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Whole rock and mineral extracts from Nigerian goldfields of late Proterozoic age are significantly more radiogenic than those from the much younger Mesozoic lead-zinc mineralization in the Benue Trough, their common formation by hydrothermal processes notwithstanding. Their marked contrasts in lead isotope compositions can be attributed to differences in source reservoirs, structural settings and geological history rather than their age of mineralization. The Mesozoic sulphides have a remarkable uniformly unradiogenic composition for their age, placing the deposits in the lower crustal geotectonic environment that indicate a source of much lower µ. In contrast, mineral extracts from the southwestern and northwestern Nigeria gold deposits show increasingly radiogenic composition and plot in the mixed and upper crustal geotectonic fields respectively, typical of sources enriched in U/Pb and Th/Pb ratios, with clear indication of larger upper crustal reservoir of much higher µ. Therefore, exploration efforts may need to emphasize near-source mineralization prospects of low radiogenic Pb composition for economic deposits.

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Natural (weathering) and anthropogenic sources (e.g., sewage discharges, agricultural activities/fertilizers, mining, atmospheric deposition) contribute to the pollution of freshwater ecosystems (e.g., lakes, streams, etc.). The impact of pollution through trace elemental and sediment discharge in freshwater due to the bioaccumulation and biomagnification effects of methyl mercury (MeHg) has been reported in recent studies. Elevated Hg concentration in fish has been found in some lakes and new impoundment reservoirs. Thus, this study investigates the presence of Mercury (Hg), arsenic (As), cadmium (Cd), selenium (Se), lead (Pb), nickel (Ni), and zinc (Zn) to determine the composite of whole-body largemouth bass (LMB; Micropterus salmoides) samples across three Missouri Lakes (Port Hudson, Buffalo Bill, and Ben Branch reservoirs). Hg was measured by atomic absorption spectrometry while other elements were determined by inductively coupled plasma – optical emission spectrometry. Our results were compared with the US EPA Standard values to determine the concentration of 26 elements (Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Se, V, Zn, B, Hg, Pb, P, Tl, Be, Ba, Sb, Ag, Al, and As). The results show a strong interrelationship of some water quality variables due to similarities in the chemical characteristics. In addition, the weekly intakes of trace elements compared with regulatory thresholds (US EPA) and the non-carcinogenic and carcinogenic risks via the consumption of muscle were observed.

The paradigm of fluvial paleodischarge and sediment influx in the tropics provides valuable information on the controls/drivers on climate evolution, eutrophication and sedimentary organic matter preservation. The seasonal migration of Intertropical Convergence Zone (ITCZ) and variability in monsoonal strength determined by precessional forcing are the main controls on precipitation and fluvial discharge. This study is comparing data from selected cores from the nearshore (40 m) and continental shelves (2,000-4,000 m) of the Gulf of Guinea (e.g., Congo, Niger Delta, Ghana/Ivory Coast margin) and Central America (CA) (e.g., Costa Rica, Panama Gulf) to test these controls during the latest Pliocene to Quaternary. Integrated terrestrial and marine palynological records from the T89-16 Core (Congo) and GCs 1-3 (Niger Delta) in the Gulf of Guinea (GoG) record these drivers at the millennial-centennial time-scale. Paleoenvironmental inferences suggest that "flood pulse events" have influenced sedimentation rates on the Congo Fan and the Niger Delta. The data highlight a sequence of abrupt changes in the two locations registered by influxes of post-depositional pollen and non-pollen data to the GoG (Cyperaceae, Poaceae, Podocarpus, charred grass cuticles, Pediastrum, Ti/Zi ratios, sedimentation rates). These sporadic influxes provide evidence for enhanced fluvial discharge and river-induced upwelling during which fresh water plume nutrient rich, sedimentary organic matter, and sedimentation rates stimulated primary production, and phytoplankton blooms and preservation (e.g., dinoflagellate cyst productivity and demise). We suggest that this fluvial paleodischarge event from the Last Glacial Maximum (20 ka yr.) and subsequent deglaciation (18 yr.) likely resulted from latitudinal migration of the mean ITCZ across the GoG from its more southerly Last Glacial Maximum, suggesting the extension of monsoonal influences and mild arid conditions over the region.