Environmental Erosion Research

fa مورفوسکوپی ذرات گرد و غبار با تأکید بر منشأ گردوغبار منطقه سرخس Morphoscopy of Dust Particles with Emphasis on the Source of Dust in Sarakhs Region مدیریت و کنترل اثرات فرسایش محیطی پژوهشي Research گرد و غبار، تودهای از ذرات جامد در مقیاس میکرون است که در هوا پخش میشود و اثرات زیانبار زیست محیطی، اجتماعی و اقتصادی بسیاری را از خود برجای میگذارد. شهرستان سرخس یکی از کانونهای بحرانی فرسایش بادی کشور و گرد و غبار است که تحتتأثیر بادهای 120 روزه قرار دارد و مسئول مشخصی برای بررسی علمی و کاربردی این پدیده در منطقه مشاهده نشدهاست. به منظور آگاهی از ویژگیهای بافتی با هدف شناسایی منشأ و ویژگیهای رسوبشناسی ذرات گرد و غبار، به جمعآوری نمونههایی از این پدیده در دو ماه متوالی (مرداد ـ مهر 1398) در منطقه سرخس پرداخته شد. سپس نمونهها توسط نرمافزار Grad State و میکروسکوپ الکترونی (SEM) به کمک نرمافزار Anix Emica، تحت آزمایش آنالیز لیزری (LPSA) قرار گرفت. نتایج نشان داد که تیپ غالب شناسایی شده، رسوبات دانهریز با بافت سیلتی با جورشدگی متوسط تا زیاد (66/2- 57/1) و کجشدگی (008/0- تا 79/0-) به سمت رسوبات دانهریز است. میزان سیلت در نمونه روستاهای مدنظر از گنبدلی تا بغبغو به ترتیب 96، 92، 89، 99، 96 درصد است و میزان رس، کمتر از پنج درصد ذرات را شامل میشود. خروجی میکروسکوپ الکترونی نیز نشان داد که ذرات در نتیجه تخریب سطحی دانه نامنظم است؛ به طوری که ممکن است در نتیجه برخورد ذرات یا عمل انحلال، قسمتی از دانه تخریب شود و اشکال ذرات به صورت نامشخص و چند وجهی نیمه گرد تا مدور باشد. در بعضی نقاط نیز سطح دانه، کثیف و خالدار یا به صورت پوسته و ورقه ورقه یا پولک دیده میشود. به علت داشتن خصوصیات فیزیکی متفاوت و چندتایی بودن نقاط پیک در نمودار توزیع اندازه ذرات، بیشتر رسوبات گرد و غبار منطقه رفتارهای چند منشأ دارند. همچنین جهت باد غالب منطقه، شمال غربی به جنوب شرقی است.   1- Introduction Dust is a mass of micron-scale solid particle that is dispersened into the air and has many harmful environmental, social and economic effects. Sarakhs city is one of the critical centers of wind erosion and dust in the country, which is affected by the 120-day winds of Sistan and no specific trustee has been observed for the scientific and practical study of this phenomenon in the region. In order to know the texture characteristics of this region with the aim of identifying the origin and sedimentological characteristics of dust particles, dust samples were collected in two consecutive months (August-October 2019) in Sarakhs region. The samples were subjected to laser analysis (LPSA) by Grad state software and electron microscopy (SEM) using Anix Emica software. In the sample of villages from Gonbadli to Baghboo, the amount and percentage of silt is 96, 92, 89, 99 and 96 and the clay content was less than 5% of the particles. Electron microscope output showed that the particles were irregular as a result of surface degradation of the grain so that, as a result of particle collision or dissolution, part of the grain is destroyed and the particle shapes are indistinct and polygonal Semi-circular to circular polyhedra. In some places, the surface of the grain was dirty and spotted or was in the form of flakes. Due to the different physical properties and the multiplicity of peak points in the particle size distribution diagram, most dust deposits in the region have multi-source characteristics. The prevailing wind direction of the northwest to southeast was also identified. 2- Methodology At first, the study section was selected with the help of experts and villagers and exisitng library studies of the villages that have mostly faced with and expereinced the dust crisis. Rural houses were established at a height of 2-4 m. Atmospheric dust was collected  by using 30 glass samplers for two months from August to October 2019. After collection and preparation, the samples were delivered to the Particle Laser Analysis (LPSA) Laboratory and Electro Microscopy(SEM) scan were performed. The results of particle size ere analyzed by using Gradl State software and the output from SEM was analyzed using Anix Emica software. Particle size samples (particle size determination) had been determined by the manufacturer: France Cordouan with Vasco3 model SEM samples were analyzed by electron microscopy with magnification of 2-5000 and EHT20 KV. Statistical parameters including sorting and mean skewness parameters and Kurtsis were calculated using Gradl State software. 