75.20 ± 5.25, 3.08 ± 0.58, 0.94 ±0.38, 0.22 ±0.40, 0.87 ± 0.42, 0.61 ± 0.32, 3.80 ±2.26, 5.68 ± 3.03, 9.63 ± 2.44, 8.19 ± 1.12

Speciation of heavy metals in the sediments of Gubi Dam in Bauchi, Nigeria was carried out between December, 2001 and March, 2002. The mean total concentrations showed that Tatimari tributary has high Fe, Zn, and Mn, confirming it source and path. The spillway result suggest intensive farming activity along the dam runway. However, the physio-chemical forms of Fe, Pb, and Cr indicate that these metals are associated in high concentration with the mineral matrix of the sediment, as such it is most unlikely to become biologically available. High levels of Cu, Cd, Zn, Mn, Co and Ni are associated with the exchangeable carbonate bound fractions, indicating that they are in potentially available forms and many pose serious problems to the dam ecosystem.

The distribution of heavy metals in Gubi Dam, Bauchi, Nigeria was studied covering the highest turbulent and non-turbulent flow periods. The average concentrations of iron, manganese, nickel, zinc, cobalt, chromium and cadmium were generally highest in filtrate water, whereas the concentrations of copper and lead were always highest in the suspended materials which indicate the dominant role played by suspended materials in the transport of these metals. The total metal levels are within WHO safety limits as such do not reflect impaired suitability of the water. The relative levels of the metals at the entry points and spillway reflect the source, the path and stopover of the tributaries of the dam, thus the variation in the amount of metals at each point.

Rainwater samples were collected during the raining season from five sites within Jos and Bukuru metropolis from April to October, 2002 and 2007. Eighty-

Submission of an original paper with copyright agreement and authorship responsibility.I (corresponding author) certify that I have participated sufficiently in the conception and design of this work and the analysis of the data (wherever applicable), as well as the writing of the manuscript, to take public responsibility for it. I believe the manuscript represents valid work. I have reviewed the final version of the manuscript and approve it for publication. Neither has the manuscript nor one with substantially similar content under my authorship been published nor is being considered for publication elsewhere, except as described in an attachment. Furthermore I attest that I shall produce the data upon which the manuscript is based for examination by the editors or their assignees, if requested.Thanking you.