## 1 Introduction  
Heavy metals (e.g., Pb, Cd, Cu, As, Sn, and Sb) are indicative of soil toxicity. They are potential sources of soil contamination and their mobility and availability affect the environment. In the previous studies, the effects of heavy metals on the environment, terrestrial biota, and human health were studied [1, 2]. Heavy metals are transported via surface water and groundwater [3, 4] and affect the surrounding area. Soils from military shooting ranges have attracted attention because they are contaminated with high concentrations of heavy metals [1, 3], which do not decompose but remain in the environment [4]. Soil contamination in military shooting ranges has been investigated in numerous previous studies [1, 3, 5, 6, 7, 8, 9, 10, 11].  
Ammunition, such as lead shots or lead bullets, is a source of the Pb pollution and soil toxicity in military shooting areas [5]. Bullets mainly consist of metallic lead (90%) and minor amounts of other heavy metals [6, 12]. Lead is accumulated in the soil via the abrasion and weathering of the bullets [7]. After Pb bullets are fired, they come in contact with the soil and eventually are welathered. Fragmented and pulverized bullets lead to the Pb contamination of the soil [13]. Metallic Pb is converted into dissolved (soluble particle) and particulate Pb by oxidation, carbonation, and hydration reactions [6] and transported to the soil [14]. Dissolved and particulate Pb species are primarily incorporated into mineral phases such as cerussite (PbCO\({}_{3}\)), hydrocerussite [Pb(CO\({}_{3}\))\({}_{2}\)(OH)\({}_{2}\)], anglesite (PbSO\({}_{4}\)), and associated/plattnerite (PbO) [15]. The physicochemical conditions of the soil control the weathering and mobility of the contaminants [2]. Therefore, the physicochemical properties of heavy metal-contaminated soil from shooting ranges and the heavy metal distribution must be determined to effectively manage and restore the soil [2].  
Worldwide, thousands of shooting ranges are utilized for recreational activities and military training [2]. Soils from shooting ranges that have been operated for many years are generally heavily contaminated [5]. In the United States, more than 3 million mg of metallic Pb were associated with hunting and recreational shooting in the 20 th century; the Pb concentration is continuously increasing at a rate of ~60,000 mg per year [12; 14; 15; 16; 17; 18]. In soils in the Netherlands, Denmark, Canada, and England, 200 to 6000 mg of metallic Pb has been detected [14]. In addition, it has been reported that metallic lead bullets in soils in Denmark can be preserved for 100-300 years [14]. In central Sweden, on average, 5% of metallic Pb in shooting range soil has been transformed into lead carbonate and lead sulfate over a period of 20 to 25 years [19]. In addition, 3400 to 5000 mg/kg of Pb has been reported in sheet shooting ranges in northern England and central Sweden [17; 19]. However, heavy metal contaminated soils in shooting ranges have been rarely studied due to the limited accessibility [3]. In addition, the environmental effects of soil contamination are poorly understood and mitigation methods have yet to be established. In the Republic of Korea, 1400 active small arms firing ranges are in operation [20], but little information is available about the effects of heavy metals from Pb bullets on the soil in military shooting ranges [21].  
To evaluate the Pb contamination of soil, the Pb distribution has been commonly analyzed in previous studies [3; 19; 22; 23; 24]. The Pb concentrations and Pb isotopic compositions of the bullets, pellets, and soils have rarely been considered [6; 10; 11; 25; 26]. Therefore, the aims of this study were to understand spatial distribution of Pb contamination and to quantify the Pb input in soils from Korean military shooting ranges using both Pb concentration and Pb isotopic data, which are considered to be powerful indicators of the soil contamination in shooting ranges as well as the Pb sources.