Seasonal variation in heavy metal distribution in the sediments of selected dams in Nasarawa State, Nigeria

The study was carried out to ascertain seasonal variation in heavy metal distribution in sediments from Dams located in Nasarawa State, Nigeria. Sediment samples were collected twice each at two different seasons for two years from May to September, 2014 and November-December, 2014 to March, 2015 for wet and dry seasons, respectively. Similarly, sediment samples were collected from May to September, 2015 and November-December, 2015 to March, 2016 for wet and dry seasons, respectively. The samples were then assessed for heavy metal properties, using atomic absorption spectrophotography (AAS). Analysis of variance (ANOVA) was then applied. The mean results of the heavy metal levels showed high values in dry seasons and low values in wet seasons in the two years of the study. Herein, the results of ANOVA revealed significant difference in the heavy metal concentrations between the seasons, dams and years. Our study also indicated that for heavy metals, the levels determined in sediments were within the WHO acceptable standards, except for Pb and Mn. These exceeded the WHO acceptable standards for drinking water. Based on these results, the dam waters are, therefore, polluted and unsuitable for human consumption, except after treatment.