بررسی تأثیر استفاده طولانی‌مدت از کمپوست پسماند شهری و کود دامی بر روی قابلیت دسترسی فلزات سنگین در خاک‌

نوع مقاله : مقاله پژوهشی

نویسنده

استادیار، گروه محیط‌زیست، دانشکده منابع طبیعی، دانشگاه سمنان، سمنان، ایران

چکیده

پسماند شهری یک منبع مقرون‌به‌صرفه و باارزشی از مواد آلی برای خاک‌های کشاورزی است. در سال‌های اخیر کمپوست پسماند شهری به‌طور گسترده‌ای در بخش کشاورزی به‌عنوان یک بهبوددهنده خاک و نیز به‌عنوان یک کود استفاده شده است، ولی کاربرد بیش ‌از حد کودهای آلی و معدنی در تولید محصولات گلخانه‌ای منجر به تجمع فلزات سنگین در خاک و خطرات سلامتی برای انسان می‌شود. بنابراین این پژوهش با هدف بررسی تأثیر کاربرد کمپوست پسماند شهری و کود دامی بر روی فلزات سنگین خاک انجام شد. همچنین خطرات بهداشتی ناشی از مصرف خیار کشت‌ شده در این خاک‌ها ارزیابی شد. در این پژوهش، غلظت فلزات سنگین کادمیوم، مس، نیکل، سرب و روی در خاک، تحرک عنصر، فراهمی زیستی، جزء‌بندی فلزات به همراه اثرات آلودگی این فلزات در خاک گلخانه و جذب این فلزات توسط گیاه خیار پس از 3 سال کشت متوالی و کاربرد کمپوست پسماند شهری و کود دامی در قالب طرح بلوک‌های کاملاً تصادفی در سه تکرار در یک گلخانه‌ای واقع در جنوب استان تهران بررسی شد. همچنین شاخص‌های آلودگی محیطی نیز ارزیابی شد. نتایج نشان داد که کاربرد کمپوست پسماند شهری و کود دامی، سبب افزایش غلظت کل و قابل‌استخراج فلزات سنگین در خاک شده است. با این ‌وجود غلظت فلزات اندازه‌گیری شده در حد مجاز غلظت فلزات سنگین در خاک‌های ایران است. فلزات مس و روی به‌ترتیب به‌عنوان متحرک‌ترین فلزات در خاک شاهد و خاک‌های تیمار شده با کمپوست پسماند شهری و کود دامی شناسایی شدند. مقدار سرب mg kg-1 26/2 و کادمیوم mg kg-1 06/0 در میوه خیار کشت‌ شده در خاک‌های تیمار شده با کمپوست پسماند شهری بیش از مقدار حد مجاز برای سبزیجات خوراکی بود. بر اساس نتایج به‌دست ‌آمده از شاخص خطر سلامتی برای سرب و مس، مصرف خیار کشت‌ شده در خاک‌های تیمار شده با کمپوست پتانسیل بالایی برای به خطر انداختن سلامتی بزرگ‌سالان و کودکان را دارد. نتایج این بررسی نشان داد که علی‌رغم کاربرد سه‌ساله کمپوست پسماند شهری و کود دامی، غلظت فلزات سنگین اندازه‌گیری شده بیش از حد مجاز نبوده است. با این‌ حال، با در نظر گرفتن قابلیت فراهمی زیستی بالای فلزات سنگین، کاربرد مکرر کمپوست پسماند شهری خطرات تجمع تدریجی فلزات سنگین در خاک در طی زمان را به‌همراه خواهد داشت. بنابراین اندازه‌گیری غلظت‌های کل و قابل‌استخراج فلزات سنگین و تعیین فاکتور تحرک هنگام ارزیابی اثرات احتمالی بر عملکرد و جذب فلزات توسط گیاه و تعیین شاخص‌های کیفیت خاک، اهمیت ویژه‌ای دارد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigating the Effect of Long-term Municipal Waste and Manure Application on Soil Heavy Metal Availability in Soil

نویسنده [English]

  • Somayeh Moharami
Assist. Prof., Dept. of Environment, Faculty of Natural Resources, Semnan University, Semnan, Iran
چکیده [English]

Municipal waste is a cost-effective and valuable source of organic matter for agricultural soils. In recent years, MSW compost has been widely used in agriculture as a soil conditioner and fertilizer. However, the excessive use of organic and mineral fertilizers in the production of greenhouse crops leads to the accumulation of heavy metals in the soil and health risks for humans. Therefore, this study investigated the effect of the municipal waste and manure application on heavy metals in the soil. Also, the health risks for humans were evaluated through the consumption of cucumber cultivated in these soil. In this study, the concentration of heavy metals Cd, Cu, Ni, Pb and Zn in soil, mobility of metals, bioavailability, fractionation of metals, effects of pollution in the greenhouse soil and uptake of these metals by cucumber plant following 3 cultivation years of application of municipal waste compost and manure were studied in a randomized complete block design with three replicates in a greenhouse located in the south of Theran province. Also, environmental pollution risks were evaluated. The results showed that the application of municipal waste compost and manure increased both the total and available concentration of heavy metals in the soil. However, the concentration of the measured metals was at the permissible limit of the concentrations of heavy metals in Iranian soils. Copper and Zn were detected as the most mobile metals in control and treated soils with municipal waste compost and manure, respectively. The amount of Pb (2.26 mg kg-1) and Cd (0.06 mg kg-1) in cucumber in treated soil with municipal waste exceeded the limit value for edible vegetables. Based on the results obtained from the health risk index, Pb and Cu represented a high potential risk for the health of adults and children by consuming cucumbers in compost-treated soils. The results of this study showed that despite the three-year application of municipal waste compost and manure, the concentration of heavy metals measured was not higher than the allowed guideline level. However, considering the high bioavailability of heavy metals, repeated application of municipal waste compost would carry a risk of gradual accumulation in the soil over time. Therefore, measuring the total and extractable concentration of heavy metals and metal mobility when assessing likely effects on plant yields and metal uptakes and setting soil quality criteria is important.

کلیدواژه‌ها [English]

  • Municipal Solid Waste
  • Heavy Metal
  • Fractionation
  • Health Risk Index
  • Mobility Factor
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