161-175页

作者： Hadi KARGAR-CHIGANI seyed Akbar JAVADI Ghavamodin ZAHEDI-AMIRI seyed jamaleddin khajeddin Mohamad JAFARI Department of Range Management Science and Research Branch Islamic Azad University Faculty of Natural Resources University of Tehran Range and Watershed Management Division Department of Natural Resources Isfahan University of Technology

A considerable proportion of Iran＇s territory is covered with arid and semi-arid rangelands and mismanagement and overexploitation of those rangelands have resulted in serious ecological degradation. Thus, the need is pressing to examine the present species composition and the relationships with environmental factors for providing the needed scientific references to species conservation and ecological rehabilitation efforts. The aims of this study were to examine the species composition and to delineate the most important factors influencing the distributions of plant species and groups in the northern rangelands of Isfahan Province （Iran） using two-way indicator species analysis （TWINSPAN）, detrended correspondence analysis （DCA）, principal component analysis （PCA）, and canonical correspondence analysis （CCA）. Field investigations were conducted in the growing season of 2014 using stratified random method in 22 homogeneous sampling units. In total, 75 plant species belonging to 52 genera and 19 families were identified. The most important families were Asteraceae and Papilionaceae, the most important genera were Astragalus, Cousinia, and Acanthophyllum, and the most important species were Artemisia aucheri and Artemisia sieberi. Plant species were classified into 10 groups using TWINSPAN. DCA was used to estimate the magnitude of changes in species composition along the first two ordination axes to provide gradient length estimations for PCA and CCA ordinations. The first three PCA axes and the first three CCA axes demonstrated similar cumulative percentage of variance, indicating that the environmental factors （selected by PCA） used in CCA ordination were acceptable for explaining the species composition and the distributions. CCA ordination showed that the first axis was closely related to elevation, slope, surface bare soil cover, surface litter cover, gravel proportion, organic matter, total nitrogen, CaCO3 content, and grazing intensity and that the second axi

关键词： rangeland classification ordination multivariate analysis plant groups Isfahan Province

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Optimization of Solid Phase Microextraction Procedure Followed by Gas Chromatography with Electron Capture Detector for Pesticides Butachlor and Chlorpyrifos

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American Journal of Analytical Chemistry 2014年第9期5卷 535-546页

作者： Fateme Ghavidel seyed jamaleddin Shahtaheri Reza Khani Jazani Marzieh Torabbeigi Abbas Rahimi Froushani Monireh Khadem Department of Epidemiology and Biostatistics School of Public Health Tehran University of Medical Sciences Tehran Iran Department of Occupational Health Engineering School of Public Health Tehran University of Medical Sciences Tehran Iran Faculty of Health Safety and Environment Shahid Beheshti University of Medical Sciences Tehran Iran Institute for Environmental Research Tehran Iran

In this study, headspace solid phase microextraction (HS-SPME) followed by gas chromatography using electron capture detection system (GC-ECD) were developed for the determination of chloraacetanilide (butachlor) and chlorpyrifos presented in biological samples. Different parameters affecting the extraction procedure were optimized including extraction time (30 minutes), extraction temperature (80°C), sample volume (3 mL), sample pH (2), added NaCl (0.3 gram) and sample stirring rate (400 rpm). Different concentrations of 1 - 100 ng/ml were applied for butachlor and a linear calibration curve was obtained. Furthermore, a similar linearity was obtained for chlorpyrifos, using a concentration range of 1 - 250 ng/ml. The limit of detection (LOD) obtained for butachlor and chlorpyrifos were 0.088 and 0.53 ng/ml respectively. The optimized methods for both compounds were validated using two concentrations of 25 and 50 ng/ml in spiked urine samples. Obtained recoveries of spiked urine samples were 83.06% - 99.8% with RSD of lower than 11%. Optimized technique was simple, inexpensive, solvent free and fast in comparison with other conventional methods and had compatibility with the chromatographic analytical system. This method offers low detection limits to analyze pesticides in urine samples that are very important in the exposure monitoring in occupational health.

关键词： HS-SPME GC-ECD Biological Samples Chlorpyrifos Butachlor

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