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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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<div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
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'''Related Article(s)''':
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'''CONTRIBUTOR(S):'''  [[Dr. Samuel Beal]]
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'''Key Resource(s)''':
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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>
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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>
  
1,4-Dioxane (14D) is a heterocyclic synthetic organic chemical that contains two ether bonds, is miscible with water, does not strongly sorb to natural or engineered materials, and does not biodegrade in many environments, all of which results in its persistence and rapid transport in aqueous environments. 14D is a suspected human carcinogen, which has resulted in relatively strict standards for drinking water sources. Advanced oxidation processes (AOPs) are the most well-developed technologies for removal of 14D from potable water supplies. Several treatment technologies are being developed for ''in situ'' treatment of 14D including chemical oxidation, cometabolic bioremediation, and thermally enhanced soil vapor extraction.
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==Introduction==
<div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
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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>]]
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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)]]
  
'''Related Article(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>.
*[[Biodegradation – 1,4-Dioxane]]
 
*[[Biodegradation - Cometabolic]]  
 
  
'''CONTRIBUTOR(S):''' [[Matthew Zenker]], [[Dr. Shaily Mahendra]], and [[Dr. Michael Hyman]]
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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>
  
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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).
  
'''Key Resource(s)''':
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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://doi.org/10.1201/EBK1566706629 Environmental Investigation and Remediation: 1,4-Dioxane and other solvent stabilizers]<ref name= "Mohr2010">Mohr, T.K., Stickney, J.A. and DiGuiseppi, W.H., 2010. Environmental investigation and remediation: 1, 4-dioxane and other solvent stabilizers. CRC Press. Boca Raton. 550 pages. [https://doi.org/10.1201/EBK1566706629 doi: 10.1201/EBK1566706629]</ref>
 
  
==Properties, Fate and Transport==
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{| class="wikitable" style="float: right; text-align: center; margin-left: auto; margin-right: auto;"
1,4-Dioxane (14D) is a heterocyclic organic compound, and the most commonly encountered of the three dioxane isomers (1,2-, 1,3- and 1,4-Dioxane). Key physical and chemical properties of 14D are listed in Table 1.  The heterocyclic, polar structure of 1,4-Dioxane causes it to be miscible with water and also unable to strongly sorb or partition to aquifer solids or engineered sorbents (i.e. activated carbon).  While 14D has a moderate vapor pressure, the high aqueous solubility results in limited volatilization.
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|+ 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.)
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{| class="wikitable" style= "float:right; margin-left: 10px;"
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! Military Range Type !! Analyte !! Range<br/>(mg/kg) !! Median<br/>(mg/kg) !! RSD<br/>(%)
|+ Table 1. Properties of 1,4-Dioxane
 
 
|-
 
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! Property
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| colspan="5" style="text-align: left;" | '''Discrete Samples'''
! Value
 
! Reference
 
 
|-
 
|-
| Chemical Formula || C<sub>4</sub>H<sub>8</sub>O<sub>2</sub> ||
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| Artillery FP || 2,4-DNT || <0.04 – 6.4 || 0.65 || 110
 
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| Chemical Abstracts Service (CAS) Number || 123-91-1 ||
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| Antitank Rocket || HMX || 5.8 – 1,200 || 200 || 99
 
|-
 
|-
| Appearance || Colorless Liquid || NIOSH, 2007<ref name= "NIOSH2007">Barsan, M.E., 2007. NIOSH pocket guide to chemical hazards. [[media:2007-NIOSH_Pocket_Guide_to_Chemical_Hazards.pdf| Report.pdf]]</ref>
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| Bombing || TNT || 0.15 – 780 || 6.4 || 274
 
|-
 
|-
| Molecular Weight ||88.105 g/mol || NIST, 2018<ref>NIST, 2018. NIST Chemistry WebBook: Standard Reference Database 69. US Department of Commerce.</ref>
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| Mortar || RDX || <0.04 – 2,400 || 1.7 || 441
 
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| Water Solubility || Miscible || NIOSH, 2007<ref name= "NIOSH2007"/>
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| Artillery || RDX || <0.04 – 170 || <0.04 || 454
 
|-
 
|-
| Specific Gravity || 1.03 || NIOSH, 2007<ref name= "NIOSH2007"/>
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| colspan="5" style="text-align: left;" | '''Incremental Samples*'''
 
|-
 
|-
| Vapor Pressure at 25&deg; C || 38.1 mm Hg || US EPA, 2017<ref name= "USEPA2017Z">US EPA, 2017. Technical Fact Sheet – 1,4-Dioxane. Publication number: EPA 505-F-17-001. [[media:2017-USEPA-_Technical_Fact_Sheet.pdf| Report.pdf]]</ref>
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| Artillery FP || 2,4-DNT || 0.60 – 1.4 || 0.92 || 26
 
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| Henry’s Law Constant at 25&deg; C || 4.80 X 10<sup>-6</sup> atm-m<sup>3</sup>/mol || US EPA, 2017<ref name= "USEPA2017Z"/>
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| Bombing || TNT || 13 – 17 || 14 || 17
 
|-
 
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| Octanol-Water Partition Coefficient (log ''K<sub>ow</sub>'') || -0.27 || US EPA, 2017<ref name= "USEPA2017Z"/>
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| Artillery/Bombing || RDX || 3.9 – 9.4 || 4.8 || 38
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|-  
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| Thermal Treatment || HMX || 3.96 – 4.26 || 4.16 || 4
 
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| Organic Carbon Partition Coefficient (log ''K<sub>oc</sub>'') || 1.23 || Lyman et al., 1990<ref>Lyman, W.J., W.F. Reehl , D.H. Rosenblatt, and N.P.E. Vermeulen, 1990. Handbook of Chemical Property Estimation Methods. American Chemical Society, 110(2), 61-61. [https://doi.org/10.1002/recl.19911100212 doi: 10.1002/recl.19911100212]</ref>
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| colspan="5" style="text-align: left; background-color: white;" | * For incremental samples, 30-100 increments and 3-10 replicate samples were collected.
 
