نوع مقاله : مقاله پژوهشی

نویسندگان

دانشگاه بوعلی سینا

چکیده

آلودگی خاک به فلزهایی مانند کادمیم با کاهش کارکرد ریزجانداران می‌تواند کربن‌اندوزی در خاک را دگرگون سازد. مانده‌های گیاهی پس از افزوده شدن به خاک، به ریخت مواد آلی دانه‌ای آزاد بوده که با گذشت زمان به کمک ریزجانداران خاک با رس‌ها پوشیده شده و در پایان به ریخت‌ هم تافته‌های آلی-کانی در می‌آیند. در این پژوهش پیامد کاربرد کادمیم در دو سطح (صفر و 10 میلی‌گرم بر کیلوگرم) و گذشت زمان در 4 سطح (1روز، 1، 3 و 5 ماه) بر بخش‌های اندازه دانه‌ای کربن آلی دو خاک همدان و شمال که با 5 درصد کاه گندم تیمار شده‌اند، در سه تکرار آزمون شد. بخش‌ هم‌اندازه شن و بخش هم‌اندازه سیلت+رس مواد آلی خاک‌ها در زمان های یاد شده به روش‌ بخش‌بندی اندازه دانه‌ای جدا شده و کربن آلی آنها به روش اکسیداسیون تر اندازه‌گیری شد. برای خاک همدان، بیشترین کربن آلی خاک در بخش شن به اندازه 12/14 ‌گرم بر کیلوگرم خاک (40 درصد)، و در خاک لاهیجان با بافتی ریزتر در بخش سیلت+رس خاک، به اندازه 80/15 ‌گرم بر کیلوگرم خاک (32 درصد) در روز نخست آزمایش بود. تندی کاهش کربن آلی با گذشت زمان در خاک همدان بیشتر از آن در خاک لاهیجان بود. آلودگی خاک به کادمیم از تندی فروزینگی و تجزیه کربن آلی در هر دو خاک کاست و مایه نگهداری کربن آلی بویژه در خاک لاهیجان شد که این می تواند وابسته به رس فراوان‌تر و بالاتر بودن زیست فراهمی و فاکتور آلودگی کادمیم در این خاک باشد.

کلیدواژه‌ها

عنوان مقاله [English]

Effect of cadmium pollution on soil organic carbon particle size fractions in Hamadan and Lahigan soils treated with wheat straw

چکیده [English]

Soil pollution by heavy metals like cadmium (Cd) with lowering the activity of microorganism can change carbon sequestration in soil. Plant residues when applied in soil are in free particulate form. They will be covered by clay particle and finally will be transformed to organomineral particles biologically. In this study, the effects of Cd addition (0 and 10 mg kg-1 soil) and time duration (1 day, 1, 3 and 5 months) on particle size fraction of organic carbon (OC) were studied in Hmadan and Lahijan soils in 3 replicates. Sand size fraction (SSF) and silt+clay size fraction (Si+CSF) of soil organic carbon were analyzed by the particle size fractionation and OC determination by wet oxidation. The main part of OC in Hamadan soil was in SSF (14.12 mg kg-1 soil or 40%) but it was in Si+CSF in Lahijan soil (15.80 mg kg-1 soil or 32%) in 1st day of soil incubation. The rate of OC decrease in Hamadan soil was markedly higher than that in Lahijan soil. Soil pollution with Cd decreased OC biodegradation in both of the studied soils. It increased OC retention especially in Lahijan soil. This effect may be related to higher clay content and higher Cd bioavailability and contamination factor in Lahijan soil.

کلیدواژه‌ها [English]

  • carbon sequestration
  • Particle size fractionation
  • Soil pollution
  • Wheat straw
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