Abstract Samples of sedimented dust on roofs from 34 locations within the Lake Nakuru Basin (LNB

Alfred O Odongo

Samuel M Kariuki

Stephen N Wangari

Thomas K Kinyanjui

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 Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X 
 Vol. 4(11), 13-17, November (2014)                       Res. J. Chem. Sci. 
 
International Science Congress Association       13 
Assessment of Heavy Metals in Rooftop dust around Lake Nakuru Basin, 
Kenya 
 
Wangari Stephen N.
1
,
 
Kinyanjui, Thomas K.
1
,
 
Odongo, Alfred O.
2
 and Kariuki, Samuel M.
1
 
1Department of Chemistry, Egerton University,. P.O. Box 536-20115, Egerton, KENYA 
2Department of Natural Sciences, Mount Kenya University,. P.O. Box 17273-00200, Nakuru, KENYA  
 
Available online at: www.isca.in, www.isca.me 
Received 10th October 2014, revised 11th November 2014, accepted 15th November 2014 
 
 
 
Abstract 
Samples of sedimented dust on roofs from 34 locations within the Lake Nakuru Basin (LNB), Kenya were analyzed for their 
heavy metals content. The samples were analyzed for Pb, Ni, Zn, Fe and Cr. Statistical analyses were done using SPSS 
version 11.5 and Microsoft EXCEL spreadsheets. The result of the analysis showed that Iron (Fe) has the highest 
concentration level followed by Zn, Cr, and Pb with mean values of 0.2 ppm, 5.1 ppm, 16.1 ppm and 0.3 ppm respectively 
while the concentration of Ni was below the detection limit. The results of the analysis were used to determine spatial 
dispersal and scale of heavy metals pollution with respect to direction. The results of this study reveal that heavy metals 
distribution is not significantly different in the various directions of the LNB. 
 
Keywords: Heavy metal; Sedimented dust; AAS; Lake Nakuru Basin; Pollution. 
 
Introduction 
The distribution of heavy metals in the soils is probably 
controlled by both geogenic and anthropogenic factors1,2. 
Human activities have drastically altered the biogeochemical 
cycles and balance of heavy metals in the environment. Where 
natural sources are dominated by parent rocks and metallic 
minerals, the principal man-made sources of heavy metals are 
agricultural activities, as fertilizers, animal manures, and 
pesticides containing heavy metals are widely used, industrial 
point sources (e.g., mines, foundries and smelters), diffuse 
sources such as combustion by-product3, vehicle emissions4, 
microelectronic products, and solid waste disposal5. Public 
electricity and heating plus residential sectors have also been 
found as major contributors towards the emission of heavy 
metals6. 
 
These anthropogenic activities have introduced contaminants in 
top soil from atmospheric deposition by sedimentation, 
impaction and interception. Soil particles are subsequently 
entrained into the atmosphere as dust7. Numerous studies of 
heavy metal contamination, of street dust have been carried out 
in developed countries7-9, but only limited information is 
available on heavy metals in the street dust of developing 
countries, including Kenya. 
 
Lead and a variety of other metals from automobile exhaust 
have been found to contaminate roadway and parking site dust 
sampled in Palermo, Italy10 and Kayseri, Turkey11. Key heavy 
metals are thereby Pd from leaded gasoline (although this is 
reducing due to use of unleaded gasoline but accumulation from 
previous years is still evident), Cu, Zn and Cd from car 
components, tyre abrasion, lubricants and industrial and 
incinerator emissions12,13. Contamination of roadway topsoil 
material from which dust maybe generated by vehicular and 
wind action is particularly prevalent in developing countries, 
where most roads are un-surfaced and in some cases leaded 
gasoline has been in use14. 
 
