نوع مقاله : علمی - پژوهشی

نویسندگان

گروه محیط زیست، دانشکده منابع طبیعی دریا، دانشگاه علوم و فنون دریایی خرمشهر، خرمشهر، ایران

چکیده

سابقه و هدف: ﺗﺎﻻب پریشان از ﺟﻤﻠﻪ اﻛﻮﺳﻴﺴﺘﻢﻫﺎی ﺑﺎ ارزش ﺟﻬﺎن اﺳﺖ ﻛﻪ از ﻧﻈﺮ اﻛﻮﻟﻮژﻳﻜﻲ دارای اﻫﻤﻴﺖ ﺑﺴﺰاﻳﻲ دارد و در چند سال اخیر به دلیل خشکسالی‌های پی‌در‌پی به صورت کامل خشک شده است. فلزات سنگین از جمله مهمترین منابع آلاینده محیط زیست به شمار می‌روند که زمان ماندگاری آنها در رسوبات بسیار زیاد است. همچنین این فلزات اثرات زیان‌آوری بر اکوسیستمهای آبی دارند و رسوبات هم به‌عنوان منشأ و هم به‌عنوان محلی برای ذخیره این عناصر محسوب می‌شوند. از اینرو کسب اطلاعات درباره این فلزات مهم است. مواد و روش‌ها: ﻫﺪف از اﻳﻦ پژوهش برآورد آﻟﻮدﮔﻲ رسوبات تالاب پریشان ﺑﻪ ﻓﻠﺰات ﺳﻨﮕﻴﻦ ﻣﺲ، آهن، منگنز و روی ﺑﺎ اﺳﺘﻔﺎده از ﺷﺎﺧﺺ‌ غنی‌سازی، شاخص انباشت ژئوشیمیایی، درجه آلودگی و ﺷﺎﺧﺺ ﺟﺎﻣﻊ ﻓﺎﻛﺘﻮر آﻟﻮدﮔﻲ است. در این بررسی، ﺗﻌﺪاد ۴۰ ﻧﻤﻮﻧﻪ رسوب با وزن ۲۰۰ گرم از ﻣﻨﻄﻘﻪ ﺑﻪ‌ﺻﻮرت ﺳﻴﺴﺘﻤﺎﺗﻴﻚ ﺑﺮداﺷﺖ ﺷﺪ و پس از هضم اسیدی و فیلتر کردن ﺑﺮای ﻗﺮاﺋﺖ ﻏﻠﻈﺖ ﻓﻠﺰات ﺳﻤﻲ آزاد ﺷﺪه در ﻫﺮ ﻧﻤﻮﻧﻪ، از دﺳﺘﮕﺎه ﺟﺬب اﺗﻤﻲ ﺷﻌﻠﻪ ﻣﺪل AAS ﻛﻤﭙﺎﻧﻲ ﺗﺮﻣﻮ اﻧﮕﻠﺴﺘﺎن اﺳﺘﻔﺎده شد. در اﻳﻦ تحقیق ﺑﻪ دﻟﻴﻞ ﻋﺪم وﺟﻮد اﺳﺘﺎﻧﺪارد ﺧﺎص ﺑﺮای آﻟﻮدﮔﻲ ﺧﺎک در ﻛﺸﻮرﻣﺎن، از اﺳﺘﺎﻧﺪاردﻫﺎی ﻣﻮﺟﻮد در دﻳﮕﺮ ﻛﺸﻮرﻫﺎ اﺳﺘﻔﺎده ﺷﺪ. ﻣﻴﺎﻧﮕﻴﻦ ﻏﻠﻈﺖ فلزات مورد بررسی در ﻣﻨﻄﻘﻪ کمتر از ﺣﺪاﻛﺜﺮ ﻏﻠﻈﺖ (mg/kg) ﻗﺎﺑﻞ‌ﻗﺒﻮل ﺑﺮای ﻛﺸﻮرﻫﺎی ﻟﻬﺴﺘﺎن، ﻛﺎﻧﺎدا و اﺳﺘﺮاﻟﻴﺎ است.نتایج و بحث: میزان تغییرات خصوصیات pH و هدایت الکتریکی(Ec) به‌ترتیب در دامنه 9/7-2/7 و 34-4/2 محاسبه شد و ﻏﻠﻈﺖ ﻓﻠﺰات ﺳﻨﮕﯿﻦ نیز ﺑﺮ ﺣﺴﺐ میلی‌گرم بر کیلوگرم در ﺑﯿﺸﺘﺮ ﻧﻤﻮﻧﻪﻫﺎ ﺑﻪ ﺗﺮﺗﯿـﺐ ﻓﺮاواﻧـﯽ ﺷـﺎﻣﻞ ﻣﻨﮕﻨـﺰ(3/71-2/18)، آهن(4/26-3/6)، روی(2/15-8/3)، مس(8/13-5/3) به‌دست آمد. ﻏﻠﻈﺖ زﻣﻴﻨﻪ ﺑﺮای ﻓﻠﺰات منگنز، ﻣﺲ، آهن و روی ﺑﻪ ﺗﺮﺗﻴﺐ 950، 50، 41000 و 75 ﻣﻴﻠﻲ‌ﮔﺮم ﺑﺮ ﻛﻴﻠﻮﮔﺮم ﺑﻪ دﺳﺖ آﻣﺪ. ﺷﺎﺧﺺﻫﺎی زﻣﻴﻦ‌اﻧﺒﺎﺷﺘﮕﻲ، ﻓﺎﻛﺘﻮر آﻟﻮدﮔﻲ و ﺷﺎﺧﺺ ﺟﺎﻣﻊ ﻓﺎﻛﺘﻮر آﻟﻮدﮔﻲ برای ﺗﻌﻴﻴﻦ ﻣﻴﺰان آﻟﻮدﮔﻲ ﻣﻨﻄﻘﻪ استفاده شدند که ﺷﺎﺧﺺ زﻣﻴﻦ‌اﻧﺒﺎﺷﺘﮕﻲ ﺑﺮای ﻫﻤﻪ ﻓﻠﺰات کمتر از صفر ﺑﻪ‌دﺳﺖ آﻣﺪ ﻛﻪ ﻧﺸﺎن‌دﻫﻨﺪه ﻏﻴﺮآﻟﻮده بودن منطقه است، در ادامه ﺷﺎﺧﺺ ﻓﺎﻛﺘﻮر آﻟﻮدﮔﻲ برای اﻛﺜﺮ ﻧﻤﻮﻧﻪﻫﺎ در ﻃﺒﻘﻪ ﺑﺪون آﻟﻮدﮔﻲ ﻗﺮار گرفت، و ﻓﺎﻛﺘﻮر آﻟﻮدﮔﻲ ﺑرای تمام فلزات مورد بررسی ﻣﻘﺪاری کمتر از یک را نشان داد ﺑﻪ ﻃﻮری ﻛﻪ تمام دادهﻫﺎ در ﻃﺒﻘﻪ بدون آلودگی ﻗﺮار گرفتند. همچنین نتایج ﻧﺸﺎن داد ﻛﻪ ﻋﻨﺎﺻﺮ منگنز، ﻣﺲ، آهن و روی ﻣﻨﺸﺄ زﻣﻴﻦﺷﻨﺎﺳﻲ و ﻛﺸﺎورزی دارﻧﺪ و ﻏﻠﻈﺖ ﻓﻠﺰات در ﺧﺎک ﺑﻪ ﻣﻨﺸﺄ ﻃﺒﻴﻌﻲ آﻧﻬﺎ ارﺗﺒﺎط داده ﺷﺪ.نتیجه‌گیری: در نهایت می‌توان بیان کرد ﻛﻪ ﻣﻨﻄﻘﻪ ﻣﻮرد بررسی کمترین رﻳﺴﻚ آﻟﻮدﮔﻲ را ﻧﺴﺒﺖ ﺑﻪ ﻓﻠﺰات ﺳﻨﮕﻴﻦ دارد. در واﻗﻊ ﻣﻲ‌ﺗﻮان ﮔﻔﺖ ﻛﻪ ﻓﻠﺰات ﻣﺲ، آهن، منگنز و روی در اﻳﻦ ﻣﻨﻄﻘﻪ ﻣﻨﺸﺄ زﻣﻴﻦﺷﻨﺎﺳﻲ دارﻧﺪ و در طی فرایندهای طبیعی زمین‌شناسی و از طریق چشمه‌های ورودی به این تالاب تغییر می‌کنند.

