Trace Metals in Groundwater of Kumba and Environs in Cameroon

摘要

Kumba and environs situate between longitudes 9.24E - 9.5E and latitudes 4.44N - 4.7N, is the economic capital of the Southwest Region-Cameroon. It is located along the Cameroon Line at northwestern edge of the Douala Basin. The inhabitants depend mostly on groundwater through springs, handdug wells and boreholes. In this area like in most of Cameroon and Africa, water from groundwater sources (springs, wells and boreholes) is not treated. Often, it is given minimal or cosmetic periodic treatment if at all. Although the concentra-tions of trace metals in groundwater affects its safety and acceptability, testing for trace metals is less common and typically occurs mostly when a specific risk has been identified. This could be attributed to the high cost of analysis and lack of technological know-how. In addition to this, testing and monitoring of groundwater is not carried out most of the time and whenever it is done, only major cations and anions are analyzed. Due to the absence of treatment and testing of groundwater before drinking in Kumba and environs, there is a need to evaluate the trace metal content. The study had 21 groundwater samples analyzed using Inductively Coupled Plasma Mass Spectroscopy. Field measurement of physicochemical parameters was determined. R-mode statistical analysis; Pearson’s Correlation Analysis (PCA) together with Hierarchical Cluster Analysis (HCA) between the trace metals and the physico-chemical parameters was carried out. Ten indices were determined: Four trace metal hazard indices: the average daily dose ADD, carcinogenic risks CR and the non-carcinogenic risk hazard quotient HQ which yields the hazard indices HI, and six trace metal pollution indices: Degree of contamination (DC), Enrichment factor (EF), Ecological risk index (Er), Potential ecological risk index (RI), Pollution load index (PLI) and Geo-accu- mulation index (Igeo). The general trend of mean trace metal concentration in the groundwater is in the order of: Mn > Fe > Ba > Sr > Zn > Ni > Cu > Co > Pb > Li > Cr > V > As > Cd. HCA distinguishes two clusters based on spatial similarities and dissimilarities. Cluster one; (01) element Ba; soluble; Cluster two (13) non soluble elements divided into three classes; class one (06) As, Cd, V, Li, Pb, and Cr; less enriched. Class two (03) Co, Cu, Ni and Zn; enriched; Class two (04) Zn, Sr, Fe and Mn; more enriched.