The mobility and bioavailability of lead (Pb) in seven military shooting range soils found in eastern and north eastern Botswana were studied using sequential extraction procedure. The different forms of Pb and their reactivity in the soil help explain their speciation, mobility and bioavailability in the environment. Mobility of Pb in the berm soils in all the seven shooting ranges was found to be over 90% implying high Pb lability. The bioavailability index of Pb was in the range 60-90%, an indication that most of the Pb can be available for plant uptake. Sequential extraction studies indicate that the partitioning of Pb was mostly confined to the carbonate compartment in all the shooting ranges. All the seven shooting ranges failed the Synthetic Precipitation Leaching Procedure (SPLP) with SPLP Pb concentrations exceeding United States Environmental Protection Agency (USEPA) 0.015 mg/kg critical level of hazardous waste, posing a pollution threat to surface and groundwater.

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Risk assessment indices such as risk assessment code (RAC), potential ecological risk index (PERI), geoaccumulation index (I geo ), contamination factor (CF) and enrichment factor (EF) provide a good measure of environmental risk posed by Pb accumulated in shooting range soils as opposed to total Pb concentration. For this reason, the S/P Pistol shooting range, even though accumulated lower concentration of Pb (685±218 mg/kg), exhibited 'very high risk' to the environment with RAC value of 77 exceeding the 51 set guideline value for 'very high risk' with a significant margin compared to MAT R2 (20888±5419 mg/kg) at RAC value of 48 and highest total Pb concentration. This implies that mobility and bioavailability of Pb at S/P Pistol shooting range will be higher posing a greater risk to biota even though contamination from Pb is low. Best shooting range management practices and low cost remedial actions such as phytoremediation and chemical immobilization should be carried out as soon as possible to minimize the bioavailability and mobility of Pb in the studied shooting ranges.

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Commissioned and de-commissioned shooting ranges continue to pose an environmental and human health risk due to the accumulation of toxic Pb emanating from spent munitions. The phytotoxic effects of Pb accumulation in plants include inhibition of root growth and lowering of plant metabolism. The uptake of Pb by plants is directly affected by factors such as plant species and physicochemical properties of the soil. However, scientists and researchers have leveraged on the ability of some plant species to accumulate and tolerate Pb toxicity and applied them in the control and management of Pb pollution of shooting range soils. This technique is called phytoremediation. The objectives of this review are: (i) to assess the prevalence of toxic Pb metal in plant species growing in and nearby shooting ranges, (ii) to establish the soil-plant mechanistic pathway for Pb (iii) discuss the effectiveness of phytoremediation technology towards shooting range soil amendment.

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Shooting ranges continue to pose environmental and human health risk due to the accumulation of toxic Pb emanating from munitions. Remediation of Pb pollution at shooting ranges has been carried out through application of various techniques of which chemical stabilization is the most common. In some instances, field chemical stabilization has achieved Pb decontamination of the soils to concentrations below the maximum contaminant limits as set by the United States Environmental Protection Agency (USEPA) and World Health Organization (WHO). However, the effectiveness of chemical additives to Pb stabilization depends to a great extent on the physicochemical properties of the soils. This review aims to: (i) discuss the effectiveness of chemical stabilization towards Pb remediation of polluted shooting range soils, (ii) establish the chemical reactions that take place between Pb and the chemical amendment and (iii) understand the influence of the soil physicochemical properties on the effectiveness of the chemical amendment.