|}
 
|}
  
Biodegradation of 14D is limited in many environments including surface water, groundwater and wastewater treatment plants (see [Biodegradation – 1,4-Dioxane]).  Currently, there is little evidence that 14D biodegrades under anaerobic conditions<ref>Shen, W., Chen, H. and Pan, S., 2008. Anaerobic biodegradation of 1, 4-dioxane by sludge enriched with iron-reducing microorganisms. Bioresource technology, 99(7), pp.2483-2487. [https://doi.org/10.1016/j.biortech.2007.04.054 doi: 10.1016/j.biortech.2007.04.054]</ref><ref name= "Zhang2017">Zhang, S., Gedalanga, P.B. and Mahendra, S., 2017. Advances in bioremediation of 1, 4-dioxane-contaminated waters. Journal of environmental management, 204, pp.765-774. [https://doi.org/10.1016/j.jenvman.2017.05.033 doi: 10.1016/j.jenvman.2017.05.033]</ref>.  In contrast, under aerobic conditions, several bacteria and fungi<ref>Skinner, K., Cuiffetti, L. and Hyman, M., 2009. Metabolism and cometabolism of cyclic ethers by a filamentous fungus, a Graphium sp. Appl. Environ. Microbiol., 75(17), pp.5514-5522. [https://doi.org/10.1128/aem.00078-09 doi:10.1128/AEM.00078-09]</ref> can grow on 14D as a sole source of carbon and energy, including well-characterized strains such as ''Pseudonocardia dioxanivorans'' CB1190<ref name= "Parales1994">Parales, R.E., Adamus, J.E., White, N. and May, H.D., 1994. Degradation of 1, 4-dioxane by an actinomycete in pure culture. Applied and Environmental Microbiology, 60(12), pp.4527-4530. [[media:1994-Parales-Degradation_of_1%2C4-Dioxane_by_an_Actinomycete_in_Pure_Culture.pdf| Report.pdf]]</ref><ref name= "Mahendra2006">Mahendra, S. and Alvarez-Cohen, L., 2006. Kinetics of 1, 4-dioxane biodegradation by monooxygenase-expressing bacteria. Environmental Science & Technology, 40(17), pp.5435-5442. [https://doi.org/10.1021/es060714v  [https://doi.org/10.1021/es060714v doi: 10.1021/es060714v]</ref>) and other closely related actinomycetes<ref name= "Zhang2017"/><ref>Yamamoto, N., Saito, Y., Inoue, D., Sei, K. and Ike, M., 2018. Characterization of newly isolated Pseudonocardia sp. N23 with high 1, 4-dioxane-degrading ability. Journal of bioscience and bioengineering, 125(5), pp.552-558. [https://doi.org/10.1016/j.jbiosc.2017.12.005 doi: 10.1016/j.jbiosc.2017.12.005]</ref><ref>Inoue, D., Tsunoda, T., Sawada, K., Yamamoto, N., Saito, Y., Sei, K. and Ike, M., 2016. 1, 4-Dioxane degradation potential of members of the genera Pseudonocardia and Rhodococcus. Biodegradation, 27(4-6), pp.277-286. [https://doi.org/10.1007/s10532-016-9772-7 doi: 10.1007/s10532-016-9772-7]</ref><ref>Kim, Y.M., Jeon, J.R., Murugesan, K., Kim, E.J. and Chang, Y.S., 2009. Biodegradation of 1, 4-dioxane and transformation of related cyclic compounds by a newly isolated Mycobacterium sp. PH-06. Biodegradation, 20(4), p.511. [https://doi.org/10.1007/s10532-008-9240-0 doi: 10.1007/s10532-008-9240-0]</ref>. However, growth of these organisms on 14D is slow<ref>Barajas-Rodriguez, F.J. and Freedman, D.L., 2018. Aerobic biodegradation kinetics for 1, 4-dioxane under metabolic and cometabolic conditions. Journal of hazardous materials, 350, pp.180-188. [https://doi.org/10.1016/j.jhazmat.2018.02.030 doi: 10.1016/j.jhazmat.2018.02.030]</ref>, and as a consequence, 14D-metabolizing microorganisms are generally not effective in degrading 14D at the lower concentrations (≤100 &mu;g/L) commonly observed in surface water and groundwater <ref name= "Adamson2014">Adamson, D.T., Mahendra, S., Walker Jr, K.L., Rauch, S.R., Sengupta, S. and Newell, C.J., 2014. A multisite survey to identify the scale of the 1, 4-dioxane problem at contaminated groundwater sites. Environmental Science & Technology Letters, 1(5), pp.254-258. [https://doi.org/10.1021/ez500092u doi: 10.1021/ez500092u]</ref><ref name= "Knappe2016">Knappe, D., Lopez-Velandia, C., Hopkins, Z. and Sun, M., 2016. Occurrence of 1, 4-Dioxane in the Cape Fear River Watershed and Effectiveness of Water Treatment Options for 1, 4-Dioxane Control. NC Water Resources Research Institute of The University of North Carolina, Report No. 478. [[media:2016-Knappe-Occurrence_of_1%2C4-dioxane_in_the_Cape_Fear_River.pdf| Report.pdf]]</ref>. 
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==Incremental Sampling Approach==
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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.
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[[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]]
  