Some heavy metals such as copper (Cu), zinc (Zn), iron (Fe), 
chromium (Cr), manganese (Mn) and nickel (Ni) though 
essential to human body, are toxic at elevated levels, whereas 
cadmium (Cd) and lead (Pb) are non-essential metals and are 
toxic even in trace amounts. Toxicity is highly aggravated by 
their non-degradability and tendency to bio-accumulate to toxic 
levels15. Heavy metal toxicity can result in lower energy levels 
and damage blood composition, lungs, liver, kidneys and other 
vital organs, damage or reduce mental and central nervous 
function or even cause cancer16, 15, 17. Heavy metal poisoning is 
more likely to result from inhalation, ingestion, skin contact 
with the metals or compounds from dust, fumes or materials 
from workplace, or in residential settings, especially homes with 
lead paints or old plumbing18. 
 
Material and Methods 
The study area: The Lake Nakuru Basin (LNB) covers an area 
of 1,800 km². At the sump of this catchment basin is the 
insulated LNNP and Nakuru Town. The soil in the catchment 
area is of volcanic origin and therefore its high porosity, 
permeability and loose structure lead to erosion, land subsidence 
and fractures during or after heavy rain19. 
 
Depending on altitude and topography, the Lake Nakuru basin 
suffers considerable variations in climate. The mean maximum 
and minimum temperature varies between 10°C – 29°C. The 
Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606X 
Vol. 4(11), 13-17, November (2014) Res. J. Chem. Sci. 
International Science Congress Association  14 
climate ranges from cold and humid to arid and semi-arid. Mean 
annual rainfall is approximately 1000 mm with peaks in the 
months of November to December and April to May20. 
 
There are various pollution sources in the Lake Nakuru 
catchment such as organic pollution from domestic, livestock, 
industry and agricultural areas; heavy metal and other chemical 
pollution from industries and dumping sites; and agricultural 
chemical and pesticide pollution from agricultural areas. 
 
The ever-increasing human population, poor enforcement of 
environmental regulations and unsustainable exploitation of 
natural resources has gradually caused conflict between humans 
and natural resources. Denaturation and degradation of 
forestlands, clearing of riverbanks, poor land use planning and 
urban development and the prevalence of poverty around the 
Lake Nakuru National Park has given rise to the conflict 
between the catchment’s natural resources and the human 
population19. 
 
Sampling and analytical procedures: Atmospherically 
deposited dust samples were collected from differing 
environments during the dry season when there was no 
precipitation. Systematic random sampling was carried out and 
samples for each location was obtained from the rooftops on an 
area of 1m2 using polyethylene brush and a tray and kept in a 
clean self-sealing plastic bag. A total 34 samples were collected 
in triplicate in all directions from the lake where we have 
buildings. The sampling locations within the LNB are indicated 
in figure-1. The locations were numbered randomly and with the 
aid of GPRS coordinate using Google maps and Scribble maps.
 
Figure-1 
The sampling locations within the LNB 
Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606X 
Vol. 4(11), 13-17, November (2014) Res. J. Chem. Sci. 
International Science Congress Association  15 
Into 350 mL of 30% H2O2, 0.42g of selenium powder and 14g 
of lithium sulphate were added and the contents mixed well. 
With care, 420mL of concentrated H2SO4 were added while 
cooling the mixture in cold water. The mixture was stored in the 
fridge which made it stable for up to four weeks21. 
 
For each sample, 0.30 ± 0.01g was weighed into a labeled 
digestion tube and 5 mL of the digestion mixture was added. 
This was digested at about 360 °C for 2 hrs in a kjeldahl flask. 
The solutions were expected to be colorless and any remaining 
sand to be white. For those that was still colored, further heating 
for one hour was done. The contents were allowed to cool after 
which 25 mL of distilled water was added and mixed well until 
no more sediments could dissolve. These were again allowed to 
cool and made-up to 100 mL with distilled water. Using 
Whatmann No.4 filter papers, filtering was done into well 
labeled containers and the samples were now ready to be run in 
Atomic Absorption Spectrophotometer. A reagent blank was 
prepared in a 100 mL volumetric flask by using all the other 
reagents except the samples by following the same procedure22. 
 
