فهرست مطالب

محیط شناسی - سال سی و هشتم شماره 1 (پیاپی 61، بهار 1391)

فصلنامه محیط شناسی
سال سی و هشتم شماره 1 (پیاپی 61، بهار 1391)

  • 200 صفحه، بهای روی جلد: 50,000ريال
  • تاریخ انتشار: 1391/04/01
  • تعداد عناوین: 15
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  • مریم فراهانی، سیداحمد میرباقری صفحه 1
    هیدروکربن های نفتی از عمده ترین آلاینده های اکوسیستم های آبی و خاکی در سراسر دنیا محسوب می شوند. در تحقیق حاضر برای کاهش هیدروکربن های نفتی در خاک آلوده پالایشگاه تهران مطالعه ای بر روی روش تجزیه بیولوژیکی صورت گرفت. در نتیجه جداسازی میکرب های تجزیه کننده هیدروکربن های نفتی از خاک منطقه صورت گرفته و در ادامه، بهینه سازی شرایط فیزیکوشیمیایی موثر بر تجزیه بیولوژیکی با استفاده از غلظت های مختلف سوبسترای نفتی و تغییر مشخصه های دما، pH و مواد غذایی انجام شد. در خاتمه نیز با تلقیح میکروارگانیسم های جداسازی شده به خاک و تغییر مشخصه های محیطی، میزان حذف بیولوژیکی هیدروکربن های آروماتیک چند حلقه ای در خاک مورد ارزیابی قرار گرفت. نتایج آزمایش ها نشان داد: حداکثر رشد باکتریایی در نسبت 20 درصد آلاینده نفتی، pH 5/7 و دمای 30 درجه سانتیگراد مشاهده می شود. همچنین با آزمایش بر روی منابع متعدد غذایی مشخص شد؛ بهترین نسبت C:N:P برای اوره، نیترات آمونیوم و سولفات آمونیوم به ترتیب 1: 5: 100، 1: 5: 100 و 1: 10: 100 است. همچنین نتایج نشان داد، روش تجزیه بیولوژیکی قادر است در تیمارهای مورد آزمایش در مدت 4 هفته بین1/32% تا 5/70% روند کاهش آلاینده های نفتی در خاک را بهبود بخشد. بنابراین، استفاده از روش بیولوژیکی برای پاکسازی هیدروکربن های نفتی در خاک به دلیل سادگی اجرا، مقرون به صرفه بودن و حذف کامل آلودگی بسیار مناسب بوده و با توجه به تنوع این هیدروکربن ها در خاکهای آلوده به مواد نفتی، پیشنهاد می شود، تحقیقات مشابه ای در سایر پالایشگاه های نفتی انجام گیرد.
    کلیدواژگان: تجزیه بیولوژیکی، هیدروکربورهای نفتی، پالایشگاه تهران، ترکیبات PAH، خاک
  • مهدیه سلمان زاده، محسن سعیدی، غلامرضا نبی بیدهندی صفحه 9
    غبارها، ترکیبات ذره ای معلق در هوا هستند که از منابع مختلف زمینی و انسان ساز به وجود می آیند که پس از گذشت زمان با توجه به اندازه و چگالی شان مجددا روی سطوح فرو می نشینند. 49 نمونه از غبارهای خیابانی از کناره چند خیابان اصلی از شرق و پایانه مسافربری جنوب تهران و یک نمونه از محوطه درون دانشگاه علم و صنعت ایران در فصل تابستان و در شرایط آب و هوایی خشک جمع آوری و غلظت فلزات آهن، منگنز، روی، سرب، نیکل، کروم، مس، لیتیم و کادمیم در آنها اندازه گیری شد. منابع احتمالی آلاینده ها با استفاده از تحلیل همبستگی، تحلیل خوشه ای، ضریب همبستگی پیرسون و تحلیل اجزای اصلی شناسایی، هم چنین با استفاده از ضریب غنی سازی آثار احتمالی فعالیت های انسانی بر غلظت فلزات سنگین ارزیابی شد. نتایج، غلظت های بالای فلزات کادمیم، سرب، مس، روی، آهن، کروم و نیکل را نسبت به میانگین غلظت این فلزات در پوسته زمین نشان داد. بیشترین غلظت فلزات مس، سرب، کروم، نیکل، روی و آهن مربوط به بزرگراه باقری است که یکی از پر تردد ترین بزرگراه های تهران است. تحلیل نتایج نشان داد آلودگی می تواند ناشی از فعالیت های مختلف انسانی از جمله ترافیک سنگین خودروها، احتراق سوخت های فسیلی، مواد افزودنی به سوخت خودروها، خوردگی سطوح فلزی اتومبیل ها و خوردگی مصالح ساختمانی باشد. مقادیر ضریب غنی سازی فلزات مس، کادمیم، سرب و روی، غنی شدگی بشدت زیاد و منشاء انسانی این عناصر نشان داد. محاسبات مربوط به ریسک اکولوژیکی نیز با استفاده از روش هاکانسون انجام گرفت. تمامی نقاط مورد مطالعه ریسک اکولوژیکی خیلی زیاد را نشان می دهند.
    کلیدواژگان: غبارهای خیابانی، فلزات سنگین، ریسک اکولوژیکی، ضریب غنی سازی، تهران
  • ظهیر شکوه سلجوقی، غلامرضا رفیعی، اکبر ملک پور، امیر شکوه سلجوقی، امید صفری صفحه 31
    استفاده از روش های تصفیه ای فاضلاب در آبزی پروری یکی از مهمترین راه های کاهش آثار زیست محیطی این صنعت و اجرای بهترین عملیات مدیریتی است. استفاده از جاذب های یونی از جمله رس ها در صنایع تصفیه فاضلاب در مقیاس وسیع صورت می گیرد، در حالی که در سیستم های پرورشی تا کنون گزارشی در زمینه استفاده از این ترکیبات صورت نگرفته است. رس ها بیشتر به دلیل منفی بودن ساختار شبکه ای خود هیچ تمایلی از خود نسبت به جذب آنیون ها نشان نمی دهند، ازاین رو با تغییر ساختار سطحی آنها می توان افزون بر جذب کاتیون ها به جذب آنیون ها نیز مبادرت ورزید. در این تحقیق با استفاده از ترکیب آلی به نام تترا دسیل تری متیل آمونیوم برماید و تیمارهای اسیدی- گرمایی به اصلاح ساختار سطحی و لایه ای رس ها پرداخته شد تا به جذب آنیون های فسفاته و سولفاته موجود در سیستم پرورشی پرداخته شود. در این بررسی از سه سطح دمایی (10، 15، 20) و پنج سطح pH (6، 5/6، 7، 5/7، 8) استفاده شد. اثر افزایش دما بر میزان جذب آنیونی در نمونه پساب آبزی پروری و در نمونه استاندارد بر جذب فسفات دارای اثر معنی داری بر روند جذبی توسط دو جاذب بود (05/0 p<)، در حالی که pH بر میزان جذب آنیون سولفات با دو جاذب روند افزایشی را از خود نشان نداد. نتایج مشخص کرد که عوامل محیطی از قبیل دما، pH، غلظت آنیونی، حضور سایر آنیون ها و یون های مزاحمتی در ظرفیت جذب موثرند. همچنین استفاده از تعویض گرهای یونی اصلاح شده جذب آنیون های مضر در مدار بسته، می تواند به عنوان ابزاری جدید مورد استفاده قرار گیرد.
    کلیدواژگان: سیستم مدار بسته، ترکیبات آنیونی، بنتونیت، سورفکتانت، جذب آنیونی، BMPs
  • حمیدرضا ناصری، یعقوب نیک قوجق صفحه 41
    سد باطله آق دره که در 23 کیلومتری شمال تکاب در استان آذربایجان غربی واقع شده است، به منظور انباشت باطله معدنی مورد استفاده قرار می گیرد. این سد در ساختگاهی احداث شده است که به علت وجود ژیپس در پی و بخش هایی از مخزن آن، ساختگاهی ویژه از دیدگاه ژئوتکنیک و مسائل زیست محیطی است و شایسته توجه خاص است. اگرچه تاکنون، ساختن سد روی ساختگاه ژیپسی منع نشده است، اما رفتار ژیپس در برابر آب ناشی از خاصیت انحلال آن همواره تهدیدبرانگیز، آسیب پذیر و هشداردهنده بوده است. در بخش هایی از کف مخزن و پی سد باطله آق دره، بخش گچی سازند قم قرار دارد که ویژگی های کارست مجرایی را داراست. در این مطالعه با استفاده از نتایج پایش زیست محیطی سد باطله و اندازه گیری بعضی از مشخصه های هیدروژئولوژی و هیدروژئوشیمی و بررسی های ژئوفیزیک به روش RI، نقش بخش گچی سازند قم در انتقال آلاینده سیانیدی سد باطله آق دره مورد مطالعه قرار گرفته است. محدوده مورد بررسی از نظر زمین ساخت منطقه ای فعال است. چشمه ها و مجاری انحلالی کارستی در بخش گچی سازند قم نیز در راستای شکستگی های موجود شکل گرفته اند. این مجاری نقش کنترل کننده ای بر جهت جریان آب زیرزمینی دارند و به دلیل توسعه آنها در ژیپس های پی و مخزن سد و ایجاد یک آبفروچاله در بخش جنوب غربی مخزن سد باطله، نشت آلاینده به پایین دست از طریق این مجاری انحلالی صورت گرفته است و موجب ارتباط هیدرولیکی بین بخش جنوب غربی مخزن سد باطله و چشمه های کارستی پایین دست شده اند.
    کلیدواژگان: کارست ژیپسی، انتقال آلاینده، سد باطله
  • ناصر مهردادی، احمدرضا محمدی، علی ترابیان صفحه 49
    امروزه مطالعه شیوه های مختلف کاهش تولید لجن در فرایند لجن فعال به خاطر محدودیت های تصفیه و دفع لجن توجه زیادی را به خود معطوف کرده است. در همین زمینه در این مقاله، روش های ازن زنی، استفاده از امواج فراصوت، تخریب حرارتی و افزایش اکسیژن محلول و کاهش توام بارگذاری، در مقیاس پایلوت و با استفاده از راکتور SBR مورد مطالعه قرارگرفت. به منظور اصلاح ضریب تولید لجن در راکتور SBR، هر کدام از روش های پیشگفت تحت شرایط زیر به کار گرفته شدند: استفاده از امواج فراصوت با شدت KJ/Kg VSS 35000، توان 100وات وفرکانس KHz 20، ازن زنی به صورت متناوب و به مقدار 25 میلی گرم ازن به ازای هر گرم لجن، تخریب حرارتی در دمای 80 درجه سانتیگراد و به مدت 3 ساعت و کاهش بارگذاری تا 19/. کیلوگرم BOD بر متر مکعب در روز و افزایش غلظت اکسیژن محلول تا 6 میلی گرم در لیتر. نتایج حاصل از این تحقیق نشان می دهد که تخریب 30 درصد از لجن راکتور و بازگشت دوباره آن به درون راکتور با امواج فراصوت، ازن و دما به ترتیب می تواند 78، 63 و 49 درصد از تولید لجن زیستی بکاهد. افزایش غلظت اکسیژن محلول تا 6 میلی گرم در لیتر و کاهش بار گذاری تا حدود 19/. کیلوگرم مواد آلی بر متر مکعب در روز می تواند باعث کاهش 37 درصدی تولید لجن شود. بازده حذف مواد آلی و نرخ ویژه جذب اکسیژن لجن در تمامی این روش ها به مقدار جزیی کاهش می یابد. خصوصیات ته نشینی لجن در حال استفاده از امواج فراصوت و دما بهبود می یابد، اما در دو حالت دیگر این خصوصیت افت پیدا می کند.
