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Metals and metalloids are deposited into small arms range soils from bullets, casings, and primers. The mobility potential depends on the individual metal(loid), its speciation, local pH, redox conditions and soil characteristics. This article discusses the speciation, mobility, and toxicity of metal(loid)s relevant to small arms ranges and briefly discusses management strategies to mitigate risk.
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The heterogeneous distribution of munitions constituents, released as particles from munitions firing and detonations on military training ranges, presents challenges for representative soil sample collection and for defensible decision making. Military range characterization studies and the development of the incremental sampling methodology (ISM) have enabled the development of recommended methods for soil sampling that produce representative and reproducible concentration data for munitions constituents. This article provides a broad overview of recommended soil sampling and processing practices for analysis of munitions constituents on military ranges.  
 
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'''Related Article(s):'''
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'''Related Article(s)''':
  
  
'''CONTRIBUTOR(S):''' [[Dr. Amanda Barker]]
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'''CONTRIBUTOR(S):''' [[Dr. Samuel Beal]]
  
  
'''Key Resource(s)''':
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'''Key Resource(s)''':  
*[[media:Fabian-2005-Army-Small-Arms-Training-Range-BMP.pdf | Army Small Arms Training Range Environmental Best Practices (BMPs) Manual]]  
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*[[media:Taylor-2011 ERDC-CRREL TR-11-15.pdf| Guidance for Soil Sampling of Energetics and Metals]]<ref name= "Taylor2011">Taylor, S., Jenkins, T.F., Bigl, S., Hewitt, A.D., Walsh, M.E. and Walsh, M.R., 2011. Guidance for Soil Sampling for Energetics and Metals (No. ERDC/CRREL-TR-11-15). [[media:Taylor-2011 ERDC-CRREL TR-11-15.pdf| Report.pdf]]</ref>
*[[media: 2014-Mgmt_of_the_Environmental_Impact_of_Shooting_Ranges_The_Finished_Env..pdf| Management of the Environmental Impact of Shooting Ranges, the Finnish Environment]]  
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*[[Media:Hewitt-2009 ERDC-CRREL TR-09-6.pdf| Report.pdf | Validation of Sampling Protocol and the Promulgation of Method Modifications for the Characterization of Energetic Residues on Military Testing and Training Ranges]]<ref name= "Hewitt2009">Hewitt, A.D., Jenkins, T.F., Walsh, M.E., Bigl, S.R. and Brochu, S., 2009. Validation of sampling protocol and the promulgation of method modifications for the characterization of energetic residues on military testing and training ranges (No. ERDC/CRREL-TR-09-6). Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) TR-09-6, Hanover, NH, USA. [[Media:Hewitt-2009 ERDC-CRREL TR-09-6.pdf | Report.pdf]]</ref>
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*[[media:Epa-2006-method-8330b.pdf| U.S. EPA SW-846 Method 8330B: Nitroaromatics, Nitramines, and Nitrate Esters by High Performance Liquid Chromatography (HPLC)]]<ref name= "USEPA2006M">U.S. Environmental Protection Agency (USEPA), 2006. Method 8330B (SW-846): Nitroaromatics, Nitramines, and Nitrate Esters by High Performance Liquid Chromatography (HPLC), Rev. 2. Washington, D.C. [[media:Epa-2006-method-8330b.pdf | Report.pdf]]</ref>
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*[[media:Epa-2007-method-8095.pdf | U.S. EPA SW-846 Method 8095: Explosives by Gas Chromatography.]]<ref name= "USEPA2007M">U.S. Environmental Protection Agency (US EPA), 2007. Method 8095 (SW-846): Explosives by Gas Chromatography. Washington, D.C. [[media:Epa-2007-method-8095.pdf| Report.pdf]]</ref>
  
 
==Introduction==
 
==Introduction==
Military small arms training uses bullets made of metals and metalloids which can include lead, antimony, copper, nickel, zinc, chromium, tungsten, mercury, and arsenic. Some of these metal(loid)s are also key ingredients of small arms ammunition primers used to initiate bullet firing. Unlike organic compounds found in propellants and explosives, metal(loid)s do not degrade in the environment. As such, the pervasive use of metal(loid)s on military training grounds and shooting ranges has resulted in contamination of soils, sediments, surface water, and groundwater both local to specific sites and off-site. A simplified schematic showing potential pathways of metal(loid) release on shooting ranges is shown in Figure 1. Upon exposure to the atmosphere, initially zero-valent metal(loid)s are oxidized, form secondary mineral phases, and subsequently release oxidized species into soil solution. The formation of a weathering crust on the surface of fired bullets is shown in Figures 2 and 3. Mobilization of metal(loid)s in pore water and soil solution is controlled by a variety of factors, including pH, oxidation-reduction (redox) environment, presence of colloids and/or soil organic matter (SOM), soil type and hydraulic characteristics, temperature, and water infiltration<ref name= "Vantelon2005">Vantelon, D., Lanzirotti, A., Scheinost, A.C. and Kretzschmar, R., 2005. Spatial distribution and speciation of lead around corroding bullets in a shooting range soil studied by micro-X-ray fluorescence and absorption spectroscopy. Environmental Science & Technology, 39(13), pp.4808-4815. [https://doi.org/10.1021/es0482740 doi: 10.1021/es0482740]</ref><ref name= "Scheinost2006">Scheinost, A.C., Rossberg, A., Vantelon, D., Xifra, I., Kretzschmar, R., Leuz, A.K., Funke, H. and Johnson, C.A., 2006. Quantitative antimony speciation in shooting-range soils by EXAFS spectroscopy. Geochimica et Cosmochimica Acta, 70(13), pp.3299-3312. [https://doi.org/10.1016/j.gca.2006.03.020 doi: 10.1016/j.gca.2006.03.020]</ref><ref name= "Ackermann2009">Ackermann, S., Gieré, R., Newville, M. and Majzlan, J., 2009. Antimony sinks in the weathering crust of bullets from Swiss shooting ranges. Science of the Total Environment, 407(5), pp.1669-1682. [https://doi.org/10.1016/j.scitotenv.2008.10.059 doi: 10.1016/j.scitotenv.2008.10.059]</ref><ref name= "Sanderson2018">Sanderson, P., Qi, F., Seshadri, B., Wijayawardena, A. and Naidu, R., 2018. Contamination, fate and management of metals in shooting range soils—A Review. Current Pollution Reports, 4(2), pp.175-187. [https://doi.org/10.1007/s40726-018-0089-5 doi: 10.1007/s40726-018-0089-5]</ref>.
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[[File:Beal1w2 Fig1.png|thumb|200 px|left|Figure 1: Downrange distance of visible propellant plume on snow from the firing of different munitions. Note deposition behind firing line for the 84-mm rocket. Data from: Walsh et al.<ref>Walsh, M.R., Walsh, M.E., Ampleman, G., Thiboutot, S., Brochu, S. and Jenkins, T.F., 2012. Munitions propellants residue deposition rates on military training ranges. Propellants, Explosives, Pyrotechnics, 37(4), pp.393-406. [http://dx.doi.org/10.1002/prep.201100105 doi: 10.1002/prep.201100105]</ref><ref>Walsh, M.R., Walsh, M.E., Hewitt, A.D., Collins, C.M., Bigl, S.R., Gagnon, K., Ampleman, G., Thiboutot, S., Poulin, I. and Brochu, S., 2010. Characterization and Fate of Gun and Rocket Propellant Residues on Testing and Training Ranges: Interim Report 2. (ERDC/CRREL TR-10-13. Also: ESTCP Project ER-1481)  [[media:Walsh-2010 ERDC-CRREL TR-11-15 ESTCP ER-1481.pdf| Report]]</ref>]]
[[File:Barker1w2 Fig1.png|thumb|500 px|left|Figure 1. Simplified schematic of shooting ranges with berm-style backstops that typically contain high loadings of metal(loid)s in the berm due to bullet fragmentation and also at the firing point as a result of residue and primer materials.]]
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[[File:Beal1w2 Fig2.png|thumb|left|200 px|Figure 2: A low-order detonation mortar round (top) with surrounding discrete soil samples produced concentrations spanning six orders of magnitude within a 10m by 10m area (bottom). (Photo and data: A.D. Hewitt)]]
[[File:Barker1w2 Fig2.png|thumb|500 px|left|Figure 2. Chemical characterization of a 5.56mm corroding bullet that underwent 15 years of weathering in Alaskan soils using scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDX). Relative concentrations for iron (red), lead (green), and antimony (purple) are shown in the right x-ray map. Data was collected at the Advanced Instrumentation Laboratory (AIL), University of Alaska Fairbanks (UAF). Data collected by A.J. Barker]]
 
[[File:Barker1w2 Fig3.png|thumb|right|Figure 3. Optical images of a new 5.56mm bullet (left) and a 5.56mm bullet that weathered for 15 years (right). The tip of the bullet fragmented and the weathering crust can be hundreds of microns thick and comprised of secondary mineral phases. Photo by A.J. Barker.]]
 
