METAL CHEMISTRY OF SPRING SEDIMENTS FROM FORT CAMPBELL, KENTUCKY/TENNESSEE
The bed sediment samples were also subjected to a selective extraction procedure which separates the metals into five operationally-defined fractions: exchangeable, carbonate, oxide, organic, and residual. Each extraction fraction was analyzed using Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). Some metals are consistently present in a single fraction regardless of the spring location and characteristics, e.g., aluminum in the residual fraction. Other metals, such as calcium, split between exchangeable, carbonate and residual at all locations. While iron is mostly in the residual fraction in the bed sediments, it has an appreciable distribution in oxide and carbonate fractions in the spring with the thickest sediments. Manganese is distributed in the greatest number of fractions in the same spring. The data suggest that sediment thickness plays a key role in metal chemical distribution due to the likely presence of reducing conditions. This may cause redox-sensitive metals to be redistributed between the fractions while stored in the sediments. For example, iron appears to be dissolved from the residual fraction and redistributed into the carbonate and oxide fractions during storage.