| کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
|---|---|---|---|---|
| 5753007 | 1620321 | 2017 | 13 صفحه PDF | دانلود رایگان |
چکیده گرافیکی
چکیده
کلیدواژه‌ها
1. مقدمه
2. روش‌شناسی
2.1. کارزار نمونه‌گیری
2.2. آنالیز آزمایشگاهی
2.3 تحلیل داده‌ها
2.4 QA / QC داده
2.5. انسداد جرم شیمیایی
2.6. تجزیه و تحلیل مؤلفه اصلی
3. نتایج و بحث
3.1 سطح PM
3.2 ترکیب فله PM2.5
3.3 کربن آلی و عنصری
3.4 سهم گرد و غبار و مولفه‌ها
شکل 1. الف) سطح PM10 و PM2.5 در پردیس دانشگاه شریف در مرکز-غرب تهران و ب) میانگین سطح PM2.5 روزانه در ایستگاه‌های مختلف نظارت در تهران (1 سپتامبر تا 31 اکتبر 2016).
شکل 2. سهم ترکیبات اصلی توده ها در PM2.5 در مرکز تهران.
جدول 1. غلظت متوسط ماهانه ترکیب فله PM2.5.
شکل 3. محتوای متوسط ماهانه کربن ماهانه PM2.5 اندازه‌گیری شده در تهران الف) EC، WSOC و WIOC. b) نسبت OC / EC.
3.5. تجزیه و تحلیل مؤلفه اصلی
جدول 2. نتایج تجزیه و تحلیل مؤلفه اصلی.
3.6. عناصر کمیاب و فلزات سنگین
4. نتیجه‌گیری
شکل 5. غلظت متوسط ماهانه فلزات سنگین انتخاب شده.
شکل 6. عوامل غنی سازی پوسته برای عناصر کمیاب انتخاب شده در PM2.5.
- Identified and quantified PM2.5 components and their seasonal variations in Tehran.
- Major PM2.5 mass components found to be organic matter, dust and sulfate.
- Factors dominated by dust oxides and toxic metals explained â¼70% of PM2.5 variances.
- Dust contribution to PM2.5 reached up to 56% in summer, while min = 7% in winter.
- Contrary to dust oxides trend, toxic metals increased significantly in cold season.
Frequent air pollution episodes have been reported for Tehran, Iran, mainly because of critically high levels of fine particulate matter (PM2.5). The composition and sources of these particles are poorly known, so this study aims to identify the major components and heavy metals in PM2.5 along with their seasonal trends and associated sources. 24-hour PM2.5 samples were collected at a main residential station every 6 days for a full year from February 2014 to February 2015. The samples were analyzed for ions, organic carbon (including water-soluble and insoluble portions), elemental carbon (EC), and all detectable elements. The dominant mass components, which were determined by means of chemical mass closure, were organic matter (35%), dust (25%), non-sea salt sulfate (11%), EC (9%), ammonium (5%), and nitrate (2%). Organic matter and EC together comprised 44% of fine PM on average (increased to >70% in the colder season), which reflects the significance of anthropogenic urban sources (i.e. vehicles). The contributions of different components varied considerably throughout the year, particularly the dust component that varied from 7% in the cold season to 56% in the hot and dry season. Principal component analyses were applied, resulting in 5 major source factors that explained 85% of the variance in fine PM. Factor 1, representing soil dust, explained 53%; Factor 2 denotes heavy metals mainly found in industrial sources and accounted for 18%; and rest of factors, mainly representing combustion sources, explained 14% of the variation. The levels of major heavy metals were further evaluated, and their trends showed considerable increases during cold seasons. The results of this study provide useful insight to fine PM in Tehran, which could help in identifying their health effects and sources, and also adopting effective control strategies.
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Journal: Atmospheric Environment - Volume 153, March 2017, Pages 70-82