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1,4-Dioxane (14D) does not readily biodegrade in most environments. However, a variety of microorganisms have been identified that can biodegrade 14D through either direct growth-related metabolism or cometabolism. During metabolic biodegradation, microorganisms use 14D as the growth substrate, however growth is slow unless 14D concentrations are very high (>100 mg/L). During cometabolic biodegradation, an additional growth substrate must be supplied to support biomass growth and induce the appropriate 14D-degrading enzymes. Unlike metabolic degradation, cometabolic processes can reduce 14D to very low concentrations.
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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]]
  
<div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
 
  
'''Related Article(s):'''
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'''Key Resource(s)''':
*[[1,4-Dioxane]]
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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>
*[[Biodegradation - Cometabolic]]
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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>
  
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==Introduction==
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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)]]
  
'''CONTRIBUTOR(S):''' [[Dr. Shaily Mahendra]] and [[Dr. Michael Hyman]]
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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>.
  
'''Key Resource(s)''':
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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://doi.org/10.1016/j.jenvman.2017.05.033 Advances in bioremediation of 1,4-dioxane-contaminated waters]<ref>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>
 
  
==1,4-Dioxane Biodegradation==
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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).
[[File:Mahendra1w2 Fig1.png|thumb|right|Figure 1. Growth Rates of Two 14D Metabolizers Versus 14D Concentration]]
 
  
1,4-Dioxane (14D) does not readily biodegrade in most anaerobic environments<ref name= "Shen2008">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>. However, multiple studies have demonstrated that 14D can be biodegraded by a variety of microorganisms under aerobic conditions<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 doi:10.1021/es060714v]</ref><ref>Mahendra, S., Petzold, C.J., Baidoo, E.E., Keasling, J.D. and Alvarez-Cohen, L., 2007. Identification of the intermediates of in vivo oxidation of 1, 4-dioxane by monooxygenase-containing bacteria. Environmental Science & Technology, 41(21), pp.7330-7336. [https://doi.org/10.1021/es0705745 doi: 10.1021/es0705745]</ref><ref name= "Skinner1536">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><ref name = "Sun2011">Sun, B., Ko, K. and Ramsay, J.A., 2011. Biodegradation of 1, 4-dioxane by a Flavobacterium. Biodegradation, 22(3), pp.651-659. [https://doi.org/10.1007/s10532-010-9438-9 doi: 10.1007/s10532-010-9438-9]</ref>. A summary of microorganisms that are reported to aerobically biodegrade 14D is presented in Table 1.
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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"/>.
  
Under aerobic conditions 14D can be biodegraded through two physiologically distinct processes: (a) metabolism; and (b) cometabolism.  Metabolism is a process in which microorganisms use the organic contaminants as a carbon and energy source to support their growth. [https://enviro.wiki/index.php?title=Biodegradation_-_Cometabolic Cometabolism] occurs when microorganisms degrade contaminants using non-specific enzymes but do not gain carbon or energy to support growth from the degradation process.
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{| class="wikitable" style="float: right; text-align: center; margin-left: auto; margin-right: auto;"
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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.)
{| class="wikitable floatright"
 
|+ Table 1. List of 1,4-Dioxane Degrading Microorganisms and Biodegradation Rates
 
 
|-
 
|-
! Strain
+
! Military Range Type !! Analyte !! Range<br/>(mg/kg) !! Median<br/>(mg/kg) !! RSD<br/>(%)
! Induced Enzyme
 
! Biodegradation Rate
 
! Reference
 
 
|-
 
|-
| colspan="4" | '''Metabolism'''
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| colspan="5" style="text-align: left;" | '''Discrete Samples'''
 
|-
 
|-
| ''Pseudonocardia dioxanivorans'' CB1190 || THFMO || 0.19 ± 0.007 mg/hr/mg-protein || Mahendra and Alvarez-Cohen (2005, 2006)<ref name= "Mahendra2005">Mahendra, S. and Alvarez-Cohen, L., 2005. Pseudonocardia dioxanivorans sp. nov., a novel actinomycete that grows on 1, 4-dioxane. International Journal of Systematic and Evolutionary Microbiology, 55(2), pp.593-598. [https://doi.org/10.1099/ijs.0.63085-0 doi: 10.1099/ijs.0.63085-0]</ref><ref name= "Mahendra2006"/>
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| Artillery FP || 2,4-DNT || <0.04 – 6.4 || 0.65 || 110
 
