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

Applied Water Science

Takeshi Ohba¹  Mabel N. Wantim²  Samuel N. Ayonghe²  Engome R. Wotany³  Mengnjo J. Wirmvem⁴  Wilson Y. Fantong⁴ 

[1] Department of Chemistry, School of Science, Tokai University;Department of Environmental Science, Faculty of Science, University of Buea;Department of Geology, Faculty of Science, University of Buea;Institute of Geological and Mining Research;

关键词: Rainfall;    Groundwater;    Stable isotopes;    Meteoric water line;    Recharge;    Ndian-Cameroon;   

DOI  :  10.1007/s13201-021-01473-7

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown