Assessment and Seasonal Variations of Heavy Metals and Mineral Elements in River Sokoto, North-western Nigeria

Abstract

The water quality of River Sokoto in North-western Nigeria was monitored from January, April, June, August, September and November, 2014. Analyses of some selected metals and mineral elements namely Na, Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ag, Cd, Sn, Sb, Hg, and Pb from six sampling points was conducted to determine their concentrations in the river during dry (January) and rainy (August) seasons. Analyses of Na and K were carried out using Flame Emission Spectroscopy, while other metals were analysed using Atomic Absorption Spectrophotometry (AAS). The elemental concentrations are generally higher in dry season than in the rainy season. Though Pb was not found in any of the water samples in the dry season, it was found in sample collected from sampling point P4 (a point on stream drainage immediately from Sokoto Cement Factory) at value above WHO’s permissible limit in the rainy season. Ag and Cd were not found in the water samples in rainy season whereas they were found at values above permissible limit in dry season. Hg was found at value above permissible limit in both seasons. The result of T-test analysis shows there was highly significant difference (p≤0.01) in the values of Mg, K, Cr, Fe, Co, Ag, Cd, Sn and Hg in all samples for dry and rainy seasons. High level of Cr, Co, Ag, Cd, Hg and Pb in River Sokoto above WHO’s permissible limit will certainly have adverse effect on the health of the residents.

Keywords: Seasonal variation, heavy metals, mineral elements, pollution, River Sokoto.