|-
 
|-
| ''Actinomycete'' CB1190* || N/A || 0.33 mg/min/mg-protein || Parales et al. (1994)<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>
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| Antitank Rocket || HMX || 5.8 – 1,200 || 200 || 99
 
|-
 
|-
| ''Amycolata'' sp. CB1190* || N/A || 0.038 ± 0.012 mg/hr/mg-protein || Kelley et al. (2001)
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| Bombing || TNT || 0.15 – 780 || 6.4 || 274
 
|-
 
|-
| ''Pseudonocardia benzenivorans'' B5 || THFMO || 0.01± 0.003 mg/hr/mg-protein || Mahendra and Alvarez-Cohen (2006)<ref name= "Mahendra2006"/>
+
| Mortar || RDX || <0.04 – 2,400 || 1.7 || 441
 
|-
 
|-
| ''Pseudonocardia carboxydivorans'' RM-31 || ? || 31.6 mg/L/hr || Matsui et al. (2016)<ref>Matsui, R., Takagi, K., Sakakibara, F., Abe, T. and Shiiba, K., 2016. Identification and characterization of 1, 4-dioxane-degrading microbe separated from surface seawater by the seawater-charcoal perfusion apparatus. Biodegradation, 27(2-3), pp.155-163. [https://doi.org/10.1007/s10532-016-9763-8 doi: 10.1007/s10532-016-9763-8</ref>
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| Artillery || RDX || <0.04 – 170 || <0.04 || 454
 
|-
 
|-
| ''Afipia'' sp. D1 || ? || 0.052 to 0.263 mg/hr/mg-protein || Sei et al. (2013)<ref name = "Sei2013">Sei, K., Miyagaki, K., Kakinoki, T., Fukugasako, K., Inoue, D. and Ike, M., 2013. Isolation and characterization of bacterial strains that have high ability to degrade 1, 4-dioxane as a sole carbon and energy source. Biodegradation, 24(5), pp.665-674. [https://doi.org/10.1007/s10532-012-9614-1 doi: 10.1007/s10532-012-9614-1]</ref>
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| colspan="5" style="text-align: left;" | '''Incremental Samples*'''
 
|-
 
|-
| ''Mycobacterium'' sp. PH-06 || PrMO || 2.5 mg/L/hr || Kim et al. (2009)<ref name = "Kim2009">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>
+
| Artillery FP || 2,4-DNT || 0.60 – 1.4 || 0.92 || 26
 
|-
 
|-
| ''Acinetobacter baumannii'' DD1 || ? || 2.38 mg/L/hr || Huang et al. (2014)<ref name = "Huang2014">Huang, H., Shen, D., Li, N., Shan, D., Shentu, J. and Zhou, Y., 2014. Biodegradation of 1, 4-dioxane by a novel strain and its biodegradation pathway. Water, Air, & Soil Pollution, 225(9), p.2135. [https://doi.org/10.1007/s11270-014-2135-2 doi: 10.1007/s11270-014-2135-2]</ref>
+
| Bombing || TNT || 13 – 17 || 14 || 17
 
|-
 
|-
| ''Xanthobacter flavus'' DT8 || ? || Similar to CB1190 || Chen et al. (2016)<ref>Chen, D.Z., Jin, X.J., Chen, J., Ye, J.X., Jiang, N.X. and Chen, J.M., 2016. Intermediates and substrate interaction of 1, 4-dioxane degradation by the effective metabolizer Xanthobacter flavus DT8. International Biodeterioration & Biodegradation, 106, pp.133-140. [https://doi.org/10.1016/j.ibiod.2015.09.018 doi: 10.1016/j.ibiod.2015.09.018]</ref>
+
| Artillery/Bombing || RDX || 3.9 – 9.4 || 4.8 || 38
 +
|-  
 +
| Thermal Treatment || HMX || 3.96 – 4.26 || 4.16 || 4
 
|-
 
|-
| ''Cordyceps sinensis'' (fungus) || ? || 0.011 mol/day || Nakamiya et al. (2005)<ref>Nakamiya, K., Hashimoto, S., Ito, H., Edmonds, J.S. and Morita, M., 2005. Degradation of 1, 4-dioxane and cyclic ethers by an isolated fungus. Appl. Environ. Microbiol., 71(3), pp.1254-1258. [https://doi.org/10.1128/aem.71.3.1254-1258.2005 doi: 10.1128/AEM.71.3.1254-1258.2005]</ref>
+
| colspan="5" style="text-align: left; background-color: white;" | * 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<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]]
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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.
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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)]]
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==Sampling Tools==
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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.
 +
 