  
==Metal(loid)s==
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Munitions constituents are released on military testing and training ranges through several common mechanisms. Some are locally dispersed as solid particles from incomplete combustion during firing and detonation. Also, small residual particles containing propellant compounds (e.g., [[Wikipedia: Nitroglycerin | nitroglycerin [NG]]] and [[Wikipedia: 2,4-Dinitrotoluene | 2,4-dinitrotoluene [2,4-DNT]]]) are distributed in front of and surrounding target practice firing lines (Figure 1). At impact areas and demolition areas, high order detonations typically yield very small amounts (<1 to 10 mg/round) of residual high explosive compounds (e.g., [[Wikipedia: TNT | TNT ]], [[Wikipedia: RDX | RDX ]] and [[Wikipedia: HMX | HMX ]]) that are distributed up to and sometimes greater than) 24 m from the site of detonation<ref name= "Walsh2017">Walsh, M.R., Temple, T., Bigl, M.F., Tshabalala, S.F., Mai, N. and Ladyman, M., 2017. Investigation of Energetic Particle Distribution from High‐Order Detonations of Munitions. Propellants, Explosives, Pyrotechnics, 42(8), pp.932-941. [https://doi.org/10.1002/prep.201700089 doi: 10.1002/prep.201700089] [[media: Walsh-2017-High-Order-Detonation-Residues-Particle-Distribution-PEP.pdf| Report.pdf]]</ref>.
  
===Lead (Pb)===
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Low-order detonations and duds are thought to be the primary source of munitions constituents on ranges<ref>Hewitt, A.D., Jenkins, T.F., Walsh, M.E., Walsh, M.R. and Taylor, S., 2005. RDX and TNT residues from live-fire and blow-in-place detonations. Chemosphere, 61(6), pp.888-894. [https://doi.org/10.1016/j.chemosphere.2005.04.058 doi: 10.1016/j.chemosphere.2005.04.058]</ref><ref>Walsh, M.R., Walsh, M.E., Poulin, I., Taylor, S. and Douglas, T.A., 2011. Energetic residues from the detonation of common US ordnance. International Journal of Energetic Materials and Chemical Propulsion, 10(2). [https://doi.org/10.1615/intjenergeticmaterialschemprop.2012004956 doi: 10.1615/IntJEnergeticMaterialsChemProp.2012004956] [[media:Walsh-2011-Energetic-Residues-Common-US-Ordnance.pdf| Report.pdf]]</ref>. Duds are initially intact but may become perforated or fragmented into micrometer to centimeter;o0i0k-sized particles by nearby detonations<ref>Walsh, M.R., Thiboutot, S., Walsh, M.E., Ampleman, G., Martel, R., Poulin, I. and Taylor, S., 2011. Characterization and fate of gun and rocket propellant residues on testing and training ranges (No. ERDC/CRREL-TR-11-13). Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) TR-11-13, Hanover, NH, USA. [[media:Epa-2006-method-8330b.pdf| Report.pdf]]</ref>. Low-order detonations can scatter micrometer to centimeter-sized particles up to 20 m from the site of detonation<ref name= "Taylor2004">Taylor, S., Hewitt, A., Lever, J., Hayes, C., Perovich, L., Thorne, P. and Daghlian, C., 2004. TNT particle size distributions from detonated 155-mm howitzer rounds. Chemosphere, 55(3), pp.357-367.[[media:Taylor-2004 TNT PSDs.pdf| Report.pdf]]</ref>
[https://en.wikipedia.org/wiki/Lead Lead] (Pb) and antimony alloy bullet cores are commonly used in small arms ammunition to provide the high density needed to penetrate surfaces. Pb is estimated to comprise approximately 90-99% of the bullet core with steel, copper, and zinc making up the majority of the remaining mass for the slug and casing<ref name= "Vantelon2005"/><ref name= "Sanderson2018"/>. Pb is also used in the compounds lead styphnate and lead azide as primers for ammunition. As a result, Pb can be found on training ranges in soils/structures where the bullet fragments and also at the firing point<ref name= "Pichtel2012">Pichtel, J., 2012. Distribution and fate of military explosives and propellants in soil: a review. Applied and Environmental Soil Science, 2012. [http://dx.doi.org/10.1155/2012/617236 doi: 10.1155/2012/617236]</ref>. Concentrations of Pb in soils at shooting ranges can vary widely depending on the number of rounds fired at the site, but concentrations often range from 55 to 80,000 mg/kg<ref name= "Vantelon2005"/><ref name= "Dermatas2006">Dermatas, D., Cao, X., Tsaneva, V., Shen, G. and Grubb, D.G., 2006. Fate and behavior of metal (loid) contaminants in an organic matter-rich shooting range soil: Implications for remediation. Water, Air, & Soil Pollution: Focus, 6(1-2), pp.143-155. [https://doi.org/10.1007/s11267-005-9003-4 doi: 10.1007/s11267-005-9003-4]</ref><ref name= "Sanderson2010">Sanderson, P., Bolan, N., Bowman, M. and Naidu, R., 2010. Distribution and availability of metal contaminants in shooting range soils around Australia. In Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world, Brisbane, Australia, 1-6 August 2010. Symposium 3.5. 1 Heavy metal contaminated soils (pp. 65-67). International Union of Soil Sciences (IUSS), c/o Institut für Bodenforschung, Universität für Bodenkultur.</ref><ref name= "Seijo2016">Rodríguez‐Seijo, A., Alfaya, M.C., Andrade, M.L. and Vega, F.A., 2016. Copper, chromium, nickel, lead and zinc levels and pollution degree in firing range soils. Land Degradation & Development, 27(7), pp.1721-1730. [https://doi.org/10.1002/ldr.2497 doi: 10.1002/ldr.2497]</ref>. The mobility of Pb is highly dependent on local pH. Acidic conditions contribute to the mobilization of Pb species in the environment whereas basic conditions tend to promote precipitation and sorption reactions<ref name= "CAO2003">Cao, X., Ma, L.Q., Chen, M., Hardison, D.W. and Harris, W.G., 2003. Weathering of lead bullets and their environmental effects at outdoor shooting ranges. Journal of Environmental Quality, 32(2), pp.526-534. [https://doi.org/10.2134/jeq2003.5260 doi:10.2134/jeq2003.5260]</ref><ref>Knechtenhofer, L.A., Xifra, I.O., Scheinost, A.C., Flühler, H. and Kretzschmar, R., 2003. Fate of heavy metals in a strongly acidic shooting‐range soil: small‐scale metal distribution and its relation to preferential water flow. Journal of Plant Nutrition and Soil Science, 166(1), pp.84-92. [https://doi.org/10.1002/jpln.200390017 doi: 10.1002/jpln.200390017]</ref>. The formation of secondary mineral phases is a common observation, including [https://en.wikipedia.org/wiki/White_lead hydrocerussite] [Pb<sub>3</sub>(CO<sub>3</sub>)<sub>2</sub>(OH)<sub>2</sub>], [https://en.wikipedia.org/wiki/Cerussite cerussite] [PbCO<sub>3</sub>], [https://en.wikipedia.org/wiki/Litharge litharge] and [https://en.wikipedia.org/wiki/Massicot massicot] [PbO polymorphs], but Pb also binds with sulfur and phosphorus depending on mineralogical conditions at a given site<ref name= "CAO2003"/><ref name= "Vantelon2005"/><ref>Scheetz, C.D. and Rimstidt, J.D., 2009. Dissolution, transport, and fate of lead on a shooting range in the Jefferson National Forest near Blacksburg, VA, USA. Environmental Geology, 58(3), pp.655-665. [https://doi.org/10.1007/s00254-008-1540-5 doi: 10.1007/s00254-008-1540-5]</ref><ref>Li, J., Wang, Q., Oremland, R.S., Kulp, T.R., Rensing, C. and Wang, G., 2016. Microbial antimony biogeochemistry: enzymes, regulation, and related metabolic pathways. Appl. Environ. Microbiol., 82(18), pp.5482-5495. [https://doi.org/10.1128/aem.01375-16 doi: 10.1128/aem.01375-16]</ref>. Additionally, Pb has been known to bind with soil organic matter, clay minerals, and iron/aluminum/manganese - oxides<ref>Manceau, A., Boisset, M.C., Sarret, G., Hazemann, J.L., Mench, M., Cambier, P. and Prost, R., 1996. Direct determination of lead speciation in contaminated soils by EXAFS spectroscopy. Environmental Science & Technology, 30(5), pp.1540-1552. [https://doi.org/10.1021/es9505154 doi: 10.1021/es9505154]</ref><ref>Mozafar, A., Ruh, R., Klingel, P., Gamper, H., Egli, S. and Frossard, E., 2002. Effect of heavy metal contaminated shooting range soils on mycorrhizal colonization of roots and metal uptake by leek. Environmental Monitoring and Assessment, 79(2), pp.177-191. [https://doi.org/10.1023/A:1020202801163 doi: 10.1023/A:1020202801163]</ref>. Pb is found in the near-surface environment in one oxidation state, Pb<sup>2+</sup>. Its toxicity is manifested primarily by effects to the central nervous system and brain function, but it can also cause damage to reproductive processes, auditory function, and vision<ref>Mason B. (1952) Principles of geochemistry, 276 p. New York, John Wiley and Sons. ISBN: 0471575224</ref>.
 
