Environmental impact of metals resulting from military training activities: A review

The deposition of metals into the environment as a result of military training activities remains a long-term concern for Defense organizations across the globe. Of particular concern for deposition and potential mobilization are antimony (Sb), arsenic (As), copper (Cu), lead (Pb), and tungsten (W), which are the focus of this review article. The fate, transport, and mobilization of these metals are complicated and depend on a variety of environmental factors that are often convoluted, heterogeneous, and site-dependent. While there have been many studies investigating contaminant mobilization on military training lands there exists a lack of cohesiveness surrounding the current state of knowledge for these five metals. The focus of this review article is to compile the current knowledge of the fate, transport, and ultimate risks presented by metals associated with different military training activities particularly as a result of small arms training activities, artillery/mortar ranges, battleruns, rocket ranges, and grenade courts. From there, we discuss emerging research results and finish with suggestions of where future research efforts and training range designs could be focused toward further reducing the deposition, limiting the migration, and decreasing risks presented by metals in the environment. Additionally, information presented here may offer insights into Sb, As, Cu, Pb, and W in other environmental settings.

The effect of phosphate application on the mobility of antimony in firing range soils

Chemical and biogenic sources of phosphate are commonly accepted in situ treatment methods for immobilization of lead (Pb) in soil. The metalloid antimony (Sb), commonly associated with Pb in the environment, exists as either a neutral species or a negatively charged oxyanion. Antimony is used in the manufacture of bullets as a hardening agent, constituting approximately 3% of the bullet mass. Technological solutions to reduce the migration of metals from small arms firing range (SAFR) soils for environmental compliance purposes must be robust with respect to multi-component systems containing both cationic and anionic contaminants. The effect of varying physico-chemical soil properties on Sb mobility post-firing was assessed in this study for six soil types using common analytical protocols and methods related to regulatory criteria. The sands (SM and SP) demonstrated the greatest Sb solubility in post-firing leachate samples and therefore were selected to evaluate the effects of five commercially available stabilization amendments on Sb mobility. Enhanced Sb leaching was experimentally confirmed in the phosphate-treated soils compared to both the untreated control soil and the sulfur-based amendment, and thus suggests competition for negative sorption sites between Sb and phosphate. However, the 5% Buffer Block® calcium phosphate amendment did not exhibit the same enhanced Sb release. This can be attributed to the inclusion of aluminum hydroxide in the amendment composition. Technologies are needed that will adequately immobilize Pb without mobilizing oxyanions such as Sb. Further research will be required to elucidate binding mechanisms and redox conditions that govern the mobility of Sb on SAFRs.