The objective of this investigation was to examine the heavy metal status of the lower basin of Kainji dam (used for hydroelectricity generation), which includes Lakes Kainji/Jebba, Nigeria, and the potential for human exposure to heavy metals from eating fish caught in the lakes. Water, sediments and fish were sampled from the lakes and evaluated for As, Cu, Co, Cr, Fe, Hg, Mn, Ni, Pb, Sb, Ti, V and Zn using the EDXRF technique. Fe and Mn were found to be present at high mean concentrations in the water (13 and 9 microg L(-1)), sediment (7,092 and 376 microg g(-1)) and fish (11.4 and 4.6 microg g(-1)) samples. Sb (3.2 microg L(-1)), Ti (4.1 mug L(-1)), Cr (2.2 microg L(-1)), Co (1.2 microg L(-1)), Cu (1.3 microg L(-1)) and Pb (1.2 microg L(-1)) in the water samples and Sb (29 microg g(-1)), Ti (27 microg g(-1)), V (27 microg g(-1)), Cr (27 microg g(-1)), Co (40 microg g(-1)), Ni (33 microg g(-1)), Cu (25 microg g(-1)), Zn (59 microg g(-1)) and Pb (19 microg g(-1)) in the sediment samples were found to be of medium mean concentrations. The other metals were present at trace levels (<1 microg), including As and Hg in the fish and sediment samples. There was an appreciable increase in metal concentrations in going from the water to the sediment samples. The probable source of the pollutants is anthropogenic, arising from agricultural activities, corrosion/abrasion of the ferrous steel material and additives in the lubricants and insulation used for auxiliary services on the turbine floor of the dam constructed on the lakes. However, natural geological sourcing from the underlying lake rock cannot be totally ignored, particularly the high levels of Fe and Mn in the sediment samples. The potential risk for human exposure to these metals emanates from the fish caught in the lakes and subsequently consumed, as there are already significant levels of these metals in the two fish species analysed, Tilapia (Oreochromis niloticus) and Chrysicthys (Chrysicthys auratus).

Gombe metropolis has been experiencing urban flooding particular in the last two decades. The flood disasters of 2004, 2012 and 2014 sub-periods, 1995-2004 and 2005-2014,

The renewable energy is a source of energy that does not deplete with time, because of this most of the research focused on this source of energy. Solar energy is among the renewable energy that is free in nature and clean from pollution, but harnessing this energy has limitation due to some environmental conditions. To solve this problem, solar tracking is used. This paper intended to review different solar tracking system that increases the solar power output. The result revealed the solar system with tracking is more efficient compared to that fixed solar system. Furthermore, dual axis tracking system is also more efficient than single axis tracking system due to the fact that dual axis tracking system have ability to track the solar irradiant on both axes. Finally, it is not recommended to use solar trackers with small PV arrays because of the energy consumption of the driving systems, which vary from 2% to 3% of the energy increase delivered by the solar trackers.

As a step towards remediation of sulphur contaminants, this study used a Crowcon Gasman (gas detection instrument) to collect and analyze Sulphuric gas samples from densely populated areas of urban Zaria. The results showed varying concentrations of Sulphur Dioxide (SO 2 ) and Hydrogen Sulphide (H 2 S). The high concentrations of these pollutants detected can be attributed to increased population growth, increased production of gaseous wastes and increased number of vehicular movement. The results indicate also that the concentrations of pollutant sulphur component SO 2 measured at all sampling points, with exception of the control site were hazardous while that of H 2 S were within safe limit set by FEPA and ACGIH respectively. Statistical tests were performed which established significant variation/relationship between detected pollutants and traffic volume. Findings from this study imply that vehicular emission within urban Zaria is not within the safe limit which further reveals that transport-related pollution in Zaria urban area can be potentially hazardous to health.

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