  
===Antimony===
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The particulate nature of munitions constituents in the environment presents a distinct challenge to representative soil sampling. Figure 2 shows an array of discrete soil samples collected around the site of a low-order detonation – resultant soil concentrations vary by orders of magnitude within centimeters of each other. The inadequacy of discrete sampling is apparent in characterization studies from actual ranges which show wide-ranging concentrations and poor precision (Table 1).
[https://en.wikipedia.org/wiki/Antimony Antimony] (Sb) is a hard, toxic, metalloid that is added to Pb in molten form to make the Pb-alloyed core of a bullet. Sb is thought to behave similarly in the environment to its group VB neighbor Arsenic (As), and, like As, it is toxic and a suspected carcinogen<ref>World Health Organization, 2003. Background document for development of WHO Guidelines for Drinking-water Quality. World Health Organization, 20, pp.4-6.</ref>. Sb is added to bullets as a hardening agent because Pb is soft and would not have the same impact capacity without it<ref name= "Scheinost2006"/><ref name= "Sanderson2010"/>. Bullet cores typically contain no more than 2% Sb and, correspondingly, concentrations in soils are typically lower than for Pb. Sb is also often found in the primers of small arms ammunition as Sb sulfide. Although Sb is present in bullets approximately two orders of magnitude less than Pb, in some aqueous systems Sb has been found to be more mobile than Pb<ref name= "Johnson2005">Johnson, C.A., Moench, H., Wersin, P., Kugler, P. and Wenger, C., 2005. Solubility of antimony and other elements in samples taken from shooting ranges. Journal of Environmental Quality, 34(1), pp.248-254. [https://doi.org/10.2134/jeq2005.0248  doi:10.2134/jeq2005.0248]</ref><ref>Sanderson, P., Naidu, R. and Bolan, N., 2015. Effectiveness of chemical amendments for stabilisation of lead and antimony in risk-based land management of soils of shooting ranges. Environmental Science and Pollution Research, 22(12), pp.8942-8956. [https://doi.org/10.1007/s11356-013-1918-0 doi: 10.1007/s11356-013-1918-0]</ref><ref name= "doherty2017">Doherty, S.J., Tighe, M.K. and Wilson, S.C., 2017. Evaluation of amendments to reduce arsenic and antimony leaching from co-contaminated soils. Chemosphere, 174, pp.208-217. [https://doi.org/10.1016/j.chemosphere.2017.01.100 doi: 10.1016/j.chemosphere.2017.01.100]</ref>. However, in more acidic soils Pb often exceeds measured Sb aqueous concentrations due to the high solubility of Pb at low pH values<ref>Okkenhaug, G., Gebhardt, K.A.G., Amstaetter, K., Bue, H.L., Herzel, H., Mariussen, E., Almås, Å.R., Cornelissen, G., Breedveld, G.D., Rasmussen, G. and Mulder, J., 2016. Antimony (Sb) and lead (Pb) in contaminated shooting range soils: Sb and Pb mobility and immobilization by iron-based sorbents, a field study. Journal of Hazardous Materials, 307, pp.336-343. [https://doi.org/10.1016/j.jhazmat.2016.01.005 doi: 10.1016/j.jhazmat.2016.01.005]</ref>. The mobility of Sb on ranges is highly dependent on its speciation, which in near-surface environments is Sb(III) or Sb(V). The trivalent form has been shown to be less mobile than the pentavalent form, but the trivalent form is considerably more toxic, particularly Sb trioxide<ref name= "Scheinost2006"/><ref name = "Wilson2010">Wilson, S.C., Lockwood, P.V., Ashley, P.M. and Tighe, M., 2010. The chemistry and behaviour of antimony in the soil environment with comparisons to arsenic: a critical review. Environmental Pollution, 158(5), pp.1169-1181.
 
[http://dx.doi.org/10.1016/j.envpol.2009.10.045 doi: 10.1016/j.envpol.2009.10.045]</ref>. Sb(V) is more mobile at higher pHs<ref>Hu, X., Guo, X., He, M. and Li, S., 2016. pH-dependent release characteristics of antimony and arsenic from typical antimony-bearing ores. Journal of Environmental Sciences, 44, pp.171-179. [https://doi.org/10.1016/j.jes.2016.01.003 doi: 10.1016/j.jes.2016.01.003]</ref>, while Sb(III) in solution is independent of pH<ref name= "Johnson2005"/>. Certain environmental factors influence Sb speciation, including pH, redox potential, biological activity, and co-contamination<ref>Filella, M., Belzile, N. and Chen, Y.W., 2002. Antimony in the environment: a review focused on natural waters: I. Occurrence. Earth-Science Reviews, 57(1), pp.125-176. [http://dx.doi.org/10.1016/s0012-8252(01)00070-8  doi:10.1016/S0012-8252(01)00070-8]</ref><ref name = "Wilson2010"/><ref name = "Ilgen2014">Ilgen, A.G., Majs, F., Barker, A.J., Douglas, T.A. and Trainor, T.P., 2014. Oxidation and mobilization of metallic antimony in aqueous systems with simulated groundwater. Geochimica et Cosmochimica Acta, 132, pp.16-30. [http://dx.doi.org/10.1016/j.gca.2014.01.019  doi:10.1016/j.gca.2014.01.019]</ref><ref name= "doherty2017"/>. Sb oxidation is rapid<ref name = "Ilgen2014"/>, forming secondary products both in soils and within the weathering crust surrounding bullets<ref name= "Ackermann2009"/>. Iron (Fe) is a natural sink for Sb, forming primarily inner sphere sorption complexes (both corner and edge-sharing) with Fe(III) oxides found in soils<ref name= "Scheinost2006"/><ref name= "Ackermann2009"/><ref>Ritchie, V.J., Ilgen, A.G., Mueller, S.H., Trainor, T.P. and Goldfarb, R.J., 2013. Mobility and chemical fate of antimony and arsenic in historic mining environments of the Kantishna Hills district, Denali National Park and Preserve, Alaska. Chemical Geology, 335, pp.172-188. [https://doi.org/10.1016/j.chemgeo.2012.10.016 doi: 10.1016/j.chemgeo.2012.10.016]</ref>.
 
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===Copper===
 
[https://en.wikipedia.org/wiki/Copper Copper] (Cu) is an essential nutrient for the body and has a relatively high maximum contaminant level (MCL) in drinking water set by the EPA (1.3 mg/kg) compared to other metal(loid)s that comprise bullets. However, toxicity from elevated Cu concentrations can arise and cause gastrointestinal distress (short-term) and liver and/or kidney damage (long-term)<ref>U. S. Environmental Protection Agency (USEPA), 2009. National Primary Drinking Water Regulations. EPA 816-F-09-004. [[media:2009-USEPA-national_Primary_Drinking_Water_Regulations.pdf| Report.pdf]]</ref>. The outer casing and jacket of a bullet is comprised primarily of Cu. When a bullet is fired, the outer Cu casing remains at the firing point along with the primer and propellant residues while the Cu jacket impacts soil and either deforms or fragments. New 5.56-mm and 7.62-mm “green” bullets contain solid Cu cores in place of Pb/Sb alloys. Copper concentrations in shooting range soils typically range from 19 to upwards of 6,000 mg/kg<ref>Robinson, B.H., Bischofberger, S., Stoll, A., Schroer, D., Furrer, G., Roulier, S., Gruenwald, A., Attinger, W. and Schulin, R., 2008. Plant uptake of trace elements on a Swiss military shooting range: Uptake pathways and land management implications. Environmental Pollution, 153(3), pp.668-676. [https://doi.org/10.1016/j.envpol.2007.08.034 doi: 10.1016/j.envpol.2007.08.034]</ref><ref name= "Seijo2016"/>. Similar to Pb, Cu mobility is highly dependent on pH<ref>Sherene, T., 2010. Mobility and transport of heavy metals in a polluted soil environment. In Biological forum - An International Journal (Vol. 2, No. 2, pp. 112-121). [[media:2010-Sherene-Mobility_and_transport_of_heavy_metals_i.pdf| Report.pdf]]</ref>, and it has been shown to easily complex with organic matter<ref>Huang, J., Huang, R., Jiao, J.J. and Chen, K., 2007. Speciation and mobility of heavy metals in mud in coastal reclamation areas in Shenzhen, China. Environmental Geology, 53(1), pp.221-228. [https://doi.org/10.1007/s00254-007-0636-7 doi: 10.1007/s00254-007-0636-7]</ref><ref>Ashraf, M.A., Maah, M.J. and Yusoff, I., 2012. Chemical speciation and potential mobility of heavy metals in the soil of former tin mining catchment. The Scientific World Journal, 2012. ISBN: 0471575224</ref>.  
 
