Effectiveness of Best Management Practices in Reducing Lead Bullet Weathering in a Recreational Shooting Range.

Lead contamination in the environment has received much attention due to its toxicity to both humans and animals. In the USA, as much as 74,500 tonnes of lead is being used per year as lead-bullets. As a result, large amounts of lead have been deposited in the recreational shooting ranges which can eventually weather and contaminate soils and waters. So it is imperative to develop best management practices (BMPs) in slowing down lead-bullet weathering in shooting ranges. This field study evaluated the effectiveness of three generally accepted BMPs in reducing the weathering of lead-bullets in a recreational shooting range in Florida. The BMPs included replacing soil berm with sand berm, liming sand berm, and removing lead-bullets from soil berm by commercial scale mechanical sieving. Berm samples were collected before and after implementing BMPs and analyzed for total lead and/or water-soluble lead. After 11 months of operation, the total lead concentrations in the sand berm (57 mg/kg) were significantly lower than that in the soil berm (277 mg/kg). The reduced weathering of lead-bullets in the sand berm was attributed to its lower moisture content and organic matter as both water and CO₂ are critical in chemical weathering. Though liming reduced total lead concentrations in the sand berm from 497–777 to 302–362 mg/kg after 15 months of application, it increased water-soluble lead in some cases. While removal of lead-bullets removed the sources of lead, X-ray diffraction analysis indicated that its abrasive action transferred metallic lead to the soil fraction (<2 mm), with total lead in soil berm increasing from 4,694 to 11,479 mg/kg. While all BMPs can be applied to manage lead in shooting ranges, cautions need to be exercised to minimize the adverse impacts.