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Munitions Constituents – Sample Extraction and Analytical Techniques

Munitions Constituents, including insensitive munitions IM), are a broad category of compounds and, in areas where manufactured or used, can be found in a variety of environmental matrices (waters, soil, and tissues). This presents an analytical challenge when a variety of these munitions are to be quantified. This article discusses sample extraction methods for each typical sample matrix (high level water, low level water, soil and tissue) as well as the accompanying HPLC-UV analytical method for 27 compounds of interest (legacy munitions, insensitive munitions, and surrogates).

Introduction

The primary intention of the analytical methods presented here is to support the monitoring of legacy and insensitive munitions contamination on test and training ranges, however legacy and insensitive munitions often accompany each other at demilitarization facilities, manufacturing facilities, and other environmental sites. Energetic materials typically appear on ranges as small, solid particulates and due to their varying functional groups and polarities, can partition in various environmental compartments^[3]. To ensure that contaminants are monitored and controlled at these sites and to sustainably manage them a variety of sample matrices (surface or groundwater, process waters, soil, and tissues) must be considered. (Process water refers to water used during industrial manufacturing or processing of legacy and insensitive munitions.) Furthermore, additional analytes must be added to existing methodologies as the usage of IM compounds changes and as new degradation compounds are identified. Of note, relatively new IM formulations containing NTO, DNAN, and NQ are seeing use in IMX-101, IMX-104, Pax-21 and Pax-41 (Table 1)^[4]^[5].

Sampling procedures for legacy and insensitive munitions are identical and utilize multi-increment sampling procedures found in USEPA Method 8330B Appendix A^[1]. Sample hold times, subsampling and quality control requirements are also unchanged. The key differences lie in the extraction methods and instrumental methods. Briefly, legacy munitions analysis of low concentration waters uses a single cartridge reverse phase SPE procedure, and acetonitrile (ACN) is used for both extraction and elution for aqueous and solid samples^[1]^[6]. An isocratic separation via reversed-phase C-18 column with 50:50 methanol:water mobile phase or a C-8 column with 15:85 isopropanol:water mobile phase is used to separate legacy munitions^[1]. While these procedures are sufficient for analysis of legacy munitions, alternative solvents, additional SPE cartridges, and a gradient elution are all required for the combined analysis of legacy and insensitive munitions.

Previously, analysis of legacy and insensitive munitions required multiple analytical techniques, however the methods presented here combine the two munitions categories resulting in an HPLC-UV method and accompanying extraction methods for a variety of common sample matrices. A secondary HPLC-UV method and a HPLC-MS method were also developed as confirmatory methods. The methods discussed in this article were validated extensively by single-blind round robin testing and subsequent statistical treatment as part of ESTCP ER19-5078. Wherever possible, the quality control criteria in the Department of Defense Quality Systems Manual for Environmental Laboratories were adhered to^[7]. Analytes included in these methods are found in Table 1.

The chromatograms produced by the primary and secondary HPLC-UV methods are shown in Figure 1 and Figure 2, respectively. Chromatograms for each detector wavelength used are shown (315, 254, and 210 nm).

Extraction Methods

High Concentration Waters (> 1 ppm)

Aqueous samples suspected to contain the compounds of interest at concentrations detectable without any extraction or pre-concentration are suitable for analysis by direct injection. The method deviates from USEPA Method 8330B by adding a pH adjustment and use of MeOH rather than ACN for dilution^[1]. The pH adjustment is needed to ensure method accuracy for ionic compounds (like NTO or PA) in basic samples. A solution of 1% HCl/MeOH is added to both acidify and dilute the samples to a final acid concentration of 0.5% (vol/vol) and a final solvent ratio of 1:1 MeOH/H2O. The direct injection samples are then ready for analysis.

Low Concentration Waters (< 1 ppm)

Aqueous samples suspected to contain the compounds of interest at low concentrations require extraction and pre-concentration using solid phase extraction (SPE). The SPE setup described here uses a triple cartridge setup shown in Figure 3. Briefly, the extraction procedure loads analytes of interest onto the cartridges in this order: Strata^TM X, Strata^TM X-A, and Envi-Carb^TM. Then the cartridge order is reversed, and analytes are eluted via a two-step elution, resulting in 2 extracts (which are combined prior to analysis). Five milliliters of MeOH is used for the first elution, while 5 mL of acidified MeOH (2% HCl) is used for the second elution. The particular SPE cartridges used are noncritical so long as cartridge chemistries are comparable to those above.

Soils

Soil collection, storage, drying and grinding procedures are identical to the USEPA Method 8330B procedures^[1]; however, the solvent extraction procedure differs in the number of sonication steps, sample mass and solvent used. A flow chart of the soil extraction procedure is shown in Figure 4. Soil masses of approximately 2 g and a sample to solvent ratio of 1:5 (g/mL) are used for soil extraction. The extraction is carried out in a sonication bath chilled below 20 ⁰C and is a two-part extraction, first extracting in MeOH (6 hours) followed by a second sonication in 1:1 MeOH:H₂O solution (14 hours). The extracts are centrifuged, and the supernatant is filtered through a 0.45 μm PTFE disk filter.

The solvent volume should generally be 10 mL but if different soil masses are required, solvent volume should be 5 mL/g. The extraction results in 2 separate extracts (MeOH and MeOH:H2O) that are combined prior to analysis.

Tissues

Tissue matrices are extracted by 18-hour sonication using a ratio of 1 gram of wet tissue per 5 mL of MeOH. This extraction is performed in a sonication bath chilled below 20 ⁰C and the supernatant (MeOH) is filtered through a 0.45 μm PTFE disk filter.

Due to the complexity of tissue matrices, an additional tissue cleanup step, adapted from prior research, can be used to reduce interferences^[8]^[2]. The cleanup procedure uses small scale chromatography columns prepared by loading 5 ¾” borosilicate pipettes with 0.2 g activated silica gel (100–200 mesh). The columns are wetted with 1 mL MeOH, which is allowed to fully elute and then discarded prior to loading with 1 mL of extract and collecting in a new amber vial. After the extract is loaded, a 1 mL aliquot of MeOH followed by a 1 mL aliquot of 2% HCL/MeOH is added. This results in a 3 mL silica treated tissue extract. This extract is vortexed and diluted to a final solvent ratio of 1:1 MeOH/H₂O before analysis.

Most federal, state, and local regulatory guidance for assessing and mitigating the vapor intrusion pathway reflects USEPA’s Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air^[9]. The paradigm outlined by that guidance includes: 1) a preliminary and mostly qualitative analysis that looks for site conditions that suggest vapor intrusion might occur (e.g., the presence of vapor-forming chemicals in close proximity to buildings); 2) a multi-step and more detailed quantitative screening analysis that involves site-specific data collection and their comparison to screening levels to identify buildings of potential VI concern; and 3) selection and design of mitigation systems or continued monitoring, as needed. With respect to (2), regulatory guidance typically recommends consideration of “multiple lines of evidence” in decision-making^[9]^[10], with typical lines-of-evidence being groundwater, soil gas, sub-slab soil gas, and/or indoor air concentrations. Of those, soil gas measurements and/or measured short-term indoor air concentrations can be weighted heavily, and therefore decision making might not be completed without them. Effective evaluation of VI risk from sub-slab and/or soil gas measurements would require an unknown building-specific attenuation factor, but there is also uncertainty as to whether or not indoor air data is representative of maximum and/or long-term average indoor concentrations. Indoor air data can be confounded by indoor contaminant sources because the number of samples is typically small, indoor concentrations can vary with time, and because a number of household products can emit the chemicals being measured. When conducting VI pathway assessments in neighborhoods where it is impractical to assess all buildings, the EPA recommends following a “worst first” investigational approach.

The limitations of this approach, as practiced, are the following:

Decisions are rarely made without indoor air data and generally, seasonal sampling is required, delaying decision making.
The collection of a robust indoor air data set that adequately characterizes long term indoor air concentrations could take years given the typical frequency of data collection and the most common methods of sample collection (e.g., 24-hour samples). Therefore, indoor air sampling might continue indefinitely at some sites.
The “worst first” buildings might not be identified correctly by the logic outlined in USEPA’s 2015 guidance and the most impacted buildings might not even be located over a groundwater plume. Recent studies have shown VI impacts in homes as a result of sewer and other subsurface piping connections, which are not explicitly considered nor easily characterized through conventional VI pathway assessment^[11]^[12]^[13]^[14]^[15].
The presumptive remedy for VI mitigation (sub-slab depressurization) may not be effective for all VI scenarios (e.g., those involving vapor migration to indoor spaces via sewer connections).

The VI Diagnosis Toolkit components were developed considering these limitations as well as more recent knowledge gained through research, development, and validation projects funded by SERDP and ESTCP.

The VI Diagnosis Toolkit Components

Figure 1. Vapor intrusion pathway conceptualization considering “alternate VI pathways”, including “pipe flow VI” and “sewer VI” pathways^[16].

The primary components of the VI Diagnosis Toolkit and their uses include:

External VI source strength screening to identify buildings most likely to be impacted by VI at levels warranting building-specific testing.
Indoor air source screening to locate and remove indoor air sources that might confound building specific VI pathway assessment.
Controlled pressurization method (CPM) testing to quickly (in a few days or less) measure the worst-case indoor air impact likely to be caused by VI under natural conditions in specific buildings. CPM tests can also be used to identify the presence of indoor air sources and diagnose active VI pathways.
Passive indoor sampling for determining long-term average indoor air concentrations under natural VI conditions and/or for verifying mitigation system effectiveness in buildings that warrant VI mitigation.
Comprehensive VI conceptual model development and refinement to ensure that appropriate monitoring, investigation, and mitigation strategies are being selected (Figure 1).

Expanded discussions for each of these are given below.

External VI source strength screening identifies those buildings that warrant more intrusive building-specific assessments, using data collected exterior to the buildings. The use of groundwater and/or soil gas concentration data for building screening has been part of VI pathway assessments for some time and their use is discussed in many regulatory guidance documents. Typically, the measured concentrations are compared to relevant screening levels derived via modeling or empirical analyses from indoor air concentrations of concern.

More recently it has been discovered that VI impacts can occur via sewer and other subsurface piping connections in areas where vapor migration through the soil would not be expected to be significant, and this could also occur in buildings that do not sit over contaminated groundwater^[15]^[12]^[13]^[14].

Therefore, in addition to groundwater and soil gas sampling, external data collection that includes and extends beyond the area of concern should include manhole vapor sampling (e.g., sanitary sewer, storm sewer, land-drain). Video surveys from sanitary sewers, storm sewers, and/or land-drains can also be used to identify areas of groundwater leakage into utility corridors and lateral connections to buildings that are conduits for vapor transport. During these investigations, it is important to recognize that utility corridors can transmit both impacted water and vapors beyond groundwater plume boundaries, so extending investigations into areas adjacent to groundwater plume boundaries is necessary.

Using projected indoor air concentrations from modeling and empirical data analyses, and distance screening approaches, external source screening can identify areas and buildings that can be ruled out, or conversely, those that warrant building-specific testing.

Demonstration of neighborhood-scale external VI source screening using groundwater, depth, sewer, land drain, and video data is documented in the ER-201501 final report^[16].

Indoor air source screening seeks to locate and remove indoor air sources^[17] that might confound building specific VI pathway assessment. Visual inspections and written surveys might or might not identify significant indoor air sources, so these should be complemented with use of portable analytical instruments^[18]^[19].

The advantage of portable analytical tools is that they allow practitioners to expeditiously test indoor air concentrations under natural conditions in each room of the building. Concentrations in any room in excess of relevant screening levels trigger more sampling in that room to identify if an indoor source is present in that room. Removal of a suspected source and subsequent room testing can identify if that object or product was the source of the previously measured concentrations.

Building-specific controlled pressurization method (CPM) testing directly measures the worst case indoor air impact, but it can also be used to determine contributing VI pathways and to identify indoor air sources^[20]^[19]^[12]^[21]^[16]^[22]. In CPM testing, blowers/fans installed in a doorway(s) or window(s) are set-up to exhaust indoor air to outdoor, which causes the building to be under pressurized relative to the atmosphere. This induces air movement from the subsurface into the test building via openings in the foundation and/or subsurface piping networks with or without direct connections to indoor air. This is similar to what happens intermittently under natural conditions when wind, indoor-outdoor temperature differences, and/or use of appliances that exhaust air from the structure (e.g. dryer exhaust) create an under-pressurized building condition.

The blowers/fans can also be used to blow outdoor air into the building, thereby creating a building over-pressurization condition. A positive pressure difference CPM test suppresses VI pathways; therefore, chemicals detected in indoor air above outdoor air concentrations during this condition are attributed to indoor contaminant sources which facilitates the identification of any such indoor air sources.

Data collected during CPM testing, when combined with screening level VI modeling, can be used to identify which VI chemical migration pathways are significant contributors to indoor air impacts^[12]. CPM testing guidelines were developed and validated under ESTCP Project ER-201501^[22]^[23].

Passive samplers can be used to measure long term average indoor air concentrations under natural conditions and during VI mitigation system operation. They will provide more confident assessment of long term average concentrations than an infrequent sequence of short term grab samples. Long term average concentrations can also be determined by long term active sampling (e.g., by slowly pulling air through a thermal desorption (TD) tube). However, passive sampling has the advantage that additional equipment and expertise is not required for sampler deployment and recovery.

Use of passive samplers in indoor air under time-varying concentration conditions was demonstrated and validated by comparing against intensive active sampling in ESTCP Project ER-201501^[16]^[24].

The purpose of maintaining an evergreen comprehensive VI conceptual model is to ensure that the most complete and up-to-date understanding of the site is informing decisions related to future sampling, data interpretation, and the need for and design of mitigation systems. The VI conceptual model can also serve as an effective communication tool in stakeholder discussions.

Use of these tools for residential neighborhoods and in non-residential buildings overlying chlorinated solvent groundwater plumes is documented comprehensively in a series of peer reviewed articles^[16]^[23]^[25]^[12]^[22]^[26]^[24]^[21].

Summary

In summary, the VI Diagnosis Toolkit provides a set of tools that can lead to quicker, more confident, and more cost effective neighborhood-scale VI pathway and impact assessments. Toolkit components and their use can complement conventional methods for assessing and mitigating the vapor intrusion pathway.

References

^ ^1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 United States Environmental Protection Agency (USEPA), 2006. EPA Method 8330B (SW-846) Nitroaromatics, Nitramines, and Nitrate Esters by High Performance Liquid Chromatography (HPLC), Revision 2. USEPA Website Method 8330B.pdf
^ ^2.0 ^2.1 Crouch, R.A., Smith, J.C., Stromer, B.S., Hubley, C.T., Beal, S., Lotufo, G.R., Butler, A.D., Wynter, M.T., Russell, A.L., Coleman, J.G., Wayne, K.M., Clausen, J.L., Bednar, A.J., 2020. Methods for simultaneous determination of legacy and insensitive munition (IM) constituents in aqueous, soil/sediment, and tissue matrices. Talanta, 217, Article 121008. doi: 10.1016/j.talanta.2020.121008 Open Access Manuscript.pdf
^ 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
^ Mainiero, C. 2015. Picatinny Employees Recognized for Insensitive Munitions. U.S. Army, Picatinny Arsenal Public Affairs. Open Access Press Release
^ Frem, D., 2022. A Review on IMX-101 and IMX-104 Melt-Cast Explosives: Insensitive Formulations for the Next-Generation Munition Systems. Propellants, Explosives, Pyrotechnics, 48(1), e202100312. doi: 10.1002/prep.202100312
^ United States Environmental Protection Agency (USEPA), 2007. EPA Method 3535A (SW-846) Solid-Phase Extraction (SPE), Revision 1. USEPA Website Method 3535A.pdf
^ US Department of Defense and US Department of Energy, 2021. Consolidated Quality Systems Manual (QSM) for Environmental Laboratories, Version 5.4. 387 pages. Free Download QSM Version 5.4.pdf
^ Russell, A.L., Seiter, J.M., Coleman, J.G., Winstead, B., Bednar, A.J., 2014. Analysis of munitions constituents in IMX formulations by HPLC and HPLC-MS. Talanta, 128, pp. 524–530. doi: 10.1016/j.talanta.2014.02.013
^ ^9.0 ^9.1 USEPA, 2015. OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, OSWER Publication No. 9200.2-154, 267 pages. USEPA Website Report.pdf
^ NJDEP, 2021. Vapor Intrusion Technical Guidance, Version 5.0. New Jersey Department of Environmental Protection, Trenton, NJ. Website Guidance Document.pdf
^ Beckley, L, McHugh, T., 2020. A Conceptual Model for Vapor Intrusion from Groundwater Through Sewer Lines. Science of the Total Environment, 698, Article 134283. doi: 10.1016/j.scitotenv.2019.134283 Open Access Article
^ ^12.0 ^12.1 ^12.2 ^12.3 ^12.4 Guo, Y., Holton, C., Luo, H., Dahlen, P., Gorder, K., Dettenmaier, E., Johnson, P.C., 2015. Identification of Alternative Vapor Intrusion Pathways Using Controlled Pressure Testing, Soil Gas Monitoring, and Screening Model Calculations. Environmental Science and Technology, 49(22), pp. 13472–13482. doi: 10.1021/acs.est.5b03564
^ ^13.0 ^13.1 McHugh, T., Beckley, L., Sullivan, T., Lutes, C., Truesdale, R., Uppencamp, R., Cosky, B., Zimmerman, J., Schumacher, B., 2017. Evidence of a Sewer Vapor Transport Pathway at the USEPA Vapor Intrusion Research Duplex. Science of the Total Environment, pp. 598, 772-779. doi: 10.1016/j.scitotenv.2017.04.135 Open Access Manuscipt
^ ^14.0 ^14.1 McHugh, T., Beckley, L., 2018. Sewers and Utility Tunnels as Preferential Pathways for Volatile Organic Compound Migration into Buildings: Risk Factors and Investigation Protocol. ESTCP ER-201505, Final Report. Project Website Final Report.pdf
^ ^15.0 ^15.1 Riis, C., Hansen, M.H., Nielsen, H.H., Christensen, A.G., Terkelsen, M., 2010. Vapor Intrusion through Sewer Systems: Migration Pathways of Chlorinated Solvents from Groundwater to Indoor Air. Seventh International Conference on Remediation of Chlorinated and Recalcitrant Compounds, May, Monterey, CA. Battelle Memorial Institute. ISBN 978-0-9819730-2-9. Website Report.pdf
^ ^16.0 ^16.1 ^16.2 ^16.3 ^16.4 Cite error: Invalid <ref> tag; no text was provided for refs named JohnsonEtAl2020
^ Doucette, W.J., Hall, A.J., Gorder, K.A., 2010. Emissions of 1,2-Dichloroethane from Holiday Decorations as a Source of Indoor Air Contamination. Ground Water Monitoring and Remediation, 30(1), pp. 67-73. doi: 10.1111/j.1745-6592.2009.01267.x
^ McHugh, T., Kuder, T., Fiorenza, S., Gorder, K., Dettenmaier, E., Philp, P., 2011. Application of CSIA to Distinguish Between Vapor Intrusion and Indoor Sources of VOCs. Environmental Science and Technology, 45(14), pp. 5952-5958. doi: 10.1021/es200988d
^ ^19.0 ^19.1 Beckley, L., Gorder, K., Dettenmaier, E., Rivera-Duarte, I., McHugh, T., 2014. On-Site Gas Chromatography/Mass Spectrometry (GC/MS) Analysis to Streamline Vapor Intrusion Investigations. Environmental Forensics, 15(3), pp. 234–243. doi: 10.1080/15275922.2014.930941
^ McHugh, T.E., Beckley, L., Bailey, D., Gorder, K., Dettenmaier, E., Rivera-Duarte, I., Brock, S., MacGregor, I.C., 2012. Evaluation of Vapor Intrusion Using Controlled Building Pressure. Environmental Science and Technology, 46(9), pp. 4792–4799. doi: 10.1021/es204483g
^ ^21.0 ^21.1 Holton, C., Guo, Y., Luo, H., Dahlen, P., Gorder, K., Dettenmaier, E., Johnson, P.C., 2015. Long-Term Evaluation of the Controlled Pressure Method for Assessment of the Vapor Intrusion Pathway. Environmental Science and Technology, 49(4), pp. 2091–2098. doi: 10.1021/es5052342
^ ^22.0 ^22.1 ^22.2 Guo, Y., Dahlen, P., Johnson, P.C., 2020a. Development and Validation of a Controlled Pressure Method Test Protocol for Vapor Intrusion Pathway Assessment. Environmental Science and Technology, 54(12), pp. 7117-7125. doi: 10.1021/acs.est.0c00811
^ ^23.0 ^23.1 Cite error: Invalid <ref> tag; no text was provided for refs named JohnsonEtAl2021
^ ^24.0 ^24.1 Guo, Y., O’Neill, H., Dahlen, P., and Johnson, P.C. 2021. Evaluation of Passive Diffusive-Adsorptive Samplers for Use in Assessing Time-Varying Indoor Air Impacts Resulting from Vapor Intrusion. Groundwater Monitoring and Remediation, 42(1), pp. 38-49. doi: 10.1111/12481
^ Cite error: Invalid <ref> tag; no text was provided for refs named JohnsonEtAl2022
^ Guo, Y., Dahlen, P., Johnson, P.C. 2020b. Temporal variability of chlorinated volatile organic compound vapor concentrations in a residential sewer and land drain system overlying a dilute groundwater plume. Science of the Total Environment, 702, Article 134756. doi: 10.1016/j.scitotenv.2019.134756 Open Access Manuscript

@@ Line 1: / Line 1: @@
-==Passive Sampling of Sediments==
+==Munitions Constituents – Sample Extraction and Analytical Techniques==
-"Passive sampling" refers to a group of methods used to quantify the availability of organic contaminants to move between different media and/or to react in environmental systems such as indoor air, lake waters, or contaminated sediment beds.  To do this, the passive sampling material is deployed in the environmental system and allowed to absorb chemicals of interest via diffusive transfers from the surroundings.  Upon recovery of the passive sampler, the accumulated contaminants are measured, and the concentrations in the sampler are interpreted to infer the chemical concentrations in specific surrounding media like porewater in a sediment bed.  Such data are then useful inputs for site assessments such as those seeking to quantify fluxes from contaminated sediment beds to overlying waters or to evaluate the risk of significant uptake into benthic infauna and the larger food web.
+Munitions Constituents, including [[Wikipedia: Insensitive munition | insensitive munitions]] IM), are a broad category of compounds and, in areas where manufactured or used, can be found in a variety of environmental matrices (waters, soil, and tissues). This presents an analytical challenge when a variety of these munitions are to be quantified. This article discusses sample extraction methods for each typical sample matrix (high level water, low level water, soil and tissue) as well as the accompanying [[Wikipedia: High-performance liquid chromatography | HPLC]]-UV analytical method for 27 compounds of interest (legacy munitions, insensitive munitions, and surrogates).
 <div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
 '''Related Article(s):'''
-* [[Contaminated Sediments - Introduction]]
-* [[In Situ Treatment of Contaminated Sediments with Activated Carbon]]
-* [[Passive Sampling of Munitions Constituents]]
-'''Contributor(s):''' [[Dr. Philip M. Gschwend]]
+*[[Munitions Constituents]]
+'''Contributor(s):'''
+*Dr. Austin Scircle
 '''Key Resource(s):'''
-* Validating the Use of Performance Reference Compounds in Passive Samplers to Assess Porewater Concentrations in Sediment Beds<ref name ="Apell2014">Apell, J.N. and Gschwend, P.M., 2014. Validating the Use of Performance Reference Compounds in Passive Samplers to Assess Porewater Concentrations in Sediment Beds.  Environmental Science and Technology, 48(17), pp. 10301-10307.  [https://doi.org/10.1021/es502694g DOI: 10.1021/es502694g]</ref>
-* ''In situ'' passive sampling of sediments in the Lower Duwamish Waterway Superfund site: Replicability, comparison with ''ex situ'' measurements, and use of data<ref name="Apell2016">Apell, J.N., and Gschwend, P.M., 2016. ''In situ'' passive sampling of sediments in the Lower Duwamish Waterway Superfund site: Replicability, comparison with ''ex situ'' measurements, and use of data. Environmental Pollution, 218, pp. 95-101.  [https://doi.org/10.1016/j.envpol.2016.08.023 DOI: 10.1016/j.envpol.2016.08.023]&nbsp;&nbsp; [[Media: ApellGschwend2016.pdf | Authors’ Manuscript]]</ref>
+*[https://www.epa.gov/sites/default/files/2015-07/documents/epa-8330b.pdf USEPA Method 8330B]<ref name= "8330B">United States Environmental Protection Agency (USEPA), 2006. EPA Method 8330B (SW-846) Nitroaromatics, Nitramines, and Nitrate Esters by High Performance Liquid Chromatography (HPLC), Revision 2. [https://www.epa.gov/esam/epa-method-8330b-sw-846-nitroaromatics-nitramines-and-nitrate-esters-high-performance-liquid USEPA Website]&nbsp; &nbsp;[[Media: epa-8330b.pdf | Method 8330B.pdf]]</ref>
-* Laboratory, Field, and Analytical Procedures for Using Passive Sampling in the Evaluation of Contaminated Sediments: User’s Manual<ref name="Burgess2017">Burgess, R.M., Kane Driscoll, S.B., Burton, A., Gschwend, P.M., Ghosh, U., Reible, D., Ahn, S., and Thompson, T., 2017. Laboratory, Field, and Analytical Procedures for Using Passive Sampling in the Evaluation of Contaminated Sediments: User’s Manual, EPA/600/R-16/357. SERDP/ESTCP and U.S. EPA, Office of Research and Development, Washington, DC 20460.  [https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=NHEERL&dirEntryID=308731 Website]&nbsp;&nbsp; [[Media: EPA600R16357.pdf | Report.pdf]]</ref>
+*Methods for simultaneous quantification of legacy and insensitive munition (IM) constituents in aqueous, soil/sediment, and tissue matrices<ref name="CrouchEtAl2020">Crouch, R.A., Smith, J.C., Stromer, B.S., Hubley, C.T., Beal, S., Lotufo, G.R., Butler, A.D., Wynter, M.T., Russell, A.L., Coleman, J.G., Wayne, K.M., Clausen, J.L., Bednar, A.J., 2020. Methods for simultaneous determination of legacy and insensitive munition (IM) constituents in aqueous, soil/sediment, and tissue matrices. Talanta, 217, Article 121008. [https://doi.org/10.1016/j.talanta.2020.121008 doi: 10.1016/j.talanta.2020.121008]&nbsp; &nbsp;[[Media: CrouchEtAl2020.pdf | Open Access Manuscript.pdf]]</ref>
 ==Introduction==
-Environmental media such as sediments typically contain many different materials or phases, including liquid solutions (e.g. water, [[Light Non-Aqueous Phase Liquids (LNAPLs)| nonaqueous phase liquids]]like spilled oils) and diverse solids (e.g., quartz, aluminosilicate clays, and combustion-derived soots).  Further, the chemical concentration in the porewater medium includes both molecules that are "truly dissolved" in the water and others that are associated with colloids in the porewater<ref name="Brownawell1986">Brownawell, B.J., and Farrington, J.W., 1986. Biogeochemistry of PCBs in interstitial waters of a coastal marine sediment. Geochimica et Cosmochimica Acta, 50(1), pp. 157-169.  [https://doi.org/10.1016/0016-7037(86)90061-X DOI: 10.1016/0016-7037(86)90061-X]&nbsp;&nbsp; Free download available from: [https://semspub.epa.gov/work/01/268631.pdf US EPA].</ref><ref name="Chin1992">Chin, Y.P., and Gschwend, P.M., 1992. Partitioning of Polycyclic Aromatic Hydrocarbons to Marine Porewater Organic Colloids. Environmental Science and Technology, 26(8), pp. 1621-1626.  [https://doi.org/10.1021/es00032a020 DOI: 10.1021/es00032a020]</ref><ref name="Achman1996">Achman, D.R., Brownawell, B.J., and Zhang, L., 1996. Exchange of Polychlorinated Biphenyls Between Sediment and Water in the Hudson River Estuary. Estuaries, 19(4), pp. 950-965.  [https://doi.org/10.2307/1352310 DOI: 10.2307/1352310]&nbsp;&nbsp; Free download available from: [https://www.academia.edu/download/55010335/135231020171114-2212-b93vic.pdf Academia.edu]</ref>. As a result, contaminant chemicals distribute among these diverse media (Figure 1) according to their affinity for each and the amount of each phase in the system<ref name="Gustafsson1996">Gustafsson, Ö., Haghseta, F., Chan, C., MacFarlane, J., and Gschwend, P.M., 1996. Quantification of the Dilute Sedimentary Soot Phase: Implications for PAH Speciation and Bioavailability. Environmental Science and Technology, 31(1), pp. 203-209.  [https://doi.org/10.1021/es960317s  DOI: 10.1021/es960317s]</ref><ref name="Luthy1997">Luthy, R.G., Aiken, G.R., Brusseau, M.L., Cunningham, S.D., Gschwend, P.M., Pignatello, J.J., Reinhard, M., Traina, S.J., Weber, W.J., and Westall, J.C., 1997. Sequestration of Hydrophobic Organic Contaminants by Geosorbents. Environmental Science and Technology, 31(12), pp. 3341-3347.  [https://doi.org/10.1021/es970512m DOI: 10.1021/es970512m]</ref><ref name="Lohmann2005">Lohmann, R., MacFarlane, J.K., and Gschwend, P.M., 2005. Importance of Black Carbon to Sorption of Native PAHs, PCBs, and PCDDs in Boston and New York Harbor Sediments. Environmental Science and Technology, 39(1), pp.141-148.  [https://doi.org/10.1021/es049424+  DOI: 10.1021/es049424+]</ref><ref name="Cornelissen2005">Cornelissen, G., Gustafsson, Ö., Bucheli, T.D., Jonker, M.T., Koelmans, A.A., and van Noort, P.C., 2005. Extensive Sorption of Organic Compounds to Black Carbon, Coal, and Kerogen in Sediments and Soils: Mechanisms and Consequences for Distribution, Bioaccumulation, and Biodegradation. Environmental Science and Technology, 39(18), pp. 6881-6895.  [https://doi.org/10.1021/es050191b  DOI: 10.1021/es050191b]</ref><ref name="Koelmans2009">Koelmans, A.A., Kaag, K., Sneekes, A., and Peeters, E.T.H.M., 2009. Triple Domain in Situ Sorption Modeling of Organochlorine Pesticides, Polychlorobiphenyls, Polyaromatic Hydrocarbons, Polychlorinated Dibenzo-p-Dioxins, and Polychlorinated Dibenzofurans in Aquatic Sediments. Environmental Science and Technology, 43(23), pp. 8847-8853.  [https://doi.org/10.1021/es9021188 DOI: 10.1021/es9021188]</ref>. As such, the chemical concentration in any one medium (e.g., truly dissolved in porewater) in a multi-material system like sediment is very hard to know from measures of the total sediment concentration, which unfortunately is the information typically found by analyzing for chemicals in sediment samples.
+The primary intention of the analytical methods presented here is to support the monitoring of legacy and insensitive munitions contamination on test and training ranges, however legacy and insensitive munitions often accompany each other at demilitarization facilities, manufacturing facilities, and other environmental sites. Energetic materials typically appear on ranges as small, solid particulates and due to their varying functional groups and polarities, can partition in various environmental compartments<ref>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]</ref>. To ensure that contaminants are monitored and controlled at these sites and to sustainably manage them a variety of sample matrices (surface or groundwater, process waters, soil, and tissues) must be considered. (Process water refers to water used during industrial manufacturing or processing of legacy and insensitive munitions.) Furthermore, additional analytes must be added to existing methodologies as the usage of IM compounds changes and as new degradation compounds are identified.  Of note, relatively new IM formulations containing NTO, DNAN, and NQ are seeing use in [[Wikipedia: IMX-101 | IMX-101]], IMX-104, Pax-21 and Pax-41 (Table 1)<ref>Mainiero, C. 2015. Picatinny Employees Recognized for Insensitive Munitions. U.S. Army, Picatinny Arsenal Public Affairs.  [https://www.army.mil/article/148873/picatinny_employees_recognized_for_insensitive_munitions Open Access Press Release]</ref><ref>Frem, D., 2022. A Review on IMX-101 and IMX-104 Melt-Cast Explosives: Insensitive Formulations for the Next-Generation Munition Systems. Propellants, Explosives, Pyrotechnics, 48(1), e202100312. [https://doi.org/10.1002/prep.202100312 doi: 10.1002/prep.202100312]</ref>.
+Sampling procedures for legacy and insensitive munitions are identical and utilize multi-increment sampling procedures found in USEPA Method 8330B Appendix A<ref name= "8330B"/>. Sample hold times, subsampling and quality control requirements are also unchanged. The key differences lie in the extraction methods and instrumental methods. Briefly, legacy munitions analysis of low concentration waters uses a single cartridge reverse phase [[Wikipedia: Solid-phase extraction | SPE]] procedure, and [[Wikipedia: Acetonitrile | acetonitrile]] (ACN) is used for both extraction and [[Wikipedia: Elution | elution]] for aqueous and solid samples<ref name= "8330B"/><ref>United States Environmental Protection Agency (USEPA), 2007. EPA Method 3535A (SW-846) Solid-Phase Extraction (SPE), Revision 1. [https://www.epa.gov/esam/epa-method-3535a-sw-846-solid-phase-extraction-spe USEPA Website]&nbsp; &nbsp;[[Media: epa-3535a.pdf | Method 3535A.pdf]]</ref>. An [[Wikipedia: High-performance_liquid_chromatography#Isocratic_and_gradient_elution | isocratic]] separation via reversed-phase C-18 column with 50:50 methanol:water mobile phase or a C-8 column with 15:85 isopropanol:water mobile phase is used to separate legacy munitions<ref name= "8330B"/>. While these procedures are sufficient for analysis of legacy munitions, alternative solvents, additional SPE cartridges, and a gradient elution are all required for the combined analysis of legacy and insensitive munitions.
+Previously, analysis of legacy and insensitive munitions required multiple analytical techniques, however the methods presented here combine the two munitions categories resulting in an HPLC-UV method and accompanying extraction methods for a variety of common sample matrices. A secondary HPLC-UV method and a HPLC-MS method were also developed as confirmatory methods. The methods discussed in this article were validated extensively by single-blind round robin testing and subsequent statistical treatment as part of ESTCP [https://serdp-estcp.mil/projects/details/d05c1982-bbfa-42f8-811d-51b540d7ebda ER19-5078]. Wherever possible, the quality control criteria in the Department of Defense Quality Systems Manual for Environmental Laboratories were adhered to<ref>US Department of Defense and US Department of Energy, 2021. Consolidated Quality Systems Manual (QSM) for Environmental Laboratories, Version 5.4. 387 pages. [https://www.denix.osd.mil/edqw/denix-files/sites/43/2021/10/QSM-Version-5.4-FINAL.pdf Free Download]&nbsp; &nbsp;[[Media: QSM-Version-5.4.pdf | QSM Version 5.4.pdf]]</ref>. Analytes included in these methods are found in Table 1.
+The chromatograms produced by the primary and secondary HPLC-UV methods are shown in Figure 1 and Figure 2, respectively. Chromatograms for each detector wavelength used are shown (315, 254, and 210 nm).
+==Extraction Methods==
+===High Concentration Waters (> 1 ppm)===
+Aqueous samples suspected to contain the compounds of interest at concentrations detectable without any extraction or pre-concentration are suitable for analysis by direct injection. The method deviates from USEPA Method 8330B by adding a pH adjustment and use of MeOH rather than ACN for dilution<ref name= "8330B"/>. The pH adjustment is needed to ensure method accuracy for ionic compounds (like NTO or PA) in basic samples. A solution of 1% HCl/MeOH is added to both acidify and dilute the samples to a final acid concentration of 0.5% (vol/vol) and a final solvent ratio of 1:1 MeOH/H2O. The direct injection samples are then ready for analysis.
+===Low Concentration Waters (< 1 ppm)===
+Aqueous samples suspected to contain the compounds of interest at low concentrations require extraction and pre-concentration using solid phase extraction (SPE). The SPE setup described here uses a triple cartridge setup shown in '''Figure 3'''. Briefly, the extraction procedure loads analytes of interest onto the cartridges in this order: Strata<sup><small>TM</small></sup> X, Strata<sup><small>TM</small></sup> X-A, and Envi-Carb<sup><small>TM</small></sup>. Then the cartridge order is reversed, and analytes are eluted via a two-step elution, resulting in 2 extracts (which are combined prior to analysis). Five milliliters of MeOH is used for the first elution, while 5 mL of acidified MeOH (2% HCl) is used for the second elution. The particular SPE cartridges used are noncritical so long as cartridge chemistries are comparable to those above.
+===Soils===
+Soil collection, storage, drying and grinding procedures are identical to the USEPA Method 8330B procedures<ref name= "8330B"/>; however, the solvent extraction procedure differs in the number of sonication steps, sample mass and solvent used. A flow chart of the soil extraction procedure is shown in '''Figure 4'''. Soil masses of approximately 2 g and a sample to solvent ratio of 1:5 (g/mL) are used for soil extraction. The extraction is carried out in a sonication bath chilled below 20 ⁰C and is a two-part extraction, first extracting in MeOH (6 hours) followed by a second sonication in 1:1 MeOH:H<sub>2</sub>O solution (14 hours). The extracts are centrifuged, and the supernatant is filtered through a 0.45 μm PTFE disk filter.
-If an animal moves into this system, it will also accumulate the chemical in its tissues from the loads in all the other materials (Figure 1).  This is important if one is concerned with exposures of the chemical to other organisms, including humans, who may eat such shellfish.  Predicting the quantity of contaminant in the clam requires knowledge of the relative affinities of the chemical for the clam versus the sediment materials.  For example, if one knew the chemical's truly dissolved concentration in the porewater and could reasonably assume the chemical of interest in the clams has mostly accumulated in its lipids (as is often the case for very hydrophobic compounds), then one could estimate the chemical concentration in the clam (''C<sub><small>clam</small></sub>'', typically in units of &mu;g/kg clam wet weight) using a lipid-water [[Wikipedia: Partition coefficient | partition coefficient]], ''K<sub><small>lipid-water</small></sub>'', typically in units of (&mu;g/kg lipid)'''/'''(&mu;g/L water), and the porewater concentration of the chemical (''C<sub><small>porewater</small></sub>'', in &mu;g/L) with Equation 1.
+The solvent volume should generally be 10 mL but if different soil masses are required, solvent volume should be 5 mL/g. The extraction results in 2 separate extracts (MeOH and MeOH:H2O) that are combined prior to analysis.
-{|
-|
-|-
-| || Equation 1.
-| style="text-align:center;"| <big>'''''C<sub><small>clam</small></sub> '''=''' f<sub><small>lipid</small></sub> '''x''' K<sub><small>lipid-water</small></sub> '''x''' C<sub><small>porewater</small></sub>'''''</big>
-|-
-| where:
-|-
-| || ''f<sub><small>lipid</small></sub>'' || is the fraction lipids contribute to the total wet weight of a clam (kg lipid/kg clam wet weight), and
-|-
-| || ''C<sub><small>porewater</small></sub>'' || is the freely dissolved contaminant concentration in the porewater surrounding the clam.
-|}
-While there is a great deal of information on the values of ''K<sub><small>lipid-water</small></sub>'' for many chemicals<ref name="Schwarzenbach2017">Schwarzenbach, R.P., Gschwend, P.M., and Imboden, D.M., 2017.  Environmental Organic Chemistry, 3rd edition. Ch. 16: Equilibrium Partitioning from Water and Air to Biota, pp. 469-521. John Wiley and Sons.  ISBN: 978-1-118-76723-8</ref>, it is often very inaccurate to estimate truly dissolved porewater concentrations from total sediment concentrations using assumptions about the affinity of those chemicals for the solids in the system<ref name="Gustafsson1996"/>. Further, it is difficult to isolate porewater without colloids and/or measure the very low truly dissolved concentrations of hydrophobic contaminants of concern like [[Polycyclic Aromatic Hydrocarbons (PAHs) | polycyclic aromatic hydrocarbons (PAHs)]], [[Wikipedia: Polychlorinated biphenyl | polychlorinated biphenyls (PCBs)]], nonionic pesticides like [[Wikipedia: DDT | dichlorodiphenyltrichloroethane (DDT)]], and [[Wikipedia: Polychlorinated dibenzodioxins | polychlorinated dibenzo-p-dioxins (PCDDs)]]/[[Wikipedia: Polychlorinated dibenzofurans | dibenzofurans (PCDFs)]]<ref name="Hawthorne2005">Hawthorne, S.B., Grabanski, C.B., Miller, D.J., and Kreitinger, J.P., 2005. Solid-Phase Microextraction Measurement of Parent and Alkyl Polycyclic Aromatic Hydrocarbons in Milliliter Sediment Pore Water Samples and Determination of K<sub><small>DOC</small></sub> Values. Environmental Science and Technology, 39(8), pp. 2795-2803.  [https://doi.org/10.1021/es0405171 DOI: 10.1021/es0405171]</ref>.
+===Tissues===
-==Passive Samplers==
+Tissue matrices are extracted by 18-hour sonication using a ratio of 1 gram of wet tissue per 5 mL of MeOH. This extraction is performed in a sonication bath chilled below 20 ⁰C and the supernatant (MeOH) is filtered through a 0.45 μm PTFE disk filter.
-One approach to address this problem for contaminated sediments is to insert organic polymers like low density polyethylene (LDPE), polydimethylsiloxane (PDMS), or polyoxymethylene (POM) that can absorb such chemicals in the sediment<ref name="Mayer2000">Mayer, P., Vaes, W.H., Wijnker, F., Legierse, K.C., Kraaij, R., Tolls, J., and Hermens, J.L., 2000. Sensing Dissolved Sediment Porewater Concentrations of Persistent and Bioaccumulative Pollutants Using Disposable Solid-Phase Microextraction Fibers. Environmental Science and Technology, 34(24), pp. 5177-5183.  [https://doi.org/10.1021/es001179g DOI: 10.1021/es001179g]</ref><ref name="Booij2003">Booij, K., Hoedemaker, J.R., and Bakker, J.F., 2003. Dissolved PCBs, PAHs, and HCB in Pore Waters and Overlying Waters of Contaminated Harbor Sediments. Environmental Science and Technology, 37(18), pp. 4213-4220.  [https://doi.org/10.1021/es034147c DOI: 10.1021/es034147c]</ref><ref name="Cornelissen2008">Cornelissen, G., Pettersen, A., Broman, D., Mayer, P., and Breedveld, G.D., 2008. Field testing of equilibrium passive samplers to determine freely dissolved native polycyclic aromatic hydrocarbon concentrations. Environmental Toxicology and Chemistry, 27(3), pp. 499-508.  [https://doi.org/10.1897/07-253.1 DOI: 10.1897/07-253.1]</ref><ref name="Tomaszewski2008">Tomaszewski, J.E., and Luthy, R.G., 2008. Field Deployment of Polyethylene Devices to Measure PCB Concentrations in Pore Water of Contaminated Sediment. Environmental Science and Technology, 42(16), pp. 6086-6091.  [https://doi.org/10.1021/es800582a DOI: 10.1021/es800582a]</ref><ref name="Fernandez2009">Fernandez, L.A., MacFarlane, J.K., Tcaciuc, A.P., and Gschwend, P.M., 2009. Measurement of Freely Dissolved PAH Concentrations in Sediment Beds Using Passive Sampling with Low-Density Polyethylene Strips. Environmental Science and Technology, 43(5), pp. 1430-1436.  [https://doi.org/10.1021/es802288w DOI: 10.1021/es802288w]</ref><ref name="Arp2015">Arp, H.P.H., Hale, S.E., Elmquist Kruså, M., Cornelissen, G., Grabanski, C.B., Miller, D.J., and Hawthorne, S.B., 2015. Review of polyoxymethylene passive sampling methods for quantifying freely dissolved porewater concentrations of hydrophobic organic contaminants. Environmental Toxicology and Chemistry, 34(4), pp. 710-720.  [https://doi.org/10.1002/etc.2864 DOI: 10.1002/etc.2864]&nbsp;&nbsp;  [https://setac.onlinelibrary.wiley.com/doi/epdf/10.1002/etc.2864 Free access article.]&nbsp;&nbsp; [[Media: Arp2015.pdf | Report.pdf]]</ref><ref name="Apell2016"/>. In this approach, the polymer is inserted in the sediment bed where it absorbs some of the contaminant load via the contaminant's diffusion into the polymer from the surroundings. When the polymer achieves sorptive equilibration with the sediments, the chemical concentration in the polymer, ''C<sub><small>polymer</small></sub>'' (&mu;g/kg polymer), can be used to find the corresponding concentration in the porewater,  ''C<sub><small>porewater</small></sub>'' (&mu;g/L), using a polymer-water partition coefficient, ''K<sub><small>polymer-water</small></sub>'' ((&mu;g/kg polymer)'''/'''(&mu;g/L water)), that has previously been found in laboratory testing<ref name="Lohmann2012">Lohmann, R., 2012. Critical Review of Low-Density Polyethylene’s Partitioning and Diffusion Coefficients for Trace Organic Contaminants and Implications for Its Use as a Passive Sampler. Environmental Science and Technology, 46(2), pp. 606-618.  [https://doi.org/10.1021/es202702y DOI: 10.1021/es202702y]</ref><ref name="Ghosh2014">Ghosh, U., Kane Driscoll, S., Burgess, R.M., Jonker, M.T., Reible, D., Gobas, F., Choi, Y., Apitz, S.E., Maruya, K.A., Gala, W.R., Mortimer, M., and Beegan, C., 2014. Passive Sampling Methods for Contaminated Sediments: Practical Guidance for Selection, Calibration, and Implementation. Integrated Environmental Assessment and Management, 10(2), pp. 210-223.  [https://doi.org/10.1002/ieam.1507 DOI: 10.1002/ieam.1507]&nbsp;&nbsp; [https://setac.onlinelibrary.wiley.com/doi/epdf/10.1002/ieam.1507 Free access article.]&nbsp;&nbsp; [[Media: Ghosh2014.pdf | Report.pdf]]</ref>, as shown in Equation 2.
-{|
-|
-|-
-|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;|| Equation&nbsp;2.
-| style="width:600px; text-align:center;" | <big>'''''C<sub><small>porewater</small></sub> '''=''' C<sub><small>polymer</small></sub> '''/''' K<sub><small>polymer-water</small></sub>'''''</big>
-|}
-Such “passive uptake” by the polymer also reflects the availability of the chemicals for transport to adjacent systems (e.g., overlying surface waters) and for uptake into organisms (e.g., [[Wikipedia: Bioaccumulation | bioaccumulation]]).   Thus, one can use the porewater concentrations to estimate the biotic accumulation of the chemicals, too.  For example, for the concentration in the clam equilibrated with the sediment, ''C<sub><small>clam</small></sub>'' (&mu;g/kg clam), would be found by combining Equations 1 and 2 to get Equation 3.
+Due to the complexity of tissue matrices, an additional tissue cleanup step, adapted from prior research, can be used to reduce interferences<ref name="RussellEtAl2014">Russell, A.L., Seiter, J.M., Coleman, J.G., Winstead, B., Bednar, A.J., 2014. Analysis of munitions constituents in IMX formulations by HPLC and HPLC-MS. Talanta, 128, pp. 524–530. [https://doi.org/10.1016/j.talanta.2014.02.013 doi: 10.1016/j.talanta.2014.02.013]</ref><ref name="CrouchEtAl2020"/>. The cleanup procedure uses small scale chromatography columns prepared by loading 5 ¾” borosilicate pipettes with 0.2 g activated silica gel (100–200 mesh). The columns are wetted with 1 mL MeOH, which is allowed to fully elute and then discarded prior to loading with 1 mL of extract and collecting in a new amber vial. After the extract is loaded, a 1 mL aliquot of MeOH followed by a 1 mL aliquot of 2% HCL/MeOH is added. This results in a 3 mL silica treated tissue extract. This extract is vortexed and diluted to a final solvent ratio of 1:1 MeOH/H<sub>2</sub>O before analysis.
-{|
-|
-|-
-|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;|| Equation&nbsp;3.
-|style="width:700px; text-align:center;" |<big>'''''C<sub><small>clam</small></sub> '''=''' f<sub><small>lipid</small></sub> '''x''' K<sub><small>lipid-water</small></sub> '''x''' C<sub><small>polymer</small></sub> '''/''' K<sub><small>polymer-water</small></sub>'''''</big>
-|}
-==Performance Reference Compounds (PRCs)==
-Perhaps unsurprisingly, pollutants with low water solubility like PAHs, PCBs, etc. do not diffuse quickly through sediment beds.  As a result, their accumulation in polymeric materials in sediments can take a long time to achieve equilibration<ref name="Fernandez2009b">Fernandez, L. A., Harvey, C.F., and Gschwend, P.M., 2009. Using Performance Reference Compounds in Polyethylene Passive Samplers to Deduce Sediment Porewater Concentrations for Numerous Target Chemicals. Environmental Science and Technology, 43(23), pp. 8888-8894. [https://doi.org/10.1021/es901877a DOI: 10.1021/es901877a]</ref><ref name="Lampert2015">Lampert, D.J., Thomas, C., and Reible, D.D., 2015. Internal and external transport significance for predicting contaminant uptake rates in passive samplers. Chemosphere, 119, pp. 910-916.  [https://doi.org/10.1016/j.chemosphere.2014.08.063 DOI: 10.1016/j.chemosphere.2014.08.063]&nbsp;&nbsp; Free download available from: [https://www.academia.edu/download/44146586/chemosphere_2014.pdf Academia.edu]</ref><ref name="Apell2016b">Apell, J.N., Tcaciuc, A.P., and Gschwend, P.M., 2016. Understanding the rates of nonpolar organic chemical accumulation into passive samplers deployed in the environment: Guidance for passive sampler deployments. Integrated Environmental Assessment and Management, 12(3), pp. 486-492.  [https://doi.org/10.1002/ieam.1697 DOI: 10.1002/ieam.1697]</ref>. This problem was recognized previously for passive samplers called [[Wikipedia: Semipermeable membrane devices | semipermeable membrane devices]] (SPMDs, e.g. polyethylene bags filled with triolein<ref name="Huckins2002">Huckins, J.N., Petty, J.D., Lebo, J.A., Almeida, F.V., Booij, K., Alvarez, D.A., Cranor, W.L., Clark, R.C., and Mogensen, B.B., 2002. Development of the Permeability/Performance Reference Compound Approach for In Situ Calibration of Semipermeable Membrane Devices. Environmental Science and Technology, 36(1), pp. 85-91.  [https://doi.org/10.1021/es010991w DOI: 10.1021/es010991w]</ref>) that were deployed in surface waters. As a result, representative chemicals called performance reference compound (PRCs) were dosed inside the samplers before their deployment in the environment, and the PRCs' diffusive losses out of the SPMD could be used to quantify the fractional approach toward sampler-environmental surroundings equilibration<ref name="Booij2002">Booij, K., Smedes, F., and van Weerlee, E.M., 2002. Spiking of performance reference compounds in low density polyethylene and silicone passive water samplers. Chemosphere 46(8), pp.1157-1161.  [https://doi.org/10.1016/S0045-6535(01)00200-4 DOI: 10.1016/S0045-6535(01)00200-4]</ref><ref name="Huckins2002"/>. A similar approach can be used for polymers inserted in sediment beds<ref name="Fernandez2009b"/><ref name="Apell2014"/>. Commonly, isotopically labeled forms of the compounds of interest such as deuterated or <sup>13</sup>C-labelled PAHs or PCBs are homogeneously impregnated into the polymers before their deployments.  Upon insertion of the polymer into the sediment bed (or overlying waters or even air), the initially evenly distributed PRCs begin to diffuse out of the sampling polymer and  into the sediment (Figure 2).
