Pore Water Quality in the Upper Part of the Vadose Zone under an Operating Canadian Small Arms Firing Range Backstop Berm

Canadian military small arms firing range (SAFR) backstop berm soils contain high concentrations of Pb, Cu, Sb, and Zn. Three Teflon® cylindrical lysimeters were installed in the vadose zone of the backstop berm in order to characterize the pore water quality. Copper-Zn concentrations were below their respective Québec drinking water thresholds, and Pb-Sb concentrations were above the criteria in many cases, indicating that a metal vertical migration occurs in the vadose zone. Metal concentrations in pore water were, in decreasing order, Zn > Pb > Sb > Cu. Calculated annual metal leaching rates showed that a rather small portion of the metals in the soil were mobilized in the vadose zone, and that metals were a potential source of contamination for extremely long periods of time, highlighting the importance of finding ways to remediate such soils in order to limit metal mobility in SAFR backstop berms.