3- Results In this study, first, the results of texture and granulation of suspended sediments deposited in different sedimentation systems in different parts of Sarakhs region were investigated. The results of granulation showed that silt has the largest share in suspended sediments and their texture is mainly in the middle range and forms particles less than 4 microns, these results were consistent with the findings of Salahi (2019) And Roghani (2018) . According to the results obtained from SEM, the shapes are hexagonal, and calcite crystals are well identified, indicating that the region contains clay silicates and carbonates as the predominant mineral of the quartz and calcite region. The results of the SEM showed that the Darta angle particles and are circular The results of PSA showed that the particles have two or more peaks, which indicates two or more peaks that indicate multiple origins (Hosseini, 2021). The particle size results indicate that the particles are very well sorted and in a way confirm the close transport distance to the particle from the harvest area to the place where the particles are trapped in the dust traps. As we move from Bazangan village to Baghbo village, which is in the south of Sarakhs region, sediments with much better sorting and inclination towards finer-grained sediments are included, which indicates that the origin of walnut particles of dust covers a longer distance It is generally stated that the sensitivity in the region is very high due to the percentage of silt frequency which is very high in the region. For dust, several sources can be considered, including local origin related to the soils of the region due to quartz and calcite minerals and human origin due to particle size outputs and descriptive statistics (sorting, Skewness, and Kurtsis) and SEM, which show very varied particle dimensions. This indicates that the wind speed from northwest to southeast has been decreasing, with the particle size tending to become smaller. 4- Discussion & Conclusions The results of PSA are related to the samples taken from the villages in question from Gonbadli to Baghbghoo. The amount Percentage of silt 96% 92% 89% and 99%. and the amount of clay is less than 5% of the particles. The distance of the particles from the medium grain silt to the clay is included, indicating that the particles have carried a medium to long distance and have a source of wind erosion. According to the results of SEM obtained from the analysis of dust particles by electron microscopy, the particles are irregular as a result of surface degradation of the grain to the extent that it may be damaged as a result of particle collision or dissolution of part of the grain. In addition, the result of mechanical destruction or dissolution of the grain surface is seen in the form of small and large cavities. Scaling or surface scratches caused by the physical destruction of the wind or the action of dissolution on the grain surface cause grooves to be formed or a part of the grain surface to be separateed in the form of flakes and dusty grains. The particles are observed in some grains and even the surface of the seeds is often abraded and the dust does not have a special radiance. In the parts that are a little brighter, the dust is seen as light spots due to the impact of light. Also, in the observed output, in some places, they can be seen on surface of the dirty and spotted grain (such as the effect of a needle on a body) or in the form of scales and flakes so that this surface causes the scattering of light in different directions and sometimes its reflection causes the grain not to be well-defined.   آنالیز لیزری, سرخس, گرد ‌‌وغبار, میکروسکوپ الکترونی, مورفوسکوپی. Laser Particle Size Analysis, Sarakhs, Dust, Scan Electron microscopy, Morphoscopy. 61 81 http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-854-1&slc_lang=fa&sid=1 masoume darmani معصومه درمانی m_darmani@semnan.ac.ir 10031947532846007049 10031947532846007049 No Semnan University دانشگاه سمنان haydeh ara هایده آرا ara338@semnan.ac.ir 10031947532846007050 10031947532846007050 Yes Department of Arid and Desert Management, Faculty of Desertology, Semnan University گروه مدیریت مناطق خشک و بیابانی، دانشکده کویرشناسی، دانشگاه سمنان alireza rashki علیرضا راشکی a.rashki@um.ac.ir 10031947532846007051 10031947532846007051 No Department of Drought and Desert Management, Ferdowsi University of Mashhad Contact number گروه مدیریت مناطق خشک و بیابانی، دانشگاه فردوسی مشهد abradat mafi آبرادات مافی abradatmafi@gmail.com 10031947532846007052 10031947532846007052 No Master of Geological and Mineral Exploration Organization of Northeast Khorasan کارشناس ارشد سازمان زمین شناسی و اکتشافات معدنی شمال شرق