REPORT: GEOCHEMICAL FIELD SAMPLING CAMPAIGN OF THE
IGCP/SIDA/UNESCO/MUT PROJECT 606-SIDA EXTRA BUDGETARY
ALLOCATION; YAOUNDE CAMEROON, 03 - 09 JULY, 2013
The Geochemical Circulation of
Selected Potentially Harmful
Elements (PHEs) in Ecosystems
Around Mining Centres in East Cameroon:
Health implications
J. Penaye
T.C. Davies
S.C. Ngueme Fils
E.E. Bate-Tibang
M.E. Mimba
M. Shapi
EXECUTIVE SUMMARY
The Swedish International Development Agency (SIDA) Extra-Budgetary Funding for 2013
was an additional grant awarded for the implementation of a proposed extension phase of
IGCP/SIDA/UNESCO/MUT Projects 954 and 606, respectively. The geochemical field
campaign undertaken in East Cameroon (Kette/Batouri) during the early part of July, 2013,
was in fulfilment of the first of four project objectives, specifically for Cameroon, among a
number of other Sub-Saharan African countries addressed in the Sub-region. The objective
was: ‘to understand how mining and ore processing activities, and particularly abandoned
mines, negatively affect the ecosystem (soils, plants, surface- and groundwater) and the health
of the neighbouring communities’.
A total of 30 soil samples in duplicate and triplicate (respectively), 22 duplicate natural water
samples, and duplicate cassava samples were collected from cultivable and uncultivable lands
and waterways in and around the alluvial gold mining towns of Kette and Batouri. Thirteen
field hydrochemical parameters were measured ‘in situ’ on the water samples. All samples
were prepared using standard laboratory procedures, professionally packed and shipped to
ACME Laboratories in Vancouver, Canada for analyses of a range of nutritional and
potentially harmful elements.
Transportation and other logistics for the fieldwork and sample preparation were provided by
the Institute of Geology and Mining Research.
INTRODUCTION
Location of study area
The study area is situated in the Kadey Division, Eastern Region of Cameroon along the
Equatorial Rainforest Belt. It extends from Kette Sub-Division (4°57'40.04''N and
14°33'45.35"E) in the north to Batouri (4°25'59.84''N and 14°22'00.49"E), the Divisional
Headquarters, covering a ground distance of about 85 km (Fig. 1).
Fig.1: Location of the study area
Climate
The study area is influenced by a hot and humid equatorial climate of the classic Guinean type,
marked by the alternation of two rainy seasons and two dry seasons. The mean annual rainfall is
between 1500 mm and 2000 mm and the average temperature ranges from 22.8 °C to 24.7 °C. During
the year, the area experiences the following seasons: the short rainy season from mid-March to June;
the short dry season from June to mid-August; the main rainy season, from mid-August to midNovember, and the long dry season from mid-November to mid-March.
Vegetation
The vegetation in Kette Sub-Division is dominated by a mosaic of shrub and herbaceous savanna
bush, with short grasses on the peneplain; this gives way to a gallery forest on the approach to
the southern fringes of Batouri.
Relief
The topography consists of gently rolling hills with an average altitude of between 600 m and
900 m (Fig. 2). The landscape comprises a peneplain, rugged in some places, and supporting
a mosaic of lush grass and thicket. A few swampy patches are observed in the shallows.
Steep slopes are observed but are very much localised.
Fig. 2: Relief and hydrography
Hydrography
The rugged terrain favours a dendritic drainage system (Fig. 2). The most important river is the Kadey
at Batouri, which is fed by the Bombé and Mama streams encountered further north in Kette SubDivision.
Geology
The Batouri region in East Cameroon is underlain by syn- to late-tectonic granitoids emplaced into
medium- to high-grade schists of the Neoproterozoic Yaounde Group. Granitoids include porphyritic
biotite-amphibolite granites and granodiorites cross-cut by numerous quartz dykes bearing localised
gold mineralization. Schists are generally observed as large xenoliths in the granitoids and include
well-deformed gneisses and amphibolites.
Soils
The study area lies along the Equatorial Rainforest Belt, with warm, wet and humid conditions,
combined with a varied topographic profile. There is widespread microbial activity. This combination
ensures rapid and prolonged weathering, including biochemical decomposition, resulting in the
formation of the typical red or yellow lateritic soils, which are again subjected to leaching. The
hydromorphic soils are found mainly in the shallows and are mainly sandy or sandy clay in
texture. Despite having soils of apparently high agricultural potential, very little food crops are
grown in the Region.
Demography and economic activities
The population of the Kette municipality is estimated at 31,129 inhabitants in 2010, and that of
Batouri, 67,007 in 2010 (3 RGPH, 2010), put together, are relatively young and cosmopolitan. These
towns consist of the following dominant ethnic groups: Gbaya Kako, Yanguélé, Bépalo and Mbororro;
and minority ethnic groups: Hausa, Mésimé, Maka, Bulu, Bamileke, Fulani, Boussougou, Ewondos,
Bamun and Bangantou. Many refugees from the Central Africa Republic are added to this national
population, particularly in Kette Sub-Division. The different religious groups existing in the area are
the Adventist, Presbyterian, Full Gospel, Muslims, Bahai and Catholics who live together
peacefully.
Geographic isolation coupled with the existence of an inadequate economic base, does not favour the
development of local economic activities such as agriculture, fishing, livestock rearing, crafts and
gemstone extraction.
Basically, only subsistence agriculture is practiced in this area. The main food and vegetable crops
cultivated in this area include Manihot esculenta, Dioscorea rotunda, Arachys hypogaea, Zea mays
and Amaranthus esculentus.
