Environmental Erosion Research

fa بررسی تغییرات شاخص‌های رسوبات بادی نهشته شده در منطقه اردمه شهرستان نیشابور Study of the Changes in Aeolian Sediment Indices in the Ardamah Region of Neyshabur County مدلسازی و تحلیل زمانی و مکانی رخداد انواع مختلف فرسایش محیطی مستخرج از پایان‌نامه / رساله / طرح پژوهشی مشخصه‌های دانه‌بندی رسوبات، اطلاعات مهمی را درباره شرایط رسوب‌گذاری و محیط حمل و نقل فراهم می‌کنند. این مشخصه‌ها شامل قطر میانه، چولگی، کشیدگی، جورشدگی، گردشدگی، فراوانی تجمعی ذرات، محتوای مواد آلی، مقدار کربنات کلسیم و بافت رسوبات هستند. در این پژوهش، ویژگی‌های گرانولومتری، مقدار مواد آلی، کربنات کلسیم و بافت رسوبات بادی مدفون در منطقه اردمه نیشابور در یک پروفیل عمودی از سطح زمین تا عمق 3 متری مورد مطالعه قرار گرفت. بدین منظور، 30 نمونه با فواصل 10 سانتی‌متری عمقی نسبت به یکدیگر از این پروفیل جمع‌آوری شده و آزمایش‌های دانه‌بندی، مواد آلی و کربنات کلسیم انجام شد. همچنین، به منظور بررسی الگوهای تغییرات این شاخص‌ها نسبت به یکدیگر، تمامی متغیرهای مورد مطالعه به‌صورت جداگانه و نیز از طریق تحلیل همبستگی مورد ارزیابی قرار گرفتند. نتایج نشان داد که منبع اصلی رسوب‌گذاری در این منطقه بیشتر به‌صورت محلی بوده است. در لایه‌های سطحی رسوبات، درصد ماسه‌های ریزدانه و متوسط دانه بالاتری نسبت به لایه‌های عمیق‌تر وجود دارد که می‌تواند نشانه‌ای از فعالیت بیشتر فرآیندهای بادی در سطح خاک باشد. بیشترین مقدار کربنات کلسیم برابر با 8.25 درصد و کمترین مقدار آن 4.25 درصد بود و با افزایش عمق، روند کاهشی نشان داد که این می‌تواند به تغییر شرایط شیمیایی خاک و فرآیندهای رسوب‌گذاری مرتبط باشد. در بررسی میزان ماده آلی، با افزایش عمق روند افزایشی (بین 1.64 تا 5.01 درصد) مشاهده شد که می‌تواند حاکی از ثبات بیشتر لایه‌های عمیق نسبت به لایه‌های سطحی یا وجود شرایط مساعدتر برای انباشتگی مواد آلی در گذشته باشد. نتایج آزمایش‌های دانه‌بندی نیز نشان داد که با افزایش عمق، شاخص‌هایی چون میانگین قطر ذرات، چولگی، جورشدگی و انحراف معیار کاهش یافته‌اند. این موضوع می‌تواند بیانگر تغییر در منبع رسوب، نوع فرآیند حمل یا شرایط رسوب‌گذاری در طول زمان باشد. در نهایت تحلیل همبستگی‌ها حاکی از هدم روابط معنی دار بین متغیرها بود.   1. Introduction Aeolian erosion is a significant geomorphological process wherein wind acts as a powerful agent, mobilizing and transporting large quantities of sediment across terrestrial surfaces. This phenomenon is particularly consequential in arid and semi-arid regions, where it impacts human settlements, infrastructure, agricultural productivity, water resources, and air quality, mainly via the generation and dispersal of dust and fine particulate matter. Over recent decades, scientific research has made considerable strides in understanding the properties and behaviors of wind-blown sediments. Globally, studies have emphasized the importance of grain size distribution, particle shape (including roundness and sphericity), and surface texture in deciphering sediment provenance, transport mechanisms, and depositional histories. These advances have been facilitated by technological innovations such as scanning electron microscopy and robust statistical modeling, which have enabled more detailed and quantitative characterization of sediments and past environmental conditions. Despite the wealth of research on aeolian processes worldwide, there is a relative paucity of studies focusing on the morphological attributes and organic matter content of buried aeolian sediments in Iran. This knowledge gap limits our ability to reconstruct sedimentary dynamics, understand paleoenvironmental evolution, and address the mechanisms behind land degradation in some of the world’s most vulnerable and rapidly changing landscapes. The present study seeks to address this gap by conducting a comprehensive, multi-parameter analysis of buried aeolian sediments from the Ardameh region of Neyshabur, located in the Razavi Khorasan Province of Iran. By integrating analyses of grain size, morphology, organic matter, and calcium carbonate content, this study aims to enhance scientific understanding of aeolian depositional systems within the Iranian desert context. 2. Materials and Methods The study area was selected based on the presence of buried aeolian sediments in a dryland setting, as identified through high-resolution satellite imagery (Google Earth) and corroborated by extensive field surveys in the Ardameh region. Soil sampling was conducted systematically along a single stratigraphic profile, with samples collected at 10-centimeter intervals to a maximum depth of three meters, resulting in a total of 30 samples. Each sample underwent laboratory analysis to determine particle size distribution, organic matter content, and calcium carbonate concentration. Granulometric parameters such as median grain size (D50), mean particle diameter, standard deviation, variance, geometric mean diameter, skewness, maximum particle size, and cumulative frequencies at the 10th, 50th, and 90th percentiles were extracted from the particle size data. These metrics allowed for a detailed assessment of the vertical variation in sediment properties throughout the profile. Further, statistical correlation analyses were performed to evaluate the relationships among these physical and chemical properties, providing a comprehensive understanding of sediment dynamics and potential environmental controls. 