ATTENUATION OF LEAD AND ANTIMONY IN SHOOTING RANGE SOILS BY IRON AMENDMENTS
As a result, stabilization of metal contaminants is of interest, particularly, what types of substrates have potential to promote the retention of Pb and Sb from migrating off-site. Treating soils with both cationic (Pb) and oxyanionic (Sb) components can be difficult due to enhanced mobility of Sb at circumneutral/high pHs and enhanced mobility of Pb at low pHs. Traditional treatments, such as phosphate or carbonate would not be approprite, however, iron (Fe) has been shown to be a potentially effective sorbent.
In the present study, we fired identical bullets in a controlled event into newly constructed berms made from four well charaterized soils. Over the past 4 years, we have been continuously monitoring both the berm soil and porewater. In addition, we designed and monitored parallel laboratory soil columns to study Pb and Sb behavior in a more controlled environment. In the past year, we added Fe(II) chloride and nanoscale zero-valent iron (NZVI), in a dispersion, to the four types of soil in both the laboratory columns and the shooting range berms in order to study the effects Fe has on metal attentuation. The field berms remain open to the environment and the columns were flushed with simulated rainwater and monitored. We found significant attentuation of Sb by Fe in certain systems, whereas Pb initially became more mobilized. The results from this study are essential for understanding the potential for off-site migration, as well as determining the ultimate bioavailability and toxicity of Pb and Sb in shooting ranges.