Metal transport to karst springs during storm flow: an example from Fort Campbell, Kentucky/Tennessee, USA

Low levels of heavy metals were investigated in a series of springs discharging from the Mississippian limestone aquifer underlying the Fort Campbell Army Base in western Kentucky/Tennessee. Springs were sampled at short time intervals through periods of storm discharge. Unfiltered samples were digested and analysed by inductively-coupled plasma mass spectrometry. Metals detected at the(mu)g/l level included As, Cd, Cr, Ni and Pb. Metal concentrations exhibited a pronounced maximum coincident with the peak of the storm hydrograph in contrast to carbonate species (Ca, Mg) which dipped to a minimum at the peak of the storm hydrograph. Metal concentrations track with aluminium and iron suggesting that the metal transport is mainly by adsorption onto suspended particulates which are mobilized during storm flow.