Nature And Properties Of Soils

The author was the Project Leader of the British Geological Survey (BGS) Research Projects on Basement Aquifers and Collector Wells. This introductory paper constitutes an overview of crystalline basement aquifer occurrence, geological and climatic controls, evolution, geometry, hydraulic parameters, resources and recharge, combined with a discussion on exploration and management. Data from the BGS Research Projects Report Series are incorporated.

The hydrogeology of crystalline basement aquifers in Africa; introduction

Heavy metals in soils

Global Isotope Hydrogeology―Review

The African continent continues to be faced with myriad of challenges, particularly in the public health sector. A few figures exemplify the magnitude of the problem. Infant and maternal mortality remains stubbornly high, compared to other regions of the world. According to the Inter-agency Group for Child Mortality Estimation [1-2], the risk of a child dying before completing the first year of age was highest in the WHO African Region (55 per 1000 live births), over five times higher than that in the WHO European Region (10 per 1000 live births). Similarly, every day about 800 women die due to complications of  pregnancy and child birth. Of the 800 daily maternal deaths, 500 occur in sub-Saharan Africa and 190 in Southern Asia, compared to 6 in developed countries. The risk of a woman in a developing country dying from a maternal-related cause during her lifetime is about 23 times higher compared to a woman living in a developed country [1-2].

Leaving no one behind

Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada Manitoba's Watershed Systems Research Program, Winnipeg, Manitoba, Canada Center for Earth Observation Science, University of Manitoba, Winnipeg, Manitoba, Canada Department of Geological Engineering, College of Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana Correspondence Samuel Bansah, Department of Geological Sciences, Wallace Building, 125 Dysart Road, Winnipeg, Manitoba, R3T 2N2, Canada. Email: bansahs@myumanitoba.ca Funding information Natural Sciences and Engineering Research Council of Canada (NSERC)

Streamwater ages in nested, seasonally cold Canadian watersheds

The application of ferrous slags as aggregate, road bed materials, soil fertility conditioner and as clinker materials depend on their chemical and mineralogical characteristics. In order to assess the possibilities of using ferrous slags generated in Ghana, selected slag samples from some foundries have been characterized. A total of six bulk samples were collected from three different foundry shops to determine their chemical and mineralogical composition. The slag samples showed varied chemical and mineralogical characteristics. Differences are as a result of the differences in furnace charge, operation temperatures, grades of refractory furnace lining and melting additives. Calcium oxide (CaO) contents observed in all investigated samples were in combined form (i.e. not free CaO). The low amounts of calcium oxide in the slag samples limit their applications in the area of cement/aggregate production. Even though slags were found to be alkaline, for these slags to effectively neutralize the acidity of soil and improve its fertility, components such as CaO, SiO2, MgO and FeO in the slag must be improved. However, these slags could be used as road bed materials.

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Chemical and Mineralogical Characterization of Ghanaian Foundry Slags

Isotope-based hydrograph separation (IHS) is a widely used method in studies of runoff generation and streamflow partitioning. Challenges in choosing and characterizing appropriate tracers and end-members have, however, led to presumably highly uncertain IHS results. Here we tested the effects of end-member definitions and tracer choices on IHS results in nested Prairie watersheds of varying size and landscape characteristics. Specifically, the consideration of eight potential “new” water end-members, eight potential “old” water end-members, and two stable water isotope tracers led to 80 potential IHS results for each stream water sample. IHS-related uncertainty was evaluated using a Gaussian error propagation method. Results show that choosing an appropriate “new” water end-member is most challenging during the freshet: highly variable “old” water fractions associated with high uncertainties were attributed to changing conditions from melting snow only to rain-on-snow. In summer and fall, it was rather the choice of an appropriate “old” water end-member that was most problematic. IHS results obtained using δ18O versus δ2H as a tracer were significantly different except in the flattest and most wind-sheltered watersheds examined. Overall, δ2H-based IHS results were more uncertain than their δ18O-based counterparts. Recommendations are therefore made toward careful selection of a tracer and a sampling strategy aimed at characterizing the most appropriate end-members for IHS, especially when dealing with seasonally cold watersheds.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1002/2016WR020252

Evaluating the Effects of Tracer Choice and End-Member Definitions on Hydrograph Separation Results Across Nested Seasonally Cold Watersheds

Groundwater chemistry and isotopes reveal vulnerability of granitic aquifer in the White Volta River watershed,West Africa

Elemental concentrations beyond stipulated thresholds are a considerable concern for environmental pollution regulators and public health administrators around the globe. Data is, however, lacking in most regions especially developing countries for practical policy decision making and management. In this study, we obtained 49 high-resolution soil cores from three vertical profiles in the Densu River Basin of Ghana and measured the concentrations of major and trace elements (Ca, K, Fe, Ti, Cr, Cu, V, Ni, and Zn). The aim was to examine and provide data on elemental levels to serve as baseline information on mobilization studies for waste management in the basin. Geochemical methods for estimation of metal enrichment and accumulation were employed to determine enrichment and pollution, sources, and mobilization of the metals in the basin. Hierichical cluster and principal components analyses were used to examine metal associations and and the effects soil physicochemical properties on the metals.. The results show spatial variations in the concentrations of the metals within and between soil profiles and were attributed to variability in soil formation processes and the locations where samples were collected in the basin, respectively. Moderate to high enrichment factors (EF) and geo-accumulation (Igeo) index were observed for Vanadium (V) and Chromium (Cr) in all profiles indicating some level of anthropogenic interference leading to pollution. The Pourbaix diagrams, however, showed that the Cr and V abundances may be natural . Vehicular activity and agricultural inputs were identified as some of the most likely source elemental contributions to soil pollution in the basin. Our analysis also showed that most of the metals investigated are of natural geologic origin. The combination of field observations and established methods (geochemical and statistical analyses) aided in extracting beneficial information from the small sample size obtained.

Samuel Bansah

Papers

Streamwater ages in nested, seasonally cold Canadian watersheds

Chemical and Mineralogical Characterization of Ghanaian Foundry Slags

Evaluating the Effects of Tracer Choice and End-Member Definitions on Hydrograph Separation Results Across Nested Seasonally Cold Watersheds

Groundwater chemistry and isotopes reveal vulnerability of granitic aquifer in the White Volta River watershed,West Africa

Geochemical and chemometric analysis of soils from a data scarce river catchment in West Africa