While 14D is not commonly used as a microbial growth substrate at ambient concentrations, there are a wide variety of microorganisms that can [https://enviro.wiki/index.php?title=Biodegradation_-_Cometabolic cometabolically biodegrade] 14D when grown on a different (primary) substrate. During cometabolism, the primary substrate supports production of active biomass and induces the appropriate enzymes that can then fortuitously biodegrade 14D. Primary substrates that have been shown to support cometabolic biodegradation of 14D include tetrahydrofuran (THF), toluene, methane, ethane, propane, and isobutane<ref name= "Mahendra2006"/><ref>Vainberg, S., McClay, K., Masuda, H., Root, D., Condee, C., Zylstra, G.J. and Steffan, R.J., 2006. Biodegradation of ether pollutants by Pseudonocardia sp. strain ENV478. Appl. Environ. Microbiol., 72(8), pp.5218-5224. [https://doi.org/10.1128/aem.00160-06 doi: 10.1128/AEM.00160-06]</ref><ref>Hatzinger, P.B., Banerjee, R., Rezes, R., Streger, S.H., McClay, K. and Schaefer, C.E., 2017. Potential for cometabolic biodegradation of 1, 4-dioxane in aquifers with methane or ethane as primary substrates. Biodegradation, 28(5-6), pp.453-468. [https://doi.org/10.1007/s10532-017-9808-7 doi: 0.1007/s10532-017-9808-7]</ref><ref>Bennett, P., Hyman, M., Smith, C., El Mugammar, H., Chu, M.Y., Nickelsen, M. and Aravena, R., 2018. Enrichment with carbon-13 and deuterium during monooxygenase-mediated biodegradation of 1, 4-dioxane. Environmental Science & Technology Letters, 5(3), pp.148-153. [https://doi.org/10.1021/acs.estlett.7b00565 doi: 10.1021/acs.estlett.7b00565]</ref><ref>Deng, D., Li, F., Wu, C. and Li, M., 2018. Synchronic Biotransformation of 1, 4-Dioxane and 1, 1-Dichloroethylene by a Gram-Negative Propanotroph Azoarcus sp. DD4. Environmental Science & Technology Letters, 5(8), pp.526-532. [https://doi.org/10.1021/acs.estlett.8b00312 doi: 10.1021/acs.estlett.8b00312]</ref>. Recent field studies have demonstrated that propane-stimulated cometabolic biodegradation can reduce 14D to below 2-3 µg/L under appropriate conditions<ref name= "Lippincott2015">Lippincott, D., Streger, S.H., Schaefer, C.E., Hinkle, J., Stormo, J. and Steffan, R.J., 2015. Bioaugmentation and propane biosparging for in situ biodegradation of 1, 4‐dioxane. Groundwater Monitoring & Remediation, 35(2), pp.81-92. [https://doi.org/10.1111/gwmr.12093 doi: 10.1111/gwmr.12093]</ref><ref name= "Chu2018">Chu, M.Y.J., Bennett, P.J., Dolan, M.E., Hyman, M.R., Peacock, A.D., Bodour, A., Anderson, R.H., Mackay, D.M. and Goltz, M.N., 2018. Concurrent Treatment of 1, 4‐Dioxane and Chlorinated Aliphatics in a Groundwater Recirculation System Via Aerobic Cometabolism. Groundwater Monitoring & Remediation, 38(3), pp.53-64. [https://doi.org/10.1111/gwmr.12293 doi: 10.1111/gwmr.12293]</ref>.
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DUs can vary in shape (Figure 4), size, number of increments, and number of replicates according to a project’s data quality objectives.
  
As a result of the low sorption, low volatilization and low biodegradation, attenuation of 14D is often limited in groundwater<ref>Nyer, E., Boettcher, G. and Morello, B., 1991. Using the properties of organic compounds to help design a treatment system. Groundwater Monitoring & Remediation, 11(4), pp.81-86. [https://doi.org/10.1111/j.1745-6592.1991.tb00395.x doi: 10.1111/j.1745-6592.1991.tb00395.x]</ref><ref>Jackson, R.E. and Dwarakanath, V., 1999. Chlorinated decreasing solvents: physical‐chemical properties affecting aquifer contamination and remediation. Groundwater Monitoring & Remediation, 19(4), pp.102-110. [https://doi.org/10.1111/j.1745-6592.1999.tb00246.x doi: 10.1111/j.1745-6592.1999.tb00246.x]</ref>, surface water<ref name= "Knappe2016"/> and traditional potable and wastewater treatment systems<ref name = "Stepien2014">Stepien, D.K., Diehl, P., Helm, J., Thoms, A. and Püttmann, W., 2014. Fate of 1, 4-dioxane in the aquatic environment: From sewage to drinking water. Water Research, 48, pp.406-419. [https://doi.org/10.1016/j.watres.2013.09.057 doi: 10.1016/j.watres.2013.09.057]</ref>.  In groundwater, the limited sorption of 14D results in relatively low concentrations in the source area and large dilute plumes<ref name= "Adamson2014"/>. Under these conditions, much of the 14D mass will be present in the downgradient plume and aggressive treatment of the source area is generally less effective in reducing 14D migration.
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[[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)]]
  
==Toxicity and Regulatory Standards (updated 2018)==
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==Sampling Tools==
The U.S. Department of Health and Human Services<ref>ATSDR, 2012. Toxicological profile for 1,4-dioxane. Agency for Toxic Substances and Disease Registry [[media:2012-ASTDR._Toxicological_profile_for_1%2C4-dioxane.pdf| Report.pdf]]</ref> classifies 14D as a reasonably anticipated human carcinogen and the International Agency for Research on Cancer<ref name= "IARC1999">IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, International Agency for Research on Cancer and World Health Organization, 1999. Re-evaluation of some organic chemicals, hydrazine and hydrogen peroxide. IARC.</ref><ref>Stickney, J.A., Sager, S.L., Clarkson, J.R., Smith, L.A., Locey, B.J., Bock, M.J., Hartung, R. and Olp, S.F., 2003. An updated evaluation of the carcinogenic potential of 1, 4-dioxane. Regulatory Toxicology and Pharmacology, 38(2), pp.183-195. [https://doi.org/10.1016/S0273-2300(03)00090-4 doi: 10.1016/S0273-2300(03)00090-4]</ref> regards 14D as possibly carcinogenic to humans (Group 2B).  These classifications are primarily based on research on mice, rats and guinea pigs<ref name= "IARC1999"/>. One human epidemiological study reported no increased deaths from cancer in workers exposed to 14D<ref>Buffler, P.A., Wood, S.M., Suarez, L. and Kilian, D.J., 1978. Mortality follow-up of workers exposed to 1, 4-dioxane. Journal of occupational medicine.: official publication of the Industrial Medical Association, 20(4), pp.255-259.</ref>.
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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.
  