    کلیدواژگان: کاهش لجن زیستی، تصفیه بیولوژیکی فاضلاب، امواج فراصوت، ازن زنی متناوب، راکتور SBR
  • محمد مهدی اسماعیلی، مصطفی اسماعیلی، هادی امیر شقاقی صفحه 61
    امروزه بحران آلودگی هوا افزون بر تاثیرات زیست محیطی، دارای واکنش های اجتماعی و سیاسی نیز است. استان اصفهان با داشتن حجم بالایی از صنایع آلاینده، درگیری بیشتری با این مسئله دارد. از این رو به نظر می رسد بهترین راه برای تغییر فضای موجود، ارائه روش های علمی برای حذف و کاهش میزان آلاینده های تولید شده به وسیله صنایع است. با توجه به اهمیت چنین مسئله ای، کاهش آلایندگی صنایع فولاد اصفهان در این مطالعه مورد توجه قرار گرفته است. بدین منظور باید منابع تولید آلودگی در این صنایع شناسایی شوند. یکی از مهمترین منابع تولید آلودگی، گازهای خروجی از کوره های قوس الکتریکی بوده که حاوی مقادیر زیادی از مونواکسیدکربن و ذرات معلق است. یکی از تجهیزاتی که در این تحقیق به معرفی و شبیه سازی عددی آن اقدام شده است، سیستم های جذب دوده و غبار هستند که از طریق انجام واکنش های احتراقی و روش های مختلف فیلتراسیون منجر به حذف گازهای آلاینده و ذرات غبار همراه با آن می شود. در این تحقیق چنین سیستمی با استفاده از دینامیک سیالات محاسباتی مورد تحلیل قرار گرفته و تاثیر تغییر مشخصه های عملکردی روی حذف آلاینده ها، کاهش دمای گازها و همچنین غلظت ذرات معلق مورد بررسی قرار گرفته است. نتایج نشان می دهد، افزایش حجم هوای اضافه شده به مخلوط دمای بالا، موجب تبدیل و کاهش غلظت آلاینده هایی از قبیل مونواکسیدکربن می شود، لیکن با توجه به افزایش تعداد مول های واکنش دهنده، دما و سرعت مخلوط افزایش، در نتیجه امکان نشست و بازده جداسازی ذرات معلق، کاهش می یابد.
    کلیدواژگان: رهیافت علمی، کاهش آلایندگی، صنایع فولاد، سیستم جذب دوده و غبار، دینامیک سیالات محاسباتی
  • علی اسکندری، روح الله نوری، حامد معراجی، امین کیاقادی صفحه 71
    محدودیت سنسورهای سخت افزاری برای اندازه گیری برخی مشخصه های کیفی آب مانند اکسیژن خواهی بیوشیمیایی 5 روزه (BOD5) که از لحاظ زمانی هزینه بر هستند، تلاش ها را به سمت استفاده از سنسورهای نرم افزای برای پیش بینی بهنگام BOD5 سوق داده است. هدف اصلی مقاله مذکور نیز توسعه سنسور نرم افزاری مناسب بر مبنای مدل های هوشمند شبکه عصبی مصنوعی (ANN) و ماشین بردار پشتیبان (SVM) برای تخمین بهنگام BOD5 در رودخانه سفیدرود است. برای این منظور با قرار دادن BOD5 به عنوان تابعی از دیگر متغیرهای کیفیت آب، مدل های مناسبی برای این موضوع با استفاده از دو مدل ANN و SVM توسعه داده شد. در توسعه مدل ANN نقش توابع آموزش لونبرگ-مارکویت (LM)، پس انتشار ارتجاعی (RP) و گرادیان مزدوج مقیاس دار (SCG) در بهینه کردن مشخصه های ANN ارزیابی شد. همچنین برای بهینه کردن مشخصه های مدل SVM از الگوریتم بهینه سازی جستجوی شبکه دو مرحله ای استفاده شد. نتایج این تحقیق مبین عملکرد برتر مدل ANN با الگوریتم LM (مدل ANN (LM)) نسبت به دو الگوریتم دیگر بود. همچنین مدل SVM نیز از عملکرد مناسبی در تخمین BOD5 برخوردار بود، به طوری که مقدار ضریب همبستگی پیرسون برای این مدل در مرحله تست معادل 95/0 به دست آمد. در نهایت نیز بررسی های بیشتر برای ارزیابی یکی از دو مدل منتخب بر مبنای آماره نسبت تفاوت توسعه داده شده انجام پذیرفت که نتایج به دست آمده از این آماره حاکی از عملکرد برتر مدل SVM نسبت به ANN (LM) بود.
    کلیدواژگان: شبکه عصبی مصنوعی، ماشین بردار پشتیبان، رودخانه سفیدرود، اکسیژن خواهی بیوشیمیایی 5 روزه
  • حسین میرشجاعیان حسینی، فرهاد رهبر، ناهید پوررستمی صفحه 83
    خودهمبستگی فضایی پدیده ای شناخته شده در مطالعات زیست محیطی است که مفهوم آن بر اساس ارتباط فضایی ویژگی های زیست محیطی واحد های مختلف جغرافیایی شکل می گیرد. برای توجیه و تفسیر پدیده خودهمبستگی فضایی پدیده های زیست محیطی، سازوکار های متعددی پیشنهاد شده است. مقاله حاضر تلاش می کند تا سازوکاری جدید به سازوکار های فوق اضافه کند که در آن خودهمبستگی فضایی پدیده های زیست محیطی از طریق سرریز فضایی حکمرانی خوب میان کشورها محقق می شود. در سازوکار پیشنهادی، تغییر کیفیت نهادی یک کشور نه فقط بر کیفیت زیست محیطی آن کشور اثرگذار است، بلکه همزمان کیفیت نهادی کشورهای همسایه و از طریق آن، کیفیت زیست محیطی آنها را نیز متاثر می سازد. از این رو، سرریز حکمرانی خوب کشورهای همجوار عامل خودهمبستگی فضایی پدیده های زیست محیطی آنها خواهد شد. به منظور بررسی سازوکار پیشنهادی فوق، اثر سرریز فضایی حکمرانی خوب بر انتشار گاز دی اکسیدکربن در قالب مدل های اقتصادسنجی با داده های تلفیقی و ساختار فضایی در حوزه جغرافیایی کشورهای خاورمیانه و شمال افریقا (منا) و در بازه زمانی1990 تا 2007 مورد بررسی قرار گرفت. نتایج تحقیق نشان می دهند که افزایش و تعمیق حکمرانی خوب در کشورهای منطقه منا نه تنها به کاهش گاز دی اکسید کربن می انجامد، بلکه با تاثیر گذاری مثبت بر کیفیت نهادی کشورهای همسایه موجبات کاهش آلاینده های زیست محیطی و افزایش کیفیت زیست محیطی آنها را نیز فراهم می آورد.
    کلیدواژگان: توسعه نهادی، خودهمبستگی زیست محیطی، مدل داده های تلفیقی
  • منصور خلیلی عراقی، غلامعلی شرزه ای، سجاد برخورداری صفحه 93
    انتشار دی اکسیدکربن ناشی از مصرف انرژی، به عنوان یکی از معضلات اساسی مطرح است. در راستای کنترل و کاهش انتشار آن، شناسایی عوامل اثرگذار نقش کلیدی دارد. در این میان، تحلیل تجزیه شاخص (IDA) به عنوان یکی از روش های شناخت عوامل اثرگذار بر انتشار دی اکسیدکربن ناشی از مصرف انرژی مورد استفاده قرار می گیرد. در این مطالعه با استفاده از روش تحلیل تجزیه شاخص و استفاده از روش میانگین لگاریتم شاخص دیویژیا (LMDI)، تغییرات انتشار دی اکسیدکربن در سطح کلان اقتصاد و در سطح بخش های اقتصادی به عوامل اثرگذار برای دوره 1346-1385 در قالب هشت دوره پنج ساله و دو دوره سه ساله برای 1383-1387 مورد بررسی قرار گرفته است. نتایج مطالعه نشان می دهد در سطح کلان اقتصاد، تغییرات سرانه تولید ناخالص داخلی، جمعیت و شدت انرژی اثر مثبت بر انتشار دی اکسیدکربن داشته اند و تغییرات شدت کربن سوخت های فسیلی در بیشتر دوره ها نقش موثری در کاهش انتشار دی اکسیدکربن داشته است. نتایج تحلیل تجزیه شاخص در بخش صنعت نیز نشان می دهد سهم سوخت های فسیلی در انرژی مصرفی و تولید این بخش از کل تولید ناخالص داخلی کشور نقش تعیین کننده در انتشار دی اکسیدکربن طی دوره 1383-1387 داشته اند. همچنین نتایج مطالعه نشان می دهد شدت کربن سوخت های فسیلی و شدت انرژی مصرفی در بخش های خدمات و کشاورزی نقش مثبت در انتشار دی اکسیدکربن داشته اند و اثر سهم بخش کشاورزی از کل تولید ناخالص داخلی بر انتشار دی اکسیدکربن در این بخش بر خلاف سایر بخش های اقتصادی منفی بوده است.
    کلیدواژگان: انتشار دی اکسیدکربن، مصرف انرژی، سوخت های فسیلی، تحلیل تجزیه شاخص
  • سیدحجت موسوی، مسعود معیری*، عبدالله سیف، عباسعلی ولی صفحه 105

    رخداد مسائل زیست محیطی و اتلاف منابع طبیعی از جمله علل ایجاد راهکارهای مدیریت ریسک و بحران محیط زیست هستند. یکی از مهمترین مشکلات زیست محیطی شمال شرق طرود، هجوم ماسه های روان به مراکز سکونتی، راه های ارتباطی و تاسیسات زیربنایی است. سیستم محیطی در مقابل تنش ماسه های متحرک، واکنش نشان داده و با ایجاد اکوسیستم نبکا سعی در تعدیل فشار فرسایش بادی می کند. بنابراین توسعه چشم انداز نبکا می تواند به عنوان عاملی به منظور حفظ هماهنگی بین نیروهای عمل کننده زیست محیطی و کاهش آثار تخریبی ماسه های روان بر سیستم های انسانی عمل کند. در این راستا شناسایی سازگارترین گونه گیاهی نبکا از اهمیت بالایی برخوردار است. هدف از این پژوهش ارزیابی مقایسه ای نبکاهای شمال شرق طرود با استفاده از مدل AHP و معرفی مناسب ترین گونه گیاهی نبکا برای تثبیت ماسه های روان از طریق تحلیل مولفه های مورفومتری آن است. به این منظور ابتدا مهمترین مشخصه های مورفومتری 67 نبکا، نظیر حجم نبکا، ارتفاع نبکا، قطر تاج پوشش گیاه، ارتفاع گیاه، قطر قاعده نبکا و شیب نبکا، از گونه های تاغ، گز، اشنان و خارشتر به روش نمونه برداری طولی اندازه گیری میدانی شد. سپس با ارزیابی مقایسه ای آنها از طریق مدل AHP، مبادرت به اولویت بندی نبکاهای مطالعاتی شد. نتایج نشان می دهد که نبکای گونه تاغ با وزن 505/0 بیشترین ارجحیت و بهره وری را برای تثبیت ماسه های روان دارد. نبکای گونه گز نیز با وزن 302/0 نسبت به نبکای گونه تاغ از اهمیت کمتر و نسبت به نبکاهای گونه اشنان و خارشتر از ارجحیت بیشتری برخوردار است.

