1. India Water Week HEAVY METAL POLLUTION OF GROUNDWATERS OF THE NTEM WATERSHED IN YAOUNDÉ-CAMEROON (WEST AFRICA) C. DEFO; B.P.K. YERIMA; R. KAUR; N. BEMMO SEMINAR SESSION (S4): “WATER AND HEALTH – MANAGING WATER QUALITY University of Dschang, Cameroon IARI, New Delhi

2. Outline of Presentation 1.Introduction 2.Objectives 3.Description of work 4.Results and Conclusions

3.  Environmental pollution management is a major challenge in many cities of sub-Saharan Africa in general and in Yaoundé in particular;  Since fifty years, the population of Yaoundé has experienced an explosive growth (averagely 4% / year), 1957 - 2005, population increased:58099 -1 817 524;  This impacted on the spatial evolution of the city multiplied by nine (09) times between 1956 and 2000 (from 1740 to 15900 ha);  In the Ntem watershed, the consequences of this urbanization are visible through:  The increase of impermeable surfaces (buildings and tarred roads); Introduction

4.  Increase in the frequency of floods;  Progressive increased rate of vehicular pollution due to the congested urban circulation;  Extension of urban agriculture, increase in sewage and solid wastes, improper waste dumping sites;  Besides, drinking water provisioning in the city of Yaoundé by the public water distribution network can satisfy less than 65 % of the city’s needs;  with the rest of the population using groundwater from wells/springs;  There are very limited investigations on the quality of these water sources as their heavy metal status is not very well quantified Introduction

5. 1.Investigation of the heavy metal concentrations (Cd, Pb, Cr, Ni, Zn, Mn, Cu and Fe) in groundwaters 2.Comparison of concentration values to the Maximum admissible Limit of WHO and emphasizing the pollution status of groundwaters Objectives

6. Description of work Location of the Ntem drainage basin within the Yaoundé city, Cameroon (adapted from Mabou, 2013)

7. Description of work Ferralsols Presentation of the Ntem watershed and the sampling points

8. Description of work  A total of twenty five (25) representative groundwater samples were collected from five (5) hand dug wells located at the selected sites P1, P2, P3, P4 and P5 in the watershed;  Plastic bottles of 500 ml capacity (previously rinsed with distillated water and sterilized with alcohol), were used to collect water samples Rodier et al. (2006). Groundwater Sampling Procedure

9. Description of work Determination of Heavy Metals Concentrations in Groundwater Samples in the Laboratory  Total Pb, Cd, Cr and Ni were primarily extracted by the digestion method with diacid. Briefly, put 50 ml groundwater sample in 250 ml conical flask, add 15 ml diacid (9V:4V ratio of Perchloric acid and Nitric acid);  total micronutrients (Zn, Cu, Mn, and Fe) extraction was performed using Mehlich 3 procedure (Mehlich, 2004);  Samples filtration using Whatman paper No. 42;  Determination of heavy metals concentrations in samples using AAS;

10. Results and Conclusion Sampling sites Heavy metals (mg/l)P5 P1P2P3P4 WHO Norms concentration in potable water (mg/l) Observations Pb0.025* Groundwater polluted in lead at P1, P2, P3 and P4 Cd 0.00  0.00 0.005* Groundwater polluted in Cd at P2 and P3 Cr0.05* Groundwater polluted in Cr at P1, P2, P3 and P4 Ni0.05* Groundwater polluted in Ni at P1, P2, P3 and P4 Zn0.21±0.020.02±0.02 5*Not polluted Cu0.01±0.000.01±0.010.01±0.00 1*Not polluted Mn0.05* Polluted at all sites Fe0.2* Polluted at all sites Results

11. Results and Conclusions  Groundwater resources in the Ntem watershed were found polluted by heavy metals. The occurrence of these pollutants in the groundwater is a consequence of anthropogenic activities in the Ntem watershed.  The pollution of groundwater resources is a potential threat to public health as well that groundwater constitutes a major source of water supply for the population in this region. Conclusions