There is currently no maximum contaminant level (MCL) for 14D. However, tap water screening (0.46 µg/L) and drinking water equivalent levels (1 mg/L)<ref>U.S. Environmental Protection Agency (USEPA), 2018(a). Edition of the Drinking Water Standards and Health Advisories. EPA 822-F-18-001 [[media:2018-USEPA-Edition_of_the_Drinking_Water_Standards_and_Health_Advisories.pdf| Report.pdf]]</ref> have been established.  For soil contamination, the US EPA has calculated a residential soil screening level (SSL) of 5.3 milligrams per kilogram (mg/kg), an industrial SSL of 24 mg/kg and leach-based SSL of 9.4 x 10<sup>-5</sup> mg/kg <ref>U.S. Environmental Protection Agency (USEPA), 2018(b). Regional Screening Level (RSL) Summary Tables. </ref>.  Many states have established drinking water and groundwater standards, which range from 0.25 (New Hampshire) to 9.1 µg/L (Texas)<ref>Suthersan, S., Quinnan, J., Horst, J., Ross, I., Kalve, E., Bell, C. and Pancras, T., 2016. Making strides in the management of “emerging contaminants”. Groundwater Monitoring & Remediation, 36(1), pp.15-25. [https://doi.org/10.1111/gwmr.12143 doi: 10.1111/gwmr.12143]</ref>
+
[[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>]]
  
==History of Use and Release to Environment==
+
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 most common use of 14D has been as a solvent stabilizer for 1,1,1-trichloroethane (TCA) utilized in metal degreasing operations. The addition of 14D to degreasing solvents such as TCA inhibits the formation of metal salts, which can result in solvent breakdown<ref name= "Mohr2010"/>. Approximately 90% of 14D produced in the 1980s was used as a stabilizer for TCA<ref name= "Mohr2010"/>.  Following the [https://en.wikipedia.org/wiki/Montreal_Protocol phase-out of ozone depleting chemicals] including TCA, the production and use of 14D has declined. Beyond its use as a solvent stabilizer, 14D has also been used in textile, paint and ink, cellulose acetate membrane and adhesive manufacturing operations<ref name= "Mohr2010"/>.
 
  
14D is an un-intended byproduct of some organic chemical synthesis processes<ref name= "Mohr2010"/>.  14D can be produced during manufacture of alcohol ethoxylates which are used in a wide variety of consumer products including soaps and detergents, cosmetics and food.  In 2001, ethoxylated raw materials were found to contain up to 1.4% 14D<ref>Black, R.E., Hurley, F.J. and Havery, D.C., 2001. Occurrence of 1, 4-dioxane in cosmetic raw materials and finished cosmetic products. Journal of AOAC international, 84(3), pp.666-670. [[media:2001-Black-Occurrence_of_1%2C4-dioxane_in_cosmetic_raw_materials....pdf| Report.pdf]]</ref>. Once this issue was recognized, measures were put into place to reduce 14D levels.  14D levels in the final product can be reduced by controlling the production process<ref>Ortega, J.A.T., 2012. Sulfonation/sulfation processing technology for anionic surfactant manufacture. In Advances in Chemical Engineering. IntechOpen. [[media:2012-Ortega-Sulfonation_sulfation.pdf| Report.pdf]]</ref> and by treatment of finished products by several approaches including vacuum stripping, steam stripping, and drying<ref>Sachdeva, Y.P. and Gabriel, R.L., Pharm-Eco Laboratories Inc, 1997. Apparatus for decontaminating a liquid surfactant of dioxane. U.S. Patent 5,643,408. [[media:1997-Sachdeva-Apparatus_for_decontaminating_a_liquid_surfractant.pdf| Report.pdf]]</ref>. 14D is produced as a byproduct during production of polyethylene terephthalate (PET), polyester and strong surfactants, as well as many other products<ref>Ellis, R.A. and Thomas, J.S., Wellman Inc, 1998. Destroying 1, 4-dioxane in byproduct streams formed during polyester synthesis. U.S. Patent 5,817,910. [[media:1998-Ellis-Destroying_1%2C4-dioxane_in_byproduct_streams_formed_during_polyester.pdf| report.pdf]]</ref>. Treated industrial wastewater containing 14D may be released to surface water or groundwater<ref name= "Knappe2016"/><ref name= "Grady1997">Grady, C.P.L., Sock, S.M. and Cowan, R.M., 1997. Biotreatability Kinetics: A Critical Component in the Scale-up of Wastewater Treatment Systems. Environmental Science Research, 54, pp.307-322. [https://doi.org/10.1007/978-1-4615-5395-3_28 doi: 10.1007/978-1-4615-5395-3_28]</ref><ref name= "Zenker 2000">Zenker, M.J., Borden, R.C. and Barlaz, M.A., 2000. Mineralization of 1, 4-dioxane in the presence of a structural analog. Biodegradation, 11(4), pp.239-246. [https://doi.org/10.1023/A:1011156924700 doi: 10.1023/A:1011156924700]</ref>
+
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>.
  
