The prime aim of our work is to report and comment on the bioaccessible concentrations – i.e., the soluble content of chemical elements in the gastrointestinal environment that is available for absorption – of a number of essential mineral nutrients and potentially harmful elements (PHEs) associated with the deliberate ingestion of African geophagical materials, namely Calabash chalk and Undongo. The pseudo-total concentrations of 13 mineral nutrients/PHEs were quantified following a nitric-perchloric acid digestion of nine different Calabash chalk samples, and bioaccessible contents of eight of these chemical elements were determined in simulated saliva/gastric and intestinal solutions obtained via use of the Fed ORganic Estimation human Simulation Test (FOREhST) in vitro procedure. The Calabash chalk pseudo-total content of the chemical elements is often below what may be regarded as average for soils/shales, and no concentration is excessively high. The in vitro leachate solutions had concentrations that were often lower than those of the blanks used in our experimental procedure, indicative of effective adsorption: lead, a PHE about which concern has been previously raised in connection with the consumption of Calabash chalk, was one such chemical element where this was evident. However, some concentrations in the leachate solutions are suggestive that Calabash chalk can be a source of chemical elements to humans in bioaccessible form, although generally the materials appear to be only a modest supplier: this applies even to iron, a mineral nutrient that has often been linked to the benefits of geophagia in previous academic literature. Our investigations indicate that at the reported rates of ingestion, Calabash chalk on the whole is not an important source of mineral nutrients or PHEs to humans. Similarly, although Undongo contains elevated pseudo-total concentrations of chromium and nickel, this soil is not a significant source to humans for any of the bioaccessible elements investigated.

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An evaluation of irrigation quality of groundwater from shallow aquifers within Wamba Sheet 210 in Nasarawa State, North Central Nigeria was carried out. The area is located between Latitudes 8°30’N and 9°00’N, and Longitudes 8°30’E and 9°00’E, covering about 3,025 Km2. It is underlain by rocks belonging to the Basement Complex, the Younger Granites, and Cretaceous sedimentary rocks. The results of field tests and laboratory analysis were used in assessing the suitability of groundwater found in the area for irrigation. Values obtained for Sodium Adsorption Ratio (SAR), Soluble Sodium Percentage (SSP), Magnesium Adsorption Ratio (MAR) and Kellys Ratio (KR) were 0.97 - 3.43, 8.18 - 81.76%, 8.03 - 80.22 and 0.04 - 3.43 respectively. These indices are largely within the safe limits for irrigation with very little likelihood that salinity hazards will develop.