A review of environmental contamination and remediation strategies for heavy metals at shooting range soils

Abstract

Many shooting ranges are contaminated by heavy metals and the used bullets have been known as a primary source. Once the bullets perch on soils, toxic metals such as lead (Pb), copper (Cu), nickel (Ni), antimony (Sb), and zinc (Zn) can be released into the soils and further transformed into available forms threatening the surrounding environment. In this review, we evaluated different sources of waste materials as soil amendments to stabilize heavy metals in soils. Amendments such as red mud, sugar foam, poultry waste, and dolomitic residue have been used to stabilize Pb at shooting ranges. Among various amendments, lime-based waste materials such as oyster shell and eggshell can effectively immobilize heavy metals, thereby reducing their bioavailability in soils. The main mechanism of Pb immobilization is closely associated with sorption and precipitation at high soil pH. Calcium aluminate hydrate (CAH) and calcium silicate hydrate (CSH) also can be formed to retain the metals in hardened soils. Overall, the use of lime-based wastes is applicable to immobilize toxic metals at shooting range soils.