The instrument parameters were set as per the manufacturer’s 
operation manual recommendations for each metal. However 
the burner height and fuel (acetylene for all the other metals but 
nitrous oxide for Cr) flow rate were optimized to obtain a 
maximum absorbance reading with the middle standard for each 
of the metals. Calibration standards of appropriate 
concentrations for each metal were prepared by serial dilutions 
from 1000 ppm stock solutions. The following standards were 
used to get a calibration curves for Pb, Ni, Zn, Fe and Cr, Zn – 
2, 4, 6, 8 and 10mg/L, Fe – 1, 2, 3, 4 and 5 mg/L, Cr – 1, 2, 3, 4, 
5, 6, 7, 8, 9 and 10mg/L, Pb – 0.5, 1, 2, 3 and 4 mg/L, Ni – 3, 4, 
5, 7.5 and 10 mg/L 
 
A reagent blank was used to zero the instrument reading for the 
respective samples. Absorbance readings were taken at 213.9 
nm for Zn, 248.3 nm for Fe, 357.9 nm for Cr, 283.3 nm for Pb 
and 232 nm for Ni. Calibration curves were obtained and used 
to determine the sample concentrations of the heavy metals in 
the sample extracts. 
 
The equations of the calibration curves of the metals are 
indicated in Table 1. All the curves gave regressions more than 
0.9, an indication of the reliability of the curves. 
 
Results and Discussion 
The descriptive statistic results of heavy metal concentrations 
investigated in the studied samples are shown in table-2. 
 
Table-1 
Calibration curves for metals 
Metal Equation R
2
 
Lead y = 0.0076x 0.9837 
Nickel y = 0.0011x 0.9928 
Zinc y = 0.0147x 0.9589 
Iron y = 0.0014x 0.9632 
Chromium y = 0.0013x 0.9884 
 
The maximum recorded levels were 0.6, 20.2, 23.3, and 0.7 
mg/L for Pb, Zn, Fe and Cr respectively while the concentration 
of nickel in all the samples was below the detection limit. The 
high concentrations of Zn and Fe suggests that metal roofs 
either galvanized iron or anodized aluminum act as a more 
potential source of these in the deposited dust. This observation 
agrees with the reports of Gadd and Kennedy who suggested 
that galvanized metal roofs contribute more zinc and iron in roof 
run-off23. The concentration of Pb and Cr was attributed to the 
pollution originated from traffic and anthropogenic sources24, 25. 
This may originate from traffic sources, such as wear, tear of 
vulcanized vehicle, tires, the corrosion of metallic parts in scrap 
yards, lubricants and exhaust emissions from both gasoline and 
diesel fuelled road vehicles26-29. 
 
The concentrations of the heavy metals according to directions 
are shown in figure-2. 
 
Concentration of heavy metals with direction: In all samples, 
the abundances of Fe (12.3-21.7 ppm), Zn (1.3-20.2 ppm), Pb 
(0.1-0.6 ppm) and Cr (0.0-1.3 ppm). These results do not show 
significant differences between samples in the four directions 
except for Zn whose concentration to the north and western 
direction is higher than in the other sampled directions. The 
variation in concentration may be mainly due to compositional 
differences of rooftops and environmental condition30.The wind 
direction during the sampling period obtained from the Kenya 
Meteorological Department was towards the north and 
northwest of the basin and the high concentrations of Zn in 
these directions could be indicative that wind could be carrying 
and dispersing the heavy metals. 
 
 
Table-2 
Heavy metal concentrations 
Metal Lead Nickel Zinc Iron Chromium 
Average±SD 0.2±0.1 BDL 5.5±5.7 16.1±2.5 0.3±0.4 
*SD = Standard deviation  *Belowdetectable limit 
 
Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606X 
Vol. 4(11), 13-17, November (2014) Res. J. Chem. Sci. 
International Science Congress Association  16 
 
Figure-2 
Concentration of heavy metals with direction 
 
Conclusion 
This is the first pollution study of rooftop dust in LNB and in 
the whole adjacent region. The present results suggest that the 
concentration of, Fe, Zn, Pb, Cr, and Ni in rooftop dusts in LNB 
are not at an alarming levels. However this may change with the 
rapid development, increase in vehicle emissions and the lack of 
sophisticated management of wastes and effluents from 
industries and other activities. Therefore, management programs 
such as planned reduction of Pb and other metal contents from 
fuel, improved treatment techniques for the wastes and effluents 
of different activities should be implemented by government to 
minimize the environment pollution in LNB. Such action would 
also improve air quality in the city. 
 