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[[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>]]
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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==
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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.
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 +
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.
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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).
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 +
<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>
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<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>
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<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>
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<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>
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<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>
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==Analysis==
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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>)
 
|-
 
|-
| colspan="4" | '''Cometabolism'''
+
! rowspan="2" | Compound
 +
! colspan="2" | Soil Reporting Limit (mg/kg)
 
|-
 
|-
| ''Mycobacterium austroafricanum'' JOB5 || ? || 0.40 ± 0.06 mg/hr/mg-protein || House and Hyman (2010)<ref>House, A.J. and Hyman, M.R., 2010. Effects of gasoline components on MTBE and TBA cometabolism by Mycobacterium austroafricanum JOB5. Biodegradation, 21(4), pp.525-541. [https://doi.org/10.1007/s10532-009-9321-8 doi: 10.1007/s10532-009-9321-8]</ref> Lan et al. (2013)<ref>Lan, R.S., Smith, C.A. and Hyman, M.R., 2013. Oxidation of cyclic ethers by alkane‐grown Mycobacterium vaccae JOB5. Remediation Journal, 23(4), pp.23-42. [https://doi.org/10.1002/rem.21364 doi: 10.1002/rem.21364}</ref><ref name= "Mahendra2006"/>
+
! HPLC (8330)  
 +
! GC (8095)
 
|-
 
|-
| ''Rhodococcus ruber'' ENV425 || ? || 10 mg/hr/g TSS || Lippincott et al. (2015)<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>; Vainberg et al. (2006)<ref name= "Vainberg2006">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>
+
| HMX || 0.04 || 0.01
 
|-
 
|-
| ''Pseudonocardia'' sp. ENV478 || THFMO || 21 mg/hr/g TSS || Masuda et al. (2012)<ref>Masuda, H., McClay, K., Steffan, R.J. and Zylstra, G.J., 2012. Biodegradation of tetrahydrofuran and 1, 4-dioxane by soluble diiron monooxygenase in Pseudonocardia sp. strain ENV478. Journal of Molecular Microbiology and Biotechnology, 22(5), pp.312-316. [https://doi.org/10.1159/000343817  doi: 10.1159/000343817]</ref> Vainberg et al. (2006)<ref name= "Vainberg2006"/>
+
| RDX || 0.04 || 0.006
 
|-
 
|-
| ''Rhodococcus'' RR1 || ? || 0.38 ± 0.03 mg/hr/mg-protein || Mahendra and Alvarez-Cohen (2006)<ref name= "Mahendra2006"/>
+
| [[Wikipedia: 1,3,5-Trinitrobenzene | TNB]] || 0.04 || 0.003
 
|-
 
|-
| ''Rhodococcus jostii'' RHA1 || PrMO || N/A || Hand et al. (2015)<ref name= "Hand2015">Hand, S., Wang, B. and Chu, K.H., 2015. Biodegradation of 1, 4-dioxane: effects of enzyme inducers and trichloroethylene. Science of the Total Environment, 520, pp.154-159. [https://doi.org/10.1016/j.scitotenv.2015.03.031 doi: 10.1016/j.scitotenv.2015.03.031]</ref>; Li et al. (2013)<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>
+
| TNT || 0.04 || 0.002
 
|-
 
|-
| ''Flavobacterium'' || ? || N/A || Sun et al. (2011)<ref name = "Sun2011"/>
+
| [[Wikipedia: 2,6-Dinitrotoluene | 2,6-DNT]] || 0.08 || 0.002
 
|-
 
|-
| ''Pseudonocardia'' K1 || THFMO || 0.26 ± 0.013 mg/hr/mg-protein || Mahendra and Alvarez-Cohen (2006)<ref name= "Mahendra2006"/>
+
| 2,4-DNT || 0.04 || 0.002
 
|-
 
|-
| ''Burkholderia cepacia'' G4 || T2MO || 0.1± 0.006 mg/hr/mg-protein || Mahendra and Alvarez-Cohen (2006)<ref name= "Mahendra2006"/>
+
| 2-ADNT || 0.08 || 0.002
 