    کلیدواژگان: ریگ نجارآباد، طرود، نبکا، مدل AHP، تثبیت ماسه
  • اسلام زرینه، مهدی نادری خوراسگانی، اسماعیل اسدی بروجنی صفحه 117
    تنوع، پویایی و وسعت مراتع ایران پایش این منابع را اجتناب ناپذیر ساخته است. هدف از این تحقیق مطالعه رابطه شاخص های گیاهی ناشی از باندهای ماهوارهIRS-P6 LISS-III با پوشش گیاهی در منطقه تنگ صیاد است. شاخص های گیاهی معیاری برای بررسی میزان پوشش به عنوان عامل حفاظت خاک، تولید، پیش بینی گستره گونه های گیاهی و مهمتر از همه تغییرات مکانی خشکسالی و بارندگی به شمار می روند. 30 واحد نمونه برداری در منطقه به صورت تصادفی با در نظر گرفتن تیپ های گیاهی انتخاب شد. در هر واحد 12 پلات به طور تصادفی انتخاب و پوشش گیاهی در هر پلات اندازه گیری شد. اطلاعات ماهواره ای از نظر رادیومتری و هندسی تصحیح شدند. ارزش رقومی پیکسل های مربوط به هر پلات نمونه برداری برای تجزیه و تحلیل آماری مورد استفاده قرار گرفت. نتایج نشان دادند که از 24 شاخص گیاهی، 15 شاخص برای تخمین پوشش گندمیان و مجموع پوشش گندمیان و پهن برگان علفی و 10 شاخص برای تخمین پوشش کل گیاهان مرتعی مناسب هستند. همچنین شاخصDVI مناسب ترین شاخص برای تخمین پوشش گندمیان و مجموع پوشش گندمیان و پهن برگان علفی و شاخص NDVI مناسب ترین شاخص برای تخمین پوشش کل گیاهان بود. نتایج نشان داد که درصد پوشش گندمیان، پهن برگان علفی، بوته ها و مجموع درصد پوشش گندمیان و پهن برگان علفی می توانند برای تخمین تولید مرتع و تعیین ظرفیت حیات وحش تنگ صیاد که بز و جبیر هستند مورد استفاده قرار گیرد. پوشش برآورد شده می تواند برای محاسبه ضریب پوشش از نظر فرسایش خاک مورد استفاده قرار گیرد.
    کلیدواژگان: پوشش گیاهی، ماهواره IRS، P6 LISS، III، تنگ صیاد، شاخص های گیاهی، مراتع
  • حمیدرضا جعفری، یوسف رفیعی، مجید رمضانی مهربان، حسین نصیری صفحه 131
    با وجود تلاش های فراوان جهت کاهش یا بازیافت پسماندها، دفن بهداشتی هنوز راهکار اصلی مدیریت پسماند است. بنابراین دفن بهداشتی پسماندهای شهری با رعایت اصول محیط زیستی و در راستای توسعه پایدار از ضرورت های عصر حاضر است. یکی از مشکلات جدی در اغلب محدوده های شهری کمبود زمین مناسب برای دفن پسماندهای شهری است. انتخاب محل مناسب برای دفن پسماندهای شهری امری مشکل، پیچیده و زمانبر است و نیاز به بررسی معیارهای بسیاری دارد. در این تحقیق برای تعیین مکان های مناسب دفن پسماند استان کهگیلویه و بویر احمد از معیارهای شیب، پوشش اراضی، فاصله از راه های اصلی، فاصله از مراکز شهری و روستایی، زمین شناسی، شبکه آبهای سطحی، فاصله از گسل، بارش و ارتفاع استفاده شد. نقشه های مربوط به هر یک از شاخص های طبیعی و انسانی مورد استفاده در محیط GIS تهیه و برای وزن دهی و تلفیق لایه ها از فرایند تحلیل سلسله مراتبی (AHP) و وزن دهی تجمعی ساده (SAW) استفاده شد. وزن دهی و محاسبه نرخ ناسازگاری جدول های مقایسه زوجی در AHP با استفاده از نرم افزارExpert Choice صورت گرفت. نواحی دارای محدودیت برای دفن که بر اساس استانداردها و یا نظرهای کارشناسی دارای ارزش برابر صفر هستند نیز از هر یک از نقشه ها استخراج و برای آن یک نقشه جداگانه به نام لایه محدودیت تهیه شد. نتایج به دست آمده در هر یک از تکنیک های مورد استفاده در لایه محدودیت ضرب و نتایج نهایی در پنج طبقه محدودیت، به نسبت نامناسب، به نسبت مناسب، مناسب و کاملا مناسب قرارگرفتند. مقایسه نتایج حاصل از دو روش در این تحقیق مبین این است که AHP نسبت به SAW نتایج محافظه کارانه تری را ارائه می کند.
    کلیدواژگان: مکانیابی، GIS، AHP، SAW، دفن پسماند، کهگیلویه و بویر احمد
  • منوچهر طبیبیان، ناصر رضایی، همایون نورایی صفحه 141
    در این پژوهش٬ نتایج پژوهش برای تبیین نقش مهاجرت - که اغلب بخشی از آنها از سیاست های بخش مسکن تاثیر می پذیرند- در ناپایداری محلات مسکونی معاصر٬ ارائه شده است. اغلب محلات کلانشهرهایی چون تهران با مفهوم محله و شاخص هایی که معرف این نوع زیستگاه انسانی است به دلایلی از جمله مهمترین، آنها یعنی عدم یکدستی ساختار اجتماعی محلات فاصله زیادی دارند. به تبع مسائل مترتب بر این موضوع٬ هدف این پژوهش تبیین تاثیر عوامل تاثیرگذار بر ناپایداری محلات شهری معاصر است با نگاهی ویژه به مسائل متاثر از مهاجرت٬ با بررسی مسائلی همچون پراکندگی کالبدی٬ ناامنی در شهرها٬ کیفیت نازل محیط٬ نزول ساختار اجتماعی محلی٬ فقدان هویت٬ فقدان الگوهای اقناع کننده مسکن٬ حضور اتومبیل و... که گریبانگیر محلات شهری معاصر شده است. با توجه به محدودیت های پژوهش٬ ارتباط مهاجرت با این مسائل منعکس کننده پاسخ پرسش اصلی این پژوهش خواهد بودکه: آیا مهاجرت بر پایداری محیط مسکونی محله «کن» منطقه 5 تهران تاثیر گذاشته است؟ طی این پژوهش از مطالعات نظری و تجربیات جهانی برای تبیین چارچوب نظری مطالعه استفاده شد و با مطالعات اسنادی و به کارگیری ابزار پرسشنامه و بهره گیری از نرم افزار SPSS به پاسخگویی به سئوال مذکور پرداخته شد نتایج پژوهش حاکی از این واقعیت است که مهاجرت های صورت گرفته به محله کن تهران در نزول کیفیت محیط مسکونی از جمله هویت، پویایی و سازگاری، ظرفیت قابل تحمل مکان و... تآثیر گذار بوده است.
    کلیدواژگان: محله، محله پایدار، قیمت مسکن، مهاجرت، محله کن
  • فیروزه آقا ابراهیمی سامانی، بهرنگ بهرامی، اسماعیل صالحی، هما ایرانی بهبهانی، رویا ساعتیان صفحه 155
    تنوع ساختار اکولوژیکی سرزمین ایران زمینه شکل گیری مناظر فرهنگی متعددی را فراهم آورده است. مناظر فرهنگی، ترکیبی از تداوم حیات انسان و هنر پیرایش سرزمین را با بهره مندی از اجزای محیط طبیعی و در قالب سکونتگاه های انسانی از دوران گذشته تاکنون به نمایش می گذارند. در شرایط کنونی رشد جوامع انسانی در کنار پیشرفت های علمی، افزایش بهره گیری بشر از منابع و پیامدهای منفی ناشی از توسعه گردشگری بدون وجود طراحی و مدیریت بهینه در پهنه های تاریخی طبیعی، امکان تخریب ساختار اکولوژیکی و تاریخی مناظر فرهنگی را فراهم آورده. بحث نوین حفاظت جامع محیطی زمینه ساز حفاظت از پهنه های زیستی تاریخی و سکونتگاه ها است. منطقه تاریخی طبیعی تالش «آق اولر مریان» با ویژگی های اکولوژیکی خاص و جاذب گردشگر دارای سکونتگاه های 4500 ساله در کنار منزلگاه عشایر فصلی است که از دوران باستان تاکنون تغییر چندانی نیافته و در بستر طبیعت تالشان در هم تنیده شده و بخش مهمی از ویژگی های منظر فرهنگی تالشان را به نمایش می گذارند. این سکونتگاه ها با معماری ویژه ای در نحوه استفاده از مصالح بومی و مکان یابی صحیح با توجه به شاخص های بستر محیطی و بویژه تنوع ساخت، در طول زمان از ماندگاری خاصی برخوردار بوده اند. از سویی توسعه ساخت و سازهای جدید بویژه ویلاسازی ساکنان شهرهای پیرامونی باعث تخریب عناصر ارزشمند منظر شده است. در تحقیق پیش رو، شناسایی و مکانیابی این سکونتگاه ها و نحوه پراکنش آنها با استفاده از فناوری دورسنجی و مطالعات گسترده محیطی، زمینه حفاظت جامع محیطی از این عناصر را به وجود آورده و با ارائه راهبردهایی، موجبات حفاظت جامع محیطی و توسعه گردشگری پایدار را فراهم آورده است.
    کلیدواژگان: مناظر فرهنگی، ساختار اکولوژیکی، حفاظت جامع، آق اولر مریان، گردشگری پایدار
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  • Farahanim., Mirbagheri, S.A Page 1
    IntroductionPolycyclic Aromatic Hydrocarbons (PAHs) are widely distributed contaminants which have drawn increasing public health concern because of their mutagenic and carcinogenic properties. In addition to their natural occurrence, anthropogenic inputs from fuel combustion, pyrolytic processes, waste incinerators, domestic heaters and spillage of petroleum products have resulted in a significant accumulation of PAHs in the environment. Petroleum contaminated soil is currently treated using three types of processes: physical, chemical, and biological. Bioremediation is an attractive approach for cleaning up petroleum hydrocarbons, because it is simple to maintain, applicable over large areas, cost-effective and leads to the complete destruction of contaminants. Organic compounds are metabolized under aerobic or anaerobic conditions by biological processes of microorganisms. Bioremediation of contaminants can be accomplished by two methods, bioaugmentation and biostimulation. The process of bioaugmentation, as it applies to remediation of petroleum hydrocarbon contaminated soil, involves the introduction of microorganisms that have been cultured to degrade various chains of hydrocarbons into a contaminated system. The process of biostimulation introduces additional nutrients in the form of organic or inorganic fertilizers into a contaminated system, which increases the population of the indigenous microorganisms. In the field of biostimulation, nutrient supplementation for hydrocarbon degradation has traditionally focused on the addition of N and P. Because C is a major constituent of petroleum fuels, its traditional role in bioremediation research has typically been as an index to determine the amount of N and P that needs to be added to reach the optimal C:N:P ratio. The indigenous microorganisms of the contaminated soils, which are adapted to hard conditions, are the best microbial population for using in bioaugmentation. Various microorganisms have different requirements for using the carbon contents of pollutants as an energy source. Thus, the successful application of bioremediation technology to contaminated soil requires knowledge about the characteristics of the site and the parameters that affect the microbial biodegradation of pollutants. This study was carried out to isolate high diversity of bacterial strain with the ability of degrading multiple PAHs from Tehran oil refinery contaminated soil and obtain the optimized conditions of biodegradation of these pollutants in laboratory. The final objective was to compare the effectiveness of natural attenuation, biostimulation and bioaugmentation for PAHs degradation in soil. Materials and MethodsSoil samples were collected in sterilized panels from four different geographical directions of a land next to the active units of Tehran oil Refinery in Iran. The soil properties of samples are provided in Table.1. The presence of PAHs contamination in the soil of this land was confirmed by solvent extraction (Dichloro methane) in an ultrasonic water bath and high HPLC analysis.