14D has been detected in air, potable water, wastewater and groundwater.  14D was detected in ambient air in several studies<ref>Harkov, R., Katz, R., Bozzelli, J. and Kebbekus, B., 1981. Toxic and carcinogenic air pollutants in New Jersey volatile organic substances. Proceedings of the International Technical Conference of Toxic Air Contaminants, p.245. Pittsburgh, PA: Air Pollution Control Association</ref><ref>Shah, J.J. and Singh, H.B., 1988. Distribution of volatile organic chemicals in outdoor and indoor air: A national VOCs data base. Environmental Science & Technology, 22(12), pp.1381-1388. [https://pubs.acs.org/doi/abs/10.1021/es00177a001 doi: 10.1021/es00177a001]</ref><ref>Keel, L. and A. Franzmann, 2000. Downtown Bellingham air toxics screening project, 1995-1999 staff report. Northwest Air Pollution Authority (NWAPA). [[media:2000-Keel-Downtown_Bellingham_Air_Toxics_Screening_Project.pdf| Report.pdf]]</ref>).  In a survey of 4,864 public drinking water systems, 14D was detected in 21% of the systems and exceeded the health-based reference concentration of 0.35 g/L in 6.9%<ref name= "Adamson2017">Adamson, D.T., Piña, E.A., Cartwright, A.E., Rauch, S.R., Anderson, R.H., Mohr, T. and Connor, J.A., 2017. 1, 4-Dioxane drinking water occurrence data from the third unregulated contaminant monitoring rule. Science of the Total Environment, 596, pp.236-245. [https://doi.org/10.1016/j.scitotenv.2017.04.085 doi: 10.1016/j.scitotenv.2017.04.085]</ref>. Municipal wastewater<ref>Abe, A., 1999. Distribution of 1, 4-dioxane in relation to possible sources in the water environment. Science of the Total Environment, 227(1), pp.41-47. [https://doi.org/10.1016/S0048-9697(99)00003-0 doi: 10.1016/S0048-9697(99)00003-0]</ref><ref>Westerhoff, P., Yoon, Y., Snyder, S. and Wert, E., 2005. Fate of endocrine-disruptor, pharmaceutical, and personal care product chemicals during simulated drinking water treatment processes. Environmental Science & Technology, 39(17), pp.6649-6663. [https://doi.org/10.1021/es0484799 doi: 10.1021/es0484799]</ref> and landfill leachates<ref>DeWalle, F.B. and Chian, E.S., 1981. Detection of trace organics in well water near a solid waste landfill. Journal‐American Water Works Association, 73(4), pp.206-211. [https://doi.org/10.1002/j.1551-8833.1981.tb04681.x doi: 10.1002/j.1551-8833.1981.tb04681.x]</ref><ref>Fujiwara, T., Tamada, T., Kurata, Y., Ono, Y., Kose, T., Ono, Y., Nishimura, F. and Ohtoshi, K., 2008. Investigation of 1, 4-dioxane originating from incineration residues produced by incineration of municipal solid waste. Chemosphere, 71(5), pp.894-901. [https://doi.org/10.1016/j.chemosphere.2007.11.011 doi: 10.1016/j.chemosphere.2007.11.011]</ref> also frequently contain 14D.
+
==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.
  
In groundwater, 14D is frequently observed as a co-contaminant with TCA<ref name= "Adamson2014"/><ref name= "Anderson2012">Anderson, R.H., Anderson, J.K. and Bower, P.A., 2012. Co‐occurrence of 1, 4‐dioxane with trichloroethylene in chlorinated solvent groundwater plumes at US Air Force installations: Fact or fiction. Integrated Environmental Assessment and Management, 8(4), pp.731-737. [https://doi.org/10.1002/ieam.1306 doi: 10.1002/ieam.1306]</ref>. As 14D was often utilized as an additive to degreasing solvents<ref name= "Mohr2010"/>, its presence is positively correlated with other chlorinated organics such as TCA, trichloroethene (TCE), and 1,1-dichloroethene (1,1-DCE)<ref name= "Adamson2017"/>  TCA and/or TCE were observed in 94% of the monitoring wells with detectable 14D<ref name= "Anderson2012"/>. In a review of groundwater results from 194 sites with detectable 14D, the median value of the range of maximal historical dioxane concentrations was 365 μg/L (10th percentile, 9 μg/L; 90th percentile, 13460 μg/L)<ref name= "Adamson2014"/>.
+
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 common presence of 14D in potable water supplies is a concern because 14D removal is low in many unit processes commonly employed in publicly owned treatment works (POTW) due to the high solubility, low volatility, and relative resistance to biodegradation (see section on physical/chemical treatment). 14D removal was not observed in several physical/chemical water treatment processes including coagulation, oxidation and air stripping processes<ref name= "McGuire1978">McGuire, M.J., Suffet, I.H. and Radziul, J.V., 1978. Assessment of unit processes for the removal of trace organic compounds from drinking water. Journal‐American Water Works Association, 70(10), pp.565-572. [https://doi.org/10.1002/j.1551-8833.1978.tb04244.x  doi: 10.1002/j.1551-8833.1978.tb04244.x ]</ref>.  Activated carbon adsorption is somewhat more successful, with reported removal efficiencies ranging from 50 to 67 percent<ref name= "McGuire1978"/><ref>Johns, M.M., Marshall, W.E. and Toles, C.A., 1998. Agricultural by‐products as granular activated carbons for adsorbing dissolved metals and organics. Journal of Chemical Technology & Biotechnology: International Research in Process, Environmental and Clean Technology, 71(2), pp.131-140. [https://doi.org/10.1002/(SICI)1097-4660(199802)71:2<131::AID-JCTB821>3.0.CO;2-K doi: 10.1002/(SICI)1097-4660(199802)71:2<131::AID-JCTB821>3.0.CO;2-K]</ref><ref name = "Stepien2014"/> reported that 14D removal was not observed in four domestic wastewater treatment plants in Germany.  In a study of North Carolina water treatment facilities, 14D removal was not observed at two of the facilities, but was reduced by 65% at a third which employed ozonation of raw and settled water<ref name= "Knappe2016"/>.  
+
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).
  
