| 1. |
- Maina, David M., et al.
(författare)
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Environmental implications of high metal content in soils of a titanium mining zone in Kenya
- 2016
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 23:21, s. 21431-21440
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Tidskriftsartikel (refereegranskat)abstract
- Mining activities contribute to an increase of specific metal contaminants in soils. This may adversely affect plant life and consequently impact on animal and human health. The objective of this study was to obtain the background metal concentrations in soils around the titanium mining in Kwale County for monitoring its environmental impacts. Forty samples were obtained with half from topsoils and the other from subsoils. X-ray fluorescence spectrometry was used to determine the metal content of the soil samples. High concentrations of Ti, Mn, Fe, and Zr were observed where Ti concentrations ranged from 0.47 to 2.8%; Mn 0.02 to 3.1%; Fe 0.89 to 3.1%; and Zr 0.05 to 0.85%. Using ratios of elemental concentrations in topsoil to subsoil method and enrichment factors concept, the metals were observed to be of geogenic origin with no anthropogenic input. The high concentrations of Mn and Fe may increase their concentration levels in the surrounding agricultural lands through deposition, thereby causing contamination on the land and the cultivated food crops. The latter can cause adverse human health effects. In addition, titanium mining will produce tailings containing low-level titanium concentrations, which will require proper disposal to avoid increasing titanium concentrations in the soils of the region since it has been observed to be phytotoxic to plants at high concentrations. The results of this study will serve as reference while monitoring the environmental impact by the titanium mining activities.
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| 2. |
- Nguli, M., et al.
(författare)
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Assessment of essential micronutrient levels in common beans (Phaseolus vulgaris) in Kenya by total reflection X-ray fluorescence
- 2022
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Ingår i: X-Ray Spectrometry. - : Wiley. - 0049-8246 .- 1097-4539. ; 51:3, s. 198-203
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Tidskriftsartikel (refereegranskat)abstract
- In Kenya, where malnutrition and hidden hunger still pose a significant challenge to growth and development, beans are an essential source of food for most of the population. However, data on micronutrient in beans are limited, and although they are required in very small amounts, they are essential for growth and development of plants as well as human beings. The aim of this study was to determine the concentrations of Mn, Fe, Cu, and Zn, in common beans in Kenya. Samples of both fresh bean leaves and dry grains of the most common bean varieties were collected from small-scale farmers in Muguga and Kyevaluki in Kiambu and Machakos Counties, respectively. They were analyzed using total reflection x-ray fluorescence (TXRF), a technique of increasing interest for food analysis since it is fast, easy, and reliable. Standard methods of sample preparation were used, and average elemental concentrations were compared with established sufficiency ranges. Bean leaves and dry bean grains from both sampling areas had sufficient concentrations of the four analyzed elements. Except for the Fe concentrations, the concentrations of the others elements were in the lower end of the sufficiency range for all bean species. The results obtained from this study are essential information for both farmers and policy makers and can be incorporated in programs to guide policy aimed at improving the nutritional quality of beans and thus food security in Kenya. © 2022 John Wiley & Sons Ltd.
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| 3. |
- Zakey, Ashraf, et al.