  • Salmanzadehm., Saeedim., Nabi Bidhendi, Gh Page 9
    IntroductionStreet dusts are suspended particle matters in the air from different natural and anthropogenic sources that may fall down because of their size and density. The growth of population, industrial activities and vehicles, has recently increased urban systems pollution. Therefore, it has recently been focused on the assessment of street dust contamination as a major source of urban environment pollution, all over the world. Heavy metals in street dusts are among major environmental pollutants that may be originated either from anthropogenic sources such as high traffic loads, industrial activities, building erosions, corrosion of tires and car parts, mineral activities and fossil fuel burnings or from natural sources such as local soil. During recent years huge amounts of atmospheric dust have entered Tehran, crossing national western borders of Iran and settled on the surfaces of urban areas.Assessing heavy metal contents of street dusts which can make serious human health risks seems to be important in this highly populated city. In this study, fifty street dust samples were collected from streets of southern and eastern parts of Tehran, the capital of Iran. The concentrations of nine metals (i.e., Cu, Cr, Pb, Ni, Cd, Zn, Fe, Mn and Li) were determined in samples. Probable natural or anthropogenic sources of metals were identified using multivariate statistical analyses. Enrichment factors and Hakanson’s ecological risk assessment method were also applied.Materials and MethodsFifty locations were selected for sampling. The distribution of sampling points is as follows: ten samples from each Resalat, Baghery and Hengam streets, five samples from Esteghlal Street which are main streets in eastern parts of Tehran. Fourteen samples were collected from the South terminal of Tehran which is located in one of the high polluted areas in the south of Tehran and the last sample was collected from the campus of Iran University of Science and Technology. Dust samples were collected during summer under dry and stable weather conditions, using broom and suction from the edge of pathways in streets and terminal. The samples were kept in special bags and were taken to laboratory. In the laboratory, the samples were air dried at room temperature until they were constantly weighted. Thereafter, they were passed through sieving sets of numbers 10, 35, 60 and 230 (63 µm). The particles with sizes lower than 63 µm can easily become suspended and emitted in the air. Therefore, their entrance into human’s respiratory system and causing serious effects are more probable than larger ones. Dust particles with the size of less than 63 µm were subjected to chemical analyses. Dust samples were acid digested (HCl, HNO3, HClO4). The metal contents of the samples were determined using Atomic Absorption Spectrometer (Buck Scientific model 210 VGP model).By using of Hakanson’s method and RI the ecological risks of each sampling location were calculated. Cluster and principal component analyses were used to identify probable sources of pollutants. In addition, possible effects of human activities on the concentrations of heavy metals were evaluated, using enrichment factor (EF).
  • Almasiehk., Kaboudvandpour, S Page 19
    IntroductionMercury (Hg) is a toxic compound that is produced in the environment by anthropogenic activities and physico-chemical interactions in the earth crust. Therefore, mercury (Hg) pollution is considered as an environmental problem in global scale. Among heavy metals, mercury is a unique element which exists in different organic and inorganic forms in the nature. This metal readily biomagnifies in the aquatic food chain, because it is almost completely absorbed and transported throughout the body, particularly the body of lower trophic levels members in natural aquatic ecosystems. The high concentration of mercury will restraint the natural growth of living creatures, disturb material exchange and transform in natural ecosystems, and cause disorders in body functions. Inorganic mercury (Hg) can be converted to methylmercury (M-Hg, the most toxic from of mercury) basically by anaerobic microorganisms existing in aquatic ecosystems substrates. The obvious characteristic of this compound is its stability in environment and long biological half-life. Previous studies showed that the level of total mercury (THg) in Sanandaj Gheshlagh Reservoir (SGR) water is higher than those limits established by WHO and Iran (i.e., 1 µg/L). Sediments and benthic invertebrates (benthos) are assumed as the indicators of the level of mercury concentration in aquatic ecosystems.The stability of mercury in sediments plays an important role in mercury cycle in natural ecosystems. On the other hand, the level of accumulated total Mercury (T-Hg) in benthos biomass is subordinated to the level of accumulated T-Hg in sediments with living organisms on them. Microorganisms inhabiting aquatic ecosystems substrates convert inorganic mercury to methylmercury during the process of bio-methylation, which is the most hazardous mercury form. Methylmercury is eliminated from live tissues much later than inorganic mercury. Field observations verified that SGR pollution was occurred by natural processes because intensive agricultural activities and other pollutant sources such as industrial activities were not observed within the SGR watershed and it's upstream. In addition, previous geological and pedological studies proved considerable levels of mercury in the SGR geological structures. The most favorite and consumed fish in the region is common carp (Cyprinus carpio) due to its high abundance and relatively low price. Common carp is a benthivorous fish and its staple food diet is benthic invertebrates. Therefore, the present study aimed to evaluate the level of total mercury in sediments and benthos masses of Sanandaj Gheshlagh Reservoir, in order to evaluate the capability of benthic invertebrates to accumulate mercury and their ability to transfer the mercury up to the higher trophic levels during July to December 2009.Materials and MethodsSanandaj Gheshlagh Reservoir (35° 26' 58'' N and 46° 59' 10'' E) is located in Northeast of Sanandaj city, west of Iran. This Reservoir covers an area of approximately 8.5 km2 and its actual water capacity is about 224 million m3. Meanwhile, Gheshlagh Reservoir is the focal resource of drinkable water for the people whom dwelled in Sanandaj region and is the main source of fisheries activities and products in this region. Sediment and benthos samples were obtained using Ekman grab (20 by 20 cm in size) in three different sites with different depths and at least three replicates, during July to December 2009. Two sites with the depth of lower than 17 m were situated at the end of the two main river basins feeding the dam lake (i.e., Gheshlagh and Chehelgazi Rivers) and the third site was located in the main water body of the dam lake with variable depths of about 30 m. Sediment samples were preserved in mercury-free screw cap bottles and were stored in the temperature of 4ºC. Obtained benthos and sediment samples were passed through 250µ sieve. Benthic organisms were isolated from sediments using stereomicroscope with optical zoom of 20 and kept in 4% buffered formalin. Although this study aimed only to measure T-Hg in benthic invertebrate benthos masses, they have been identified in family and genus levels as well. As methylmercury is a volatile compound, to prevent methylmercury volatilization, sediment and benthos samples were dried out for 24 hours in -54ºC by a Freeze drier (Operon, FDCF-12012). Fifty mg of each sample was grinded and the level of the total accumulated mercury in sediments and benthic samples was measured by Advanced Mercury Analyzer (Model; Leco 254 AMA) according to ASTM, D-6722 standard and on the ngg-1 dry weight basis.Biota-Sediment Accumulation Factor (BSAF) was calculated based on the suggested equation by Szefer and his colleagues (i.e., BSAF= Hg in benthos/Hg in associated sediment) in 1996. SPSS 16 software (SPSS Inc., 2002), SAS software (Version 9.1 ref.) and Excel (Microsoft office 2007) were used for statistical analysis as well as drawing relative graphs. Kolmogorov-Smirnov and Shapiro-wilk tests were considered to check data normality, which later was proved to be unnecessary. Randomizes Complete Block Design (RCBD) was used to compare the level of accumulated T-Hg in sediments and benthos biomass between different months and sites. Duncan test was used to compare the mean values with significant statistical difference. Paired T-test was used to compare the level of concentrated T-Hg in sediments and benthos. Pearson correlation was also used to show the correlation between T-Hg in sediments and benthos.ResultsThe most abundant macrozoobenthos observed in the reservoir were mostly members of Oligochaeta sub-class and Tubificidae family. In summer, few numbers of Chironomidae family and Chironomus genus were also identified. Mean total mercury (± S.E.) concentration in benthos and sediment samples were 94.3±5.02 and 117.66±9.72 ngg-1, respectively. The highest monthly mean concentration of accumulated mercury (171.7±28.82 ngg-1) and the lowest monthly mean concentration of accumulated mercury in the sediment samples (91.93±13.3 ng g-1) were detected in July and November, respectively. The highest monthly mean concentration of accumulated mercury (115.89±12.83 ngg-1) and the lowest monthly mean concentration of accumulated mercury (79.11±6.22 ngg-1) in benthos biomass were measured in August and October, respectively. Mean total mercury in benthos masses was not significantly different among sampling efforts (F5,10=2.16, P=0.14), whereas the levels of total mercury in sediments were significantly different (F5,10=4.88, P=0.02) amongst the sites. The mean values of accumulated mercury concentration in benthos biomass samples (F2,10=5.37, P=0.03) and sediments (F2,10=7.88, P=0.008) demonstrated significant differences among sampling sites. The highest mercury concentration in benthos biomass (110.69±11.83 ngg-1) and in sediment (147.04±19.86 ngg-1) was observed in the deeper site. Monthly mean values of the obtained benthos biomass were significantly different (F5,10=4.55, P=0.02) among different months as well as different sites (F2,10 = 4.55, P=0.01). Duncan test showed that the benthos biomass in November was significantly greater than that of other months. There were similar conditions for Chehelgazi River site. Wong, et al., (1996) method was followed to determine the potential transferable Hg from benthos trophic level to higher trophic level (i.e., Fish). Hg pools (ngm-2 dry weight) were estimated by multiplying Hg concentration (ngg-1 dry weight) and the mean benthic invertebrate biomass (gm-2 dry weight). Mean Hg pools with 95% confidence interval (in parentheses) for benthic invertebrate was 114.1 (79.61, 148.77) on the ngm-2 dry weight basis. The correlation between T-Evaluation of Mercury Accumulation in Sediments and Hg in benthos and associated sediments was significant (r = 0.528, P = 0.026). In general, T-Hg was higher in sediment samples compared with benthos samples based on the paired T-test (T=2.83, P=0.0116). All calculated BSAF in this study were lower than one. Discussion of ResultGheshlagh watershed runoffs carry soil from the watershed and add it to the SGR substrates. In freshwater ecosystems sediments are the main source of mercury pollution. Therefore, those organisms which live in sediments are subject to being polluted by this hazardous heavy metal. Benthic invertebrates are associated to the sediments via dietary needs or their habitat requirements. Oligochaetas members have been used frequently to indicate water quality and test sediment toxicity. A majority of oligochaetes members fed by ingesting sediment, extract nutrition from the organic matter particularly the bacteria. Organisms fed directly by sediments typically have higher overall mercury levels in comparison with those fed by the above sediment–water interface. Since benthos and sediments are appropriate indicators for measuring mercury pollution of SGR, the results of this study showed that the mean accumulated T-Hg in sediments and benthos biomass from SGR varies between summer and autumn months (P<0.05). High concentrations of the accumulated T-Hg in the sediment and benthos biomass samples in summer months could be due to the dissolved oxygen reduction in water column, reduction in water volume, physical, chemical and biological changes, increasing material deposition and higher water temperatures in summer. It has been proven that the rate of methylation process will be elevated during summer times in lenthic aquatic ecosystems. Results showed that the amounts of the accumulated T-Hg in the sediment and benthos biomass samples were higher in deeper sites in comparison with the shallower ones. This could be due to the dissolved oxygen reduction, decreasing the sun light absorption in the deep water, increasing the rate of anaerobic bacteria (sulfate-reducing bacteria) activities and increasing the bioavailability of mercury along with increasing the water depth. Similar results have been reported by other researchers. Despite the lower T-Hg accumulated in benthos samples collected in autumn, benthic invertebrate Hg pools were higher in autumn as a result of higher benthos biomass. Therefore it seems that benthivorous fish such as common carps, receive higher amounts of mercury in autumn which is the open season for fisheries activities in the region. Correlation between T-Hg in sediments and benthos was significant (P<0.05); which means that benthic mercury intakes are associated with the amount of mercury in sediments. The calculated amount of BSAF in the present study was lower than one. This means that the capacity of benthos collected from SGR to accumulate mercury from sediments is not an important fact with respect to the accumulated T-Hg in their body. It has been assumed that the incapability of SGR benthic invertebrates in mercury bioaccumulation is related to the SGR substrates composition and texture, and the stage of benthos life cycle during this study as well as some specific physico-chemical characteristics of SGR that reduce the bioavailability of mercury for benthic invertebrate.ConclusionThis study proved mercury contamination in benthic invertebrates and associated sediments in SGR. T-Hg in benthos and sediment in the summer months were higher than that in the autumn months. However, due to the higher benthos biomass in autumn, the rate of mercury transformations could be higher in this season (open season for fisheries). In this study all calculated BSAF values were lower than one. However, due to the mercury methylation by benthos and its biomagnifications capability, strong considerations have to be taken into account with respect to the consumption of SGR benthivorous fish. Thus, it needs more investigations.
