Monitoring the Quality of Soils around Rivers Wouri and Meme of Cameroon Using Plasticity and XRF

Mangroves play important roles in the environment such as sequestration, spawning of fishes and source of medicinal plants. Two rivers which feed the mangroves of Cameroon are Rivers Wouri and Meme. While River Wouri that feeds the Douala-Edea mangrove receives smaller water bodies that pass through an industrial environment, River Meme that feeds the Rio del Rey mangrove receives small water bodies that pass through an environment harbouring a lot of agricultural activities. The rural and urban communities use water from the rivers to grow vegetables (plant production). The quality of water that feeds the mangroves is of paramount importance. This in turn depends on the mineralogical content of the soils around the rivers and adjourning water sources. This is because soils act as sinks for pollutants. Different clay minerals have different capacities to retain and release chemical entities. Therefore, they contribute differently in the protection of catchment areas. This work was therefore aimed at investigating the role played by soils in controlling the movement of these chemical elements into the rivers. Clays extracted from soils around these water sources were analyzed for mineralogical composition. All analyses were carried out using standard plasticity and XRF methods. Clay content (2 to 7%) in Wouri was lower than in Meme (4 to 34%). The majority of the clay was dominated by SiO2, Al2O3, Fe2O3, and TiO2 and was a mixture of non-expandable (2:1 and 1:1) and sesquioxide clays. The soils have low pollutant retention capacity and are therefore vulnerable to anthropogenic activities. Hence, stringent measures should be taken to monitor soil/water quality with respect to waste disposal and use of agrochemicals. The use of compost in place of fertilizers by farmers should also be encouraged.