==Above Ground Treatment==
+
<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>
Air stripping is generally not effective for removing 14D from contaminated water due its low Henry’s Law constant. While 14D can be removed from water by sorption to granular activated carbon (GAC), sorption capacities are low resulting in high capital and operating costs<ref name= "Woodard2014">Woodard, S., Mohr, T. and Nickelsen, M.G., 2014. Synthetic Media: A Promising New Treatment Technology for 1, 4‐Dioxane. Remediation Journal, 24(4), pp.27-40. [https://doi.org/10.1002/rem.21402 doi:10.1002/rem.21402]</ref>. In contrast, polymeric sorbents (e.g. Ambersorb<sup>TM</sup> 560) are reported to have 5 to 10 times the sorption capacity of GAC, making sorption a more attractive alternative, though with additional operational requirements of adsorbent regeneration and proper disposal of spent waste<ref name= "Woodard2014"/>. While 14D can be degraded by high energy UV radiation in high purity water<ref>Hentz, R.R. and Parrish, C.F., 1971. Photolysis of gaseous 1, 4-dioxane at 1470 Ang. The Journal of Physical Chemistry, 75(25), pp.3899-3901. [https://doi.org/10.1021/j100694a023  doi: 10.1021/j100694a023]</ref>, direct ultraviolet photolysis is not economically viable due to operational challenges and high costs<ref name= "Mohr2010"/>.
+
<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>
  
Advanced oxidation processes (AOPs) using combinations of ozone (O<sub>3</sub>), hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and ultraviolet (UV) radiation produce highly reactive hydroxyl radicals (•OH) which are effective in destroying 14D.  In the peroxone process (O<sub>3,</sub> + H<sub>2,</sub>O<sub>2</sub>), O<sub>3</sub> reacts with H<sub>2</sub>O<sub>2</sub> giving rise to hydroxyl radicals<ref>Fleming, E.C., Zappi, M.E., Toro, E., Hernandez, R., Myers, K., Kodukula, P. and Gilbertson, R., 1997. Laboratory assessment of advanced oxidation processes for treatment of explosives and chlorinated solvents in groundwater from the former Nebraska Ordnance Plant. Technical Report SERDP-97-3 [[media:1997-Fleming-Laboratory_assessment_of_advanced_oxidation_process.pdf| Report.pdf]]</ref>.  In a variation of this approach ([http://aptwater.com/hipox/technology/overview-advanced-oxidation-process-for-water-treatment/ HiPOx™ process]), H<sub>2</sub>O<sub>2</sub> is added first followed by high pressure O<sub>3</sub><ref>Bowman, R.H., Lahey, T. and Herlihy, P., Applied Process Tech Inc, 2007. System and method for remediating contaminated soil and groundwater in situ. U.S. Patent 7,264,419. [[media:2007-Bowman-System_and_method_fo_remediating_contaminated_soil_and_groundwater.pdf| Report .pdf]]</ref>.  Hydroxyl radicals are produced in UV + H<sub>2</sub>O<sub>2</sub> systems by direct photolysis of H<sub>2</sub>O<sub>2</sub> caused by absorption of energy from an ultraviolet lamp<ref>Omura, K. and Matsuura, T., 1968. Photo-induced reactions—IX: The hydroxylation of phenols by the photo-decomposition of hydrogen peroxide in aqueous media. Tetrahedron, 24(8), pp.3475-3487. [https://doi.org/10.1016/S0040-4020(01)92645-6 doi: 10.1016/S0040-4020(01)92645-6]</ref><ref>Stefan, M.I. and Bolton, J.R., 1998. Mechanism of the degradation of 1, 4-dioxane in dilute aqueous solution using the UV/hydrogen peroxide process. Environmental Science & Technology, 32(11), pp.1588-1595. [https://doi.org/10.1021/es970633m doi: 10.1021/es970633m]</ref>.
+
==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.
  
AOPs are commonly employed for 14D treatment because of their high removal efficiencies with low contact times<ref name= "Mohr2010"/><ref name= "Ikehata">Ikehata, K., Jodeiri Naghashkar, N. and Gamal El-Din, M., 2006. Degradation of aqueous pharmaceuticals by ozonation and advanced oxidation processes: a review. Ozone: Science and Engineering, 28(6), pp.353-414. [https://doi.org/10.1080/01919510600985937 doi: 10.1080/01919510600985937]</ref>.  The degradation mechanisms and kinetics of these processes are well understood, with multiple systems in current use<ref name= "Mohr2010"/>. All of these systems are effective in destroying 14D, but have some limitations including the potential for bromate formation (when Br is present), reduced efficiency in the presence of free radical scavengers (e.g. HCO<sub>3</sub>) and high capital and operating costs associated with energy and chemical consumption<ref name= "Mohr2010"/><ref>Woodward, C., Shulmeister, J., Larsen, J., Jacobsen, G.E. and Zawadzki, A., 2014. The hydrological legacy of deforestation on global wetlands. Science, 346(6211), pp.844-847. [https://doi.org/10.1126/science.1260510 doi: 10.1126/science.1260510]</ref>.
+
{| 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>)
Biological wastewater treatment has not been widely applied for 14D removal.  While high concentrations of 14D will support growth of 14D degraders<ref>Sock, S.M., 1993. A comprehensive evaluation of biodegradation as a treatment alternative for the removal of 1, 4-dioxane (Doctoral dissertation, Clemson University)</ref> growth rates on 14D are slow<ref name= "Grady1997"/><ref name= "Parales1994"/><ref>Roy, D., Anagnostu, G. and Chaphalkar, P., 1994. Biodegradation of dioxane and diglyme in industrial waste. Journal of Environmental Science & Health Part A, 29(1), pp.129-147. [https://doi.org/10.1080/10934529409376026 doi: 10.1080/10934529409376026]</ref><ref>Bernhardt, D. and Diekmann, H., 1991. Degradation of dioxane, tetrahydrofuran and other cyclic ethers by an environmental Rhodococcus strain. Applied Microbiology and Biotechnology, 36(1), pp.120-123. [https://doi.org/10.1007/bf00164711 doi: 10.1007/BF00164711]</ref> and the low 14D concentrations in many systems are not sufficient to maintain an adequate level of 14D degraders for effective treatment.  To overcome this problem, 14D degrading biomass was supported by addition of tetrahydrofuran (THF) to a continuously fed trickling filter for over 1 year. The system was effective in reducing 14D concentrations by 93–97% while influent 14D concentrations were varied from 200 to 1200 µg/L<ref>Zenker, M.J., Borden, R.C. and Barlaz, M.A., 2003. Occurrence and treatment of 1, 4-dioxane in aqueous environments. Environmental Engineering Science, 20(5), pp.423-432. [https://doi.org/10.1089/109287503768335913 doi: 10.1089/109287503768335913]</ref>.  This basic approach was applied to full-scale treatment of leachate from the Lowry Landfill Superfund site where both THF and 14D were present as co-contaminants<ref>Shangraw, T. and Plaehn, W.  2012. Full-scale treatment of 1,4-dioxane using a bioreactor. Federal Remediation Technologies Roundtable Meeting. [[media:2012-Shangraw-Full-scale_Treatment_of_1%2C4-dioxane.pdf | Report.pdf]]</ref>.
+
|-
 