Little attention has been paid to other trace elements, such as 
Cd, therefore, its ecological and health implications need further 
detailed investigations. 
 
The rain water collected for use by the people within the LNB 
need to be assessed so as to ascertain whether the heavy metals 
found in the suspended particles do end up in the rain water at 
levels above the recommended limits. 
 
Acknowledgment 
The authors wish to thank the Chemistry department of Egerton 
University for providing the laboratory facilities and the AAS 
instrument for the analysis of dust samples. 
 
References 
1. Adamu C. I., Nganje T. N., Ukwang E.E., Keneth A. and 
Peter N., A Study of the Distribution pattern of Heavy 
metals in surface soils around ArufuPb-Zn mine, 
Northeastern Nigeria, Using Factor Analysis, Res. J. 
Chem. Sci., 1(2), 70-80 (2011) 
2. Iwuoha G.N., Osuji L.C. and Horsfall M. Jnr., Index 
Model Analysis Approach to Heavy Metal Pollution 
Assessment in Sediments of Nworie and Otamiri Rivers 
in Imo State of Nigeria, Res. J. Chem. Sci., 2(8), 1-8 
(2012) 
3. Mohaupt V., Sieber U., van den Roovaart J., Verstappen, 
C.G., Langenfeld F. and Braun M., Diffuse sources of 
heavy metals in the Rhine basin, Water, Science and 
Technology, 44, 41−49 (2001) 
4. Davis B.S. and Birch G.F., Spatial distribution of bulk 
atmospheric deposition of heavy metals in Metropolitan 
Sydney, Australia, Water, Air, and Soil Pollution, 214, 
147-162 (2011) 
5. Abii T.A., Levels of Heavy Metals (Cr, Pb, Cd) 
Available for Plants within Abandoned Mechanic 
Workshops in Umuahia Metropolis, Res. J. Chem. Sci., 
2(2), 79-82 (2012) 
6. EMEP Status Report 2, 2005. Heavy metals: 
Transboundary pollution of the Environment, Retrieved 
on July 10, 2012. Available at: 
http://www.chem.unep.ch/ pb_and_cd/SR/ 
Files/Submission%20IGO/ Submis_IGO_MSC-E.pdf, 
(2012) 
7. Li X.D., Poon C.S. and Pui S.L., Heavy metal 
contamination of urban soils and street dust in Hong 
Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606X 
Vol. 4(11), 13-17, November (2014) Res. J. Chem. Sci. 
International Science Congress Association  17 
Kong, Applied Geochemistry,16, 1361-1368 (2001) 
8. Sezgin N., Özcan H.K., Demir G., Nemlioğlu S. and 
Bayat C., Determination of heavy metal concentrations in 
street dusts in Istanbul E-5 highway, Environment 
International, 29, 979-985 (2003) 
9. Charlesworth S., Everett M., McCarthy R., Ordoňez A. 
and de Miguel E.A., A comparative study of heavy metal 
concentration and distribution in deposited street dusts in 
a large and a small urban area: Birmingham and 
Coventry, West Midlands, UK, Environmental 
International,29, 563-573 (2003) 
10. Varrica  D., Dongarra G., Sabatino G. and Monna F., 
Inorganic geochemistry of roadway dust from the 
metropolitan area of Palermo, Italy, Environmental 
geology, 44, 222-230 (2003) 
11. Tokahoğlu Ş. And Kartal Ş., Multivariate analysis of the 
data and speciation of heavy metals in street dust samples 
from the Organized Industrial District in Kayseri 
(Turkey), Atmospheric Environment,40, 2797 – 2805 
(2006) 
12. Markus J.A. and McBratney A.B., An urban soil study: 
heavy metals in Glebe, Australia, Australian Journal of 
Soil Research, 34, 453-465 (1996) 
13. Thornton I., Metal contamination of soils in urban areas. 
