Characterization and metal availability of copper, lead, antimony and zinc contamination at four Canadian small arms firing ranges

Abstract

Backstop soils of four small‐arms firing ranges (SAFRs) of the Canadian Force Bases (CFBs) were characterized in terms of their total soil Cu, Pb, Sb and Zn concentrations, grain size distribution, mineralogy, chemical properties, vertical in‐depth contamination distribution (for one CFB), and scanning electron microscope (SEM–EDS) characterization. Metal availability from the soils was evaluated with three leaching tests: the toxicity characteristics leaching procedure (TCLP), representing a landfill leachate; the synthetic precipitation leaching procedure (SPLP), representing field conditions; and the gastric juice simulation test (GJST), representing the leachate of the human stomach during the digestive process and, therefore, the potential metal transfer to humans in the case of soil ingestion. Metal analyses of soils and leaching test extracts were conducted with an Inductively Coupled Plasma Atomic Emission Spectrometry (ICP‐AES) instrument. Total soil results showed maximal concentrations of 27,100 mg/kg for Pb, 7720 mg/kg for Cu, 1080 mg/kg for Zn, and 570 mg/kg for Sb. The SEM–EDS analysis showed significant amounts of lead carbonates, which resulted from the alteration of the initial metallic Pb particles. Metal availability evaluation with the leaching tests showed that TCLP Pb and Sb thresholds were exceeded. For the SPLP and the GJST, the drinking water thresholds of the Ministère du Développement Durable, de l’Environnement et des Parcs (MDDEP) of Québec were exceeded by Pb and Sb. The metal availability assessment showed that SAFR backstop soils may pose a potential risk to the environment, groundwater and humans, and affect the management of such soils in order to minimize potential metal dispersion in the environment.

Keywords:

• contaminated soils
• metal availability
• TCLP
• SPLP
• GJST

Acknowledgements

The authors would like to acknowledge the Director of Land and Environment (DLE) of the National Defence and the Canadian Forces for funding; the Canadian Force Bases (CFB) Environment Officers Kelly Sturgess (CFB 1), Garnet Shearer (CFB 2) and Sheldon Down (CFB 4); Sylvie Brochu of Defence Research and Development Canada (DRDC‐Valcartier), for site access and her critical review of the paper; the Range Control staff of CFB 3, especially Master Warrant Officer Lafleur; Myriam Chartier for her useful laboratory assistance; and Michelle Bordeleau and René Rodrigue for chemical analyses.