Article pubs.acs.org/est
Antimony (Sb) Contaminated Shooting Range Soil: Sb Mobility and Immobilization by Soil Amendments Gudny Okkenhaug,*,†,‡ Katja Amstaẗ ter,‡,§ Helga Lassen Bue,∥ Gerard Cornelissen,†,‡,⊥ Gijs D. Breedveld,‡,# Thomas Henriksen,¶ and Jan Mulder† †
Norwegian University of Life Sciences (UMB), Department of Plant and Environmental Sciences (IPM), P.O. Box 5003, N-1432, Ås, Norway ‡ Norwegian Geotechnical Institute (NGI), Department of Environmental Engineering, P.O. Box 3930, Ullevaal Stadion, NO-0806 Oslo, Norway § CDM Consult GmbH, Neue Bergstr. 13, 64665 Alsbach, Germany ∥ Norwegian University of Science and Technology, Department of Geology and Mineral Resources Engineering, Sem Sælands veg 1, N-7491 Trondheim, Norway ⊥ Stockholm University, Department of Applied Environmental Sciences, 10691 Stockholm, Sweden # Department of Geosciences, University of Oslo, P.O. Box 1047 Blindern, N-0316 Oslo, Norway ¶ Lindum AS, Lerpeveien 155, N-3036 Drammen, Norway S Supporting Information *
ABSTRACT: Antimony (Sb) in lead bullets poses a major environmental risk in shooting range soils. Here we studied the effect of iron (Fe)-based amendments on the mobility of Sb in contaminated soil from shooting ranges in Norway. Untreated soil showed high Sb concentrations in water extracts from batch tests (0.22−1.59 mg L−1) and soil leachate from column tests (0.3−0.7 mg L−1), occurring exclusively as Sb(V). Sorption of Sb to different iron-based sorbents was well described by the Freundlich equation (Fe2(SO4)3, log KF = 6.35, n = 1.51; CFH-12 (Fe oxyhydroxide), log KF = 4.16−4.32, n = 0.75−0.76); Fe0 grit, log KF = 3.26, n = 0.47). These sorbents mixed with soil (0.5 and 2% w/w), showed significant sorption of Sb in batch tests (46−92%). However, for Fe2(SO4)3 and CFH-12 liming was also necessary to prevent mobilization of lead, copper, and zinc. Column tests showed significant retention of Sb (89−98%) in soil amended with CFH-12 (2%) mixed with limestone (1%) compared to unamended soil. The sorption capacity of soils amended with Fe0 (2%) increased steadily up to 72% over the duration period of the column test (64 days), most likely due to the gradual oxidation of Fe0 to Fe oxyhydroxides. Based on the experimental results, CFH-12 and oxidized Fe0 are effective amendments for the stabilization of Sb in shooting range soils.
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INTRODUCTION
small arm shooting ranges are major deposits of metals and Sb, and may pose a threat to the environment and human health.9,11,12 Antimony is listed as a priority pollutant by the U.S. Environmental Protection Agency due to its toxicity.13 Furthermore Sb trioxide (Sb2O3) is considered as probably carcinogenic to humans by the International Agency for Research on Cancer (IARC) 14 Weathering and corrosion of spent bullets and a subsequent dissolution with soil water leads to mobilization of heavy metals and Sb,5 and Sb concentrations far above background levels have been reported in runoff water from shooting ranges (5−20
Antimony (Sb) is an element of growing environmental concern due to the increased use in various products (e.g., flame retardants, alloys, semiconductors, plastics) and often uncontrolled release of Sb compounds into the environment, e.g., through mining and smelting activities, combustion of fossil fuels, and spent ammunition.1−3 A significant input of Sb into the environment occurs at shooting ranges due to Sb used as hardener in lead (Pb) bullets, which contain between 2% and 8% Sb.4−6 As an example, approximately 12 tons of Sb together with Pb (103 t), Cu (73 t), and Zn (12 t) were deposited at small arms training areas in Norway in 2006.7 In these areas high concentrations of heavy metals and Sb are common in the stop butt zones, but spent bullets may be heterogeneously spread over large areas depending on the targets with concentrations up to several grams per kg soil.8−10 Thus, © 2013 American Chemical Society
Received: Revised: Accepted: Published: 6431
June 18, 2012 April 26, 2013 May 13, 2013 May 13, 2013 dx.doi.org/10.1021/es302448k | Environ. Sci. Technol. 2013, 47, 6431−6439
Environmental Science & Technology
Article
Table 1. Soil Characteristics of Stop Butts from Military Shooting Ranges in Norway (standard deviations (SD) of triplicates) location Evjemoen Rena Sessvollmoen Steinsjøen Ulven a
soil texture Silty Silty Silty Silty Silty
sand sand sand sand sand
organic contenta (%) 1.6 0.5 1.7 0.4b 0.1
Sbtot (mg kg−1)
pHc 7.4 7.6 7.2 5.8 8.8
± ± ± ± ±
0.5 0.3 0.3 0.1 0.6
1050 2900 240 123 260
± 170 ± 660 ± 60
Pb (mg kg−1) 8700 30000 2200 2050 2000
± 100
± 1200 ± 6700 ± 530 ± 790
Cu (mg kg−1) 1350 2300 350 145 148
± 180 ± 1750 ± 15 ± 16
Loss on ignition. bTotal organic carbon. cMeasured in water extracts (liquid solid ration 10:1, 24 h shaking).
Table 2. Elemental Composition of Soil Amendments Used in the Study Ferrix-3 (Fe2(SO4)3) CFH-12 FG 0300/1000 (Fe0) Fe-sand LS 1 (VK 0/5) Olivine No11
CaO (%)
MgO (%)
Fe (g kg−1)
Sbtot (mg kg−1)
Pb (mg kg−1)
Cu (mg kg−1)
Zn (mg kg−1)
55
