اثر تشکیل و تخریب پوسته فیزیکی بر فرسایش‌پذیری و انتشار گرد و غبار در شرایط آزمایشگاهی

نوع مقاله : مقاله پژوهشی

نویسنده

گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه شهید چمران اهواز، اهواز، ایران

چکیده

تشکیل پوسته سطحی به ویژه از نوع فیزیکی ویژگی اصلی خاکِ­ اکثر کانون­های گرد و غبار در استان خوزستان بوده که می­تواند نقش اساسی در حفاظت خاک در برابر فرسایش بادی به عهده داشته باشد، اما در اکثر مطالعات فرسایش بادی توجهی به آن­ها نشده است. این مطالعه با هدف بررسی اثر به­هم­خوردگی پوسته­های فیزیکی سطح خاک ناشی از تردد دام بر میزان فرسایش­پذیری خاک­های پوسته­ای و انتشار گرد و غبار انجام شد. برای این منظور سه نمونه خاک غالب منطقه با ویژگی پتانسیل تشکیل پوسته سطحی انتخاب و به آزمایشگاه منتقل شدند. خاک­ها در سینی­های تونل باد ریخته شدند و جهت ایجاد شرایط طبیعی و تشکیل پوسته فیزیکی در سطح آن­ها تحت یک بارندگی شبیه­سازی شده قرار گرفتند. پس از خشک­شدن و تشکیل پوسته فیزیکی، سینی­ها در معرض تردد چند دام سبک با تعداد دفعات 1 ، 2 و 5 بار قرار گرفتند. سپس سینی­ها به آزمایشگاه تونل باد منتقل شدند و آستانه سرعت اصطکاکی (TFV)، مقدار فرسایش بادی و شار انتشار PM10 اندازه­گیری شد. نتایج نشان داد که در هر سه نوع خاک مقدار فرسایش و انتشار گرد و غبار در تیمار شاهد (بدون تردد دام) صفر بود و با افزایش تعداد دفعات تردد دام از یک بار تا 5 بار آستانه سرعت اصطکاکی 25 تا 49 درصد کاهش، و مقدار فرسایش خاک و انتشار گرد و غبار به ترتیب بین 54 -317 درصد و 80 - 545 درصد افزایش یافت. پوسته فیزیکی خاک لوم شنی نسبت به خاک لوم رسی و لوم سیلتی حساسیت بیشتری در برابر تردد دام داشت. یافته­های این تحقیق نشان می­دهد که تشکیل پوسته فیزیکی در این نوع مناطق یک ویژگی مطلوب و با ارزش برای مهار فرسایش و گرد و غبار است که به عنوان یک تثبیت کننده طبیعی عمل می­کند و حفظ آنها می­تواند تاثیر بسیار زیادی در کنترل گرد و غبار داشته باشد.

کلیدواژه‌ها


عنوان مقاله [English]

The Effect of Physical Crust Development and Disturbance on Erodibility and Dust Emission in Laboratory Conditions

نویسنده [English]

  • Heidar Ghafari
Soil Sciences Dept- Faculty of Agriculture - Shahid Chamran University of Ahvaz -Ahvaz -Iran
چکیده [English]

Soil surface crusting, especially the physical type, is an important feature of dust source areas in Khuzestan province, which can have a significant impact on soil protection against wind erosion. But in most wind erosion studies, it has not been considered. The aim of this study was to investigate the effect of physical crust disturbance caused by livestock traffic on soil crusted erodibility and dust emission. For this purpose, three dominant soils with the characteristic of surface crust formation were selected from the areas and transferred to the laboratory. The soils were placed into wind tunnel trays and subjected to a simulated rainfall to form a physical crust on their surfaces. After the soils dried and the physical crust formed, the trays were exposed to different trampling by livestock's hoof including 1, 2 and 5 crossings. The trays were then transferred to a wind tunnel laboratory and threshold friction velocity (TFV), erosion rate and PM10 emission flux were measured. The results showed that erosion and dust diffusion in the control treatment (without livestock traffic) was zero in all three soil types and with increasing the number of livestock traffic from one to five times TFV decreased by 25 to 49%, and the amount soil erosion and dust emission increased between 54-317% and 80-545%, respectively. The physical crust of sandy soil was more sensitive to livestock traffic than clay loam and silt loam. The findings of this study show that the formation of physical crust in this area is a desirable and valuable feature for inhibiting erosion and dust, which acts as a natural stabilizer and protecting them can have a huge impact on dust control.

کلیدواژه‌ها [English]

  • Livestock Traffic
  • Wind tunnel
  • PM10 Emission
  • Threshold friction velocity
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