3. Results The sediment samples analyzed in this study predominantly exhibited sandy textures—classified as sand, sandy loam, and loamy sand which are characteristic of the local parent materials and sediment sources typically found in arid environments. Organic matter content showed considerable variability with depth, reaching a maximum of 5.01% at a depth of 205 cm and a minimum of 1.64% at 65 cm. This pronounced decrease in organic matter toward the surface is consistent with the ecological limitations of desert landscapes, where sparse vegetation, high evaporation rates, and minimal biological activity inhibit the accumulation and preservation of organic material in surface layers. The mean particle diameter did not display a strictly monotonic trend with depth; however, a general decrease in grain size was observed toward the uppermost layers. This pattern may indicate a transition toward more localized sediment sources in recent depositional episodes, likely as a result of intensified surface disturbance, diminished vegetation cover, and increased dust availability. Thus, changes in grain size distribution provide indirect evidence for recent landscape instability and heightened aeolian activity. Sorting indices indicated moderately poor to moderate sorting throughout the profile, reflecting deposition under variable wind turbulence. Notably, sorting improved with increasing depth, suggesting that older, deeper sediments were deposited during more stable and less energetic environmental conditions possibly when vegetation cover was denser and wind velocities lower. The progressive decline in both standard deviation and variance with depth supports this interpretation, indicating a narrowing of particle size distribution in older strata and more consistent transport and depositional dynamics in the past. Importantly, statistical analyses revealed no significant correlations between organic matter content and granulometric parameters, underscoring the independence of organic matter fluctuations from textural variability. 4. Discussion and Conclusion The results of this study suggest a temporal shift in the Ardameh region from historically stable, low-energy depositional environments to a modern regime marked by increased landscape dynamism and erosion. These trends mirror broader patterns observed in Iran, where both anthropogenic activities and climatic changes are accelerating the expansion of desertification. In the Ardameh region, aeolian sediments are primarily derived from local sources, with ongoing desertification raising erosion rates and promoting the movement of coarser grains over relatively short distances. As sediment depth increases, organic matter content generally declines, reflecting reduced external organic input and a shift toward more localized sediment sources. Collectively, these findings highlight the significant roles played by both climatic and anthropogenic factors in shaping the sedimentary and ecological landscapes of Iran’s arid regions. The study underscores the need for continued research and monitoring to better understand the dynamics of aeolian processes and to develop strategies for mitigating the impacts of land degradation and desertification.   توزبع دانه‌بندی رسوبات – مورفولوژی – رسوبات بادی- تغییرات عمقی– اردمه. Grain size distribution–Morphology–Aeolian sediments–Vertical distribution– Ardameh 0 0 http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-70-3&slc_lang=fa&sid=1 Mohammad Javad Yousefi محمدجواد یوسفی m.j.yoosefi90@gmail.com 100319475328460010163 100319475328460010163 No Gorgan University of Agricultural Sciences and Natural Resources دانشگاه علوم کشاورزی و منابع طبیعی گرگان Mohsen Hosseinalizadeh محسن حسینعلی زاده mhalizadeh@gau.ac.ir 100319475328460010164 100319475328460010164 Yes Gorgan University of Agricultural Sciences and Natural Resources دانشگاه علوم کشاورزی و منابع طبیعی گرگان Alireza Rashki علیرضا راشکی arrashki@gmail.com 100319475328460010165 100319475328460010165 No Ferdowsi University of Mashhad دانشگاه فردوسی مشهد Hamidreza Abbasi حمیدرضا عباسی hamidabbasi9999@gmail.com 100319475328460010166 100319475328460010166 No National Forest and Rangeland Research Institute, Agricultural Research, Education and Extension Organization سازمان تحقیقات آموزش و ترویج کشاورزی Ali Mohammadian Behbahani علی محمدیان بهبهانی ali.mohammadian@gau.ac.ir 100319475328460010167 100319475328460010167 No Gorgan University of Agricultural Sciences and Natural Resources دانشگاه علوم کشاورزی و منابع طبیعی گرگان Narges Kariminejad نرگس کریمی نژاد narges.karimi991@gmail.com 100319475328460010168 100319475328460010168 No Shiraz University دانشگاه شیراز