|-
 
|-
| ''Ralstonia pickettii'' PKO1 || T3MO || 0.31± 0.007 mg/hr/mg-protein || Mahendra and Alvarez-Cohen (2006)<ref name= "Mahendra2006"/>
+
| 4-ADNT || 0.08 || 0.002
 
|-
 
|-
| ''Pseudomonas mendocina'' KR1 || T4MO || 0.37± 0.04 mg/hr/mg-protein || Mahendra and Alvarez-Cohen (2006)<ref name= "Mahendra2006"/>
+
| NG || 0.1 || 0.01
 
|-
 
|-
| ''Aureobasidium pullmans'' NRRL 21064 || ? || 6-8 mg/L within a day || Patt and Abebe (1995)<ref name= "Patt1995">Patt, T.E. and Abebe, H.M., Upjohn Co, 1995. Microbial degradation of chemical pollutants. U.S. Patent 5,399,495. [[media:1995-Patt-Microbial_degradation_of_chemical_pollutants.pdf| Report.pdf]]</ref>
+
| [[Wikipedia: Dinitrobenzene | DNB ]] || 0.04 || 0.002
 
|-
 
|-
| ''Graphium'' sp. ATCC 58400 (fungus) || CYP || 4 ± 1 nmol/min/mg dry weight (with Propane) <br/>9 ± 5 nmol/min/mg dry weight (with THF) || Skinner et al. (2009)<ref name= "Skinner2009">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>
+
| [[Wikipedia: Tetryl | Tetryl ]]  || 0.04 || 0.01
 +
|-
 +
| [[Wikipedia: Pentaerythritol tetranitrate | PETN ]] || 0.2 || 0.016
 
|}
 
|}
==Aerobic Metabolism==
 
While several microorganisms have been isolated that can metabolize 14D<ref name= "Mahendra2006"/><ref name = "Kim2009"/><ref>Sei, K., Kakinoki, T., Inoue, D., Soda, S., Fujita, M. and Ike, M., 2010. Evaluation of the biodegradation potential of 1, 4-dioxane in river, soil and activated sludge samples. Biodegradation, 21(4), pp.585-591. [https://doi.org/10.1007/s10532-010-9326-3 doi: 10.1007/s10532-010-9326-3]</ref><ref name =  "Sei2013"/><ref name = "Huang2014"/>, these organisms are not common.  The best characterized 14D-metabolizing strain is ''Pseudonocardia dioxanivorans'' CB1190<ref name= "Mahendra2005"/>. This bacterium was originally enriched from industrial activated sludge, fed with tetrahydrofuran (THF) and then subsequently fed with 14D<ref name= "Parales1994"/>.  The doubling time of CB1190 was about 30 hours when it was grown in ammonium mineral salts medium at 30 °C amended with 5.5 mM (484 mg/L) 14D<ref name= "Parales1994"/>.
 
 
Degradation of 14D by strain CB1190 may be inhibited by elevated concentrations of chlorinated solvents and their degradation products, and by some metals. Inhibition of 14D degradation was strongest for 1,1-dichloroethene (1,1-DCE) followed by ''cis''-1,2-diochloroethene (cDCE) > trichloroethene (TCE) > 1,1,1-trichloroethane (TCA). 14D biodegradation was completely inhibited by 5 mg/L 1,1-DCE<ref>Mahendra, S., Grostern, A. and Alvarez-Cohen, L., 2013. The impact of chlorinated solvent co-contaminants on the biodegradation kinetics of 1, 4-dioxane. Chemosphere, 91(1), pp.88-92. [https://doi.org/10.1016/j.chemosphere.2012.10.104 doi: 10.1016/j.chemosphere.2012.10.104]</ref><ref name= "Hand2015"/><ref name= "Zhang2016">Zhang, S., Gedalanga, P.B. and Mahendra, S., 2016. Biodegradation kinetics of 1, 4-dioxane in chlorinated solvent mixtures. Environmental Science & Technology, 50(17), pp.9599-9607. [https://doi.org/10.1021/acs.est.6b02797 doi: 10.1021/acs.est.6b02797]</ref>. Cu(II) was the strongest metal inhibitor of 14D degradation by CB1190, causing an increase in the lag period at 1 mg/L and an order of magnitude reduction in 14D degradation rates at 10 and 20 mg/L Cu(II).  14D degradation was less sensitive to Cd(II) and Ni(II), while Zn(II) had no impact on 14D biodegradation at the maximum concentration tested (20 mg/L Zn)<ref>Pornwongthong, P., Mulchandani, A., Gedalanga, P.B. and Mahendra, S., 2014. Transition metals and organic ligands influence biodegradation of 1, 4-dioxane. Applied biochemistry and biotechnology, 173(1), pp.291-306. [https://doi.org/10.1007/s12010-014-0841-2 doi: 10.1007/s12010-014-0841-2]</ref>.
 
