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

Abstract

Abstract:The present work highlights the influence of lithology on water quality in Méiganga and its surroundings. The main geological formations in this region include gneiss, granite and amphibolite. The soils developed on these rocks are of ABC type, which are acidic to slightly acidic. Electrical conductivity (EC), organic matter, total nitrogen, nitrate-nitrogen, sulfate, chloride, phosphorus and exchangeable base values were low to very low in the soil samples. Groundwater samples were investigated for their physicochemical characteristics. The wide ranges of EC values (15.1-436 µS/cm) and total dissolved solids (9-249 mg/L) revealed the heterogeneous distribution of hydrochemical processes within the groundwater of the area. The relative abundance of major dissolved species (mg/L) was Ca 2+ > Na + > Mg 2+ > K + for cations and HCO 3 − >> NO 3 − > Cl − > SO 4 2− for anions.All the groundwater samples were soft, with total hardness values (2.54-136.65 mg/L) below the maximum permissible limits of the World Health Organization (WHO) guideline. The majority of water samples (67%) were classified as mixed CaMg-HCO 3 type. Alkaline earth metal contents dominated those of alkali metals in 66.66% of samples. Thus, for the studied groundwater, Mg 2+ and Ca 2+ ion adsorption by clay minerals was almost nonexistent; this implies their release into the solution, which accounts for their high concentrations compared to alkali metals. Ion geochemistry revealed that water-rock interactions (silicate weathering) and ion exchange processes regulated the groundwater chemistry. One water sample points towards the evaporation domain of this diagram, indicating that groundwater probably does not originate from a deeper system. Kaolinite is the most stable secondary phase in the waters in the study area, in accordance with the geochemical process of monosiallitization, which predominated in the humid tropical zone.

Groundwater resources for domestic and irrigation purposes in Melong (Littoral Region, Cameroon): Hydrogeochemical constraints

“…The highest average Mg 2+ concentration (1.7 mg/L) was observed at MT64 meanwhile, lowest one (0.59 mg/L) was noted at MW11. The Ca 2+ may stem from the dissociation of gypsum in the aquifer system (Gountié et al, 2017). In both seasons the levels of Ca 2+ , Mg 2+ , Na + and K + were by far lower than the permissible limits of WHO (2017) for drinking water and therefore would not pose any threat on the health of the consumers.…”

Hydrochemical and Stable Isotope Analyses Show Limited Interactions Between Groundwater and Lake Water in the Lake Bosomtwi Impact Crater, Ghana.

“…'Hard' rock and associated silicate mineral dissolution is aided by acidic conditions as a result of low pH, which explains the relatively high levels of Si in C1 members as compared to the other clusters as observed in Table 1. These processes cause the incongruent dissolution of mainly plagioclase, biotite and potassium feldspar, which are common minerals identified in the underlying geology of the study area (Garrels and Mackenzie, 1967;Dedzo et al, 2017).…”

Hydrogeophysical Investigation for Groundwater Resources from Electrical Resistivity Tomography and Self-Potential Data in the Méiganga Area, Adamawa, Cameroon

“…Méiganga is the main town of the Mbéré department, located in the Adamawa region of Cameroon. This study area, with about 1129 km 2 of surface area, is situated between longitudes 14 ∘ 00 and 14 ∘ 25 and latitudes 06 ∘ 28 and 06 ∘ 43 ( Figure 2), with altitudes ranging from 920 to 1200 m [3]. The climate is subhumid, with a mean annual rainfall of 1662 mm [4].…”

“…In Cameroon, the region of Adamawa called the water tower of Cameroon is one of the ten regions with significant freshwater resources, including surface water (streams, rivers, lakes) and groundwater [3]. Despite this endowment, access to drinking water is rare in many rural and periurban areas of the region and especially in the area of Méiganga.…”