    Keywords: Mercury, Bioaccumulation, Sediments, Benthic invertebrate, Sanandaj Gheshlagh Reservoir
  • Shokouh Saljoughiz., Rafiee, Gh., Malekpoura., Shokouh Saljoughia., Safari, O Page 31
    IntroductionAquaculture wastewaters when discharged to the environment or another receiving body of water can create serious problems. These effluents contain large amounts of harmful material such as organic compounds, anionic and cationic species, uneaten food and etc., which have undesirable effects on the health of aquatic ecosystems and aquaculture facilities. Aquaculture systems produce large quantities of nutrients (phosphorus and sulphate) that require treatment and/or disposal. Principal sources of aquaculture wastes are uneaten foods. The presence of trace amounts of phosphate (even less than 1 ppm) in treated wastewater is often responsible for eutrophication; particularly in lakes and slow moving rivers. Sulphate and phosphorus, discharged with these effluents, result in enhanced growth of organisms associated with eutrophication. However, regulatory agencies are becoming increasingly concerned over elevated sulfate concentrations in effluents, owing largely to its impact on the salinity of receiving waters. There are several methods to treat wastewater containing sulfate anions. The removal of the anion by means of adsorption on the activated carbon, neutralization with CaCO3, biological treatment, reverse osmosis and dialysis and ion exchange were studied. Aiming for the high quality of receiving waters in aquaculture systems, various techniques such as settling systems, centrifugal systems, mechanical filters (media filter and screen filter) and biological processes have been introduced and were applied. Inorganic ion exchanger materials such as zeolites are utilized to remove ammonia from fish raring facilities. Clay is another material that can be used as an ion exchange adsorbent. However, it is utilized very poorly in the existing aquaculture wastewater treatment facilities. The use of clay as anion exchanger in aquaculture has not been considered yet. After modification, clay is also capable of removing anions and other compounds with negative charges. In this study, by using a cationic surfactant TDTMA, and acid thermo activation methods, the surface of bentonite was changed and the capability of the exchanged clay for the adsorption of anionic compounds such as sulfate and phosphate from aquaculture effluent was analyzed.Materials and MethodsBentonite, natural clay, was acquired from Tabas Iran Co. in Tehran and was used without any further purification. All chemicals were of analytical reagent type and were used as received. The standard solutions were prepared using NaNO3, NaNO2, Na3PO4 and Na2SO4 salts in Milli-Q water.Fish culture system containing two 200-L fish tanks and a sump tank was designed and constructed. Each tank was stocked with 30 trout of 120g mean weight (9.37 Kg/m3). It also included a combined unit of sand and biological filter to remove faces and other suspended particles and biological inter-conversion of nitrogenous wastes, respectively. The X-Ray diffraction pattern of the mineral sample showed that the major clay material present in the sample is bentonite.The main mineralogical impurities are Quartz, hydrated silicates of sodium, calcium, magnesium and aluminum, Stellerite-(Na), Illite, Muscovite and Gypsum. The composition of bentonite in terms of its oxide forms provided by the manufacturer is listed in Table 1. Elemental analysis of the sample using XRF showed that the raw material had Si/Al ratio of 3.46. The Na-exchanged form of bentonite was prepared by stirring samples for 6h with a 1M aqueous solution of NaCl. Excess NaCl and other exchangeable cations were removed from the exchanged bentonite via filtering. Then, it was washed several times with deionized water until a negative chloride test was obtained with 0.1M AgNO3. The Na-saturated bentonite (50g) was dispersed in 1L of distilled water. TDTMA–bentonite was prepared by adding quantities of the respective surfactant equal to twice the cation exchange capacity of the bentonite and was stirred for 6h. After treatment, bentonite was washed with deionized water to obtain salt-free minerals and a negative chloride test was carried out with 0.1M AgNO3. Finally, it was dried, grounded and sieved to a size range of 0.8-1.2mm.The acid thermo activated clay was obtained from a natural sodium bentonite. The raw material was first decarbonated and homoionized. Acid thermo activation is a process that allows controlled extraction of aluminum ions from crystalline structure of clay, also introducing an acceptable acidity level. This process modifies the textural properties of clays, favoring a greater porosity and surface area. To carry out acid thermo activation, the purified clay was put in a flask with an acid solution (10 mL acid/1 g clay), stirred and refluxed and heated to 105°C for 3h. The utilized acid solution was: HNO3 (2N). Thereafter, the clay was washed with de-ionized water and dried at 70°C. The powders were ground to a particle size of 0.8-1.2mm and then heated for 4h at 300°C.The solution pH was carefully adjusted by adding small amounts of HCl or NaOH solutions and measured using a pH-meter (corning 120). The samples were filtered and the equilibrium concentrations ascertained by photometer (palintest® 8000). The amount of anions adsorbed onto TDTMA–Bentonite (SMB) was determined by the difference between the initial and remaining concentrations of anionic solutions. The distribution coefficient (Kd) was determined by using the following equation: Where Ci and Ce are the initial and the equilibrium anions concentrations (mg/L), V is the volume of solution (mL) and m is the amount of the used adsorbent (g).Results and Discussion Structural comparisons between modified and natural bentonite imply that modification procedures have changed crystal lattice and layered structure of the mineral smoothly (Figs. 3 and 4). Heating resulted in increased distance between layers and consequently yielded higher anion uptake compared with natural bentonite. Surfactant layer grafted on surface and within the layers of mineral resulted in anions removal by the modified bentonite.The present study was set out in a laboratory condition to evaluate the anion absorption capacity of surfactant acid thermo modified bentonites so as to reveal the potential of the compound as an alternative water remediation method for aquaculture recirculation system. The research clearly suggests that modified bentonite acts as a proper adsorbent for the removal of harmful anions from aquaculture and aqueous solutions. Because of the importance of generating a viable ion uptake tool for toxic species, different studies have been carried out regarding the use of a low-cost adsorbent for the selective removal of anions from aqueous solutions.ConclusionIt has been shown that bentonite modified by TDTMA and acid thermo activation method provides a considerable ion uptake capacity. The main advantages of this procedure are as follows:1- Natural bentonite is very cheap and abundant.Application of Modified Bentonites (SMB and ATB) for Decreasing… 122- Results showed that bentonite modified by TDTMA was efficient for removing harmful ions from aquaculture wastewater and decreasing anions under the critical levels.3- Since the bentonite clays even in modified forms can remove cationic species, so this adsorbent is very effective for the simultaneous removal of cationic and anionic species from aquaculture recirculation effluents. 4- This new adsorbent can be utilized as a supportive filter in RAS to remove toxic compounds such as NO3-, NO2-, PO43- and SO4 from aquaculture systems.
    Keywords: Recirculation system, Anionic compounds, Bentonite, surfactant, anion adsorption, BMPs
  • Nassery, H.R., Nick Ghojough, Y Page 41
    IntroductionThousands of tailing dams worldwide contain billions of tones of mineral processing industry wastes. Tailing dams possess specific characteristics and are used for disposal of dangerous or undangerous wastes. Tailing dam is one of the most important mining operations interface with surrounding environment respect to future limitations of environmental regulations. If the dams are constructed on carbonate or gypsiferous terrains, they might be exposed to karstification hazards. Active solutional caves in karst area could provide a hydraulic connection between surface and ground water. These solutional caves consequently can accelerate the groundwater flow and result in contaminant transportation. Groundwater pollution from sources such as waste disposal sites is a worldwide problem. Mining of mineral ores and disposal of resulting wastes pose a significant risk to the groundwater.Agh Darreh polymetal processing factory is located within 23 Km in the north direction of Takab in West Azarbayjan province, northwest of Iran. Study area is about 4 Km2. The climate is of upland continental type with temperatures reportedly down to -20ºC in winter and up to +30ºC in summer. Most of the precipitations are snow in winter (estimated to be over one meter per year in average); with minor rain in summer and autumn. Precipitation in the whole area is sufficient to sustain permanent creeks and rivers in the lower valleys (overall average is about 325 mm).After processing works in the factory, remaining wastes which have cyanide as a main contaminant, are disposed in a tailings dam. The tailing dam has been constructed with local fill materials (clay, granular and rock fill) at the end of a naturally occurring valley. From geological view, the study area is generally covered with alluvium and some members of Qom formation. Qom formation was deposited in central and northern Iran with a thickness of more than 2,700m in the south of Mianeh. The lower layers of this formation include salt, gypsum and anhydrite with alternating layers of silt and clay. The upper layers include siltstone, clay and sandstone. The studying area is tectonically active and quaternary and Pliocene deposits have experienced faulting. The tailing dam is located on an alluvial basin with sediments of clay, silt and marl sandstone.In this study, the role of gypsum member of Qom formation in hydraulic connection between the tailing dam and downstream karst springs and cyanide contaminant transportation between them are discussed.Materials and MethodsGeological map of area (1:2000) was provided using aerial photo interpretations and field works. Water levels in piezometers and some selected spring discharges were measured weekly between September 2005 and February 2006. In order to determine the hydrogeochemical conditions in the dam area, water samples were collected from one well and seven piezometers and two selected springs in August 2006. Major ion concentrations (HCO3-, SO42-, Cl-, Ca2+, Mg2+, Na++K+) and some parameters such as temperature, electrical conductivity (EC) and pH were measured. For the interpretation of chemical Analysis results and determining the saturation indexes (SI) for calcite, dolomite and gypsum, the Piper diagram and some ionic ratios were used. Geophysical investigations with ERI (Electrical Resistivity Imaging) method were carried out at the downstream part of the dam in order to obtain underground geological information and provide a schematic image of gypsum karst and fractured zones development.Apparent electrical resistivity measured along a 950m line parallel to the dam axis at the downstream region of the dam. The results of the measurements were provided and interpreted as an apparent resistivity traverse section along this line. For environmental monitoring, cyanide concentrations were measured in the water resources of the study area from September 2005 to February 2006. Variations of cyanide concentrations in water resources of area at this period were then discussed. Tracing inspections were also carried out at April 2006 using the NaCl in order to discuss the hydraulic connection between the tailing dam reservoir and the downstream. DiscussionThe study area is geologically located in Alborz zone and beside the folded vast Persian plateau. Structural geology of the area includes two orogenic phases of Precambrian and Albian. The study area generally consists of quaternary depositions and Qom formation members such as red to brown sandstone and yellow to green gypsy marls that outcrops in the area. Southern part of the area consists of about 200m thick green to yellow marlstones with intercalations of sandstone. The tailing dam and its reservoir were constructed on these layers. These marlstones containing white to gray gypsiferous layers in the area were expanded from the tailing dam reservoir to karst springs in the vicinity of Agh Darreh River. The dominant layers at northern part of the area include dark brown to red sandstones. Agh Darreh factory and tailing dam were constructed on the anticlinal folded structure that tends to southeast at 5-15 degrees. One fault was reported in the study area in northeast-southwest direction. This fault is responsible for the geological layer displacement at southern part of the area. Also, along this fault some sinkholes exist in marl-Gypsum layers of Qom formation. All sinkholes are solutional and of falling type. This kind of interstratal karstification results from contemporary underground erosion processes and karstic evolution. These sinkholes provide a connection between surface flows and canalized underground flows. This sinkholes exist in the west side of the tailing dam and in the vicinity of the factory main road. These fractures cause the development of gypsum solution and provide conduits for groundwater flow towards the east. Water resources in the study area consist of surface and ground water. Agh Darreh River in the west side of the study area has a permanent flow and numerous small springs appeared at the rim of this river. Gorgha River with seasonal flow lies in the vicinity of the study area in the east side. Some springs with low discharges are present near the Agh Darreh River among which N-3 and N-4 karst springs are the main ones. According to information obtained from the drilling of over 100 piezometers and the results of water level measurements in the area, there is an aquifer characterized as a joint dominated aquifer. With respect to topographic conditions, the aquifer recharge is only dependent on precipitation. According to these measurements, the groundwater flow direction depends on the area’s topography. General groundwater flow direction is from north of the area towards the south. In the southern part of the area where karstified gypsum layers exist, these layers pose a controlling role on groundwater flow direction. With respect to Piper diagram, most of the samples are from magnesium bicarbonate type and samples N-3, N-4 and N-8 are from calcium