 
An important challenge for in situ bioremediation of 14D is the slow growth of 14D metabolizers at typical groundwater concentrations.  Figure 1 shows estimated growth rates for two 14D metabolizing organisms (''P. dioxanivorans'' CB1190 and ''P. benzenivorans'' B5) computed using published kinetic parameters<ref name= "Mahendra2006"/>.  At a 14D concentrations of 1000 µg/L, CB1190 and B2 have growth rates of 0.015 and 0.002 per day.  At typical groundwater concentrations (<1000 µg/L), growth rates are expected to be less than the endogenous decay rate, resulting in a steady decline in the number of 14D metabolizers.
 
 
==Aerobic Cometabolism==
 
Unlike 14D-metabolizing microorganisms, 14D-cometabolizing organisms do not grow on 14D but can degrade this compound after growth on a primary, growth-supporting substrate. As cometabolically active microorganisms do not use co-substrates as either major carbon or energy sources, they can often degrade co-substrates at concentrations well below those that can be achieved by organisms that metabolize and grow on these co-substrates. A wide variety of bacteria<ref name= "Mahendra2006"/> and some fungi<ref name= "Patt1995"/><ref name= "Skinner2009"/> can cometabolically degrade 14D (see Table 1).  These include model organisms that grow on primary substrates such as toluene or methane<ref name= "Mahendra2006"/> and involve well-characterized enzymes such as soluble methane monooxygenase (sMMO) or toluene monooxygenases (TxMO), respectively.  Other 14D-cometabolizing strains that grow on THF<ref name= "Vainberg2006"/>, ethane<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>, and isobutane<ref name= "Bennett2017">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> have also been described.
 
 
Much of the research into 14D cometabolism has focused on high concentrations of 14D (≥100 mg/L), and less is currently known about the activity of specific microorganisms and their monooxygenases at lower, more environmentally relevant 14D concentrations (<100 µg/L). Despite this, many bacterial monooxygenases can concurrently oxidize multiple co-substrates, and recent field studies have demonstrated that cometabolic approaches involving either propane biostimulation and bioaugmentation<ref name= "Lippincott2015"/> or propane biostimulation alone<ref>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> can be highly effective treatment strategies for degrading contaminant mixtures that contain parts-per-billion concentrations of both 14D and associated chlorinated co-contaminants.
 
 
==Anaerobic Biodegradation==
 
To date, there is little evidence of metabolic or cometabolic anaerobic 14D biodegradation.  In a microcosm study using samples of aquifer material from several different 14D impacted sites, there was no evidence of 14D biodegradation<ref>Zenker, M.J., Borden, R.C. and Barlaz, M.A., 1999. Investigation of the intrinsic biodegradation of alkyl and cyclic ethers. The Fifth International In Situ and On-Site Bioremediation Symposium</ref>.  However, there is one study that reported anaerobic growth of an iron-reducing bacterium on 14D<ref name= "Shen2008"/>.
 
 
An indirect method of anaerobic 14D biodegradation exists via a microbially driven Fenton reaction. ''Shewanella oneidensis'', an Fe(III)-reducing facultative anaerobe, is able to generate hydroxyl radicals that can then break down 14D<ref>Sekar, R. and DiChristina, T.J., 2014. Microbially driven Fenton reaction for degradation of the widespread environmental contaminant 1, 4-dioxane. Environmental science & technology, 48(21), pp.12858-12867. [https://doi.org/10.1021/es503454a doi: 10.1021/es503454a]</ref>. Under anaerobic conditions, ''S. oneidensis'' produces Fe(II)  that can then interact chemically with H<sub>2</sub>O<sub>2</sub> to yield HO• radicals which can oxidatively degrade 1,4-dioxane.
 
