نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه فردوسی مشهدو دانشکده کشاورزی، بخش آموزش

2 عضو هیات علمی دانشگاه ارومیه، دانشکره کشاورزی، گروه علوم خاک

چکیده

به منظور مطالعه تغییرات شکلهای مختلف فلزات روی، مس، کادمیوم و سرب در طی فرآیند تهیه ورمی کمپوست، آزمایشی برمبنای طرح کاملا تصادفی با آرایش فاکتوریل با سه تکرار انجام شد. فاکتور اول این آزمایش شامل تاثیر حضور و عدم حضور کرم خاکی بود و روند فرایند تولید ورمی کمپوست در بازه های زمانی صفر، 30، 60 و 90 روز بعنوان فاکتور دوم انتخاب شد. بخشهای مختلف (تبادلی، کربناتی، بخش آلی، پیوند شده با اکسیدهای آهن و منگنز و باقیمانده) فلزات روی، مس، کادمیوم و سرب با استفاده از روش عصارهگیری پی در پی و 5 مرحله‌ای روش تسیر در طی فرآیند تهیه ورمی کمپوست از کود گاوی تعیین شدند. نتایج نشان داد که اسیدیته ورمی کمپوست در تیمارهای دارای کرم خاکی 4/0 واحد کاهش و میزان کربن آلی محلول 15/0 درصد افزایش را نشان داد. فراهمی زیستی عناصر روی، مس و کادمیوم بجز سرب نیز در تیمار های کرم خاکی افزایش معنی داری را نشان دادند. بیشترین مقادیر روی، مس و کادمیوم در نتیجه فعالیت کرمهای خاکی به ترتیب در بخش‌های کربناتی، مواد آلی و تبادلی نشان داده شد، اما بیشترین سهم سرب در بخش پیوند شده با مواد آلی بود. غلظت عناصر روی وکادمیوم در بخش های تبادلی و کربناتها به طور معنیداری در حضور کرمهای خاکی افزایش یافت، عنصر روی 4/16 و 21/ 18 درصد و کادمیوم 10 درصد افزایش را در این بخش ها نشان دادند، لیکن غلظت این عناصر در بخش باقی مانده در انتهای دوره کاهش یافت. چنین استنباط می شود که فراهمی زیستی عناصر سنگین با فعالیت کرمهای خاکی در فرایند تولید ورمی کمپوست افزایش می یابد.

کلیدواژه‌ها

عنوان مقاله [English]

Study of different fractions of Zn, Cu, Pb and Cd during vermicomposting of cattle manure

نویسندگان [English]

  • atena mirbolook 1
  • mirhasan rasouli sadaghiani 2

چکیده [English]

In order to study the changes in different fractions of Zn, Cu, Cd and Pb during the vermicomposting process of cattle manure, an experiment was conducted based on completely randomized design with factorial arrangement replicated three times. The first experimental factor was presence and absence of earthworm, and period of vermicomposting (0, 30, 60 and 90 days) was taken into account as the second factor. A five-step sequential extraction procedure recommended by Tessier was used for fractionation of Zn, Cu, Cd and Pb during the process of vermicomposting of caw manure. The exchangeable, carbonate-bound, Fe-Mn oxides-bound, organic matter-bound and residual fractions of metals were determined using atomic absorption apparatus (FAAS, Thermo element MK-M6). The results showed that pH of vermicompost decreased 0.4 of unit and dissolved organic carbon (DOC) increased 0.15 percent in treatments of with worm. The bioavailability of Zn, Cu and Cd, not Pb increased significantly in the compost samples. Following earthworm activity, the highest content of Zn, Cu and Cd were observed as bounded by carbonate, organic matter and exchangeable fractions, respectively, while the most amount of Pb was found in organic band fraction. Zn and Cd concentrations in carbonate and exchangeable fractions significantly increased in earthworm treatments, Zn 16.4 and 18.21 percent and Cd 10 percent increased in this fractions, however the concentration of those in residual fraction decreased by the end of incubation period. It is concluded that earthworm activity increases the bioavailability of some of metals (Cd, Zn, and Cu) during the vermicomposting process.

کلیدواژه‌ها [English]

  • Vermicompost
  • cattle manure
  • heavy metal
  • sequential extraction
  • Bioavailability
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