sulfate type. This indicates the solution of sulfate minerals in aquifer. The source of these minerals is gypsum member of Qom formation which expanded in the tailing dam and reservoir area. The ratio of Ca2+/ Ca2++ SO42- equals to 0.5 and the ratio of HCO3-/all anions is below 0.8, which indicates the solution of gypsum. Most of the groundwater samples are saturated with respect to calcite and dolomite and under saturated with respect to gypsum. Samples N-3, N-4 and N-8 have saturation indices near zero and are nearly saturated. This indicates the accelerated solution in these samples. The ionic ratios in samples collected from the downstream of the dam indicate the solution of gypsum at the karstic conduits of this zone. According to the geophysical investigations with ERI method, the apparent resistivity generally decreases from the left bank to the right bank of the dam. These decreases can be due to lithologic variations of sandstone to marl and gypsum and also can be due to increase of moisture content of rocks and the saturation of fractures with water. In addition to these, some anomalies with low resistivity at the deepest part of the valley as well as some parts of the right bank can be witnessed. With respect to geological setting and drilling data, it is obvious that some gypsum caves exist under the valley. If these caves were filled with air, it was expected that they show high resistance anomalies, but the anomalies with low resistivity in the deepest part of the valley show that the gypsum caves at present act as passways for groundwater.The low resistance anomalies in the right bank could also result from the development of water saturated small fractures in marlstones. Abnormal high hydraulic gradients can drive the water impounded in the reservoir downstream through fractures reaching below the dam. Under such conditions, the natural process of karstification is accelerated to such an extent that high leakage rates may arise, which endanger the tailing dam. The first leakage of cyanide bearing liquid occurred as a leakage surface at the elevation of 1922m in downstream marlstones. By the time, the tailings level behind the dam was 1934m. Contamination of the N-3 and N-4 springs due to this leakage was reported. These springs lie in the elevation of 1865m with 450m distance from the tailing dam. This leakage occurred in result of the sudden occurrence of a sinkhole in the southwest part of the dam reservoir in the elevation of 1931m. In N-8 piezometer water seepage with cyanide concentrations equal to that of the tailings liquid was also reported in the elevation of 1893m. This indicates the direct relation of them. According to results from environmental monitoring data of the study area, except for N-8 well and the karstic springs of N-3 and N-4, other water resources had no pollution. In order to inspect the variations of cyanide concentration in these three resources, cyanide concentration versus time was prepared as a line diagram. With respect to the high differences in the values of the three resources, the vertical axis of the diagram was considered logarithmic. This contributes to easier comparison and interpretation of the data. In order to specify dry and wet periods of the year, the discharge of the karstic springs of N-3 and N-4 were used. With respect to hydrogeological conditions of the study area, excess of N-3 spring discharge compared to N-4 spring discharge indicates the dry period of the year. According to this diagram, at the dry period of the year until well N-8 was not pumped, cyanide concentration in this well and springs of N-3 and N-4 are the same and low in value. Disposal of mine tailings in southwestern part of the dam reservoir both in dry and wet periods causes the increase of cyanide concentration in well N-8 and springs of N-3 and N-4. This indicates that the southwestern part of the dam reservoir has inherent potential for the seepage of tailing liquids. Pumping of well N-8 at the dry period can cause a decrease in cyanide concentration of spring N-3 and N-4. While the water table depression resulted from pumping, ultimately causes an increase in hydraulic gradient towards the well N-8 and increases the entrance of the polluted liquid to this well. According to the effect of precipitation and increasing the gradient behind the dam, passing water amount from well N-8 area increases so that pumping of this well cannot discharge all of this water. This results in an increase in cyanide concentration in the downstream karst springs.Results Karst system development in gypsum layers of tailing dam reservoir area poses a controlling role on the trend of groundwater flow. This trend is from northern part of the area to the southwest. According to ERI investigations which were accomplished along a line downwards of the tailing dam axis, the values of apparent resistivity generally decrease from the north bank of the dam to the south one. This can occur due to both lithologic variations from sandstone to marlstone and gypsum and increase in moisture contents and saturation of the fractures with water. Low resistance anomalies in deepest part of the valley indicate that solutional conduits act as a passway for groundwater. With respect to the investigations on the behaviors of N-3 and N-4 springs, these two karstic springs have a unique source and their water is provided from solutional conduit that ends to the well N-8 area. According to cyanide concentration measurements in well N-8 and springs of N-3 and N-4, carried out from September 2005 to February 2006, it can be concluded that there is a hydraulic relation between the southwestern part of the tailing dam reservoir and well N-8 and karstic springs of N-3 and N-4 at downstream.
    Keywords: Gypsum karst, contaminant transportation, tailing dam
  • Mehrdadin., Mohammadi, A.R., Torabian, A Page 49
    IntroductionA problem with Conventional Activated Sludge (CAS) is that it yields too much sludge in such a way that biomass yield coefficient in this process is approximately 0.5 kg of biomass per removal of one kg of the removed COD. Treatment and disposal of sludge resulted from municipal wastewater treatment comprises approximately 50 to 60 percent of the total costs of a wastewater treatment plant. Therefore, regarding the environmental constraints for final disposal of sludge and soaring costs of sludge treatment and disposal in current methods, naturally, research centers all over the world are attempting to find and develop new methods for minimizing produced sludge in wastewater treatment plants. One of these ideal solutions for solving the sludge problem fundamentally is using those sludge processes which yield less sludge compared to current processes.Lysis-cryptic Growth: When a cell is disintegrated, its contents and its stored nutrients release within the wastewater. This increases the organic load of wastewater. Organic materials released due to disintegration of cells re-enter into the metabolic cycle of other microorganisms. Some of such carbonic materials are consumed for vital activities of other microorganisms which in turn generally reduce the amount of yielded sludge. Since the biomass growth due to the existence of such carbonic materials can’t be measured separately from the growth due to that of original carbonic materials, it is called cryptic-growth. Cell disintegration processes used whether in laboratory and pilot scales or in full scale so far include:1-Thermal lysis in temperature range between 40 to 180° C 2-lysis due to chemical agents such as acids and bases 3-Mechanical or physical disintegration such as milling, equalizers or ultrasonic energy 4-Consequent freezing and thawing 5-Biological hydrolysis by adding enzymes 6-Using advanced oxidation processes such as using ozone and water peroxide 7-Combined methods such as thermal - chemical lysis or ultrasonic energy and alkalis All studied methods so far have their own advantages and disadvantages and most of the studies are in the laboratory and pilot scale and need further researches. Accordingly, this paper aims to study and compare the efficiency of some methods based on lysis and cryptic growth process in pilot-scale, using SBR reactor. These methods include: lysis using ultrasonic waves, intermittent ozonation, thermal lysis and loading reduction and dissolved oxygen increase. Materials and MethodsSludge lysis using ultrasonic waves For producing ultrasonic waves, an ultrasonic homogenizer device (Bandelin-SONOPULS HD3400) made in Germany with a 25mm-probe (VS 200T) and adjustable output power ranging from 0 to 300 watts was used. The waves generated by this device are of 20 KHz frequency and it can generate both continuous and pulsed waves. When in pulsation mode, the duration of pulses can be adjusted by the user.In this study pulsed waves with generating duration of 1.5 seconds and rest intervals of 0.5 second were used. The supplied energy to the cellular mass unit was approximately 35000 (KJ/KgVSS). This energy was provided using the power of 100 Watts. The volume of sludge, which was disintegrated each time and returned to the system, was approximately 30 percent of the total available sludge in the system. Sludge lysis using OzoneAt this stage of the research, to study the impact of ozone on about 30 percent sludge reduction in the test reactor, the sludge was extracted and exposed to ozone with the ratio of 25mg of ozone per 1 gram of SS. The sludge was then returned into the reactor. For producing ozone, an ozone producer device in laboratory scale (CGET company, Model: KED-A08-20, made in China) with the capacity of 20 liters ozone per hour was used.Thermal lysisThermal degradation of about 30 percent of the total sludge was carried out in the temperature of 80ºC for 3 hours. The disintegrated sludge was returned to the system.Simultaneous loading reduction and DO increase In order to investigate the impact of loading and dissolved oxygen concentration on the biological sludge yield, the operating conditions of the test reactor were changed. Its loading was decreased from 0.6 to 0.19 Kg/m3.day. Also dissolved oxygen concentration was increased up to about 6 mg/l.SBR ReactorFor this study, two SBR reactors (one as the control and one for performing tests) made of Plexi glass were used with an internal diameter of 20 cm, a height of 50 cm, and useful volume of 12 liters and treatment capacity of 7 liters in each working cycle. Reactors were operated at room temperature and for supplying required airflow. Also, some aerators with the capacity of 11 liters per minute are equipped with an air distributor of circular shape with 18cm diameter and air particle size of 1 to 3 mm, were employed. To ensure the uniform air distribution, especially in lower aeration rates and to provide the necessary mixing energy, a mixer with a flat tow-paddle blade, a vertical shaft and an engine with the speed of 110 rpm (made in France) was installed on each reactor. Results and DiscussionAs obviously indicated in Fig. 1, in all of the employed methods, sludge yield coefficient is lower than that of the control reactor. The amount of sludge yield will be the minimum in the case of using waves with aforementioned amplitude. Ozonation also reduces the amount of sludge but at a lower level compared to the waves being added. Fig. 1 shows the mean amounts of the measured values during 60 working cycles. According to this figure, operation yield is 0.48 in the control reactor but it is 0.1, 0.18, 0.24 and 0.3 for ultrasonic, ozonation, thermal and low rate loading reactors, respectively. Therefore, the highest efficiency in sludge reduction is attributed to ultrasonic waves with up to 78 percent of reduction in sludge yield.The performance of this technique in sludge reduction is highly depended on the ability of these agents in sludge degradation. Sludge decay is the disintegration of sludge and converting their components into solution so that it can be used by other microorganisms and this process is called “Solubilisation”.ConclusionThe results of this study show that the disintegration of 30 percent of the sludge of a reactor using ultrasonic waves of 35000 (KJ/KgVSS) can reduce bio-sludge yield as much as 78 percent in a SBR reactor. This is due to the Solubilisation of COD of sludge and its reuse by other microorganisms. In this case, the COD removal efficiency decreases slightly and reaches down to 84 percent, which is still suitable for effluent discharge to receiving water resources according to environmental standards provided by Iranian Department of Environment. Ultrasonic waves, with aforementioned conditions can convert up to 53 percent of COD of sludge into solution (i.e. soulubilisation), a usable form for other microorganisms, so these waves can be used as a pre-treatment on sludge digestion. The waves have a negative impact on specific oxygen uptake rate (SOUR), but it is not so great to disrupt the treatment process, the SOUR rate will decrease from 17.4 (mg DO/gSS.hr) to 11.6 (mg DO/gSS.hr), but the sedimentation properties of sludge improves significantly, and the SVI rate improves from 104 to 82, so ultrasonic waves can be used as a controlling factor of bulking in wastewater treatment.Low rate of loading, in the presence of high concentrations of oxygen (mg/l >6), yields less sludge in comparison with normal loading and normal dissolved oxygen rate. The amount of yielded sludge in these systems is about 0.3 Kg of suspended solids per 1 Kg of removed COD, which is approximately 37 percent lower than the rate in the control reactor. COD removal efficiency of such reactors is desirable, but the sedimentation properties and specific oxygen uptake rate of them decreases and their sludge volume index amounts to 124 (ml/g).Alternating ozonation of 30 percent of the sludge of the system with the amount of 25 (mgO3/gSS) can reduce the sludge yield coefficient (operation yield) from 0.48 to 0.18 which means 63 percent reduction of biological sludge. In this case, COD removal efficiency decreases down to 83 percent which makes some problems for wastewater discharge into surface water bodies and groundwater resources. Thus, it is recommended that a lower amount of ozone per mass unit of sludge is used. Specific oxygen uptake rate of the sludge in ozonated reactors decreases drastically and SOUR rate reaches down to 8 (mg DO/gSS.hr.) and sludge sedimentation properties also declines, leading to the possible occurrence of dispersed growth phenomenon.Thermal lysis of 30 percent of the system sludge at the temperature of 80°C for 3 hours and returning the sludge back into the reactor can reduce the biological sludge yield up to 49 percent. COD removal efficiency in this case is 86 percent. Sludge sedimentation properties improve in this situation, but specific oxygen uptake rate slightly decreases in such a reactor down to 12 (mg DO/gSS.hr.).
    Keywords: Excess Sludge Reduction, Biological Wastewater Treatment, Ultrasonic, Ozonation, Thermal lysis, SBR Reactors
  • Esmaeili, M.M., Esmaeilim., Amirshaghaghi, H Page 61
    IntroductionToday, in addition to environmental effects, air pollution has economical, social and political consequences. Such a problem is more striking in metropolitans where accumulating population, vehicles and industries, altogether produces large amounts of pollution. A discernible example is Isfahan city and province. Isfahan has one of the largest steel-producing facilities in the entire region as well as facilities for producing special alloys. Isfahan contains a major oil refinery and a large aircraft manufacturing plant. Unfortunately, on the other side, this city is one of most polluted cities in Iran. In recent years, this problem turned to be more severe due to climate changes. Consequently, finding clean and efficient solutions to contaminant industries is crucial. It should be noted that among the mentioned industries located in Isfahan, steel making plants play a major role in air pollution. In fact, in every metric ton of steel produced, 10 to 25 kilograms of dust is accumulated. Further, a large portion of exhaust gases of electric arc furnaces (EAF) consists of CO, NOx and Sox, which proved to be a threat to human health and environment. Thus, control and reduction of pollution production in steel making plants is essential. Until now, various clean air solutions to EAFs and fume de-dusting systems, have been developed. Definitely, there is no question that de-dusting systems are crucial. However, the costs and outlay of fume extraction systems operation should be no higher than absolute necessary. To be practical, the most important goals are high efficiency, compliance with prescribed threshold values and low consumption of energy. One reliable and feasible method to ensure the functionality and efficiency of these systems are Computational Fluid Dynamic (CFD) simulations. In such a modeling, the effect of various parameters can be studied, which leads to improved designs and higher efficiencies. Therefore, developing models for de-dusting systems of steel making plants would be a useful practice. Despite several studies in the field of modeling and optimization of fume extraction systems, no one has addressed the problem of turbulent reactive two-phase flow in industrial fume de-dusting systems and investigations are limited to approximate zero or one dimensional thermodynamic solutions. The present study aims to fill this gap in literature. In this paper the Mobarakeh Steel Making Plant is examined and the effect of operating parameters on the overall fume de-dusting system performance and efficiency is investigated.Materials and Methods The mathematical model of processes inside the fume extraction system is constituted of four different parts: swirling turbulent flow, Heat and mass transport by convection, chemical reactions and radiation. Hence, in order to model the problem, five sets of equations should be solved: continuity, momentum, energy (including radiation), species transport and turbulent flow modeling equations (in time averaged form).
  • Eskandaria., Nourir., Meraji, S.H., Kiaghadi, A Page 71
    IntroductionFive-day biochemical oxygen demand (BOD5) is one of the key parameters which is widely applied to evaluate the biological and chemical conditions of rivers, and to study the effects of releases in rivers from wastewater treatment plants, factories, farms, etc. Measurement of this parameter requires about 5 days. However, 5 days is a long time for the determination of BOD5. Therefore, in the present research two software sensors, i.e. artificial neural network (ANN) and support vector machine (SVM) are developed for the online estimation of BOD5. To achieve this goal, the Sefidrood River in Iran was selected. It is pointed out that although ANN models have been used to predict BOD5, but using SVM techniques for the online estimation of this parameter have never been reported.Materials and Methods ANN and SVM models are two well known artificial intelligent techniques which have frequently been used for modeling nonlinear parameters in engineering problems. In this research, a feed-forward ANN technique and a regression model is considered for online prediction of BOD5. To optimize ANN parameters, three optimization algorithms, i.e. Levenberg-Marquardt (LM), resilient back-propagation (RP), and scaled conjugate gradient (SCG) are used. Besides, two-steps grid search algorithm is considered for the optimization of SVM parameters, i.e. ε, C and γ.Results and DiscussionTo achieve the best network geometry according to the highest correlation (R), and the lowest root mean square error (RMSE) of the testing sets for online estimation of BOD5, various structures of NN model with different training functions are investigated. Finally, the network with LM algorithm (ANN (LM) model) is selected as the best ANN model. The results of training and testing steps for developed ANN models with different training functions are given in Table 1.In addition, for SVM model development, first, ε, C and γ should be determined. In this research, the best fitting value was obtained by trial and error procedure. Therefore, this parameter was set to several values. Thus, 14 models were developed (ε and C are considered to be varied). The RMSE value has been assessed on different values in the different -SVM regression models. Obtained results indicated that the SVM model including the value equal to 1.472 has the least RMSE. Therefore, it can be chosen as the best SVM model for the online prediction of BOD5. However, optimal values for C and using two-step grid search were 13 and 0.037, respectively. Finally SVM model is trained and tested using the determined best fitted values.
  • Mirshojaeian Hosseinih., Rahbarf., Pour Rostami, N Page 83
    IntroductionSpatial autocorrelation is a known phenomenon in ecological studies that refer to the relationship between certain variables observed in different localities. Whereas correlation statistics were designed to show the relationship between variables, autocorrelation statistics are designed to show the correlations within variables, and spatial autocorrelation shows the correlation within variables across space. Most natural ecological phenomena display spatial autocorrelation found at all spatial scales. Although the spatial autocorrelation concept was developed principally in the late 1950s, it has been applied in environmental economic studies for less than a decade and primarily as a new explanatory variable in the environmental Kuznets curve (EKC) relationship. Spatial ecological autocorrelation is often driven by multiple causes that may be exogenous or endogenous. Maddison (2007) specifies three endogenous mechanisms of spatial environmental autocorrelation: pollution displacement hypothesis, foreign direct investment (FDI) and international trade, and finally, the strategic response of countries to transboundary pollution flows. In the pollution displacement hypothesis, higher-income countries import pollution-intensive goods and in fact export their pollution to lower-income countries. As numerous empirical analyses have identified distance as an important factor in determining the volume of trade, a country’s emissions should be influenced by its neighbors. FDI and international trade are the mechanisms of technology diffusion. Again, distance is a determinant of technology diffusion, and consequently one might expect spatial autocorrelation through FDI and international trade. Finally, spatial autocorrelation may occur as a consequence of countries’ strategic response to transboundary pollution flows. In this case, the spatial relationship between countries is defined not by distance, but by the meteorologically determined pattern of transboundary deposition of pollutions.This paper examines a new mechanism for spatial environmental autocorrelation through institutions. In this mechanism, when the institutions of a country affect its own environmental quality, they affect the institutions of their neighbors simultaneously. This mechanism, which can be called the spatial institutional spillover effect, links the environmental quality of countries together. Materials and MethodsTwo recent findings about the features of institutions influence the subject of this paper. First, institutions and institutional quality can affect the quality of environment. Second, institutional quality can spread spatially. Theoretically, a combination of these two features paves our way to the idea that the environmental quality of geographic units (especially countries) can spread through institutions.
  • Khalili Araghim., Sharzei, Gh.A., Barkhordari, S Page 93
    Introduction Carbon Dioxide emissions related to energy consumption is an important challenge for the world economy. According to reports, 84% of the total CO2 emissions in the world are related to energy consumption. Also, 64% of green house gases emissions in the world are CO2 emissions. On the basis of the IEA scenarios (2009), the growth of CO2 emissions related to energy consumption will continue as a result of growing demand for fossil fuels by 2030. The CO2 emissions related to energy consumption increased from 20.9 G.T, in 1990 to 28.8 G.T, in 2007. The forecasts of IEA in 2009 show that the CO2 emissions related to energy consumption will increase to 34.5 G.T, and 40.2 G.T, by 2020 and 2030, respectively. Its implications are that CO2 emissions related to energy consumption will increase on average by 1.5% in the period of 2000-2030, while the other green house gases will increase on average by 0.3%. The Iranian resource-based structure of the economy and the energy-based production system has caused the consumption of fossil fuels and non-fossil fuels to increase. Although the interrelation between energy consumption and green house gases, especially CO2, shows the green house gas emissions will be high in the future. The statistics show that CO2 emissions per capita in Iran have increased from 3.6 T in 1990 to 6.9 T in 2008, while the CO2 emissions per capita decreased in the United States and Europe. Predictions show that the CO2 related to energy consumption will be an important challenge for the economic future in many countries including Iran. Considering the importance of this challenge, several countries have considered decreasing the CO2 emissions by the definition of policy tools. To achieve this goal, knowing the structure of CO2 emissions related to energy consumption is required. In the present research, the structure of CO2 emissions related to energy consumption at the macroeconomic and sectoral levels is considered. Materials and MethodsThe theoretical evidence shows that there is a relationship between energy consumption, CO2 emissions and economic growth. The structure of these relations depends on the economic structure and economic development stages of the countries in question. The empirical evidence has not been considered as demonstrating the structure of the relationship between energy consumption, CO2 emissions and economic growth.Review of the economic literature verifies the relationship between energy consumption, CO2 emissions and economic growth. However, this relationship has been affected by other factors such as population, composition of fuels consumed, and the carbon contents of the fuels being consumed. It is noteworthy that most studies have not paid attention to these factors. Considering the importance of this subject for gaining knowledge about the CO2 emissions structure and the importance of using policy tools, in this paper CO2 emissions structure using the Index Decomposition approach was studied.
