Distribution and Seasonal variation of total metals in surface water of the Tennessee River Basin

Heavy metals in surface water were measured to determine their distribution and seasonal variation in the Flint Creek and Flint River watersheds. Bi-weekly stream water samples were collected from six selected sites within the watersheds. The samples were digested using EPA method SW 846–3015 in a microwave accelerated reaction system (MARS). The targeted elements (Al, Co, Ni, Cu, Fe, Mn, Cd, As, Se, Zn, Pb, and P) were analyzed using ICP-OES. Heavy metal concentrations ranged from undetectable to 123μg/l (Pb), 409 μg/l (Al), and 453 μg/l (Zn). Physical and chemical water quality parameters were also measured. The concentrations for the metals detected were mostly below the EPA guidelines for acceptable concentrations in drinking water; however, exceptions were observed for Al, Pb, Fe and the nutrient phosphorus (P). Results also indicated that the dissolved oxygen (DO) concentrations in three of the sites were very low (< 5 mg/l) and could possibly have an adverse effect on aquatic organisms. All metals were statistically significant (at P < 0.05) by watershed. Patterns observed revealed a steady increment in metal concentrations from upstream to downstream in both watersheds. The seasonal variation was also evident, in that the rivers had higher heavy metal content (> 45%) during winter and spring than in summer and fall. These findings suggest that agriculture and past and present land use practices may have had significant impacts on the study areas.