Trace metal concentrations in shallow ground water

Trace metal clean sampling and analysis techniques were used to examine the temporal patterns of Hg, Cu, and Zn concentrations in shallow ground water, and the relationships between metal concentrations in ground water and in a hydrologically connected river. Hg, Cu, and Zn concentrations in ground water ranged from 0.07 to 4.6 ng L-1, 0.07 to 3.10 micrograms L-1, and 0.17 to 2.18 micrograms L-1, respectively. There was no apparent seasonal pattern in any of the metal concentrations. Filtrable Hg, Cu, and Zn concentrations in the North Branch of the Milwaukee River ranged from below the detection limit to 2.65 ng Hg L-1, 0.51 to 4.30 micrograms Cu L-1, and 0.34 to 2.33 micrograms Zn L-1. Thus, metal concentrations in ground water were sufficiently high to account for a substantial fraction of the filtrable trace metal concentration in the river. Metal concentrations in the soil ranged from 8 to 86 ng Hg g-1, 10 to 39 micrograms Cu g-1, and 15 to 84 micrograms Zn g-1. Distribution coefficients, KD, in the aquifer were 7900, 22,000, and 23,000 L kg-1 for Hg, Cu, and Zn, respectively. These values were three to 40 times smaller than KD values observed in the Milwaukee River for suspended particulate matter.