+
! rowspan="2" | Compound
==''In-Situ'' Treatment==
+
! colspan="2" | Soil Reporting Limit (mg/kg)
A variety of methods have been attempted for ''in situ'' treatment of 14D impacted soil and groundwater including [https://enviro.wiki/index.php?title=Chemical_Oxidation_(In_Situ_-_ISCO) in situ chemical oxidation (ISCO)], thermally enhanced soil vapor extraction, bioremediation, phytoremediation, and [https://enviro.wiki/index.php?title=Monitored_Natural_Attenuation_(MNA) monitored natural attenuation (MNA)].
+
|-
 
+
! HPLC (8330)  
ISCO can be used to degrade 14D in source areas with a variety of oxidants including permanganate<ref>Waldemer, R.H. and Tratnyek, P.G., 2006. Kinetics of contaminant degradation by permanganate. Environmental Science & Technology, 40(3), pp.1055-1061. [https://doi.org/10.1021/es051330s  doi: https://doi.org/10.1021/es051330s]</ref>, persulfate<ref>Félix-Navarro, R.M., Lin-Ho, S.W., Barrera-Díaz, N. and Pérez-Sicairos, S., 2007. Kinetics of the degradation of 1, 4-dioxane using persulfate. Journal of the Mexican Chemical Society, 51(2), pp.67-71. ISSN 1870-249X</ref>, Fenton’s reagent<ref>Kiker, J.H., Connolly, J.B., Murray, W.A., Pearson, S.C.P., Reed, S.E.R. and Tess, R.J., 2010. Ex-situ wellhead treatment of 1, 4-dioxane using fenton's reagent. In Proceedings of the Annual International Conference on Soils, Sediments, Water and Energy (Vol. 15, No. 1, p. 18).</ref> and ozone<ref name= "Ikehata"/>.  However, ISCO treatment of 14D in source areas is not common because much of the mass is in the downgradient plume.  Dilute plumes can potentially be treated using cylinders placed in wells that slowly release oxidant over time.  In a field demonstration, a system of slow release persulfate cylinders was effective in reducing 14D and chlorinated solvent concentrations by over 99% for 119 days<ref>Evans, P., Hooper, J., Lamar, M., Nguyen, D., Dugan, P., Crimi, M. and Ruiz, N., 2018. Sustained In situ Chemical Oxidation (ISCO) of 1, 4 Dioxane and Chlorinated VOCs Using Slow release Chemical Oxidant Cylinders. ESTCP Cost and Performance Report, ER-201324. [[media:2018-Evans-ER-201324_Cost_%26_Performance_Report.pdf| Report.pdf]]</ref>.
+
! GC (8095)
 
+
|-
Thermal remediation of source areas is not frequently utilized for 14D remediation because much of the 14D mass is in the dissolved plume. However, when applied to treat a source area, thermal remediation can be effective. Following electrical resistive heating of a chlorinated solvent source area, 14D levels in groundwater were reduced >99%<ref>Oberle, D., Crownover, E. and Kluger, M., 2015. In situ remediation of 1, 4‐dioxane using electrical resistance heating. Remediation Journal, 25(2), pp.35-42. [https://doi.org/10.1002/rem.21422 doi: 10.1002/rem.21422]</ref>.  14D source areas can also be treated using a combination of heated air injection and focused air extraction from areas with elevated 14D concentrations.  In a field demonstration, thermally enhanced [https://enviro.wiki/index.php?title=Soil_Vapor_Extraction_(SVE) soil vapor extraction] reduced 14D levels by 94%<ref>Hinchee, R.E., P.C. Johnson, P.R. Dahlen, and D.R. Durris, 2017. 1,4-Dioxane remediation by extreme soil vapor extraction (XSVE). Final Report ESTCP Project 201326 [[media:2017-Hinchee-1.4_Dioxane_remediation_by_extreme_soil_XSVE_ER-201326_Final_Report.pdf| Report.pdf]]</ref><ref>Hinchee, R.E., Dahlen, P.R., Johnson, P.C. and Burris, D.R., 2018. 1, 4‐Dioxane Soil Remediation Using Enhanced Soil Vapor Extraction: I. Field Demonstration. Groundwater Monitoring & Remediation, 38(2), pp.40-48. [https://doi.org/10.1111/gwmr.12264 doi: doi.org/10.1111/gwmr.12264]</ref>. Modeling results indicate that removal increases with increasing air injection temperature and relative humidity and decreases with initial soil moisture content<ref>Burris, D.R., Johnson, P.C., Hinchee, R.E. and Dahlen, P.R., 2018. 1, 4‐Dioxane Soil Remediation Using Enhanced Soil Vapor Extraction (XSVE): II. Modeling. Groundwater Monitoring & Remediation, 38(2), pp.49-56. [https://doi.org/10.1111/gwmr.12277 doi: 10.1111/gwmr.12277]</ref>.
+
| HMX || 0.04 || 0.01
 
