Origin and residence time of shallow groundwater resources in Lagos coastal basin, south-west Nigeria: An isotopic approach.

摘要: Abstract Knowledge of the source water in Lagos coastal basin (LCB) groundwater system was to be found vital future development and management system. Stable radioactive isotopic measurements have been employed unravel recharge residence time shallow system, based on sampling conducted 2016 2017 groundwater, surface rainfall. The concentration tritium samples were very low ranged from less than 1 2.8 TU, while measured 14C contents 59.1 88 pMC. δ18O values 4.81 3.98 ‰, δ2H -24.75 -19.70 ‰ for wet dry seasons, respectively. obtained results indicated non-existence paleo recharge; rather all essentially meteoric origin with intermittent contributions. Moreover, considerable variations compositions, reflecting evaporation preservation seasonal fluctuation. Though there an observed generally content, however, it proved useful identification recent active taking place across basin. deduced radiocarbon age reflected presence "modern water" thus supports present Therefore, actively renewable particularly during season exploitation is potentially sustainable