  
===Nickel===
+
In comparison to discrete sampling, incremental sampling tends to yield reproducible concentrations (low relative standard deviation [RSD]) that statistically better represent an area of interest<ref name= "Hewitt2009"/>.
[https://en.wikipedia.org/wiki/Nickel Nickel] (Ni) toxicity is typically a concern to humans due to its prevalence as an allergen and the ability of Ni to interfere with other essential metals in cellular processes<ref>Coogan, T.P., Latta, D.M., Snow, E.T., Costa, M. and Lawrence, A., 1989. Toxicity and carcinogenicity of nickel compounds. CRC Critical reviews in toxicology, 19(4), pp.341-384. [https://doi.org/10.3109/10408448909029327 doi: 10.3109/10408448909029327]</ref><ref> Sharma, A.D., 2013. Low nickel diet in dermatology. Indian Journal of Dermatology, 58(3), p.240. [https://doi.org/10.4103/0019-5154.110846 doi: 10.4103/0019-5154.110846]</ref>. Trace amounts of Ni are found in the casing and jacket of a bullet, used to make the alloy with Cu. Ni is a biologically important micronutrient and an essential trace element for plants, microbes, animals, and humans<ref>Mason B. (1952) Principles of geochemistry, 276 p. New York, John Wiley and Sons. ISBN: 0471575224</ref><ref name = "Coleman2004">Coleman D.C., Crossley Jr. D.A. and Hendrix P.F., 2004. Fundamentals of Soil Ecology, 2nd ed. Elsevier Inc. New York City, NY.  ISBN: 9780121797263/e: 9780080472812</ref><ref>Nieminen, T.M., Ukonmaanaho, L., Rausch, N. and Shotyk, W., 2007. Biogeochemistry of nickel and its release into the environment. Metal Ions in Life Sciences, nickel and its surprising impact in nature. 2nd Volume. Chichester: John Wiley & Sons, pp.1-30.  ISSN: 1559-0836. </ref>. Ni concentrations in environmental systems tend to be conservative and uniformly distributed<ref>Iyaka, Y.A., 2011. Nickel in soils: a review of its distribution and impacts. Scientific Research and Essays, 6(33), pp.6774-6777. [[media:2011-Iyaka-Nickel_in_soils._A_review_of_its_distribution_and_impacts.pdf| Report.pdf]]</ref>. In shooting ranges, typical concentrations of Ni are lower compared to the other metal(loid)s like Pb, Sb, Cu, and Zn<ref>Mariussen, E., Johnsen, I.V. and Strømseng, A.E., 2017. Distribution and mobility of lead (Pb), copper (Cu), zinc (Zn), and antimony (Sb) from ammunition residues on shooting ranges for small arms located on mires. Environmental Science and Pollution Research, 24(11), pp.10182-10196. [https://doi.org/10.1007/s11356-017-8647-8 doi: 10.1007/s11356-017-8647-8]</ref>. Ni tends to be relatively immobile in soil solution under neutral and alkaline conditions, but can become highly mobilized under acidic conditions (similar to the other cationic metals; Pb, Cu, and Zn). Similar to other metal(loid)s, key environmental processes that affect Ni cycling in geomedia include adsorption, (co)precipitation, and complexation<ref>Harasim, P. and Filipek, T., 2015. Nickel in the environment. Journal of Elementology, 20(2). [https://doi.org/10.5601/jelem.2014.19.3.651 doi: 10.5601/jelem.2014.19.3.651]</ref>.  
 
  
===Zinc===
+
{| class="wikitable" style="float: right; text-align: center; margin-left: auto; margin-right: auto;"
[https://en.wikipedia.org/wiki/Zinc Zinc] (Zn) is an essential micronutrient for sustained existence<ref name = "Coleman2004"/>. Similar to Ni, trace amounts of Zn are found in the casing and jacket of a bullet, used to make the alloy with Cu. Zn has been found to become mobilized at acidic pHs, similar to other cationic metals (Pb, Cu, and Ni) and often associates with clay minerals, soil organic matter, and the roots and shoots of plants, if available <ref>Haslett, B.S., Reid, R.J. and Rengel, Z., 2001. Zinc mobility in wheat: uptake and distribution of zinc applied to leaves or roots. Annals of Botany, 87(3), pp.379-386. [https://doi.org/10.1006/anbo.2000.1349 doi: 10.1006/anbo.2000.1349]</ref><ref>Rutkowska, B., Szulc, W., Bomze, K., Gozdowski, D. and Spychaj-Fabisiak, E., 2015. Soil factors affecting solubility and mobility of zinc in contaminated soils. International Journal of Environmental Science and Technology, 12(5), pp.1687-1694. [https://doi.org/10.1007/s13762-014-0546-7 doi: 10.1007/s13762-014-0546-7]</ref>.
+
|+ Table 1. Soil Sample Concentrations and Precision from Military Ranges Using Discrete and Incremental Sampling. (Data from Taylor et al. <ref name= "Taylor2011"/> and references therein.)
 +
|-
 +
! Military Range Type !! Analyte !! Range<br/>(mg/kg) !! Median<br/>(mg/kg) !! RSD<br/>(%)
 +
|-
 +
| colspan="5" style="text-align: left;" | '''Discrete Samples'''
 +
|-
 +
| Artillery FP || 2,4-DNT || <0.04 – 6.4 || 0.65 || 110
 +
|-
 +
| Antitank Rocket || HMX || 5.8 – 1,200 || 200 || 99
 +
|-
 +
| Bombing || TNT || 0.15 – 780 || 6.4 || 274
 +
|-
 +
| Mortar || RDX || <0.04 – 2,400 || 1.7 || 441
 +
|-
 +
| Artillery || RDX || <0.04 – 170 || <0.04 || 454
 +
|-
 +
| colspan="5" style="text-align: left;" | '''Incremental Samples*'''
 +
|-
 +
| Artillery FP || 2,4-DNT || 0.60 – 1.4 || 0.92 || 26
 +
|-
 +
| Bombing || TNT || 13 – 17 || 14 || 17
 +
|-
 +
| Artillery/Bombing || RDX || 3.9 – 9.4 || 4.8 || 38
 +
|-  
 +
| Thermal Treatment || HMX || 3.96 – 4.26 || 4.16 || 4
 +
|-
 +
| colspan="5" style="text-align: left; background-color: white;" | * For incremental samples, 30-100 increments and 3-10 replicate samples were collected.
 +
|}
  
===Chromium===
+
==Incremental Sampling Approach==
[https://en.wikipedia.org/wiki/Chromium Chromium (Cr)] in the +3 valence state (Cr(III)) is an essential micronutrient, but has been found to be toxic in large doses. Chromium in the +6 valence state (Cr(VI)) is classified as a human carcinogen<ref>Wilbur, S.B., 1998. Toxicological profile for chromium. US Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry.</ref><ref>U.S. Environmental Protection Agency (USEPA), 1999. Integrated Risk Information System (IRIS) on chromium VI. National Center for Environmental Assessment. Office of Research and Development, Washington.</ref>. Depending on the quality of the source of metals used for the production of bullets, Cr may be found as an impurity in steel<ref name= "Levonmaki2002">Levonmäki, M. and Kairesalo, T., 2002. Do steel shots raise a chromium problem on shooting range areas. ISSF News, 2, pp.9-10. </ref><ref>Sorvari, J., Antikainen, R. and Pyy, O., 2006. Environmental contamination at Finnish shooting ranges—the scope of the problem and management options. Science of the Total Environment, 366(1), pp.21-31. [https://doi.org/10.1016/j.scitotenv.2005.12.019 doi: 10.1016/j.scitotenv.2005.12.019]</ref><ref name= "Seijo2016"/>. One study on Cr presence at shooting range soils estimated the Cr content of steel to be up to 27%, which is a much higher estimate than other studies have reported<ref name= "Levonmaki2002"/>. Typically, Cr concentrations in shooting range soils are reported comparable to background concentrations in local soils, indicating minimal environmental impact from training<ref name= "Seijo2016"/>. Cr is primarily found in the near-surface environment as Cr(III) and Cr(VI). In its hexavalent oxidation state Cr is highly mobile, while Cr(III) is more likely to participate in precipitation and sorption reactions, and therefore mobility in aqueous environments and sediments is limited<ref>Gorny, J., Billon, G., Noiriel, C., Dumoulin, D., Lesven, L. and Madé, B., 2016. Chromium behavior in aquatic environments: a review. Environmental Reviews, 24(4), pp.503-516. [https://doi.org/10.1139/er-2016-0012 doi: 10.1139/er-2016-0012]</ref>.
+
ISM is a requisite for representative and reproducible sampling of training ranges, but it is an involved process that is detailed thoroughly elsewhere<ref name= "Hewitt2009"/><ref name= "Taylor2011"/><ref name= "USEPA2006M"/>. In short, ISM involves the collection of many (30 to >100) increments in a systematic pattern within a decision unit (DU). The DU may cover an area where releases are thought to have occurred or may represent an area relevant to ecological receptors (e.g., sensitive species). Figure 3 shows the ISM sampling pattern in a simplified (5x5 square) DU. Increments are collected at a random starting point with systematic distances between increments. Replicate samples can be collected by starting at a different random starting point, often at a different corner of the DU. Practically, this grid pattern can often be followed with flagging or lathe marking DU boundaries and/or sampling lanes and with individual pacing keeping systematic distances between increments. As an example, an artillery firing point might include a 100x100 m DU with 81 increments.
 +
[[File:Beal1w2 Fig3.png|thumb|200 px|left|Figure 3. Example ISM sampling pattern on a square decision unit. Replicates are collected in a systematic pattern from a random starting point at a corner of the DU. Typically more than the 25 increments shown are collected]]
  
===Tungsten===
+
DUs can vary in shape (Figure 4), size, number of increments, and number of replicates according to a project’s data quality objectives.
Exposure to high [https://en.wikipedia.org/wiki/Tungsten tungsten] (W) concentrations has been linked to altered thyroid function, heart disease, and potentially childhood leukemia and lung cancer<ref name = "Datta2017">Datta, S., Vero, S.E., Hettiarachchi, G.M. and Johannesson, K., 2017. Tungsten contamination of soils and sediments: current state of science. Current Pollution Reports, 3(1), pp.55-64. [https://doi.org/10.1007/s40726-016-0046-0 doi: 0.1007/s40726-016-0046-0]</ref>. Historically, W and nylon have been used as an alternative for Pb in bullets<ref name = "Datta2017"/>. The tungsten-nylon bullets were termed ‘green bullets’, but did not stay in production for longer than a decade as subsequent research eventually revealed W to be both toxic and highly mobile<ref>Agency for Toxic Substances and Disease Registry (ATSDR), 2005. Toxicological Profile for Tungsten. U.S. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA.</ref>. Concentrations of W in shooting range soils where green bullets have been spent ranged from below detection to greater than 2,000 mg/kg<ref>Clausen, J.L. and Korte, N., 2009. Environmental fate of tungsten from military use. Science of the total environment, 407(8), pp.2887-2893.
 
  
[https://doi.org/10.1016/j.scitotenv.2009.01.029 doi: 10.1016/j.scitotenv.2009.01.029]</ref>. W has been shown to be relatively mobile in the environment, with its mobility dependent on speciation. However, there is evidence to suggest W mobility decreases as soil ages, as long as the source is limited<ref>Bednar, A.J., Jones, W.T., Boyd, R.E., Ringelberg, D.B. and Larson, S.L., 2008. Geochemical parameters influencing tungsten mobility in soils. Journal of environmental quality, 37(1), pp.229-233. [https://doi.org/10.2134/jeq2007.0305 doi:10.2134/jeq2007.0305]</ref>. W metal is not stable in the environment and instead primarily exists as W(VI) and prefers to form a variety of polyatomic anions (like WO<sub>4</sub><sup>2-</sup> and H<sub>2</sub>W<sub>12</sub>O<sub>40</sub><sup>6-</sup>, etc.) and polyoxometalates in solution<ref>Bostick, B.C., Sun, J., Landis, J.D. and Clausen, J.L., 2018. Tungsten Speciation and Solubility in Munitions-Impacted Soils. Environmental science & technology, 52(3), pp.1045-1053. [https://doi.org/10.1021/acs.est.7b05406 doi: 10.1021/acs.est.7b05406]</ref>.
+
[[File:Beal1w2 Fig4.png|thumb|right|250 px|Figure 4: Incremental sampling of a circular DU on snow shows sampling lanes with a two-person team in process of collecting the second replicate in a perpendicular path to the first replicate. (Photo: Matthew Bigl)]]
  
===Mercury===
+
==Sampling Tools==
A compound containing [https://en.wikipedia.org/wiki/Mercury_(element) mercury] (Hg) (mercury fulminate, Hg(CNO)<sub>2</sub>) was previously used as a primer for ammunition for approximately 100 years before it was widely replaced by lead azide, silver azide, or lead styphnate which have greater stability<ref>Beck, W., Evers, J., Göbel, M., Oehlinger, G. and Klapötke, T.M., 2007. The crystal and molecular structure of mercury fulminate (Knallquecksilber). Zeitschrift für anorganische und allgemeine Chemie, 633(9), pp.1417-1422. [https://doi.org/10.1002/zaac.200700176 doi: 10.1002/zaac.200700176]</ref><ref name= "Pichtel2012"/>. Despite the minimal to negligible use in recent history, there is some evidence to suggest that legacy shooting ranges may have persistent Hg contamination in soil<ref name= "Stauffer2017">Stauffer, M., Pignolet, A. and Alvarado, J.C., 2017. Persistent mercury contamination in shooting range soils: the legacy from former primers. Bulletin of environmental contamination and toxicology, 98(1), pp.14-21. [https://doi.org/10.1007/s00128-016-1976-3 doi: 0.1007/s00128-016-1976-3]</ref><ref name = "Bigham2017">Bigham, G.N., Murray, K.J., Masue‐Slowey, Y. and Henry, E.A., 2017. Biogeochemical controls on methylmercury in soils and sediments: Implications for site management. Integrated environmental assessment and management, 13(2), pp.249-263. [https://doi.org/10.1002/ieam.1822 doi: 10.1002/ieam.1822]</ref>. Additionally, marine environments near legacy military training grounds may contain elevated concentrations of Hg from the dumping of ammunition after World War II, including the Baltic Sea<ref>Gębka, K., Bełdowski, J. and Bełdowska, M., 2016. The impact of military activities on the concentration of mercury in soils of military training grounds and marine sediments. Environmental Science and Pollution Research, 23(22), pp.23103-23113. [https://doi.org/10.1007/s11356-016-7436-0 doi: 10.1007/s11356-016-7436-0]</ref>. Similar to other primer metal(loid)s, Hg in firing range soils should primarily be located near the firing point instead of traveling with the bullet. An old Swiss shooting range was found to have slightly elevated total Hg concentrations above background values (44-315 μg/kg) with maximum values ranging from 906 to 1,517 μg/kg in soils at the firing point, with concentrations decreasing with increasing distance from the firing point<ref name= "Stauffer2017"/>. While the concentrations of Hg found at shooting ranges are significantly lower than concentrations reported for Pb and Sb, it still remains a health and environmental hazard due to its harmful effects and toxicity even at low concentrations<ref name = "Bigham2017"/>.
+
In many cases, energetic compounds are expected to reside within the soil surface. Figure 5 shows soil depth profiles on some studied impact areas and firing points. Overall, the energetic compound concentrations below 5-cm soil depth are negligible relative to overlying soil concentrations. For conventional munitions, this is to be expected as the energetic particles are relatively insoluble, and any dissolved compounds readily adsorb to most soils<ref>Pennington, J.C., Jenkins, T.F., Ampleman, G., Thiboutot, S., Brannon, J.M., Hewitt, A.D., Lewis, J., Brochu, S., 2006. Distribution and fate of energetics on DoD test and training ranges: Final Report. ERDC TR-06-13, Vicksburg, MS, USA. Also: SERDP/ESTCP Project ER-1155. [[media:Pennington-2006_ERDC-TR-06-13_ESTCP-ER-1155-FR.pdf| Report.pdf]]</ref>. Physical disturbance, as on hand grenade ranges, may require deeper sampling either with a soil profile or a corer/auger.
  
===Arsenic===
+
[[File:Beal1w2 Fig5.png|thumb|left|200 px|Figure 5. Depth profiles of high explosive compounds at impact areas (bottom) and of propellant compounds at firing points (top). Data from: Hewitt et al. <ref>Hewitt, A.D., Jenkins, T.F., Ramsey, C.A., Bjella, K.L., Ranney, T.A. and Perron, N.M., 2005. Estimating energetic residue loading on military artillery ranges: Large decision units (No. ERDC/CRREL-TR-05-7). [[media:Hewitt-2005 ERDC-CRREL TR-05-7.pdf| Report.pdf]]</ref> and Jenkins et al. <ref>Jenkins, T.F., Ampleman, G., Thiboutot, S., Bigl, S.R., Taylor, S., Walsh, M.R., Faucher, D., Mantel, R., Poulin, I., Dontsova, K.M. and Walsh, M.E., 2008. Characterization and fate of gun and rocket propellant residues on testing and training ranges (No. ERDC-TR-08-1). [[media:Jenkins-2008 ERDC TR-08-1.pdf| Report.pdf]]</ref>]]
[[File:Barker1w2 Fig4.png|thumb|Figure 4. Soil berms with high amounts of soil organic matter and clay minerals as shown in this picture tend to retain concentrations of metal(loid)s as a result of large surface area and active binding sites. Image shows constructed shooting range berms in Delta Junction, Alaska on the Donnelly Training Area. Photo by A.J. Barker.]]
 
[https://en.wikipedia.org/wiki/Arsenic Arsenic] (As) is a highly toxic and carcinogenic metalloid that affects nearly all organ systems<ref>Ratnaike, R.N., 2003. Acute and chronic arsenic toxicity. Postgraduate medical journal, 79(933), pp.391-396. [[media:2003-Ratnaike-Acute_and_chronic_arsenic_toxicity.pdf| Report.pdf]]</ref>. Arsenic has been found at shooting ranges to a much lesser extent than other metal(loid)s, as it is associated with Pb as an impurity. While As is a well-known contaminant in other systems, at shooting ranges it is often not measured or measured at concentrations close to background concentrations in nearby soils<ref name= "Dermatas2006"/><ref>Bannon, D.I., Drexler, J.W., Fent, G.M., Casteel, S.W., Hunter, P.J., Brattin, W.J. and Major, M.A., 2009. Evaluation of small arms range soils for metal contamination and lead bioavailability. Environmental science & technology, 43(24), pp.9071-9076. [https://doi.org/10.1021/es901834h doi: 10.1021/es901834h]</ref>. Arsenic exhibits multiple oxidation states in the near-surface environment, but is most often found as arsenite (As(III)) and/or arsenate (As(V)). Major environmental factors that affect As mobility are pH, redox condition, and soil type<ref>Bissen, M. and Frimmel, F.H., 2003. Arsenic - a review. Part I: occurrence, toxicity, speciation, mobility. Acta hydrochimica et hydrobiologica, 31(1), pp.9-18. [https://doi.org/10.1002/aheh.200390025 doi: 10.1002/aheh.200390025]</ref>.
 
 
==Management Practices==
 
Range design is an important factor in containing metal(loid)s and preventing their migration into the subsurface. Target berms may be comprised of a natural hillside or slope, or constructed with off-site source material that is shaped into an artificial barrier (as shown in Figure 4). Ensuring berm construction includes a berm face that is steep enough to prevent bullet skipping, but stable enough to minimize soil erosion, can minimize contaminated sediment losses. Siting the berm with respect to hydrologic pathways to waterbodies, aquifers, and potential ecological receptors is crucial. Additionally, it is important to decide what type of soil will comprise the berm or hillside (i.e. sand, organic-rich material, etc.) and determining soil texture and major mineral and element fractions. These soil composition variables will affect the overall speciation and mobility of the target contaminant species in bullets (Pb, Sb, etc.).  
 
Bullet catchers (see Additional Resources) are designed to catch bullets and contain bullet-related metal(loid)s for later collection and disposal.  These systems are designed for long-term use on range. The bullet-related metal(loid)s are stored internally in a protective liner to minimize soil and water interactions with the fired bullet rounds.  
 
  
Additionally, soil amendments such as phosphate and lime can alter soil pH to inhibit mobility of some metals (mainly cationic metals like Pb, Cu, Ni, and Zn), and other amendments such as Fe/Mn hydro(oxides) can facilitate sorption reactions with metal(loid)s, such as Sb and As. Although costly, spent bullets and large bullet fragments can also be removed from soils.
+
Soil sampling with the Cold Regions Research and Engineering Laboratory (CRREL) Multi-Increment Sampling Tool (CMIST) or similar device is an easy way to collect ISM samples rapidly and reproducibly. This tool has an adjustable diameter size corer and adjustable depth to collect surface soil plugs (Figure 6). The CMIST can be used at almost a walking pace (Figure 7) using a two-person sampling team, with one person operating the CMIST and the other carrying the sample container and recording the number of increments collected. The CMIST with a small diameter tip works best in soils with low cohesion, otherwise conventional scoops may be used. Maintaining consistent soil increment dimensions is critical.
 +
 
 +
The sampling tool should be cleaned between replicates and between DUs to minimize potential for cross-contamination<ref>Walsh, M.R., 2009. User’s manual for the CRREL Multi-Increment Sampling Tool. Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) SR-09-1, Hanover, NH, USA.  [[media:Walsh-2009 ERDC-CRREL SR-09-1.pdf | Report.pdf]]</ref>.
 +
 
 +
==Sample Processing==
 +
While only 10 g of soil is typically used for chemical analysis, incremental sampling generates a sample weighing on the order of 1 kg. Splitting of a sample, either in the field or laboratory, seems like an easy way to reduce sample mass; however this approach has been found to produce high uncertainty for explosives and propellants, with a median RSD of 43.1%<ref name= "Hewitt2009"/>. Even greater error is associated with removing a discrete sub-sample from an unground sample. Appendix A in [https://www.epa.gov/sites/production/files/2015-07/documents/epa-8330b.pdf U.S. EPA Method 8330B]<ref name= "USEPA2006M"/> provides details on recommended ISM sample processing procedures.
 +
 
 +
Incremental soil samples are typically air dried over the course of a few days. Oven drying thermally degrades some energetic compounds and should be avoided<ref>Cragin, J.H., Leggett, D.C., Foley, B.T., and Schumacher, P.W., 1985. TNT, RDX and HMX explosives in soils and sediments: Analysis techniques and drying losses. (CRREL Report 85-15) Hanover, NH, USA. [[media:Cragin-1985 CRREL 85-15.pdf| Report.pdf]]</ref>. Once dry, the samples are sieved with a 2-mm screen, with only the less than 2-mm fraction processed further. This size fraction represents the USDA definition of soil. Aggregate soil particles should be broken up and vegetation shredded to pass through the sieve. Samples from impact or demolition areas may contain explosive particles from low order detonations that are greater than 2 mm and should be identified, given appropriate caution, and potentially weighed.
 +
 
 +
The <2-mm soil fraction is typically still ≥1 kg and impractical to extract in full for analysis. However, subsampling at this stage is not possible due to compositional heterogeneity, with the energetic compounds generally present as <0.5 mm particles<ref name= "Walsh2017"/><ref name= "Taylor2004"/>. Particle size reduction is required to achieve a representative and precise measure of the sample concentration. Grinding in a puck mill to a soil particle size <75 µm has been found to be required for representative/reproducible sub-sampling (Figure 8). For samples thought to contain propellant particles, a prolonged milling time is required to break down these polymerized particles and achieve acceptable precision (Figure 9). Due to the multi-use nature of some ranges, a 5-minute puck milling period can be used for all soils. Cooling periods between 1-minute milling intervals are recommended to avoid thermal degradation. Similar to field sampling, sub-sampling is done incrementally by spreading the sample out to a thin layer and collecting systematic random increments of consistent volume to a total mass for extraction of 10 g (Figure 10).
 +
 
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig6.png|thumb|200 px|Figure 6: CMIST soil sampling tool (top) and with ejected increment core using a large diameter tip (bottom).]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig7.png|thumb|200 px|Figure 7: Two person sampling team using CMIST, bag-lined bucket, and increment counter. (Photos: Matthew Bigl)]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig8.png|thumb|200 px|Figure 8: Effect of machine grinding on RDX and TNT concentration and precision in soil from a hand grenade range. Data from Walsh et al.<ref>Walsh, M.E., Ramsey, C.A. and Jenkins, T.F., 2002. The effect of particle size reduction by grinding on subsampling variance for explosives residues in soil. Chemosphere, 49(10), pp.1267-1273. [https://doi.org/10.1016/S0045-6535(02)00528-3 doi: 10.1016/S0045-6535(02)00528-3]</ref> ]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig9.png|thumb|200 px|Figure 9: Effect of puck milling time on 2,4-DNT concentration and precision in soil from a firing point. Data from Walsh et al.<ref>Walsh, M.E., Ramsey, C.A., Collins, C.M., Hewitt, A.D., Walsh, M.R., Bjella, K.L., Lambert, D.J. and Perron, N.M., 2005. Collection methods and laboratory processing of samples from Donnelly Training Area Firing Points, Alaska, 2003 (No. ERDC/CRREL-TR-05-6). [[media:Walsh-2005 ERDC-CRREL TR-05-6.pdf| Report.pdf]]</ref>.]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig10.png|thumb|200 px|center|Figure 10: Incremental sub-sampling of a milled soil sample spread out on aluminum foil.]]</li>
 +
 
 +
==Analysis==
 +
Soil sub-samples are extracted and analyzed following [[Media: epa-2006-method-8330b.pdf | EPA Method 8330B]]<ref name= "USEPA2006M"/> and [[Media:epa-2007-method-8095.pdf | Method 8095]]<ref name= "USEPA2007M"/> using [[Wikipedia: High-performance liquid chromatography | High Performance Liquid Chromatography (HPLC)]] and [[Wikipedia: Gas chromatography | Gas Chromatography (GC)]], respectively. Common estimated reporting limits for these analysis methods are listed in Table 2.
 +
 
 +
{| class="wikitable" style="float: center; text-align: center; margin-left: auto; margin-right: auto;"
 +
|+ Table 2. Typical Method Reporting Limits for Energetic Compounds in Soil. (Data from Hewitt et al.<ref>Hewitt, A., Bigl, S., Walsh, M., Brochu, S., Bjella, K. and Lambert, D., 2007. Processing of training range soils for the analysis of energetic compounds (No. ERDC/CRREL-TR-07-15). Hanover, NH, USA. [[media:Hewitt-2007 ERDC-CRREL TR-07-15.pdf| Report.pdf]]</ref>)
 +
|-
 +
! rowspan="2" | Compound
 +
! colspan="2" | Soil Reporting Limit (mg/kg)
 +
|-
 +
! HPLC (8330)
 +
! GC (8095)
 +
|-
 +
| HMX || 0.04 || 0.01
 +
|-
 +
| RDX || 0.04 || 0.006
 +
|-
 +
| [[Wikipedia: 1,3,5-Trinitrobenzene | TNB]] || 0.04 || 0.003
 +
|-
 +
| TNT || 0.04 || 0.002
 +
|-
 +
| [[Wikipedia: 2,6-Dinitrotoluene | 2,6-DNT]] || 0.08 || 0.002
 +
|-
 +
| 2,4-DNT || 0.04 || 0.002
 +
|-
 +
| 2-ADNT || 0.08 || 0.002
 +
|-
 +
| 4-ADNT || 0.08 || 0.002
 +
|-
 +
| NG || 0.1 || 0.01
 +
|-
 +
| [[Wikipedia: Dinitrobenzene | DNB ]] || 0.04 || 0.002
 +
|-
 +
| [[Wikipedia: Tetryl | Tetryl ]]  || 0.04 || 0.01
 +
|-
 +
| [[Wikipedia: Pentaerythritol tetranitrate | PETN ]] || 0.2 || 0.016
 +
|}
  
 
==References==
 
==References==
 
+
<references/>
<references />
 
  
 
==See Also==
 
==See Also==
*[https://www.stappebc.com/environmental-bullet-catcher/about/ Environmental Bullet Catcher]
+
*[https://itrcweb.org/ Interstate Technology and Regulatory Council]
 +
*[http://www.hawaiidoh.org/tgm.aspx Hawaii Department of Health]
 +
*[http://envirostat.org/ Envirostat]

Latest revision as of 18:58, 29 April 2020

The heterogeneous distribution of munitions constituents, released as particles from munitions firing and detonations on military training ranges, presents challenges for representative soil sample collection and for defensible decision making. Military range characterization studies and the development of the incremental sampling methodology (ISM) have enabled the development of recommended methods for soil sampling that produce representative and reproducible concentration data for munitions constituents. This article provides a broad overview of recommended soil sampling and processing practices for analysis of munitions constituents on military ranges.

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CONTRIBUTOR(S): Dr. Samuel Beal


Key Resource(s):

Introduction

Figure 1: Downrange distance of visible propellant plume on snow from the firing of different munitions. Note deposition behind firing line for the 84-mm rocket. Data from: Walsh et al.[5][6]
Figure 2: A low-order detonation mortar round (top) with surrounding discrete soil samples produced concentrations spanning six orders of magnitude within a 10m by 10m area (bottom). (Photo and data: A.D. Hewitt)

Munitions constituents are released on military testing and training ranges through several common mechanisms. Some are locally dispersed as solid particles from incomplete combustion during firing and detonation. Also, small residual particles containing propellant compounds (e.g., nitroglycerin [NG] and 2,4-dinitrotoluene [2,4-DNT]) are distributed in front of and surrounding target practice firing lines (Figure 1). At impact areas and demolition areas, high order detonations typically yield very small amounts (<1 to 10 mg/round) of residual high explosive compounds (e.g., TNT , RDX and HMX ) that are distributed up to and sometimes greater than) 24 m from the site of detonation[7].

Low-order detonations and duds are thought to be the primary source of munitions constituents on ranges[8][9]. Duds are initially intact but may become perforated or fragmented into micrometer to centimeter;o0i0k-sized particles by nearby detonations[10]. Low-order detonations can scatter micrometer to centimeter-sized particles up to 20 m from the site of detonation[11]

The particulate nature of munitions constituents in the environment presents a distinct challenge to representative soil sampling. Figure 2 shows an array of discrete soil samples collected around the site of a low-order detonation – resultant soil concentrations vary by orders of magnitude within centimeters of each other. The inadequacy of discrete sampling is apparent in characterization studies from actual ranges which show wide-ranging concentrations and poor precision (Table 1).

In comparison to discrete sampling, incremental sampling tends to yield reproducible concentrations (low relative standard deviation [RSD]) that statistically better represent an area of interest[2].

Table 1. Soil Sample Concentrations and Precision from Military Ranges Using Discrete and Incremental Sampling. (Data from Taylor et al. [1] and references therein.)
Military Range Type Analyte Range
(mg/kg)
Median
(mg/kg)
RSD
(%)
Discrete Samples
Artillery FP 2,4-DNT <0.04 – 6.4 0.65 110
Antitank Rocket HMX 5.8 – 1,200 200 99
Bombing TNT 0.15 – 780 6.4 274
Mortar RDX <0.04 – 2,400 1.7 441
Artillery RDX <0.04 – 170 <0.04 454
Incremental Samples*
Artillery FP 2,4-DNT 0.60 – 1.4 0.92 26
Bombing TNT 13 – 17 14 17
Artillery/Bombing RDX 3.9 – 9.4 4.8 38
Thermal Treatment HMX 3.96 – 4.26 4.16 4
* For incremental samples, 30-100 increments and 3-10 replicate samples were collected.

Incremental Sampling Approach

ISM is a requisite for representative and reproducible sampling of training ranges, but it is an involved process that is detailed thoroughly elsewhere[2][1][3]. In short, ISM involves the collection of many (30 to >100) increments in a systematic pattern within a decision unit (DU). The DU may cover an area where releases are thought to have occurred or may represent an area relevant to ecological receptors (e.g., sensitive species). Figure 3 shows the ISM sampling pattern in a simplified (5x5 square) DU. Increments are collected at a random starting point with systematic distances between increments. Replicate samples can be collected by starting at a different random starting point, often at a different corner of the DU. Practically, this grid pattern can often be followed with flagging or lathe marking DU boundaries and/or sampling lanes and with individual pacing keeping systematic distances between increments. As an example, an artillery firing point might include a 100x100 m DU with 81 increments.

Figure 3. Example ISM sampling pattern on a square decision unit. Replicates are collected in a systematic pattern from a random starting point at a corner of the DU. Typically more than the 25 increments shown are collected

DUs can vary in shape (Figure 4), size, number of increments, and number of replicates according to a project’s data quality objectives.

Figure 4: Incremental sampling of a circular DU on snow shows sampling lanes with a two-person team in process of collecting the second replicate in a perpendicular path to the first replicate. (Photo: Matthew Bigl)

Sampling Tools

In many cases, energetic compounds are expected to reside within the soil surface. Figure 5 shows soil depth profiles on some studied impact areas and firing points. Overall, the energetic compound concentrations below 5-cm soil depth are negligible relative to overlying soil concentrations. For conventional munitions, this is to be expected as the energetic particles are relatively insoluble, and any dissolved compounds readily adsorb to most soils[12]. Physical disturbance, as on hand grenade ranges, may require deeper sampling either with a soil profile or a corer/auger.

Figure 5. Depth profiles of high explosive compounds at impact areas (bottom) and of propellant compounds at firing points (top). Data from: Hewitt et al. [13] and Jenkins et al. [14]

Soil sampling with the Cold Regions Research and Engineering Laboratory (CRREL) Multi-Increment Sampling Tool (CMIST) or similar device is an easy way to collect ISM samples rapidly and reproducibly. This tool has an adjustable diameter size corer and adjustable depth to collect surface soil plugs (Figure 6). The CMIST can be used at almost a walking pace (Figure 7) using a two-person sampling team, with one person operating the CMIST and the other carrying the sample container and recording the number of increments collected. The CMIST with a small diameter tip works best in soils with low cohesion, otherwise conventional scoops may be used. Maintaining consistent soil increment dimensions is critical.

The sampling tool should be cleaned between replicates and between DUs to minimize potential for cross-contamination[15].

Sample Processing

While only 10 g of soil is typically used for chemical analysis, incremental sampling generates a sample weighing on the order of 1 kg. Splitting of a sample, either in the field or laboratory, seems like an easy way to reduce sample mass; however this approach has been found to produce high uncertainty for explosives and propellants, with a median RSD of 43.1%[2]. Even greater error is associated with removing a discrete sub-sample from an unground sample. Appendix A in U.S. EPA Method 8330B[3] provides details on recommended ISM sample processing procedures.

Incremental soil samples are typically air dried over the course of a few days. Oven drying thermally degrades some energetic compounds and should be avoided[16]. Once dry, the samples are sieved with a 2-mm screen, with only the less than 2-mm fraction processed further. This size fraction represents the USDA definition of soil. Aggregate soil particles should be broken up and vegetation shredded to pass through the sieve. Samples from impact or demolition areas may contain explosive particles from low order detonations that are greater than 2 mm and should be identified, given appropriate caution, and potentially weighed.

The <2-mm soil fraction is typically still ≥1 kg and impractical to extract in full for analysis. However, subsampling at this stage is not possible due to compositional heterogeneity, with the energetic compounds generally present as <0.5 mm particles[7][11]. Particle size reduction is required to achieve a representative and precise measure of the sample concentration. Grinding in a puck mill to a soil particle size <75 µm has been found to be required for representative/reproducible sub-sampling (Figure 8). For samples thought to contain propellant particles, a prolonged milling time is required to break down these polymerized particles and achieve acceptable precision (Figure 9). Due to the multi-use nature of some ranges, a 5-minute puck milling period can be used for all soils. Cooling periods between 1-minute milling intervals are recommended to avoid thermal degradation. Similar to field sampling, sub-sampling is done incrementally by spreading the sample out to a thin layer and collecting systematic random increments of consistent volume to a total mass for extraction of 10 g (Figure 10).

  • Figure 6: CMIST soil sampling tool (top) and with ejected increment core using a large diameter tip (bottom).
  • Figure 7: Two person sampling team using CMIST, bag-lined bucket, and increment counter. (Photos: Matthew Bigl)
  • Figure 8: Effect of machine grinding on RDX and TNT concentration and precision in soil from a hand grenade range. Data from Walsh et al.[17]
  • Figure 9: Effect of puck milling time on 2,4-DNT concentration and precision in soil from a firing point. Data from Walsh et al.[18].
  • Figure 10: Incremental sub-sampling of a milled soil sample spread out on aluminum foil.
  • Analysis

    Soil sub-samples are extracted and analyzed following EPA Method 8330B[3] and Method 8095[4] using High Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC), respectively. Common estimated reporting limits for these analysis methods are listed in Table 2.

    Table 2. Typical Method Reporting Limits for Energetic Compounds in Soil. (Data from Hewitt et al.[19])
    Compound Soil Reporting Limit (mg/kg)
    HPLC (8330) GC (8095)
    HMX 0.04 0.01
    RDX 0.04 0.006
    TNB 0.04 0.003
    TNT 0.04 0.002
    2,6-DNT 0.08 0.002
    2,4-DNT 0.04 0.002
    2-ADNT 0.08 0.002
    4-ADNT 0.08 0.002
    NG 0.1 0.01
    DNB 0.04 0.002
    Tetryl 0.04 0.01
    PETN 0.2 0.016

    References

    1. ^ 1.0 1.1 1.2 Taylor, S., Jenkins, T.F., Bigl, S., Hewitt, A.D., Walsh, M.E. and Walsh, M.R., 2011. Guidance for Soil Sampling for Energetics and Metals (No. ERDC/CRREL-TR-11-15). Report.pdf
    2. ^ 2.0 2.1 2.2 2.3 Hewitt, A.D., Jenkins, T.F., Walsh, M.E., Bigl, S.R. and Brochu, S., 2009. Validation of sampling protocol and the promulgation of method modifications for the characterization of energetic residues on military testing and training ranges (No. ERDC/CRREL-TR-09-6). Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) TR-09-6, Hanover, NH, USA. Report.pdf
    3. ^ 3.0 3.1 3.2 3.3 U.S. Environmental Protection Agency (USEPA), 2006. Method 8330B (SW-846): Nitroaromatics, Nitramines, and Nitrate Esters by High Performance Liquid Chromatography (HPLC), Rev. 2. Washington, D.C. Report.pdf
    4. ^ 4.0 4.1 U.S. Environmental Protection Agency (US EPA), 2007. Method 8095 (SW-846): Explosives by Gas Chromatography. Washington, D.C. Report.pdf
    5. ^ Walsh, M.R., Walsh, M.E., Ampleman, G., Thiboutot, S., Brochu, S. and Jenkins, T.F., 2012. Munitions propellants residue deposition rates on military training ranges. Propellants, Explosives, Pyrotechnics, 37(4), pp.393-406. doi: 10.1002/prep.201100105
    6. ^ Walsh, M.R., Walsh, M.E., Hewitt, A.D., Collins, C.M., Bigl, S.R., Gagnon, K., Ampleman, G., Thiboutot, S., Poulin, I. and Brochu, S., 2010. Characterization and Fate of Gun and Rocket Propellant Residues on Testing and Training Ranges: Interim Report 2. (ERDC/CRREL TR-10-13. Also: ESTCP Project ER-1481) Report
    7. ^ 7.0 7.1 Walsh, M.R., Temple, T., Bigl, M.F., Tshabalala, S.F., Mai, N. and Ladyman, M., 2017. Investigation of Energetic Particle Distribution from High‐Order Detonations of Munitions. Propellants, Explosives, Pyrotechnics, 42(8), pp.932-941. doi: 10.1002/prep.201700089 Report.pdf
    8. ^ Hewitt, A.D., Jenkins, T.F., Walsh, M.E., Walsh, M.R. and Taylor, S., 2005. RDX and TNT residues from live-fire and blow-in-place detonations. Chemosphere, 61(6), pp.888-894. doi: 10.1016/j.chemosphere.2005.04.058
    9. ^ Walsh, M.R., Walsh, M.E., Poulin, I., Taylor, S. and Douglas, T.A., 2011. Energetic residues from the detonation of common US ordnance. International Journal of Energetic Materials and Chemical Propulsion, 10(2). doi: 10.1615/IntJEnergeticMaterialsChemProp.2012004956 Report.pdf
    10. ^ Walsh, M.R., Thiboutot, S., Walsh, M.E., Ampleman, G., Martel, R., Poulin, I. and Taylor, S., 2011. Characterization and fate of gun and rocket propellant residues on testing and training ranges (No. ERDC/CRREL-TR-11-13). Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) TR-11-13, Hanover, NH, USA. Report.pdf
    11. ^ 11.0 11.1 Taylor, S., Hewitt, A., Lever, J., Hayes, C., Perovich, L., Thorne, P. and Daghlian, C., 2004. TNT particle size distributions from detonated 155-mm howitzer rounds. Chemosphere, 55(3), pp.357-367. Report.pdf
    12. ^ Pennington, J.C., Jenkins, T.F., Ampleman, G., Thiboutot, S., Brannon, J.M., Hewitt, A.D., Lewis, J., Brochu, S., 2006. Distribution and fate of energetics on DoD test and training ranges: Final Report. ERDC TR-06-13, Vicksburg, MS, USA. Also: SERDP/ESTCP Project ER-1155. Report.pdf
    13. ^ Hewitt, A.D., Jenkins, T.F., Ramsey, C.A., Bjella, K.L., Ranney, T.A. and Perron, N.M., 2005. Estimating energetic residue loading on military artillery ranges: Large decision units (No. ERDC/CRREL-TR-05-7). Report.pdf
    14. ^ Jenkins, T.F., Ampleman, G., Thiboutot, S., Bigl, S.R., Taylor, S., Walsh, M.R., Faucher, D., Mantel, R., Poulin, I., Dontsova, K.M. and Walsh, M.E., 2008. Characterization and fate of gun and rocket propellant residues on testing and training ranges (No. ERDC-TR-08-1). Report.pdf
    15. ^ Walsh, M.R., 2009. User’s manual for the CRREL Multi-Increment Sampling Tool. Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) SR-09-1, Hanover, NH, USA. Report.pdf
    16. ^ Cragin, J.H., Leggett, D.C., Foley, B.T., and Schumacher, P.W., 1985. TNT, RDX and HMX explosives in soils and sediments: Analysis techniques and drying losses. (CRREL Report 85-15) Hanover, NH, USA. Report.pdf
    17. ^ Walsh, M.E., Ramsey, C.A. and Jenkins, T.F., 2002. The effect of particle size reduction by grinding on subsampling variance for explosives residues in soil. Chemosphere, 49(10), pp.1267-1273. doi: 10.1016/S0045-6535(02)00528-3
    18. ^ Walsh, M.E., Ramsey, C.A., Collins, C.M., Hewitt, A.D., Walsh, M.R., Bjella, K.L., Lambert, D.J. and Perron, N.M., 2005. Collection methods and laboratory processing of samples from Donnelly Training Area Firing Points, Alaska, 2003 (No. ERDC/CRREL-TR-05-6). Report.pdf
    19. ^ Hewitt, A., Bigl, S., Walsh, M., Brochu, S., Bjella, K. and Lambert, D., 2007. Processing of training range soils for the analysis of energetic compounds (No. ERDC/CRREL-TR-07-15). Hanover, NH, USA. Report.pdf

    See Also