+Most federal, state, and local regulatory guidance for assessing and mitigating the [[Vapor Intrusion (VI) | vapor intrusion]] pathway reflects USEPA’s ''Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air''<ref name="USEPA2015">USEPA, 2015. OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, OSWER Publication No. 9200.2-154, 267 pages. [https://www.epa.gov/vaporintrusion/technical-guide-assessing-and-mitigating-vapor-intrusion-pathway-subsurface-vapor USEPA Website]&nbsp;&nbsp; [//www.enviro.wiki/images/0/06/USEPA2015.pdf  Report.pdf]</ref>. The paradigm outlined by that guidance includes: 1) a preliminary and mostly qualitative analysis that looks for site conditions that suggest vapor intrusion might occur (e.g., the presence of vapor-forming chemicals in close proximity to buildings); 2) a multi-step and more detailed quantitative screening analysis that involves site-specific data collection and their comparison to screening levels to identify buildings of potential VI concern; and 3) selection and design of mitigation systems or continued monitoring, as needed. With respect to (2), regulatory guidance typically recommends consideration of “multiple lines of evidence” in decision-making<ref name="USEPA2015" /><ref>NJDEP, 2021. Vapor Intrusion Technical Guidance, Version 5.0. New Jersey Department of Environmental Protection, Trenton, NJ. [https://dep.nj.gov/srp/guidance/vapor-intrusion/vig/ Website]&nbsp;&nbsp; [//www.enviro.wiki/images/e/ee/NJDEP2021.pdf  Guidance Document.pdf]</ref>, with typical lines-of-evidence being groundwater, soil gas, sub-slab soil gas, and/or indoor air concentrations.  Of those, soil gas measurements and/or measured short-term indoor air concentrations can be weighted heavily, and therefore decision making might not be completed without them. Effective evaluation of VI risk from sub-slab and/or soil gas measurements would require an unknown building-specific attenuation factor, but there is also uncertainty as to whether or not indoor air data is representative of maximum and/or long-term average indoor concentrations. Indoor air data can be confounded by indoor contaminant sources because the number of samples is typically small, indoor concentrations can vary with time, and because a number of household products can emit the chemicals being measured. When conducting VI pathway assessments in neighborhoods where it is impractical to assess all buildings, the EPA recommends following a “worst first” investigational approach.
-[[File: Schwartz1w2Fig1.PNG | thumb | 500px | Figure 1.  Conceptual model of mercury speciation in the environment<ref>European Commission's Joint Research Centre, 2017. A new CRM to make mercury measurements in food more reliable. [https://ec.europa.eu/jrc/en/science-update/new-crm-make-mercury-measurements-food-more-reliable Website]</ref>]]
-[[Wikipedia: Mercury (element) | Mercury]] (Hg) is released into the environment typically in the inorganic form. Natural emissions of Hg(0) come mainly from volcanoes and the ocean. Anthropogenic emissions are mainly from artisanal and small-scale gold mining, coal combustion, and various industrial processes that use Hg ( see the [https://www.unep.org/explore-topics/chemicals-waste/what-we-do/mercury/global-mercury-assessment UN Global mercury assessment]). Industrial and natural emissions of gaseous elemental mercury, Hg(0), can travel long distances in the atmosphere before being oxidized and deposited on land and in water as inorganic Hg(II). The long range transport and atmospheric deposition of Hg results in widespread low-level Hg contamination of soils at concentrations of 0.01 to 0.3 mg/kg<ref name="Eckley2020"/>.
-Hg-contaminated sites are most commonly contaminated with Hg(II) from industrial discharge and have soil concentrations in the range of 100s to 1000s of mg/kg<ref name="Eckley2020"/>.  Direct exposure to Hg(II) and Hg(0) can be a human health risk at heavily contaminated sites. However, the organic form of Hg, [[Wikipedia: Methylmercury | methylmercury]] (MeHg or CH<sub>3</sub>Hg<sup>+</sup>) is typically the greater concern. MeHg is a neurotoxin that is particularly harmful to developing fetuses and young children. Direct contamination of the environment with MeHg is not common, but has occurred, most notably in [https://www.minamatadiseasemuseum.net/10-things-to-know Minamata Bay, Japan] (see also [https://en.wikipedia.org/wiki/Minamata_disease Minamata disease]). More commonly, MeHg is formed in the environment from Hg(II) in oxygen-limited conditions in a processes mediated by anaerobic microorganisms. Because MeHg [[Wikipedia: Biomagnification | biomagnifies]] in the aquatic food web, MeHg concentrations in fish can be elevated in areas that have relatively low levels of Hg contamination. The MeHg production depends heavily on site geochemistry, and high total Hg sediment concentrations do not always correlate with MeHg production potential.
+The limitations of this approach, as practiced, are the following:
-==Biogeochemistry/Mobility of Hg in soils==
+*Decisions are rarely made without indoor air data and generally, seasonal sampling is required, delaying decision making.
-In the environment, Hg mobility is largely controlled by chelation with various ligands or adsorption to particles<ref name ="Hsu-Kim2018"/>. Hg(II) is most strongly attracted to the sulfur functional groups in dissolved organic matter (DOM) and to sulfur ligands. Over time, newly released Hg(II) “ages” and becomes less reactive to ligands and is less likely to be found in the dissolved phase. Legacy Hg(II) found in sediments and soils is more likely to be strongly adsorbed to the soil matrix and not very bioavailable compared to newly released Hg(II)<ref name ="Hsu-Kim2018"/>. MeHg has mobility tendencies similar to Hg, with DOM and sulfur ligands competing with each other to form complexes with MeHg<ref name="Loux2007">Loux, N.T., 2007. An assessment of thermodynamic reaction constants for simulating aqueous environmental monomethylmercury speciation. Chemical Speciation and Bioavailability, 19(4), pp.183-196.  [https://doi.org/10.3184/095422907X255947  DOI: 10.3184/095422907X255947]&nbsp;&nbsp; [https://www.tandfonline.com/doi/pdf/10.3184/095422907X255947?needAccess=true Free access article]&nbsp;&nbsp; [[Media: Loux2007.pdf | Report.pdf]]</ref>. However, unlike Hg-S complexes, MeHg-S does not have limited solubility.
+*The collection of a robust indoor air data set that adequately characterizes long term indoor air concentrations could take years given the typical frequency of data collection and the most common methods of sample collection (e.g., 24-hour samples).  Therefore, indoor air sampling might continue indefinitely at some sites.
+*The “worst first” buildings might not be identified correctly by the logic outlined in USEPA’s 2015 guidance and the most impacted buildings might not even be located over a groundwater plume.  Recent studies have shown [[Vapor Intrusion – Sewers and Utility Tunnels as Preferential Pathways |VI impacts in homes as a result of sewer and other subsurface piping connections]], which are not explicitly considered nor easily characterized through conventional VI pathway assessment<ref> Beckley, L, McHugh, T., 2020. A Conceptual Model for Vapor Intrusion from Groundwater Through Sewer Lines. Science of the Total Environment, 698, Article 134283. [https://doi.org/10.1016/j.scitotenv.2019.134283 doi: 10.1016/j.scitotenv.2019.134283]&nbsp;&nbsp; [//www.enviro.wiki/images/4/4e/BeckleyMcHugh2020.pdf  Open Access Article]</ref><ref name="GuoEtAl2015">Guo, Y., Holton, C., Luo, H., Dahlen, P., Gorder, K., Dettenmaier, E., Johnson, P.C., 2015. Identification of Alternative Vapor Intrusion Pathways Using Controlled Pressure Testing, Soil Gas Monitoring, and Screening Model Calculations. Environmental Science and Technology, 49(22), pp. 13472–13482. [https://doi.org/10.1021/acs.est.5b03564 doi: 10.1021/acs.est.5b03564]</ref><ref name="McHughEtAl2017">McHugh, T., Beckley, L., Sullivan, T., Lutes, C., Truesdale, R., Uppencamp, R., Cosky, B., Zimmerman, J., Schumacher, B., 2017.  Evidence of a Sewer Vapor Transport Pathway at the USEPA Vapor Intrusion Research Duplex.  Science of the Total Environment, pp. 598, 772-779. [https://doi.org/10.1016/j.scitotenv.2017.04.135 doi: 10.1016/j.scitotenv.2017.04.135]&nbsp;&nbsp; [//www.enviro.wiki/images/6/63/McHughEtAl2017.pdf  Open Access Manuscipt]</ref><ref name="McHughBeckley2018">McHugh, T., Beckley, L., 2018. Sewers and Utility Tunnels as Preferential Pathways for Volatile Organic Compound Migration into Buildings: Risk Factors and Investigation Protocol. ESTCP ER-201505, Final Report. [https://serdp-estcp.mil/projects/details/f12abf80-5273-4220-b09a-e239d0188421 Project Website]&nbsp;&nbsp; [//www.enviro.wiki/images/5/55/2018b-McHugh-ER-201505_Conceptual_Model.pdf  Final Report.pdf]</ref><ref name="RiisEtAl2010">Riis, C., Hansen, M.H., Nielsen, H.H., Christensen, A.G., Terkelsen, M., 2010. Vapor Intrusion through Sewer Systems: Migration Pathways of Chlorinated Solvents from Groundwater to Indoor Air. Seventh International Conference on Remediation of Chlorinated and Recalcitrant Compounds, May, Monterey, CA. Battelle Memorial Institute. ISBN 978-0-9819730-2-9. [https://www.battelle.org/conferences/battelle-conference-proceedings Website]&nbsp;&nbsp; [//www.enviro.wiki/images/9/95/2010-Riis-Migratioin_pathways_of_Chlorinated_Solvents.pdf  Report.pdf]</ref>.
+*The presumptive remedy for VI mitigation (sub-slab depressurization) may not be effective for all VI scenarios (e.g., those involving vapor migration to indoor spaces via sewer connections).
+The '''VI Diagnosis Toolkit''' components were developed considering these limitations as well as more recent knowledge gained through research, development, and validation projects funded by SERDP and ESTCP.
