A GEOCHEMICAL SURVEY OF THE BLACK WARRIOR RIVER, ALABAMA

The Black Warrior River is one of the largest basins in the Mobile/Alabama River System (MARS). This study was initiated to determine the influence of anthropogenic activities on water quality in the Black Warrior River. On three occasions from 1997 to 1999 samples were collected at ten locations throughout the Black Warrior basin and two on the Tombigbee River. Dissolved concentrations of eight major elements (Li, Na, K, Mg, Ca, F, Cl, Br), alkalinity (as HCO₃), three nutrients (NO₃, SO₄, and PO₄), and eleven trace metals (V, Mn, Co, Cu, As, Rb, Sr, Mo, Sb, Ba, and U) were determined. In general, major elements showed enrichment in areas influenced by anthropogenic activities. This is seen in the high concentrations of SO₄ and Cl. Within the areas influenced by anthropogenic activities, mining areas had the highest average SO₄ but relatively low Cl concentrations while agricultural areas showed a relatively low average SO₄ and high Cl concentrations. The increased Cl in the agricultural areas could be entering the river through groundwater discharge from the Eutaw aquifer. Although only Mn, Co, Mo, and Sb concentrations were above the world river averages in anthropogenically active areas, all trace metals except U were higher in these areas when compared to local pristine locations. As with some of the major elements, areas influenced by mining and those influenced by agriculture could be distinguished using certain trace metals. For example, concentrations of Mn, Mo, and Rb were higher and Ba lower in mining areas when compared to agricultural areas. It appears that there are discernable anthropogenic inputs for most of the elements in this study.