Metal Contamination Hotspots at Unregulated Firearm Target Shooting Sites in the Everglades

Hunters and target shooters can introduce metals into the environment in the form of firearm ammunition, elevating environmental levels of these metals, which may cause plant and animal toxicity. We explored metal accumulation in the Florida Everglades at sites used for firearm target shooting that are unlicensed, unregulated, and not patrolled by law enforcement. We compared concentrations of Pb, Cu, and Al in water and soil among study sites, control sites, and a public shooting range. We also tested plants and invertebrates to identify bioaccumulation or biomagnification. Lead and Cu concentrations in the soil at the target sites were elevated (Pb mean: 11,500.1 μg g ⁻¹ ; Cu mean: 1558.7 μg g ⁻¹ ) compared with control sites (Pb mean: 35.3 μg g ⁻¹ ; Cu mean: 49.3 μg g ⁻¹ ) and were more similar to the shooting range (Pb mean: 3194.7 μg g ⁻¹ ; Cu mean: 567.1 μg g ⁻¹ ). Organisms had elevated Pb and Cu at the target sites, indicating bioaccumulation. For example, Spanish needle [ Bidens alba (L.) DC] had a Pb concentration of 356.9 μg g ⁻¹ at one site but averaged 80.3 μg g ⁻¹ at the control sites. Grass shrimp ( Palaemonetes paludosus ) had Pb concentrations averaging 416.1 μg g ⁻¹ at target sites but only 18.9 μg g ⁻¹ at control sites. Water samples did not have elevated metal levels at the sites. Aluminum levels did not correspond to firearms use. We conclude that the illicit shooting sites are hotspots of metal pollution and pose a risk of contamination to several types of organisms. Because these sites are undocumented and unregulated, remediation may be difficult.