The hydrological network encourages the development of artisanal fishing. Cattle rearing is widely
practiced by the indigenes. This constitutes the main economic resource of the locality. The Kette
basement has been unsustainably exploited; notably, through artisanal mining activities (gold and
diamond). However, this activity provides these locals with substantial income (Mengue, 2012).
METHODOLOGY
Soil and water samples were collected in accordance with the project sampling protocol. The GPS
coordinates (latitude, longitude and altitude) as well as other geoenvironmental characteristics were
recorded at each sampling site.
Soil sampling
A total of thirty soil samples (Fig. 3) were collected; two composite samples from 2 farms and
twenty eight other soil samples at 15 m on either side of the road from Kette to Batouri. On each of
the two farms, a composite near-surface (30 cm below A0 ) soil sample was collected. Using a
pick, hoe and shovel, four holes were made at the corners of a square. This square had dimensions
20 x 20 m in accordance with IGCP 259 recommendations (Darnley et al., 1995). The sub-samples
were homogenised and quartered on a plastic sheet using a trowel; and approximately 250 g of
this sample taken and stored in labelled Kraft paper envelopes. Duplicate samples were
collected from each site. The different crop types, geology, topography, vegetation and other
geoenvironmental variables of the area were noted.
The other soil sampling sites are located along the road from Kette to Batouri (Fig. 3). A 1m
X 1m pit was dug using the pick and shovel to a depth of 40 cm. About 250 g of the bulk
sample was collected at depth of 30 cm using a trowel, followed by description of the soil
colour, texture and other pedological characteristics; these samples were then stored in labelled
Kraft sample bags. Samples were collected in duplicate or triplicate from each site. The
samples were later oven-dried (30˚ C) at the Hydrological Laboratory at the Institute for
Geological and Mining Research (IRGM), Nkolbisson, and submitted for geochemical analysis.
The geology, topography, vegetation and other geoenvironmental variables of the area were
also noted.
Fig. 3 : Soil sampling sites
Water sampling
Twenty-two water samples (Fig. 4) were collected from accessible water points. Ten samples from
boreholes (BH), two from open wells (OW), four from springs (SP), five from streams and one from a
river, were collected. At each water sampling point, the multiparameter water analyser and new 250
ml HDPE sample bottles were washed three times with distilled water and the water to be sampled
before determination of water quality parameters (Table 1). The collected water sample was then
stored in the pre-labelled HDPE bottles after thorough rinsing. Collected water samples were properly
capped and preserved without cooling. Three samples (A, B, C) were collected from each sampling
site. These were later filtered (less than forty-eight hours) at the Hydrological Laboratory at IRGM
Nkolbisson. To one 250 ml aliquot of the samples was added two drops of ARISTAR grade
concentrated hydrochloric acid (HCl), to another 250 ml aliquot was added two drops of ARISTAR
grade concentrated nitric acid (HNO3), and one 250 ml aliquot was preserved without acidification.
These were preserved under cooling conditions and shipped to Vancouver for chemical analyses. The
geology and land use practices in the area were also noted.
Fig. 4 : Water sampling stations
Dried cassava chips cultivated in the study area was bought for chemical analysis. Cassava (Manihot
esculenta), the staple food of this region, is the main subsistence crop. However, subsistence
agriculture is seldom practiced by the indigenes. The enigma of having very large areas of
apparently high quality-, very cultivable soils in East Cameroon, accompanied by very little
agricultural productivity, is being urgently investigated by the project team.
Geochemical analysis
All the samples collected have been professionally packed and shipped to ACME Laboratories
in Vancouver, Canada, for analyses of 36 trace elements, including PHEs by ICP/MS and
ICP/OES techniques.
Conclusion
The analytical results would be synthesised and interpreted so as to provide tangible scientific
support for use in the formulation of environmental norms in individual Sub-Saharan African
countries, for improving the efficiency of governments in addressing the challenges related to
the adverse effects of abandoned mines; in particular, using the results to provide advice on
tangible measures for mitigating the effects of PHEs migrating from mine sites all the way
into the food chain, and for obviating accompanying environmental health consequences.
Integration of these results with conclusions drawn from the ‘outreach and educational
research’ component of these projects, would help strengthen awareness (science-based
knowledge and advices) in governments, the private sector and the public on the impact of
abandoned and derelict mines on the environment, ecosystem services and health.
Recommendation
It is noted that the land in this part of the country is very fertile, with very low input of
PHEs from mining. On the basis of our field observations and analytical results, we
recommend provisionally,
the adoption of new land use policies for Eastern Cameroon, that favour the intensification of
agricultural activities.
References
- 3ème Recensement Général de la Population et des Habitats du Cameroun (RGPH), 2010. Bureau
Central des Recensements et des Etudes de la Population (BUCREP). http://www.bucrep.cm/
Darnley, A.R., Darnley A. G., Bjorklund A., Bolviken B., Gustavsson N., Koval P. V., Plant J. A.,
Steenfelt A., Tauchid M. and Xie X., 1995. A Global Geochemical Database for
Environmental and Resource Management. Recommendations for International
Geochemical Mapping. Final Report of IGCP Project 259. Earth Sciences 19,
UNESCO.
Fordyce, F.M, Zhang Guangdi, Green, K. and Liu Xinping, 2000. Soil, grain and water
chemistry in relation to human selenium-responsive diseases in Enshi District, China. Applied
Geochemistry, Vol. 15, p. 117 - 132.
- Mengue F. D., 2012. Qualité des eaux de puits et forages du secteur de Ketté. Mémoire présenté et
soutenu en vue de l’obtention du Diplôme de Professeur d’Enseignement Secondaire Général
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