Effectiveness of best management practices in reducing Pb-bullet weathering in a shooting range in Florida.

This field study evaluated the effectiveness of three best management practices (BMPs) in reducing the weathering of Pb-bullets in a shooting range. The BMPs included replacing soil berm with sand berm, liming sand berm, and removing Pb-bullets from soil berm. Berm samples were collected before and after implementing BMPs and analyzed for total Pb and/or water-soluble Pb. After 11 months of operation, the total Pb concentrations in the sand berm (57 mg kg(-1)) were significantly lower than that in the soil berm (277 mg kg(-1)). The reduced weathering of Pb-bullets in the sand berm was attributed to its lower moisture content and organic matter as both water and CO(2) are critical in chemical weathering. Though liming reduced total Pb concentrations in the sand berm from 497-777 to 302-362 mg kg(-1) after 15 months of application, it increased water-soluble Pb in some cases. While removal of Pb-bullets removed the sources of Pb, X-ray diffraction analysis indicated that its abrasive action transferred metallic Pb to the soil fraction (<2 mm), with total Pb in soil berm increasing from 4,694 to 11,479 mg kg(-1). While all BMPs can be applied to mange Pb in shooting ranges, cautions need to be excised to minimize the adverse impacts.