C. Amrhein et al., HEAVY-METALS IN THE ENVIRONMENT - TRACE-METAL SOLUBILITY IN SOILS ANDWATERS RECEIVING DEICING SALTS, Journal of environmental quality, 23(2), 1994, pp. 219-227
Laboratory batch incubation studies were carried out to determine the
effects of aerobic and anaerobic conditions on the solubility of trace
metals in soils and waters treated with the deicing salts calcium mag
nesium acetate (CMA) and NaCl. The concentrations of trace metals were
, in general, not controlled by equilibrium reactions but rather by th
e relative rates of several simultaneous and sequential reactions. In
three soils from CA, NJ, and MI, and water treated with CMA the produc
tion of HCO3 from acetate decomposition initially increased the soluti
on concentration of Pb and Zn as PbCO30 and ZnCO30 . Eventually, super
saturation with respect to calcite occurred and the concentrations of
Cu, Cd, Zn, V, and Cr decreased because of coprecipitation with the ca
lcite. The precipitation of pyromorphite [Pb-5(PO4)Cl] was suspected b
ased on elevated saturation indexes for this mineral. At low redox con
ditions, the solubilization of Fe- and Mn-oxides increased the concent
ration of the trace metals that were adsorbed or coprecipitated with t
hese phases. Supersaturation with respect to MnCO3, FeCO3, and VO(OH)(
2) occurred under low redox conditions. The rate constant for acetate
decomposition under anaerobic conditions was 18 times lower than the r
ate constant for aerobic decomposition. This suggests that if a soil r
eceived a high loading of CMA, low Ct conditions could occur and CMA m
ight leach to groundwater. There is evidence that the use of CMA could
result in Pb and Zn mobilization as neutral ion pairs with carbonate.