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Arsenic (As), chromium (Cr), and vanadium (V) are naturally occurring, redox-active elements that can become human health hazards when they are released from aquifer substrates into groundwater that may be used as domestic or irrigation source. As such, there is a need to develop incisive conceptual and quantitative models of the geochemistry and transport of potentially hazardous elements to assess risk and facilitate interventions. However, understanding the complexity and heterogeneous subsurface environment requires knowledge of solid-phase minerals, hydrologic movement, aerobic and anaerobic environments, microbial interactions, and complicated chemical kinetics. Here, we examine the relevant geochemical and hydrological information about the release and transport of potentially hazardous geogenic contaminants, specifically As, Cr, and V, as well as the potential challenges in developing a robust understanding of their behavior in the subsurface. We explore the development of geochemical models, illustrate how they can be utilized, and describe the gaps in knowledge that exist in translating subsurface conditions into numerical models, as well as provide an outlook on future research needs and developments.

African locus beans (Parkia biglobosa) tree is a perennial legume tree that grows naturally in Africa and one of the trees the Forest Rangers enforced that farmers must preserve in their farmland because of its usefulness.  Parkia biglobosa when fermented can be used to produce Iru and other useful products. This work employed the Particle Induced X-ray Emission (PIXE) in the determination of major, minor and trace element constituents of leaves, seeds, stem in Parkia biglobosa from Igbope, using a 2.5 MeV proton ion beam analysis (IBA) facility.  The samples contain nineteen (19) elements namely; Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Cu, Zn, Br, Sr, Y and Ba.  Calcium has the highest average concentration 17183.2±25.8 ppm in the stem, followed by Sulphur 15361.7±20.0 ppm in the seed.   The seed that is locally fermented to produce Iru has a higher concentration of Fe 1266.8±12.3 ppm.  The results showed that Parkia biglobosa analysed in this work consist of several micro, major and trace elements of importance to human health.  The plant is also free of harmful elements that can be hazardous to human health when consumed or used as herbal medicine.

I needed clarification on several abstruse portions of my research, especially. Thank you, for your tolerance, constructive comments, fund and liberty given me to conduct and express myself with this research work. My unreserved appreciation goes to Dr. Nadine Kabengi, whose doors were always opened to me whenever I needed assistance in understanding some key concepts in the field of aqueous geochemistry. Her motivation, and contribution in helping proffer logical solutions to some conundrums attached to my experimental protocols and results are highly appreciated. Furthermore, her Environmental Instrumentations class allowed me to conceptualize and implement solutions to some challenges faced during the research work. Noteworthy is Dr. Crawford Elliot. Thank you for your serving on my thesis committee on short notice. Also, I appreciate the assistance you rendered with your AAS machine. It's also noteworthy to acknowledge the contribution of Doctoral Candidates, Nicholas Allen and Nate Rabideaux. Their comments were very insightful in deciphering some challenges associated with my experimental protocol. Gratitude to David Davis who assisted with the sample preparation for XRD analysis. Lastly, I would like to thank all Grad students, and the administrative staffs of the Department of Geosciences, GSU who have contributed in one capacity or the other in making sure I had all the administrative help I needed to successfully complete my work and have hitchfree time in the department.

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