 
==Molecular Biological Tools==
 
[https://enviro.wiki/index.php?title=Quantitative_Polymerase_Chain_Reaction_(qPCR) Quantitative polymerase chain reaction (qPCR)] quantifies the abundance of specific microorganisms and functional genes capable of degrading a particular contaminant.  qPCR analyses have been employed to quantify the abundance of microorganisms that can degrade 14D through the activity of tetrahydrofuran monooxygenase (THFMO) in samples from industrial activated sludge and groundwater<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>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><ref>Li, M., Mathieu, J., Liu, Y., Van Orden, E.T., Yang, Y., Fiorenza, S. and Alvarez, P.J., 2013. The abundance of tetrahydrofuran/dioxane monooxygenase genes (thmA/dxmA) and 1, 4-dioxane degradation activity are significantly correlated at various impacted aquifers. Environmental Science & Technology Letters, 1(1), pp.122-127. [https://doi.org/10.1021/ez400176h doi: 10.1021/ez400176h]</ref><ref name= "Li2013"/><ref name= "Zhang2016"/>. However, care is warranted in the interpretation of qPCR results in other cases (e.g. propane-stimulated cometabolic 14D degradation) where the role of enzymes such as propane monooxygenase (PrMO) in 14D degradation is less clearly established.  Studies also suggest that these biomarkers can be used to detect the abundance of 14D-degraders ''in situ'' and how they compete within the larger microbial community<ref>Miao, Y., Johnson, N.W., Gedalanga, P.B., Adamson, D., Newell, C. and Mahendra, S., 2019. Response and recovery of microbial communities subjected to oxidative and biological treatments of 1, 4-dioxane and co-contaminants. Water research, 149, pp.74-85. [https://doi.org/10.1016/j.watres.2018.10.070 doi:10.1016/j.watres.2018.10.070]</ref>. Microbial community analyses can be an asset towards guiding treatment strategies and predicting treatment synergies.
 
 
[https://enviro.wiki/index.php?title=Compound_Specific_Isotope_Analysis_(CSIA) Compound specific isotope analysis (CSIA)] refers to measurement of the isotopic signatures of individual chemical compounds and can be used to differentiate contaminant sources, delineate reaction pathways, and provide evidence of ''in situ'' contaminant degradation.  CSIA methods are now available to measure isotopic fractionation of carbon and hydrogen<ref name= "Bennett2017"/>. For example, the aerobic biodegradation of 14D by a THF-grown 14D-degrading ''Pseudonocardia'' strain exhibited an isotopic fractionation factor (<big>''ε'' </big>) for carbon (<big>''ε''</big><sub>''c''</sub>)  of −4.73 ± 0.9‰ and hydrogen (<big>ε</big><sub>''H''</sub>) of -147  ± 22‰, respectively. Smaller <big>''ε''</big><sub>''c''</sub>and <big>ε</big><sub>''H''</sub> values, (-2.7 ± 0.3‰ and -21 ± 2‰, respectively) were determined for aerobic 14D degradation by a propane-grown ''Rhodococcus'' strain. As many ''Pseudonocardia'' strains use THFMO to initiate 14D degradation, CSIA, in conjunction with qPCR analyses, may be able to discriminate the roles of metabolism and cometabolism in 14D biodegradation at field sites<ref>Gedalanga, P., Madison, A., Miao, Y., Richards, T., Hatton, J., DiGuiseppi, W.H., Wilson, J. and Mahendra, S., 2016. A Multiple Lines of Evidence Framework to Evaluate Intrinsic Biodegradation of 1, 4‐Dioxane. Remediation Journal, 27(1), pp.93-114. [https://doi.org/10.1002/rem.21499 doi: 10.1002/rem.21499]</ref>.
 
 
==Summary==
 
14D is not readily biodegraded under ambient conditions in most environments.  However, a variety of microorganisms have been identified that can biodegrade 14D through either growth-related metabolism or fortuitous cometabolism. Metabolic growth on the target pollutant is the more traditional approach for both above ground and ''in situ'' bioremediation approaches.  However, approaches based on metabolic growth may not be feasible for treatment of 14D at typical concentrations.  Cometabolic treatment approaches can reduce 14D to very low levels and have been demonstrated in the field.  However, implementation of cometabolic treatment is more complex, and there is currently less engineering experience in the design and operation of these systems. 
 
  
 
==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