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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. Copyright © 2004 John Wiley & Sons, Ltd.

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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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Cadmium and zinc from anthropogenic sources in Lake Nakuru were investigated. High metal levels (mg/kg) in soils (Cd < or = 16.3 and Zn < or = 280) and Acacia xanthophloea (Cd < or = 32 and Zn < or = 310) were observed at polluted sites. Significant variations in metal values were evaluated using ANOVA (F test) and student's t test at p < 0.05 and metal correlations studied. High levels of metals in soils and unhealthy/dying Acacia were obtained at polluted sites. Significant positive correlation was obtained between Cd and Zn in soils and plants. Acacia sp are effective biomonitor of environmental quality in areas subjected to pollution.

Dietary quality is vital in maintaining sound nutritional status. The ecological conditions thus influence the type of diets and their nutritional quality. The purpose of this study was to determine the trace element/mineral content of some of the commonly consumed diets in Machakos, Kitui, Makueni and Mwingi districts. Decorticated maize, beans and finger millet flour samples were purchased from the local markets. For each category, a total of ten samples were collected from each district. The samples were put in plastic bags, sealed and transported to the laboratory in the Institute of Nuclear Science & Technology, University of Nairobi for preparation and analysis. The cooking of the samples was carried out according to local traditional methods. In the decorticated samples, mean copper concentrations were observed to be below 20 μg·g^-1; mean zinc concentrations ranged from 34 to 63 μg·g^-1 and mean manganese concentrations were in a similar range of 34 to 78 μg·g^-1. The mean iron concentrations were significantly high with a range of 161 μg·g-1 to 287 μg·g^-1. A similar trend was observed in the beans where the mean copper concentrations varied from 11 to 33 μg·g^-1, mean zinc concentrations ranged from a low value of 24 μg·g^-1 to a high value of 35 μg·g^-1, mean manganese concentrations varied from 33 μg·g^-1 to 98 μg·g^-1 and the mean iron concentrations ranged from 227 μg·g^-1 to 647 μg·g^-1. The cooked Muthokoi samples from Machakos district had relatively high mean trace element concentrations: manganese—109 μg·g^-1; iron—280 μg·g^-1; copper—19 μg·g^-1; and zinc—41 μg·g^-1. The only exception was mean iron concentrations which were extremely high in samples from Mwingi District where the concentrations varied from 73 μg·g^-1 to 1597 μg·g^-1. In finger millet flour, the mean manganese concentrations varied from 95 to 290 μg·g^-1, whereas the mean iron concentrations ranged from 127 μg·g^-1 to 259 μg·g^-1. In contrast, the mean copper and zinc concentrations were low in comparison to the manganese and iron concentrations. As a whole, the mean copper concentrations in the diets are significantly low compared to the other three trace elements. However, the total content is not necessarily a reflection of the amount assimilated in the body. Finger millet was found to be an excellent source of manganese and iron whereas beans were observed to be good sources of iron. All the food crops were observed to poor sources of copper