-The bioavailability of Hg(II) is one of the factors controlling MeHg production in the environment. MeHg production occurs in anoxic environments and is affected by: (1) the bioavailability of Hg(II) complexes to Hg-[[Wikipedia: Methylation | methylating]] microorganisms, (2) the activity of Hg-methylating microorganisms, and (3) the rate of biotic and abiotic [[Wikipedia: Demethylation | demethylation]]. MeHg is produced by anaerobic microorganisms that contain the ''hgcAB'' gene<ref name="Parks2013">Parks, J.M., Johs, A., Podar, M., Bridou, R. Hurt, R.A., Smith, S.D., Tomanicek, S.J., Qian, Y., Brown, S.D., Brandt, C.C., Palumbo, A.V., Smith, J.C., Wall, J.D., Elias, D.A., Liang, L., 2013. The Genetic Basis for Bacterial Mercury Methylation. Science, 339(6125), pp. 1332-1335.  [https://science.sciencemag.org/content/339/6125/1332 DOI: 10.1126/science.1230667]</ref>. These microorganisms are a diverse group and include, sulfate-reducing bacteria, iron-reducing bacteria, and methanogenic bacteria. Site geochemistry has a significant effect on MeHg production. Methylating microorganisms are sensitive to oxygen, and MeHg production occurs in oxygen-depleted or anaerobic zones in the environment, such as anoxic aquatic sediments, saturated soils, and biofilms with anoxic microenvironments<ref name="Bravo2020">Bravo, A.G., Cosio, C., 2020. Biotic formation of methylmercury: A bio–physico–chemical conundrum. Limnology and Oceanography, 65(5), pp. 1010-1027. [https://doi.org/10.1002/lno.11366 DOI: 10.1002/lno.11366]&nbsp;&nbsp; [https://aslopubs.onlinelibrary.wiley.com/doi/epdf/10.1002/lno.11366 Free Access Article]&nbsp;&nbsp; [[Media: Bravo2020.pdf | Report.pdf]]</ref>. The activity of methylating microorganisms can be impacted by redox conditions, the concentrations of organic carbon, and different electron acceptors (e.g. sulfate vs iron)<ref name="Bravo2020"/>. Overall, MeHg concentrations and production are impacted by demethylation as well. Demethylation can occur both abiotically and biotically and occurs at a much faster rate than methylation. The main routes of abiotic demethylation are photochemical reactions and demethylation catalyzed by reduced sulfur surfaces<ref name="Du2019">Du, H. Ma, M., Igarashi, Y., Wang, D., 2019. Biotic and Abiotic Degradation of Methylmercury in Aquatic Ecosystems: A Review. Bulletin of Environmental Contamination and Toxicology, 102 pp. 605-611. [https://doi.org/10.1007/s00128-018-2530-2 DOI: 10.1007/s00128-018-2530-2]</ref><ref name="Jonsson2016">Jonsson, S., Mazrui, N.M., Mason, R.P., 2016. Dimethylmercury Formation Mediated by Inorganic and Organic Reduced Sulfur Surfaces. Scientific Reports, 6, Article 27958.  [https://doi.org/10.1038/srep27958 DOI: 10.1038/srep27958]&nbsp;&nbsp; [https://www.nature.com/articles/srep27958.pdf Free access article]&nbsp;&nbsp; [[Media: Jonsson2016.pdf | Report.pdf]]</ref>. Methylmercury can be degraded biotically by aerobic bacteria containing the mercury detoxification, ''mer'' [[Wikipedia: Operon | operon]] and through oxidative demethylation by anaerobic microorganisms<ref name="Du2019"/>.
+==The VI Diagnosis Toolkit Components==
+[[File:DahlenFig1.png|thumb|450px|Figure 1. Vapor intrusion pathway conceptualization considering “alternate VI pathways”, including “pipe flow
+VI” and “sewer VI” pathways<ref name="JohnsonEtAl2020" />.]]
+The primary components of the VI Diagnosis Toolkit and their uses include:
-==Bioaccumulation and Toxicology==
+*'''External VI source strength screening''' to identify buildings most likely to be impacted by VI at levels warranting building-specific testing.
-Regulatory criteria are most often based on total Hg concentrations, however, MeHg is the form of Hg that can [[Wikipedia: Bioaccumulation | bioaccumulate]] in wildlife and is the greatest human and ecological health risk<ref name=”ATSDR1999”>Agency for Toxic Substances and Disease Registry (ATSDR), 1999. Toxicological Profile for Mercury.  [https://www.atsdr.cdc.gov/ToxProfiles/tp46.pdf Free download]&nbsp;&nbsp; [[Media: ATSDR1999.pdf | Report.pdf]]</ref>. MeHg represents over 95% of the Hg found in fish<ref name="Bloom1992">Bloom, N.S., 1992. On the Chemical Form of Mercury in Edible Fish and Marine Invertebrate Tissue. Canadian Journal of Fisheries and Aquatic Sciences 49(5), pp. 1010-117.  [https://doi.org/10.1139/f92-113 DOI: 10.1139/f92-113]</ref>. Hg and MeHg can be taken up directly from contaminated water into organisms, with the identity of the Hg-ligand complexes determining how readily the Hg is taken up into the organism<ref name="Kidd2012">Kidd, K., Clayden, M., Jardine, T., 2012. Bioaccumulation and Biomagnification of Mercury through Food Webs. Environmental Chemistry and Toxicology of Mercury, pp. 453-499. Liu, G., Yong, C. O’Driscoll, N., Eds. John Wiley and Sons, Inc. Hoboken, NJ.  [https://doi.org/10.1002/9781118146644.ch14 DOI: 10.1002/9781118146644.ch14]</ref>. Direct bioconcentration from water is the major uptake route at the base of the food web. Hg and MeHg can also enter the food web when benthic organisms ingest contaminated sediments<ref name="Mason2001">Mason, R.P., 2001. The Bioaccumulation of Mercury, Methylmercury and Other Toxic Elements into Pelagic and Benthic Organisms. Coastal and Estuarine Risk Assessment, pp. 127-149. Newman, M., Roberts, M., and Hale, R.C., Ed.s. CRC Press. ISBN: 978-1-4200-3245-1  Free download from: [https://www.researchgate.net/profile/Robert-Mason-13/publication/266354387_The_Bioaccumulation_of_Mercury_Methylmercury_and_Other_Toxic_Elements_into_Pelagic_and_Benthic_Organisms/links/55083eff0cf26ff55f80662d/The-Bioaccumulation-of-Mercury-Methylmercury-and-Other-Toxic-Elements-into-Pelagic-and-Benthic-Organisms.pdf ResearchGate]</ref>. Further up the food web organisms are exposed to Hg and MeHg both through exposure to contaminated water and through their diet. The higher up the trophic level, the more important dietary exposure becomes. Fish obtain more than 90% of Hg from their diet<ref name="Kidd2012"/>.
+*'''Indoor air source screening''' to locate and remove indoor air sources that might confound building specific VI pathway assessment.
+*'''Controlled pressurization method (CPM)''' testing to quickly (in a few days or less) measure the worst-case indoor air impact likely to be caused by VI under natural conditions in specific buildings. CPM tests can also be used to identify the presence of indoor air sources and diagnose active VI pathways.
+*'''Passive indoor sampling''' for determining long-term average indoor air concentrations under natural VI conditions and/or for verifying mitigation system effectiveness in buildings that warrant VI mitigation.
+*'''Comprehensive VI conceptual model development and refinement''' to ensure that appropriate monitoring, investigation, and mitigation strategies are being selected (Figure 1).
-Humans are mainly exposed to Hg in the forms of MeHg and Hg(0). Hg(0) exposure comes from dental amalgams and industrial/contaminated site exposures. Hg(0) readily crosses the blood/brain barrier and mainly effects the nervous system and the kidneys<ref name="Clarkson2003">Clarkson, T.W., Magos, L., Myers, G.J., 2003. The Toxicology of Mercury — Current Exposures and Clinical Manifestations. New England Journal of Medicine, 349, pp. 1731-1737. [https://doi.org/10.1056/NEJMra022471 DOI: 10.1056/NEJMra022471]</ref>. MeHg exposure comes from the consumption of contaminated fish. In the human body, MeHg is readily absorbed through the gastrointestinal tract into the bloodstream and crosses the blood/brain barrier, affecting the central nervous system. MeHg can also pass through the placenta to the fetus and is particularly harmful to the developing nervous system of the fetus.
+Expanded discussions for each of these are given below.
-MeHg and Hg toxicity in the body occurs through multiple pathways and may be linked to the affinity of Hg for sulfur groups. Hg and MeHg bind to S-containing groups, which can block normal bodily functions<ref name="Bjørklund2017">Bjørklund, G., Dadar, M., Mutter, J. and Aaseth, J., 2017. The toxicology of mercury: Current research and emerging trends. Environmental Research, 159, pp.545-554.  [https://doi.org/10.1016/j.envres.2017.08.051 DOI: 10.1016/j.envres.2017.08.051]</ref>.
+'''External VI source strength screening''' identifies those buildings that warrant more intrusive building-specific assessments, using data collected exterior to the buildings. The use of groundwater and/or soil gas concentration data for building screening has been part of VI pathway assessments for some time and their use is discussed in many regulatory guidance documents. Typically, the measured concentrations are compared to relevant screening levels derived via modeling or empirical analyses from indoor air concentrations of concern.
-==Regulatory Framework for Mercury==
+More recently it has been discovered that VI impacts can occur via sewer and other subsurface piping connections in areas where vapor migration through the soil would not be expected to be significant, and this could also occur in buildings that do not sit over contaminated groundwater<ref name="RiisEtAl2010" /><ref name="GuoEtAl2015" /><ref name="McHughEtAl2017" /><ref name="McHughBeckley2018" />.
-In the United States, mercury is regulated by several different [[Wikipedia: Mercury regulation in the United States | environmental laws]] including: the Mercury Export Ban Act of 2008, the Mercury-Containing and Rechargeable Battery Management Act of 1996, the Clean Air Act, the Clean Water Act, the Emergency Planning and Community Right-to-Know Act,  the Resource Conservation and Recovery Act, and the Safe Drinking Water Act<ref name=”USEPA2021”>US EPA, 2021.  Environmental Laws that Apply to Mercury.  [https://www.epa.gov/mercury/environmental-laws-apply-mercury US EPA Website]</ref>.
-In 2013, the United States signed the international [https://www.epa.gov/international-cooperation/minamata-convention-mercury Minamata Convention on Mercury]. The Minamata Convention on Mercury seeks to address and reduce human activities that are contributing to widespread mercury pollution. Worldwide, 128 countries have signed the Convention.
+Therefore, in addition to groundwater and soil gas sampling, external data collection that includes and extends beyond the area of concern should include manhole vapor sampling (e.g., sanitary sewer, storm sewer, land-drain). Video surveys from sanitary sewers, storm sewers, and/or land-drains can also be used to identify areas of groundwater leakage into utility corridors and lateral connections to buildings that are conduits for vapor transport. During these investigations, it is important to recognize that utility corridors can transmit both impacted water and vapors beyond groundwater plume boundaries, so extending investigations into areas adjacent to groundwater plume boundaries is necessary.
-==Remediation Technologies==
+Using projected indoor air concentrations from modeling and empirical data analyses, and distance screening approaches, external source screening can identify areas and buildings that can be ruled out, or conversely, those that warrant building-specific testing.