کلیدواژه‌ها

عنوان مقاله [English]

Estimates of heavy metals pollution in parishan wetland sediments using pollution indices

نویسندگان [English]

  • Heeva Elmizadeh
  • Saeid Farhadi
  • Maryam Razmi

Environmental Group, Natural Resources Department, Khorramshahr University of Marine Sciences and Technology, Khuzestan, Iran

چکیده [English]

Introduction: Parishan wetland is one of the most valuable and ecologically important ecosystems in the world which has completely dried up in recent years due to successive droughts (Dehghani, 2007). Considering that heavy metals are among the most important pollutants of the environment, their survival time is high in sediments (Ullah et al., 2017). Also, these metals have harmful effects on aquatic ecosystems, and sediments are both a source of and a place to store these elements. Acquiring information about these metals is important (Bhuiyana et al., 2010). Materials and methods: The purpose of this study was to estimate the level of contamination of Perishan wetland sediments with the heavy metals copper, iron, manganese and zinc using the enrichment index, geochemical accumulation index, degree of contamination and the comprehensive pollution factor index. In this study, 40 sediment samples with a weight of 200 g were systematically harvested. After acid digestion and filtering to read the concentration of toxic metals liberated in each sample, an AAS atomic absorption device by the Thermo Company (UK) was used. In this study, because of the lack of any specific standard for soil contamination in our country, standards from other countries were used. The average concentration of the metals studied in the region is lower than the maximum acceptable concentration (mg / kg) for the countries of Poland, Canada and Australia.Results and discussion: The changes in pH and electrical conductivity (Ec) were calculated in the range of 2.7-9.2 and 4.2-34, respectively, and the concentration of heavy metals based on mg/kg was found in most samples including manganese (2.18-3.71), iron (3.6-4.26), zinc (2.15-8.3) and copper (5.3-8.13), respectively. The background concentration for manganese, copper, iron and zinc was 950, 50, 41000 and 75 mg/kg, respectively. The geochemical accumulation index, the pollution factor and the comprehensive pollution factorindex were all used to determine contamination levels in the area. The geochemical accumulation index was less than zero for all metals, which shows the non-contamination class of the area. In addition, the factor of contamination index for most of the samples was in the class unpolluted, and the contamination factor for all metals was less than one, so that all data were placed in the non-contaminated class. The results also showed that the elements of manganese, copper, iron and zinc have a geological and agricultural origin, while the concentration of metals in the soil was related to their natural origin.Conclusion: Finally, it can be stated that the studied area has the lowest risk of contamination with heavy metals. In fact, it can be said that the copper, iron, manganese and zinc found in this region have a geological origin and they change through the natural processes of geology and through springs in the wetland.

کلیدواژه‌ها [English]

  • Geochemical Accumulation Index
  • Contamination factor
  • Heavy Metals
  • Parishan wetland

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