A study was conducted to estimate the terrestrial gamma radiation (TGR) dose rates associated with the natural radionuclides 238U, 232Th and 40K in the characteristic geological formations of Jos Plateau. A total of 51 surface soils from all the geological units were collected and measured using high-resolution gamma ray spectrometry system. From the measured activity concentrations of 238U, 232Th and 40K, TGR dose rates in air outdoors 1 m above ground surface, were estimated to be in the range of 36 nGy h-1 to 456 nGy h-1, depending on the geological formation, with an overall mean value of 143 nGy h-1. The estimated mean value is by a factor of two higher than the world average value of 59 nGy h-1. Geological formation G8 (Younger granites) appear to have the highest mean TGR dose rate while G7 (sandstone, clay and shale) show the lowest mean TGR dose rate. The results of this study inferred that, TGR dose rates outdoors for Jos Plateau differs with the different geological formations and significantly contributed by 232Th. An isodose map for the distribution of TGR and exposure rate to the public due to natural sources was also plotted using ArcGIS software. The data here presented can be used to evaluate public radiation dose and to produce radiological map for the country.

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Gamma spectrometry was used to measure gamma dose rate in air and to determine the activity concentration of naturally occurring radionuclides viz. 226Ra 232Th and 40K in soil samples collected across the geological formations of Barkin Ladi. Dose rates measured in-situ ranged from 5 nGy h−1 to 1265 nGy h−1 with a mean value of 325 nGy h−1. The activity concentrations of 226Ra ranged from 27 to 327 Bq kg−1, 34 to 457 Bq kg−1 for 232Th and 43 to 1055 Bq kg−1 for 40K. Their mean values are significantly higher than their corresponding global average values. Annual effective dose due to exposure to gamma dose is calculated at 0.34 mSv y−1. Mass concentrations of uranium (238U) and thorium (232Th) determined in groundwater samples using Inductive Coupled Plasma Mass Spectrometry (ICP-MS) ranged from 2.5 to 35 µg l−1 for 238U and 0.5 to 15 µg l−1 for 232Th. Ingestion effective dose varies between 10.5 and 142 mSv y−1 for 238U and between 0.34 and 10.2 mSv y−1 for 232Th. Mass concentration of three water samples exceed the toxicity limit of U in groundwater provided by WHO. The result revealed that human risk due to ingestion of groundwater is from chemical toxicity rather than radiological effects.  The results of this work will be useful for radio-geochemical investigation and groundwater resources management.

In this study we investigated the impact of climate change on groundwater quality in Gashua northeast Nigeria. The results of the time series analysis of the meteorological data obtained from the area showed high variability in rainfall and temperature due to climate change. This variability is responsible for the extreme and erratic rainfall which cause flooding in the area. The flood water are associated with both organic and inorganic contaminants which infiltrate into the subsurface to pollute the groundwater. Geophysical and Hydrochemical methods were used to investigate the groundwater quality in the area. The results of the Vertical Electrical Sounding (VES) showed that the area is composed of five geoelectric layers which are; topsoil, clay, sand, sandy-clay and sand. The second layer which is clay enhances the retention of the flood water in the study area due to its proximity to the surface. Contaminated zones in the subsurface of the study area were identified as low resistivity areas with resistivity values ranging from 2 -25 Ωm. The results of the hydro-chemical analysis of the groundwater samples showed that the groundwater is polluted. Based on the findings of this study, we recommend that a high capacity drainage system should be constructed in Gashua and its environs to protect the area from extreme flooding and groundwater pollution. Gashua river channel should be improved through excavation and river bank protection to accommodate floodwater.