| 1. |
- Gaita, Samuel Mwaniki, 1976, et al.
(författare)
-
Source apportionment and seasonal variation of PM2.5 in a Sub-Sahara African city : Nairobi, Kenya
- 2014
-
Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 14:18, s. 9977-9991
-
Tidskriftsartikel (refereegranskat)abstract
- Sources of airborne particulate matter and their seasonal variation in urban areas in Sub-Saharan Africa are poorly understood due to lack of long-term measurement data. In view of this, filter samples of airborne particulate matter (particle diameter ≤2.5 μm, PM2.5) were collected between May 2008 and April 2010 at two sites (urban background site and suburban site) within the Nairobi metropolitan area. A total of 780 samples were collected and analyzed for particulate mass, black carbon (BC) and 13 trace elements.The average PM2.5 concentration at the urban background site was 21±9.5 μg m−3, whereas the concentration at the suburban site was 13±7.3 μg m−3. The daily PM2.5 concentrations exceeded 25 μg m−3 (the World Health Organization 24 h guideline value) on 29% of the days at the urban background site and 7% of the days at the suburban site. At both sites, BC, Fe, S and Cl accounted for approximately 80% of all detected elements. Positive matrix factorization analysis identified five source factors that contribute to PM2.5 in Nairobi, namely traffic, mineral dust, industry, combustion and a mixed factor (composed of biomass burning, secondary aerosol and aged sea salt).Mineral dust and traffic factors were related to approximately 74% of PM2.5. The identified source factors exhibited seasonal variation, apart from the traffic factor, which was prominently consistent throughout the sampling period. Weekly variations were observed in all factors, with weekdays having higher concentrations than weekends. The results provide information that can be exploited for policy formulation and mitigation strategies to control air pollution in Sub-Saharan African cities.
|
|
| 2. |
- Shaltout, Abdallah A., et al.
(författare)
-
Method development for the determination of Cd, Cu, Ni and Pb in PM2.5 particles sampled in industrial and urban areas of Greater Cairo, Egypt, using high-resolution continuum source graphite furnace atomic absorption spectrometry
- 2014
-
Ingår i: Microchemical journal. - : Elsevier BV. - 0026-265X .- 1095-9149. ; 113, s. 4-9
-
Tidskriftsartikel (refereegranskat)abstract
- Energy-dispersive X-ray fluorescence spectrometry (EDXRF) is not adequate for the determination of some potentially hazardous trace elements, such as Cd, Cu, Ni and Pb at low concentration in PM2.5 atmospheric aerosol particles Therefore, a method has been developed for the determination of these elements in atmospheric aerosol particles using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GF-AAS) without using modifiers. The pyrolysis and atomization temperatures were optimized for this analysis. The samples were collected from industrial and urban areas of Greater Cairo, Egypt. Atmospheric aerosol particles, PM2.5, have been collected on polycarbonate filters loaded by a cyclone sampler. The duration of the collection was 24 h at an air flow-rate of 3 L min-1. Microwave-assisted acid digestion with ultra-pure nitric acid was used to dissolve the polycarbonate filters, including the atmospheric aerosol particles. For the validation of the methods, the results were compared with those obtained by total reflection X-ray fluorescence (TXRF) and inductively coupled plasma mass spectrometry (ICP-MS). Good agreement between the results of the different spectrometric techniques was found. The measured concentrations of Cd, Cu, Ni, and Pb were below the limits defined by international guidelines and national standards of ambient air quality.
|
|