  • Mousavi, S.H., Moayerim., Safea., Vali, A.A Page 105

    IntroductionThe protection of environment and natural resources has high importance in achieving sustainable development. Nowadays, environmental crisis and loss of natural resources are the principle causes for the creation of environmental management systems. The optimal management of natural resources requires the assessment and classification of ecological and environmental potentials. By this method, we can recognize the abilities and restrictions of resources, and predict their future trends. Thus, according to the present environmental conditions, a suitable method with high accuracy is required in order to evaluate and manage natural resources and environment for achieving sustainable development. Thirty million hectares of Iran’s areas are recently affected by wind erosion processes due to special environmental conditions such as rainfalls being less than 150 mm, lack of vegetation and fast and strong winds. These factors have caused influx of quicksand into infrastructures, settlements, communication ways and industrial and agricultural installations. This problem is considered as one of the most important environmental issues in some parts of Iran, especially in the Northeastern part of Toroud. In this context, the recognition and control of environmental limiting factors is very important.Nebkas are of condensation forms of wind erosion resulting from sequestration of wind sediments by plants. These features generally appear in regions with average sand amount, and where ground water tables or surface moisture are enough for plant life. The form of Nebka is a function of size, density and growth rate of plant, time, equilibrium form, size and grains sorting, climate and sediment supply source. Nebka, in local scale, shows the efficiency of sand stabilization. Thus, their development can prevent the influx of flowing sand into residential areas and infrastructures. As a result, identification of the most adaptable Nebka species according to its morphology and type of natural conditions will be very important in stabilization plans of quicksand through the development of Nebka landscapes. The aims of this study include the comparative evaluation of Nebkas of Najjar Abad Erg and the identification of the most appropriate type of them, using their morphometric parameters analysis by the Analytic Hierarchical Process model. The results of this research will be fruitful in systemic management approach of desert regions, and also can be procreator for quicksand stabilization projects.Materials and MethodsThe study area, Najjar Abad Erg, with an area of 2864.886 hectares is situated in the north of great central plateau of Iran. The area is located between the latitudes of 350, 25’ to 350, 30’ N and the longitudes of 540, 59’ to 550, 10’ E.

  • Zarinehi., Naderi Khorasganim., Asadi Borujeni, E Page 117
    IntroductionRangelands encompass about 55% of Iran's total area. These lands are the habitat of Iranian nomads and their animals. The extension, variations in climate, soil and vegetation cover require specific management. Having knowledge about the vegetation parameters, especially the coverage, is highly significant for efficient utilization and erosion control of the rangelands. Vegetation cover is defined as the percentage of ground covered by live vegetation within a given reference area such as a plot. Normally vegetation cover is measured using a reference frame, a ring, a square or a circle. The reference frame allows the researcher to focus on a small area (depending on the size of the frame) and estimate vegetation cover versus bare rangeland areas. Point-intercept and line-intercept methods were suggested by some researchers. Vegetation cover is an indicator for some environmental indices. For instance, Amaral, et al. (2007) applied normalized difference vegetation index (NDVI) along with climatic and topographical factors for the probability distribution of five plant species. They reported that the application of NDVI had increased the efficiency of models. Firmino, et al. (2009) studied the relationship between NDVI and precipitation. They concluded that NDVI is a spatial function of precipitation. Using remote sensing techniques for the monitoring of vegetation cover in rangelands of Iran is inevitable due to the extensive and dynamic behavior of these land covers. Normally, using remote sensing for vegetation monitoring corresponds to the application of vegetation indices, which are suggested to minimize the external impacts on spectral data and determining vegetation cover and leaf area index. Taylor et al. (1985) reported the existence of significant correlation coefficients between biomass and grass-prosopis cover, and NDVI and ratio vegetation index (RVI), calculated from NOAA-7 data. Rondeaux, et al. (1996) compared the correlation coefficients of six vegetation indices of SAVI, OSAVI, TSAVI, GEMI, NDVI and MSAVI with vegetation cover and reported that MSAVI is the most sensitive index to vegetation cover. Zhaa, et al. (2003) studied the vegetation cover of grasslands in Western China using 68 plots, and reported that NDVI had the highest correlation coefficient with vegetation cover percentage. Madoganda et al. (2008) assessed biomass and leaf area index of deciduous forests of Westchatz in India, by using IRS-P6 LISS-IV. They reported existence of positive correlation coefficients between satellite data and leaf area index and biomass. Tang e Sayyad National Park is the habitat of precious wild life in the semi arid zone of Charmahal-o-Bakhtiari Province. Assessing the vegetation cover of this national park contributes to management, indirect estimation of animal capacity, and soil conservation of the park. This study was carried out at the early season of drought of 2008.
  • Jafari, H.R., Rafiiy., Ramezani Mehrianm., Nasiri, H Page 131
    IntroductionEnvironmental conservation and optimal utilization of natural resources, is considered as the requirements of sustainable development at all levels, including regional levels. Sanitary urban landfill like any other engineering project needs basic information and accurate planning. Today, geographic information system (GIS) is widely utilized in environmental planning and engineering problems. Selecting a suitable location for a landfill requires considering several factors. Thus, the necessity of using spatial information technology and its integration with other planning and management issues will be inevitable.Multi-criteria decision-making systems include models and methods that have been provided by different people to make the process of planning easier for planners. These systems gradually improve their performance by others. Analytical Hierarchy Process (AHP) and simple Additive weighting (SAW) are systems of multi-criteria decision making that have been used in this paper.Materials and MethodsCriteria to this case were selected based on existing resources and environmental principles. These criteria include: distance from city, main roads, faults, main waterways and villages, rainfall, slope, elevation, land cover and Geology. Based on the weight that was assigned to layers in each of the two methods 10 weighted layers were created using GIS. In the next step, constraint map of the burial areas was prepared. Finally, the prepared maps were incorporated and multiplied in constraint layers in GIS, according to acquisitive weights in both AHP and SAW. Fig. 1 shows this process simply.Results and DiscussionAccording to the results of this process and classifying output maps, the priorities of areas for landfill was identified in Arc GIS. Given that in this study, two models were used to compare the quality of the output map, it is normal that the results obtained from these two models are different.After combining layers and their integration with the constraint map, output maps (Figures 2 and 3) were prepared for each of the two methods. Final map were classified in five categories based on the current classification as follows: Due to differences in methods of weighting of criteria and alternatives, the outcomes of AHP and SAW are to some extent different. In AHP method, perfect, Appropriate, relatively good and relatively poor Priorities respectively are 19%, 18%, 2% and 1%. While in SAW, perfect, Appropriate and relatively poor Priorities respectively are 22%, 18% and 1%. The restriction in both methods was 59%.ConclusionPair-wise comparison is more appropriate for determining the weight than their direct determination (SAW), because in the pair-wise comparisons (AHP) classes’ weight for each criterion is obtained based on a class priority rather than all classes of the criterion, but this process is not done in the direct determination of weight (SAW).After the production of output layers by the two methods, can be concluded with a superficial analysis that the AHP model presented more conservative results than the SAW. Finally, it can be claimed that the integrated system of GIS and multi-criteria decision-making can be a useful tool for environmental planning.
    Keywords: Site selection, AHP, SAW, Landfill, KohkiluyeoBoyer Ahmad province
  • Tabibianm., Rezaien., Nouraie, H Page 141
    Introduction Following developments in contemporary urban context and the new urban tissue replacement (with new needs and issues) instead of the old urban environment, the importance of urban neighborhoods have been extraordinary. The process of evolution and development of old urban neighborhoods suits the needs of residents, in both individual and social levels. Cities in general and in particular localities have had considerable negative effects on their performance and placement in the evolution of sustainable inner city. What has gripped today’s urban modern neighborhoods in common and specifically in the metropolitan areas like Tehran, is the adverse effects caused by immigration in the last decades. Metropolitan neighborhoods like “Kan” in Tehran have faced with issues like physical dispersion, lack of safety, low quality of environment, community structure degradation, identity degradation, lack of Supplementary housing patterns, the presence of cars, etc. Therefore, review is necessary when considering the various factors for the settlers in the selected areas. These factors include: housing price and level of cultural and living expenses in the area etc. factors in the next priority may be moving -as the next factor- by household income. The presence of different classes with different ownership types (private or leased) could raise issues in different levels to suit different classes of immigrants. Migration at various levels i.e. International, national, and local, subject to a hierarchy of needs, expectations and aspirations in different stages of human life. In fact, human spatial behavior can be a function of values and standards that he has experienced at different times and situations. These values not only comes from his economic, social and cultural conditions, but also is affected by the conditions that the environment imposes upon him. Such values provide explanation to change human’s lifestyle and location. The result of this sentiment - any stimulus that occurs - will follow the social-spatial Impact. The process of interaction between humans and space in the form of social-spatial dialectics has been considered at micro-level (urban areas) due to unavoidable cause-effect relationship between changes in location (inside urban migration) and their social-spatial structure in urban studies - especially analysis of social geography of cities.In the analyzing of urban issues In Iran, focus has often been raised on rural-urban migration, without paying attention to migration within the cities. However, the migration within the cities affects the social- spatial structure of urban areas. This kind of migration is increasing and also has its own rules. Thus, for maintaining urban sustainability, attention to this kind of migration is the inevitable urgency to achieve the appropriate strategies in urban planning. Therefore, among important issues, which must be considered in the organization and realization of Tehran metropolitan sustainability development, migration within the city is included.
  • Agha Ebrahimi Samanif., Bahramib., Salehis., Irani Behbahanih., Saatian, R Page 155
    IntroductionThe variety of Iran’s ecological structures has created many cultural landscapes. Cultural landscapes illustrate a combination of man’s persistent life and the art of land modification by means of natural environment and in the form of human settlements in the past ages. Currently, the human society’s development in addition to the scientific progresses, man’s increasing use of resources and negative consequences of tourism development without any correct design and optimal management in natural historical areas, has led to the destruction of ecological and historical structures of cultural landscapes. The new consideration of general environmental protection has been the context for protecting biological historical areas and settlements. Natural and historical region of Talesh with special ecological characteristics is one of the most valuable and attractive areas which has settlements of 4500 years old. One of the valuable parts of Talesh cultural landscape, especially in Agh-evlar Maryan studying region of Talesh countryside near Karganrood River, is the permanent and seasonal settlements of local nomads. These settlements with special architecture, methods of utilizing local materials, correct location and particularly various times of building, have specific persistent and attract many tourists. On the other hand, the development of new constructions and villa building of surrounding cities has led to the gradual destruction of cultural landscapes of the region. Identifying these settlements and the way of their being spread by means of new technology of telemetry has created the basis for the general environmental protection of their cultural characters. In addition, the presentation of rules for developing the new buildings to match with the cultural landscape leads to stable tourism development.Considering that cultural landscape is a combination of man, nature and history, we can conclude that all cultural landscapes have originated from nature or have been developed in nature and the continuance of their lives depends on the nature. Natural resources such as natural structure of the earth (geomorphology), groundwater structure (underground streams, springs, aqueducts) and surface water (rivers, lakes and seas), plantation structure (trees, bushes and covering plants specially the local ones), wild life, weather, climate and other natural factors make a dynamic background on which humankind changes, evolves and is permanently developing.Materials and MethodTaking the general purpose of the study into consideration and introducing the natural historical bed and Agh-evlar Maryan cultural landscape in terms of a cultural landscape, in the process of studies, an analysis of natural bed characteristics and the historical and archeological features of the monument and works scattered throughout the plains and along Karaganrood river valley, has been carried out.