بررسي تغييرپذيري برخي خصوصيات فيزيكي و شيميايي خاك در طول يك ترانسكت تحت تأثير فرسايش بادي در منطقه سگزي اصفهان

آب و خاک  

دوره 30 - شماره 1

نوع مقاله: Original Article
چكيده: فرسايش بادي يكي از اصلي ترين فرآيندهاي تخريب اراضي و يكي از جدي ترين مشكلات اكوسيستم و محيط زيست در مناطق خشك و نيمه‌خشك نظير مناطق مركزي ايران است. فرسايش بادي در منطقه شرق اصفهان و ناحيه سگزي به علت بهره‌برداري نامناسب از اراضي فقير، بهره‌برداري از معادن رس و گچ و خشكسالي هاي اخيرافزايش داشته است. فرآيند درشت شدنبافت خاك (نتيجه كاهش اندازه ريز ذرات خاك)، از دست رفتن مواد آلي و تخريب پوشش گياهي پيامدهاي فرسايش بادي بوده است. بنابراين نياز به اطلاعات معتبر در مورد شدت فرسايش بادي و تأثير فرسايش بادي بر روي خصوصيات فيزيكي و شيميايي خاك براي انجام عمليات حفاظت خاك ضروري مي باشد. در اين تحقيق به كمك روش سزيم-۱۳۷ نقاط فرسايش و رسوب در طول يك ترانسكت در منطقه سگزي (شرق اصفهان) تعيين و سپس اثر فرسايش بادي بر برخي ويژگي هاي فيزيكي و شيميائي خاك در نقاط فرسايش و رسوبگذاري بررسي شد. در اين پژوهش، درمنطقه مورد مطالعه در طول يك ترانسكت شمال شرقي- جنوب غربي به طول ۴۲ كيلومتر به فواصل ۲ تا ۵ كيلومتر در ۱۶ نقطه نمونه برداري صورت گرفت. در هر نقطه از اعماق ۵-۰، ۱۰-۵ ، ۲۰-۱۰، ۳۰-۲۰ و۵۰-۳۰ نمونه‌برداري خاك انجام شد و نمونه هاي برداشت شده مورد آناليزهاي فيزيكي، شيميائي و اندازه‌گيري محتواي سزيم-۱۳۷ قرار گرفتند. نتايج اين مطالعه نشان داد كه در نقاط ۱ تا ۸، ۱۰ و ۱۲ تا ۱۶ فرآيند فرسايش و در نقاط ۹ و ۱۱ فرآيند رسوب‌گذاري اتفاق افتاده است. نتايج نشان داد روش سزيم- ۱۳۷ مي تواند به صورت كمّي ميزان فرسايش و رسوب بادي در منطقه مورد مطالعه را تخمين بزند. مقايسه ميانگين خصوصيات فيزيكي و شيميايي خاك در اين مطالعه بين مناطق فرسايش، رسوب‌گذاري و مرجع نشان داد فرآيندهاي فرسايش و رسوب به شدت ويژگي هاي فيزيكي و شيميائي خاك رادر طول ترانسكت تحت تأثير قرار داده است. اين نتايج برگرفته از سزيم-۱۳۷ براي اولين بار نتايج قابل توجهي براي تحقيقات آينده در مورد فرسايش بادي در مناطق خشك ايران به دست آورد.
Variability of Some soil physical and chemical properties along a transect under wind erosion processes in Segzi district, Isfahan
Article Type: Original Article
Abstract: Introduction: Arid and semiarid environment is the main climatic condition in central Iran, as well as 80 million km 2 of Iran (> 50%) is affected by wind erosion. During the last decades, the area affected by wind erosion and desertification processes has increased as a result of human activity, climate change and recent drought (Karimzadeh, 2001). Thus, it is crucial to control wind erosion in the arid regions of Iran as the most serious environmental problem. In this regard, the information on the rate of soil erosion is needed for developing management practices and making strategic decisions.. Soil erosion rate has increased as a result of improper gypsum and clay mining operations In the Segzi region of Isfahan,. coarsening of the soil texture (as a result of the loss of fine textured materials), depletion of soil organic matter and degeneration of vegetation are wind erosion damages occurred widely. The objective of this study was to estimate wind erosion rates with 137Cs technique, and also to determine changes in soil physical and chemical properties by wind erosion process, along the wind erosion transect across the Segzi district, east of Isfahan.
Materials and Methods: This study was conducted in arid region of east of Isfahan Province. sixteen sites were selected along a northeast- southwest transect with 42 km length. Eighty soil samples were taken from 0-30 cm in 5 cm layer depth sections. Some physical and chemical properties were measured and a reference site with lowest rate of soil erosion and sedimentation was also studied. 137-Cs technique was used for determination of erosional and depositional sites. Analysis of variance was used to compare physical and chemical properties sites to reference site .
Results and Discussion: The results showed that sites of 1 to 8, 10 and 12-16 were identified as erosional sites and two sites of 9 and 11 were recognized as depositional sites. Soil organic matter and total nitrogen contents were reduced significantly In eroded sites compared to reference site. Similarly, clay content was reduced in the eroded sites compared to depositional sites. But,the amount of gypsum and calcium carbonate equivalent increased in eroded sites. Bulk density significantly declined in eroded (23.95%) and depositional (33.33%) sites comparing to reference site. Silt and sand content significantly were increased and decreased in depositional sites respectively compared to reference site. High speed winds caused to translocate the fine and coarser particles to farther and closer distances from detachment locations. Therefore, soil texture was mainly affected by soil erosion and changed to coarser classes. Compare means between physical and chemical properties in the eroded and deposited sites and reference site showed that physical and chemical properties were affected by erosion and deposition processes significantly
Conclusion: Overall results indicated that Cs-137 is powerful technique for differentiation between erosional and depositional sites in the regions under wind erosion. Moreover, the this study confirmed that eroded and depositional sites wrer significantly affected by wind erosion process and soil attributes were changed compared to reference site. and proper management, especially in gypsum mines of Segzi district should be considered .
قیمت : 20,000 ريال