In: Bullock, P., Gregory, P. J. (Eds.), Soils in the urban 
environment, Blackwell, Oxford., 47-75 (1991) 
14. Wilcke W., Muller S., Kanchanakool N. and Zech W., 
Urban soil contamination in Bangkok: heavy metals and 
aluminium partitioning in topsoils, Geoderma, 86, 211-
228 (1998) 
15. Tüzen M., Determination of heavy metals in fish samples 
of the MidDamLake Black Sea (Turkey) by graphite 
furnace atomic absorption spectrometry, Food Chemistry, 
80, 19-123 (2003) 
16. Canlý M. and Atlý G., The relationships between heavy 
metal (Cd, Cr, Cu, Fe, Pb, Zn) levels and the size of six 
Mediterranean fish species, Environmental Pollution, 
121, 129-136 (2003) 
17. Fernandes C., Fontaínhas-Fernandes A., Cabral D. and 
Salgado M.A., Heavy metals in water, sediment and 
tassues of Liza Saliensfrom Esmoriz–Paramos lagoon, 
Portugal, Environmental Monitory Assess, 136, 267-275 
(2008) 
18. Mtanga A. and Machiwa J.F., Heavy metal pollution 
levels in water and oysters, Saccostreacucullata, from 
Mzinga Creek and RasDege mangrove ecosystems, 
Tanzania, Africa, Journal of Aquatic Science, 32, 235-
244 (2007) 
19. McClanahan T.R. and Young T.P., East African 
Ecosystems and their Conservation. Oxford University 
Press, New York (1996) 
20. Department of Environment, Pollution Control Section. 
State of Environment Report. Toward better water 
quality management, Municipal Council of Nakuru, 
(2009) 
21. Parkinson J.A. and Allen S.E., A wet oxidation procedure 
suitable for the determination of nitrogen and mineral 
nutrients in biological materials, Commun. Soil Sci. Plant 
Anal., 6, 1-11(1975) 
22. Grimshaw H.M., The determination of total phosphorus 
in soils by acid digestion. In: Rowland, A.P., (ed.) 
Chemical analysis in environmental research, Abbotts 
Ripton, NERC/ITE, 92-95 (1987) 
23. Gadd J. and Kennedy P., House runoff: Is it as clean as 
we think? Second South Pacific Stormwater Conference 
(2001) 
24. Ferguson J.E., and Kim N., Trace elements in street dust 
and house dusts source and separation. Science of Total 
Environment, 100, 125-150 (1991) 
25. Akhter M., S. and Madany I. M., Heavy metals in street 
dust and house dust in Bahrain. Water, Air and Soil 
pollution, 66, 111-119 (1993) 
26. Pacyna J., M. In: Nriagu, J. O. and Davidson, C. I. (Eds.), 
Toxic Metals in the Atmosphere. Wiley, New York. pp. 
1-32 (1986) 
27. Arslan H., Heavy metals in street dust in Bursa, Turkey, 
J. Trace Microprobe Tech., 19, 439–445 (2001) 
28. Jiries A., Hussein H. and Halaseh Z., The quality of 
water and sediments of street runoff in Amman, Jordan,  
Hydrol. Process, 15, 815–824 (2001) 
29. Bhattacharya T., Chakraborty S., Fadadu B. and 
Bhattacharya P., Heavy Metal concentrations in Street 
and Leaf Deposited Dust in Anand City, India, Res. J. 
Chem. Sci., 1(5), 61-66(2011) 
30. Kumar S., Singh J., Das S. and Garg M., AAS Estimation 
of Heavy Metals and Trace elements in Indian Herbal 
Cosmetic Preparations, Res. J. Chem. Sci., 2(3), 46-51, 
(2012) 


Assessment of Heavy Metals in Rooftop dust around Lake Nakuru Basin, Kenya

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Assessment of Heavy Metals in Rooftop dust around Lake Nakuru Basin, Kenya

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