(författare)
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Seasonal and spatial variation of atmospheric particulate matter in a developing megacity, the Greater Cairo, Egypt
- 2008
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Ingår i: Atmósfera. ; 21:2, s. 171-189
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Tidskriftsartikel (refereegranskat)abstract
- As an example of a developing megacity the Greater Cairo (GC) area in Egypt has been evaluated with respect to atmospheric particulate matter (PM) and lead (Pb). Particulate matter was collected during 2001-2002 in the two size fractions PM2.5 and PM10 at 17 sites representing different activities (industrial, urban, residential and background condition). The PM concentrations were generally high, with yearly average PM2.5 and PM10 values of 85 ± 12 and 170 ± 25 μg/m-3, respectively. On an annual scale, the high PM levels were due to many sources that included traffic, waste burning and wind blown dust particles emitted from the desert outside GC and the Moqattam hill inside GC. On a seasonal scale, the PM concentrations were highest in the industrial sector during spring, the dusty season, due to the combined effect of dust storm events and anthropogenic emissions over GC. The lowest seasonal concentrations were recorded in the summer season at the background sites. There was a marked increase in PM levels during the period Octoberto December due to burning of waste from harvested rice in the agriculture area in the Nile Delta (north of Cairo). The highest PM2.5/PM10 ratio was recorded in the urban sector (0.59) while the lowest ratio was recorded in the residential sector (0.32). The PM2.5 and PM10 samples were also analyzed for Pb in order to address the influence of different emission sources. The monthly average concentrations of Pb in both PM2.5 (Pb2.5) and PM10 (Pb10) varied between 0.4 and 1.8 ± μg m-3 at the non industrial sites. The concentrations were significantly higher in the industrial areas, where concentration up to a maximum of 16 ± g m-3 could be observed. Both the high lead and PM concentrations measured are contributing to local environmental pollution. GC is subjected to high concentrations of particulates most of the year. There is no annual limit for PM10 concentrations in the Egyptian law of environment, but comparing to the 24 hour average, PM10 is representing health risks on the long-term that will give both regionally and globally environmental effects. High volume samplers measuring PM10 as daily average shows that the air quality limit value has been exceeded at sites Heliopolis (35), Maadi (6) and 6th October (13) during 60.47, 79.07, and 62.96% of the measuring period of 2001, and at Shoubra El-Kheima (20), El-Qolaly Sq (1), and Abbasiya (36) during 100.0, 91.7, and 89.8% of the measuring period of 2002. Thus, the evaluation of the data presented in this paper will serve as a basis for future regional and global modelling and source apportionment.
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| 4. |
- Boman, Johan, 1955, et al.
(författare)
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Elemental characterization of aerosols in urban and rural locations in Bangladesh
- 2005
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Ingår i: X-Ray Spectrometry. - : Wiley. - 0049-8246 .- 1097-4539. ; 34:5, s. 460-467
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Tidskriftsartikel (refereegranskat)abstract
- Bangladesh became the first country in South Asia to ban the use of lead in gasoline in 1999. In 2003, two-stroke engine auto rickshaws were banned in the city centre of Dhaka, the capital of Bangladesh and one of the Asian mega-cities, in an attempt to improve the air quality. In July and August 2003, fine aerosol particles (PM2.5) were collected in Dhaka and in Rangpur in the northern part of the country. The aim was to study the effect of the action and to characterize PM2.5 particles in urban and rural areas of Bangladesh. Sampling was done with a cyclone of Dewell-Higgins type equipped with Teflon filters with a pore size of 3 mu m. Day- and night-time filters were collected in an attempt to understand the possible difference in air pollution between the two periods. An energy-dispersive x-ray fluorescence (EDXRF) spectrometer with three-axial geometry was utilized for the analysis of the elemental content of the particles. Large variations of concentrations for most elements in both Dhaka and in Rangpur were observed. Most of the elemental concentrations in Dhaka in daytime were higher than at night whereas the opposite was the case for Rangpur. The concentrations showed a significant influence of human activities and weather. Considerable concentrations of Pb were found despite the official ban of leaded gasoline. Motor transport, especially the two-stroke engine taxis and elements remobilized by burning, were the major sources identified. This is the first report on elemental concentrations in PM2.5 particles in both Dhaka and Rangpur. Copyright (c) 2005 John Wiley & Sons, Ltd.
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| 5. |
- Egondi, Thaddaeus, et al.
(författare)
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Measuring exposure levels of inhalable airborne particles (PM2.5) in two socially deprived areas of Nairobi, Kenya
- 2016
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Ingår i: Environmental Research. - : Elsevier BV. - 0013-9351 .- 1096-0953. ; 148, s. 500-506
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Ambient air pollution is a growing global health concern tightly connected to the rapid global urbanization. Health impacts from outdoor air pollution exposure amounts to high burdens of deaths and disease worldwide. However, the lack of systematic collection of air pollution and health data in many low-and middle-income countries remains a challenge for epidemiological studies in the local environment. This study aimed to provide a description of the particulate matter (PM2.5) concentration in the poorest urban residential areas of Nairobi, Kenya. Methods: Real-time measurements of (PM2.5) were conducted in two urban informal settlements of Nairobi City, Kenya"s Capital, from February 2013 to October 2013. The measurements were conducted using DustTrak II 8532 hand-held samplers at a height of about 1.5 m above ground level with a resolution of 1-min logging. Sampling took place from early morning to evenings according to a fixed route of measurement within areas including fixed geographical checkpoints. Results: The study period average concentration of PM2.5 was 166 mu g/m(3) in the Korogocho area and 67 mu g/m(3) in the Viwandani area. The PM2.5 levels in both areas reached bimodal daily peaks in the morning and evening. The average peak value of morning concentration in Korogocho was 214 mu g/m(3), and 164 mu g/m(3) in the evening and in Viwandani was 76 mu g/m(3) and 82 mu g/m(3) respectively. The daily midday average low observed during was 146 mu g/m(3) in Korogocho and 59 mu g/m(3) in Viwandani. Conclusion: The results show that residents in both slums are continuously exposed to PM2.5 levels exceeding hazardous levels according to World Health Organization guidelines. The study showed a marked disparity between the two slum areas situated only 7 km apart indicating the local situation and sources to be very important for exposure to PM2.5.
