Isotopic composition of precipitation and groundwater onshore of the Rio del Rey Basin, southwest Cameroon: local meteoric lines and recharge

Abstract

The link between rainfall and groundwater recharge in the Rio del Rey Basin, which is of socio-economic importance to Cameroon, is poorly understood. Accordingly, the stable isotopes in monthly rainfall from January to December 2012 (in Lobe and Mundemba) and 52 surface water and groundwater samples were investigated. High values of δ18O and δD were recorded in the dry period (February to March), and the least values of δ18O and δD were observed in the wet period (September). This indicates that different condensation processes primarily influenced stable isotopes in rainfall as a function of the difference in moisture sources. The relationship between δD and δ18O defined the Lobe meteoric water line as δD = 7.97 δ18O + 12.48 and Mundemba water line as δD = 7.75 δ18O + 10.79. The similarity of their slopes to the global meteoric line suggests that the isotopic composition of investigated rains was not significantly affected by evaporation during precipitation. The ranges in deuterium-excess of precipitation from 5.8 to 16.56‰ suggest the source of vapour is from the Atlantic Ocean. The groundwater isotope values (ranging from −3.81 to −2.52‰ for δ18O) plotted close to and along the GMWL, showing that its isotopic composition is of meteoric origin under rapid recharge conditions. The isotopic similarity between groundwater and June–August rains suggests a significant recharge during this period.

Hydrogeochemical characterization of groundwater quality, East of Mount Cameroon and West of the Penda Mboko River, suitability for drinking and irrigation use

“…3 d) with 211 mg / l at the maximum and 102 mg / l at the minimum. Low TDS (<352mg/l), below the WHO(2017) limit of 700mg/l signified low mineralization as due to short residence time and also indicates fresh water conditions [62].…”

“…Understanding groundwater systems is important because surface waters are becoming increasingly unreliable due to pollution and climate change. Hydrogeologists in urban and rural areas deal with many water-related problems [27,48], including groundwater pollution due to the presence of soil bacteria animal waste, organic fertilizers, sewage and chemical fertilizers [15] [62][44] [46].…”

“…The study area is a predominantly agricultural locality where the use of pesticides, chemical fertilizers, and poor sanitation facilities make shallow aquifer contamination much easier than contamination of deep groundwater by vertical flow in a downward direction. [61] The goal of this study was to determine the physicochemical characteristics of groundwater sources impact of water-rock interactions, and the suitability of the water sources for drinking and agricultural purposes for sustainable development and management of the water sources.…”

Hydrogeochemical monitoring of groundwater and surface water quality, East of Mount Cameroon and West of the Penda Mboko River, suitability for drinking and irrigation

“…Physical and chemical parameters are the functional features for groundwater quality appraisal which are particularly affected by natural processes such as geological formations and anthropogenic activities [27] [45] The occurrence of pollution in groundwater depends on external physical factors such as, pit-latrines, animal wastes[15], organic manure [44], sewerage [46] and fertilizers [62]. In addition, other factors such as the physical composition of the vadose zone substances, accumulation of chemicals, weathering, dissolution, precipitation, ion exchange, and various biological processes usually occurring below the surface can also influence water quality.…”

“…Most people use shallow aquifer water for their daily activity which is more susceptible to contamination. The study area is an agriculture dominant locality which uses pesticides, chemical fertilizers and improper sanitation facilities allowing contamination of shallow aquifer much easily rather than deep groundwater by vertical flow in downward direction [61]. The data collected will be significant for developing, harnessing and managing of portable water sources for the population.…”