نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی شیمی، دانشگاه آزاد اسلامی، واحد مسجد سلیمان، مسجد سلیمان، ایران

2 گروه فناوری محیط زیست، پژوهشکده علوم محیطی، دانشگاه شهید بهشتی، تهران، ایران

چکیده

سابقه و هدف :
ذرات معلق موجود در هوا شاخص مهمی در کیفیت هوای خارجی است. غلظت‌های بالای این ذرات منجر به بسیاری از مشکلات بهداشتی می‌شود. تماس با آلودگی ناشی از هواویزهای زیستی تقریباً در زندگی شهری در سراسر جهان ‌اجتناب‌ناپذیر است. حضور میکروارگانیسم‌های بیماری‌زا در ذرات گردوغبار منجر به بیماری‌های دستگاه تنفسی، آسم و ذات‌الریه می‌شود. جمعیت میکروبی موجود در ذرات گردوغبار در روزهای عادی و روزهای غباری و نیز تطابق بین افزایش ذرات PM10 و افزایش جمعیت میکروبی در این تحقیق بررسی شده است. 
مواد و روش‌ها:
نمونه‌برداری توسط نمونه‌بردار میکروبی هوا 1 و در ارتفاع 5/1 الی 2 متری از سطح زمین با جریان  L/min3/14 و به مدت 5 دقیقه انجام شد. شناسایی جمعیت میکروبی با رقیق‌سازی‌های متوالی تا 5-10 از نمونه‌های گردوخاک در سرم فیزیولوژیک و کشت در محیط‌های کشت مربوطه و به مدت 5-3 روز در دمای محیطی C 2±25 گرمخانه‌گذرای انجام شد. 
نتایج و بحث:
در طوفان‌های غباری بر فراز شهر اهواز در فصول گرم (فروردین الی شهریورماه) سال 1390 هر نوع افزایش در غلظت ذرات PM10 حاضر در هوا در تطابق با افزایش غلظت باکتریایی و قارچی بوده است. در ماه‌های خرداد، تیر و مرداد سال 1390 غلظت ذرات PM10 به‌طور مداوم بیشتر از حد استاندارد بوده است. افزایش غلظت باکتریایی در شهر اهواز به دلیل طوفان‌های غباری در روزهای غباری 5 برابر و غلظت قارچی نیز در روزهای غباری 7/1 برابر روزهای عادی افزایش‌یافته است. در روزهای غباری غلظت میکروارگانیسم‌های غالب با افزایش مواجه بوده است و باکتری غالب باسیلوس 45% جمعیت کل باکتریایی و قارچ غالب آسپرژیلوس 44% جمعیت کل قارچی را در ذرات گردوغبار شامل می‌شود. نتایج حاصل افزایش جمعیت میکروبی حاضر در ذرات گردوغبار در روزهای غباری را نشان می‌دهد. هر نوع افزایش در جمعیت میکروبی حاضر در ذرات گردوغبار می‌تواند منجر به تأثیرات منفی بر سلامتی انسان شود.
 نتیجه‌گیری:
با بررسی روند تغییرات سالیانه و فصلی پارامترهای هواشناسی و استفاده از نرم‌افزار HYSPLIT می‌توان دریافت که منشأ احتمالی این ذرات در شهر اهواز، کشورهای همسایه در جنوب غرب ایران به‌ویژه مناطق شمال غرب کشور عراق و شرق کشور سوریه است.

کلیدواژه‌ها

عنوان مقاله [English]

The effect of dust storm on the microbial quality of ambient air in Ahvaz city and dust source identification using numerical modeling

نویسندگان [English]

  • Parya Broomandi 1
  • Yousef Rashidi 2

1 Department of Chemical Engineering, Islamic Azad University, Masjed-Soleiman Branch, Masjed-Soleiman, Iran

2 Environmental Sciences Research Institute, Shahid Beheshti University, Tehran, Iran

چکیده [English]

Introduction:
Airborne particles are considered to be an important indicator of air quality and high concentrations of these particles cause many health problems. Around the world, it is impossible to avoid contact with bio-aerosol contamination in urban life. The presence of pathogenic microorganisms in dust storms can cause diseases such as pneumonia, asthma, and other respiratory infections. The aim of this study was to investigate the relationship between airborne particles with airborne microorganisms in normal and dusty days.  
Materials and methods:
The sampling method was quick take 30 equipped with a single-stage sampler at the elevation of 1.5 to 2 meters above the ground. Air flow was 14.3 L/min and its duration was 5 min. The original samples were diluted several times (10-5 - 10-4) to reduce the microbial population sufficiently to obtain separate colonies upon plating. All cultures were  incubated at environmental temperature (25 ± 2 °C) for 3 to 5 days and repeated twice. Any increase in PM10 concentrations were in agreement with an increase of bacterial and fungal concentrations during dusty days in Ahvaz city during the warm period (April to September) in 2011.  
Results and discussion:
The concentration of particles in June, July and August was greater than the standard value. The results of the present study illustrated that the average number of bacteria and fungi, respectively, in dusty days was 5 and 1.7 times that of normal days. Also, the predominant species of bacteria and fungi during the occurrence of dust storms were Bacillus sp. (45% of total bacteria) and Aspergillus sp. (44% of total fungi), respectively. Therefore, any increase in the number of airborne microorganisms (bacteria and fungi) during dust storms can cause biologically harmful effects on human health.  
Conclusion:
Based on the annual and seasonal changes in meteorological parameters and HYSPLIT, it can be seen that the probable origin of airborne particles are neighbouring countries to southwestern Iran, especially the northwestern parts of Iraq and the eastern parts of Syria.

کلیدواژه‌ها [English]

  • Air pollution
  • Dust storms
  • PM10 particles
  • Bacterial
  • Fungi

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