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| 6. |
- Gatari, M. J., et al.
(författare)
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Characterization of aerosol particles at an industrial background site in Nairobi, Kenya
- 2009
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Ingår i: X-Ray Spectrometry. - : Wiley. - 0049-8246 .- 1097-4539. ; 38:1, s. 37-44
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Tidskriftsartikel (refereegranskat)abstract
- Air pollutants from industrial and urban sources contain harmful elements and chemical compounds. This work presents a study on background industrial and urban aerosol particles in the city of Nairobi. Its main focus was the understanding of elemental, black carbon (BC) and particulate mass (PM) concentrations in the perspective of identifying their sources. Aerosol particles were collected on Teflon filters in two size fractions, a fine fraction of particles having an aerodynamic diameter (da) < 2.5 µm and a coarse fraction with particles between 2.5 and 10 µm. A photometer and an energy dispersive x-ray fluorescence spectrometer were used to analyse BC and trace elements (Si, S, Cl, K, Ca, Ti, V, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr and Pb), respectively. The sampled mass of the particulate matter was determined gravimetrically. The measured concentrations of the analysable species were dominated by BC, K and S in the fine fraction and Si, Ca and Fe in the coarse fraction. Principal component analysis and correlation evaluation of the fine fraction concentrations implicated industrial, vehicular and biomass-burning emissions as the main sources of the measured elements. The average Pb concentration of 105 ng m-3 in the PM10 samples at the background industrial site was approximately 20% of the air quality guideline (AQG) recommended by World Health Organisation (WHO). Most of the measured elements exhibited higher concentrations than those measured in Francistown in Botswana, Dar es Salaam in Tanzania and Edinburgh in United Kingdom but less than those measured in Barcelona in Spain and from previous studies in Nairobi.
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| 7. |
- Gatari, Michael J, et al.
(författare)
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Trace element categorization of pollution sources in the equator town of Nanyuki, Kenya
- 2005
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Ingår i: X-Ray Spectrometry. ; 34:2, s. 118-123
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Tidskriftsartikel (refereegranskat)abstract
- An air pollution campaign was carried out in the town of Nanyuki at four different sites during July and August 1999. Nanyuki is situated on the equator on the northwestern slope of Mount Kenya at about 1930 m above sea level. The intention of the project was to characterize aerosol elemental compositions in two size fractions, associated with specific natural and anthropogenic activities. A dichotomous impactor was used for sampling and an energy-dispersive x-ray fluorescence spectrometer was used for the analysis. Fourteen elements (Si, S, K, Ca, Ti, Mn, Fe, Cu, Zn, Ga, Br, Rb, Sr and Pb) were analysed in all the samples. The concentration of Pb was highest at a site in the vicinity of open-air vehicle garages. The four sites recorded high concentrations of fine S, Cl and K. Fine Zn and Br were also measured at all the sites. In the coarse size range, the concentrations of soil-derived elements (Si, K, Ca and Fe) were dominant. The high concentration of coarse Cl was considered to be due to the contribution of sea salt and that of S to be a contribution of gas to particle conversion of SO2. The two elements S and Cl signified the influence of long-distance transported aerosols. The comparatively high concentrations of fine Pb and Br signified the high rate of vehicle repairs, which is a major activity close to one of the sites. Generally, soil dust-derived particles and those from biomass burning dominated the town aerosols.
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