Hydrogeochemistry and quality of surface water and groundwater in the vicinity of Lake Monoun, West Cameroon: approach from multivariate statistical analysis and stable isotopic characterization

Abstract

With the use of conventional hydrogeochemical techniques, multivariate statistical analysis, and stable isotope approaches, this paper investigates for the first time surface water and groundwater from the surrounding areas of Lake Monoun (LM), West Cameroon. The results reveal that waters are generally slightly acidic to neutral. The relative abundance of major dissolved species are Ca(2+) > Mg(2+) > Na(+) > K(+) for cations and HCO3 (-) ≫ NO3 (-) > Cl(-) > SO4 (2-) for anions. The main water type is Ca-Mg-HCO3. Observed salinity is related to water-rock interaction, ion exchange process, and anthropogenic activities. Nitrate and chloride have been identified as the most common pollutants. These pollutants are attributed to the chlorination of wells and leaching from pit latrines and refuse dumps. The stable isotopic compositions in the investigated water sources suggest evidence of evaporation before recharge. Four major groups of waters were identified by salinity and NO3 concentrations using the Q-mode hierarchical cluster analysis (HCA). Consistent with the isotopic results, group 1 represents fresh unpolluted water occurring near the recharge zone in the general flow regime; groups 2 and 3 are mixed water whose composition is controlled by both weathering of rock-forming minerals and anthropogenic activities; group 4 represents water under high vulnerability of anthropogenic pollution. Moreover, the isotopic results and the HCA showed that the CO2-rich bottom water of LM belongs to an isolated hydrological system within the Foumbot plain. Except for some springs, groundwater water in the area is inappropriate for drinking and domestic purposes but good to excellent for irrigation.

Importance of Rocks and Their Weathering Products on Groundwater Quality in Central-East Cameroon

“…It indicates that most of the samples belong to the kaolinite stability field, demonstrating that kaolinite is the most stable secondary phase for the waters in the study area. This result is consistent with what has been reported by some authors [7,28,31,39,40] under humid tropical climatic conditions. Kaolinite constituted the main clay mineral formed through the monosiallitization process, which characterizes the humid tropical zone [45].…”

“…The compositional relations between the dissolved ions (Table 6) were computed using stoichiometric relations. The (Ca + Mg)/total cations ratios of all the samples varied from 0.36 to 0.75, with 83% of the values higher than 0.5, implying a high contribution of Ca 2+ and Mg 2+ in cations [28,50]. Further, the plot of (Ca + Mg) versus total cations for all the water samples (Figure 6a) showed that the whole points were below the 1:1 line, suggesting a contribution from the weathering reactions.…”

“…Despite their relatively low pH values below the WHO guideline value, TDS and EC exhibited a wide range. The high standard deviation of 65.45 and 114.67 for TDS and EC, respectively, indicates the heterogeneity of the hydrochemical processes evolving within the groundwater of the Méiganga area [27,28]. Nevertheless, all the investigated samples were fresh (TDS < 1000 mg/L), and, for the most part (10 samples over 12), soft (TH < 60 mg/L) [29]; the two other investigated water samples (W1 and W3) situated on amphibolite were moderately hard, with TH = 65.86 and 136.65 mg/L, respectively.…”

Pencirian Sifat Akuifer dalam Batuan Granit di Selangor

“…Rajah 6 menunjukkan korelasi yang baik antara nilai kekonduksian dan nilai jumlah pepejal terlarut bagi sampel air di kawasan kajian. Menurut Kamtchueng et al (2016), nilai-nilai ini menunjukkan keadaan air bawah tanah yang secara relatifnya adalah muda serta mempunyai tindakbalas kimia yang terhad dengan batuan akuifer dominan silika di kawasan kajian. Selain itu, ia menggambarkan kepelbagaian proses hidrokimia yang berlaku di dalam air bawah tanah di kawasan Selangor ini.…”

Seasonal Hydrological Inputs of Major Ions and Trace Metal Composition in Streams Draining the Mineralized Lom Basin, East Cameroon: Basis for Environmental Studies

“…Hydrogeochemical processes help to unravel changes in surface water quality relating to water-rock interaction or anthropogenic impacts (Singh et al 2005;Kumar et al 2006;Franz et al 2014;Nganje et al 2015;Kamtchueng et al 2016). The geochemical properties of surface water also depend on the chemistry of the recharging source as well as the various geochemical processes occurring within the drainage basin.…”