+
|-
''In situ'' bioremediation has not been commonly applied to 14D treatment due to the slow growth of bacteria using 14D as a growth substrate (see [Biodegradation – 1,4-Dioxane]). However, there has been some success in stimulating cometabolic biodegradation of 14D using gaseous substrates. In a biosparging pilot test, air amended with propane was injected into a single well that was bioaugmented with the propanotroph ''Rhodococcus ruber'' ENV425.  14D levels decreased by >99% in the sparge well and two nearby monitor wells<ref name= "Lippincott2015"/>. A propane-stimulated groundwater recirculation system has also recently been reported to effectively reduce concentrations of 14D as well as several chlorinated aliphatics such as TCE and 1,2-dichloroethane<ref name= "Chu2018"/>.
+
| RDX || 0.04 || 0.006
 
+
|-
Phytoremediation has been reported as a viable treatment alternative for 14D<ref>Aitchison, E.W., Kelley, S.L., Alvarez, P.J. and Schnoor, J.L., 2000. Phytoremediation of 1, 4-dioxane by hybrid poplar trees. Water Environment Research, 72(3), pp.313-321. [https://doi.org/10.2175/106143000X137536 doi: 10.2175/106143000X137536]</ref>. The primary removal process is via phytovolatilization, which involves transpiration of chemicals from the leaf surfaces to the atmosphere<ref>Ouyang, Y., 2002. Phytoremediation: modeling plant uptake and contaminant transport in the soil–plant–atmosphere continuum. Journal of Hydrology, 266(1-2), pp.66-82. [https://doi.org/10.2175/106143000X137536 doi: 10.2175/106143000X137536]</ref>. Addition of 14D degrading bacteria (e.g. CB1190) and appropriate co-substrates can further enhance the removal of 14D in soil planted with poplar trees<ref>Kelley, S.L., Aitchison, E.W., Deshpande, M., Schnoor, J.L. and Alvarez, P.J., 2001. Biodegradation of 1, 4-dioxane in planted and unplanted soil: effect of bioaugmentation with Amycolata sp. CB1190. Water Research, 35(16), pp.3791-3800. [https://doi.org/10.1016/S0043-1354(01)00129-4 doi: 10.1016/S0043-1354(01)00129-4]</ref>.
+
| [[Wikipedia: 1,3,5-Trinitrobenzene | TNB]] || 0.04 || 0.003
 
+
|-
Early microcosm studies indicated that 14D did not degrade in the presence of impacted aquifer material under ''in situ'' conditions<ref name= "Zenker 2000"/>. However, a statistical analysis of multiple Air Force and California sites found evidence of 14D removal in 19% of the sites<ref name= "Adamson2015">Adamson, D.T., Anderson, R.H., Mahendra, S. and Newell, C.J., 2015. Evidence of 1, 4-dioxane attenuation at groundwater sites contaminated with chlorinated solvents and 1, 4-dioxane. Environmental Science & Sechnology, 49(11), pp.6510-6518.[ https://doi.org/10.1021/acs.est.5b00964 doi:10.1021/acs.est.5b00964]</ref>, similar to other chlorinated VOCs (TCE and 1,1-DCE). The decay rates were positively correlated to dissolved oxygen, and negatively correlated to high metals and chlorinated VOC concentrations<ref name= "Adamson2015"/>. 14D decay has also been positively correlated to the presence of oxidizing enzymes<ref name= "Li2013">Li, M., Mathieu, J., Yang, Y., Fiorenza, S., Deng, Y., He, Z., Zhou, J. and Alvarez, P.J., 2013. Widespread distribution of soluble di-iron monooxygenase (SDIMO) genes in arctic groundwater impacted by 1, 4-dioxane. Environmental science & technology, 47(17), pp.9950-9958. [https://doi.org/10.1021/es402228x doi: 10.1021/es402228x]</ref><ref>Gedalanga, P.B., Pornwongthong, P., Mora, R., Chiang, S.Y.D., Baldwin, B., Ogles, D. and Mahendra, S., 2014. Identification of biomarker genes to predict biodegradation of 1, 4-dioxane. Appl. Environ. Microbiol., 80(10), pp.3209-3218. [https://doi.org/10.1128/aem.04162-13 doi: 10.1128/AEM.04162-13]</ref>. Native 14D degrading microorganisms have also been detected in field studies using a number of environmental diagnostic assays, such as microarray<ref name= "Li2013"/> and stable isotope probing<ref>Chiang, S.Y.D., Mora, R., Diguiseppi, W.H., Davis, G., Sublette, K., Gedalanga, P. and Mahendra, S., 2012. Characterizing the intrinsic bioremediation potential of 1, 4-dioxane and trichloroethene using innovative environmental diagnostic tools. Journal of Environmental Monitoring, 14(9), pp.2317-2326. [https://doi.org/10.1039/c2em30358b doi: 10.1039/C2EM30358B]</ref><ref>Li, M., Liu, Y., He, Y., Mathieu, J., Hatton, J., DiGuiseppi, W. and Alvarez, P.J., 2017. Hindrance of 1, 4-dioxane biodegradation in microcosms biostimulated with inducing or non-inducing auxiliary substrates. Water Research, 112, pp.217-225. [http://dx.doi.org/10.1016/j.watres.2017.01.047 doi: 10.1016/j.watres.2017.01.047]</ref>, suggesting that monitored natural attenuation (MNA) may be a feasible and cost-efficient alternative to mitigate 14D at some sites.  
+
| 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://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.

Related Article(s):


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