ارزیابی اولیه‌ی امکان استفاده از رادیونوکلید سرب-210 اضافی در برآورد توزیع مجدد خاک در اراضی دیم منطقه‌ی کوهین

نوع مقاله: مقاله پژوهشی

نویسندگان

1 پژوهشگاه علوم و فنون هسته ای، سازمان انرژی اتمی، صندوق پستی: 836-14395، تهران ـ ایران

2 گروه مهندسی علوم خاک، دانشکده ی علوم و مهندسی کشاورزی، پردیس کشاورزی و منابع طبیعی، دانشگاه تهران، صندوق پستی: 4111، کرج ـ ایران

3 پژوهشکده ی چرخه ی سوخت هسته ای، پژوهشگاه علوم و فنون هسته‌ای، سازمان انرژی اتمی ایران، صندوق پستی: 8486-11365، تهران ـ ایران

4 گروه مهندسی جنگلداری و اقتصاد جنگل، دانشکده ی منابع طبیعی، پردیس کشاورزی و منابع طبیعی، دانشگاه تهران، صندوق پستی: 4111، کرج ـ ایران

چکیده

در دهه‌های اخیر، در کشور ما از سزیم-137 برای برآورد آهنگ فرسایش خاک و ته‌نشینی استفاده شده است. لیکن به دلیل کاهش مقدار آن در خاک در اثر فروپاشی پرتوزا، نیاز به بررسی امکان استفاده از یک ردیاب جای‌گزین با نهشت مداوم مانند سرب-210 اضافی، ضروری به نظر می‌رسد. در مطالعه‌ی حاضر، نمونه‌‌های خاک جمع‌آوری شده از یک مزرعه با وسعت هفت هکتار، برای تعیین مقدار و الگوی توزیع مکانی خاک مورد استفاده قرار گرفت. میزان فرسایش خالص خاک با استفاده از مدل‌ موازنه‌ی جرم 2، برای روش‌های مبتنی بر استفاده از سزیم-137 و سرب-210 اضافی، به ترتیب، 6/4 و 3/12 تن بر هکتار- سال و نسبت باردهی ته‌نشت به ترتیب، 52 و 60 درصد محاسبه شد. به طور کلی میانگین فرسایش و ته‌نشینی برآورد شده با استفاده از سرب-210 اضافی بسیار بیش‌تر از سزیم-137 بود، زیرا سزیم-137، تخمینی از میانگین فرسایش از سال 1963 تا زمان نمونه‌برداری را به دست می‌دهد، در حالی‌که نتیجه‌های سرب-210 اضافی بازتابی از دوره‌ی زمانی طولانی‌تر است. تغییرهایی که در مدیریت خاک و ویژگی‌های بارش‌ها در طی قرن گذشته در منطقه رخ داده است، تأثیر مهمی بر برآورد توزیع مجدد خاک با استفاده از سرب-210 اضافی گذاشته است. به طور کلی نتیجه‌های پژوهش حاضر امکان استفاده از سرب-210 اضافی در منطقه‌های نیمه خشک را تأیید نمود.

کلیدواژه‌ها


عنوان مقاله [English]

Preliminary assessment of using 210Pbex radionuclide to estimate soil redistribution rate in kouhin dry farming region

نویسندگان [English]

  • Maral Khodadadi 1
  • Manuchehr Gorji 2
  • Mohammad GhanadiMaragheh 3
  • Ali Bahrami-Samani 3
  • Moein Meftahi 3
  • Hossein Mirseyedhosseini 2
  • Ghavamodin ZahediAmiri 4
چکیده [English]

Over the past decades, the 137Cs approach has been successfully applied in Iran for estimating soil erosion and sedimentation rates. By the progressive reduction in 137Cs activity due to radioactive decay, however, it is essential to investigate the use of an alternative environmental radionuclide with a constant deposition through time, such as Lead-210. In this study, soil samples were collected within seven hectares cultivated field to determine the magnitude and spatial pattern of soil redistribution budgets. The net erosion rates for 137Cs and 210Pbex techniques were estimated to be 4.6 and 12.3t ha-1 yr-1 respectively and the sediment delivery ratio reached 52 and 60 percent respectively using mass balance model 2. Totally, soil erosion and deposition mean estimated from the 210Pbex measurements were much higher than those of 137Cs, since in the case of 137Cs, the results provided an estimate of the mean erosion rate over a period from 1963 to the time of sampling, whereas for the 210Pbextechnique, the estimates reflect a longer time period. The changes in the land management and rainfall characteristics that have occurred during the past century in the area under the study have had important influence on the soil redistribution estimates by the 210Pbex. This study has demonstrated the potential of using 210Pbex measurements to estimate soil erosion and deposition in semiarid regions.

کلیدواژه‌ها [English]

  • 210Pbex
  • 137Cs
  • Soil erosion
  • Fallout radionuclides
  • Mass balance models

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