-As a chemical element, Hg cannot be destroyed, so the goal of Hg-remediation is immobilization and prevention of food web bioaccumulation. At very highly contaminated sites (>100s ppm), sediments are often removed and landfilled<ref name="Eckley2020"/>. ''In situ'' capping is also a common remediation approach. Both dredging and capping can be costly and ecologically destructive, and the development of less invasive, less costly remediation technologies for Hg and MeHg contaminated sediments is an active research field. Eckley et al.<ref name="Eckley2020"/>and Wang et al.<ref name="Wang2020">Wang, L., Hou, D., Cao, Y., Ok, Y.S., Tack, F., Rinklebe, J., O’Connor, D., 2020. Remediation of mercury contaminated soil, water, and air: A review of emerging materials and innovative technologies. Environmental International, 134, 105281.  [https://doi.org/10.1016/j.envint.2019.105281  DOI: 10.1016/j.envint.2019.105281]&nbsp;&nbsp; [https://www.sciencedirect.com/science/article/pii/S0160412019324754 Free access article]</ref> give thorough reviews of standard and emerging technologies.
+Demonstration of neighborhood-scale external VI source screening using groundwater, depth, sewer, land drain, and video data is documented in the ER-201501 final report<ref name="JohnsonEtAl2020" />.
+'''Indoor air source screening''' seeks to locate and remove indoor air sources<ref>Doucette, W.J., Hall, A.J., Gorder, K.A., 2010. Emissions of 1,2-Dichloroethane from Holiday Decorations as a Source of Indoor Air Contamination. Ground Water Monitoring and Remediation, 30(1), pp. 67-73. [https://doi.org/10.1111/j.1745-6592.2009.01267.x doi: 10.1111/j.1745-6592.2009.01267.x] </ref> that might confound building specific VI pathway assessment. Visual inspections and written surveys might or might not identify significant indoor air sources, so these should be complemented with use of portable analytical instruments<ref>McHugh, T., Kuder, T., Fiorenza, S., Gorder, K., Dettenmaier, E., Philp, P., 2011. Application of CSIA to Distinguish Between Vapor Intrusion and Indoor Sources of VOCs. Environmental Science and Technology, 45(14), pp. 5952-5958. [https://doi.org/10.1021/es200988d doi: 10.1021/es200988d]</ref><ref name="BeckleyEtAl2014">Beckley, L., Gorder, K., Dettenmaier, E., Rivera-Duarte, I., McHugh, T., 2014. On-Site Gas Chromatography/Mass Spectrometry (GC/MS) Analysis to Streamline Vapor Intrusion Investigations. Environmental Forensics, 15(3), pp. 234–243. [https://doi.org/10.1080/15275922.2014.930941 doi: 10.1080/15275922.2014.930941]</ref>.
+The advantage of portable analytical tools is that they allow practitioners to expeditiously test indoor air concentrations under natural conditions in each room of the building. Concentrations in any room in excess of relevant screening levels trigger more sampling in that room to identify if an indoor source is present in that room. Removal of a suspected source and subsequent room testing can identify if that object or product was the source of the previously measured concentrations.
+'''Building-specific controlled pressurization method (CPM) testing''' directly measures the worst case indoor air impact, but it can also be used to determine contributing VI pathways and to identify indoor air sources<ref>McHugh, T.E., Beckley, L., Bailey, D., Gorder, K., Dettenmaier, E., Rivera-Duarte, I., Brock, S., MacGregor, I.C., 2012. Evaluation of Vapor Intrusion Using Controlled Building Pressure. Environmental Science and Technology, 46(9), pp. 4792–4799. [https://doi.org/10.1021/es204483g doi: 10.1021/es204483g]</ref><ref name="BeckleyEtAl2014" /><ref name="GuoEtAl2015" /><ref name="HoltonEtAl2015">Holton, C., Guo, Y., Luo, H., Dahlen, P., Gorder, K., Dettenmaier, E., Johnson, P.C., 2015. Long-Term Evaluation of the Controlled Pressure Method for Assessment of the Vapor Intrusion Pathway. Environmental Science and Technology, 49(4), pp. 2091–2098.  [https://doi.org/10.1021/es5052342 doi: 10.1021/es5052342]</ref><ref name="JohnsonEtAl2020" /><ref name="GuoEtAl2020a">Guo, Y., Dahlen, P., Johnson, P.C., 2020a. Development and Validation of a Controlled Pressure Method Test Protocol for Vapor Intrusion Pathway Assessment.  Environmental Science and Technology, 54(12), pp. 7117-7125. [https://dx.doi.org/10.1021/acs.est.0c00811 doi: 10.1021/acs.est.0c00811]</ref>. In CPM testing, blowers/fans installed in a doorway(s) or window(s) are set-up to exhaust indoor air to outdoor, which causes the building to be under pressurized relative to the atmosphere. This induces air movement from the subsurface into the test building via openings in the foundation and/or subsurface piping networks with or without direct connections to indoor air. This is similar to what happens intermittently under natural conditions when wind, indoor-outdoor temperature differences, and/or use of appliances that exhaust air from the structure (e.g. dryer exhaust) create an under-pressurized building condition.
+The blowers/fans can also be used to blow outdoor air into the building, thereby creating a building over-pressurization condition. A positive pressure difference CPM test suppresses VI pathways; therefore, chemicals detected in indoor air above outdoor air concentrations during this condition are attributed to indoor contaminant sources which facilitates the identification of any such indoor air sources.
+Data collected during CPM testing, when combined with screening level VI modeling, can be used to identify which VI chemical migration pathways are significant contributors to indoor air impacts<ref name="GuoEtAl2015" />. CPM testing guidelines were developed and validated under ESTCP Project ER-201501<ref name="GuoEtAl2020a" /><ref name="JohnsonEtAl2021" />.
+'''Passive samplers''' can be used to measure long term average indoor air concentrations under natural conditions and during VI mitigation system operation. They will provide more confident assessment of long term average concentrations than an infrequent sequence of short term grab samples. Long term average concentrations can also be determined by long term active sampling (e.g., by slowly pulling air through a thermal desorption (TD) tube). However, passive sampling has the advantage that additional equipment and expertise is not required for sampler deployment and recovery.
+Use of passive samplers in indoor air under time-varying concentration conditions was demonstrated and validated by comparing against intensive active sampling in ESTCP Project ER-201501<ref name="JohnsonEtAl2020" /><ref name="GuoEtAl2021">Guo, Y., O’Neill, H., Dahlen, P., and Johnson, P.C.  2021.  Evaluation of Passive Diffusive-Adsorptive Samplers for Use in Assessing Time-Varying Indoor Air Impacts Resulting from Vapor Intrusion.  Groundwater Monitoring and Remediation, 42(1), pp. 38-49.  [https://doi.org/10.1111/gwmr.12481 doi: 10.1111/12481]</ref>.
+The purpose of maintaining an evergreen '''comprehensive VI conceptual model''' is to ensure that the most complete and up-to-date understanding of the site is informing decisions related to future sampling, data interpretation, and the need for and design of mitigation systems. The VI conceptual model can also serve as an effective communication tool in stakeholder discussions.
+Use of these tools for residential neighborhoods and in non-residential buildings overlying chlorinated solvent groundwater plumes is documented comprehensively in a series of peer reviewed articles<ref name="JohnsonEtAl2020" /><ref name="JohnsonEtAl2021" /><ref name="JohnsonEtAl2022" /><ref name="GuoEtAl2015" /><ref name="GuoEtAl2020a" /><ref name="GuoEtAl2020b">Guo, Y., Dahlen, P., Johnson, P.C. 2020b. Temporal variability of chlorinated volatile organic compound vapor concentrations in a residential sewer and land drain system overlying a dilute groundwater plume. Science of the Total Environment, 702, Article 134756.  [https://doi.org/10.1016/j.scitotenv.2019.134756 doi: 10.1016/j.scitotenv.2019.134756]&nbsp;&nbsp; [//www.enviro.wiki/images/e/e5/GuoEtAl2020b.pdf  Open Access Manuscript]</ref><ref name="GuoEtAl2021" /><ref name="HoltonEtAl2015" />.
+==Summary==
+In summary, the VI Diagnosis Toolkit provides a set of tools that can lead to quicker, more confident, and more cost effective neighborhood-scale VI pathway and impact assessments. Toolkit components and their use can complement conventional methods for assessing and mitigating the vapor intrusion pathway.
-Recently application of ''in situ'' sorbents has garnered interest as a remediation solution for Hg<ref name="Eckley2020"/>. Many different materials, including biochar and various formulations of [[In Situ Treatment of Contaminated Sediments with Activated Carbon | activated carbon]], are successful in lowering porewater concentrations of Hg and MeHg in contaminated sediments<ref name="Gilmour2013">Gilmour, C.C., Riedel, G.S., Riedel, G., Kwon, S., Landis, R., Brown, S.S., Menzie, C.A., Ghosh, U., 2013. Activated Carbon Mitigates Mercury and Methylmercury Bioavailability in Contaminated Sediments. Environmental Science and Technology, 47(22), pp. 13001-13010.  [https://doi.org/10.1021/es4021074 DOI: 10.1021/es4021074]&nbsp;&nbsp; Free download from: [https://www.researchgate.net/profile/Steven-Brown-18/publication/258042399_Activated_Carbon_Mitigates_Mercury_and_Methylmercury_Bioavailability_in_Contaminated_Sediments/links/5702a10e08aea09bb1a30083/Activated-Carbon-Mitigates-Mercury-and-Methylmercury-Bioavailability-in-Contaminated-Sediments.pdf ResearchGate]</ref>. More research is needed to determine whether Hg and MeHg sorbed to these materials are available for uptake into organisms. Site biogeochemistry can also impact the efficacy of sorbent materials, with dissolved organic matter and sulfide concentrations impacting Hg and MeHg sorption. Overall, knowing site biogeochemical characteristics is important for predicting Hg mobility and MeHg production risks as well as for designing a remediation strategy that will be effective.
-<br clear="left" />
 ==References==
 <references />
 ==See Also==
+*[https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4000681 Evaluation of Radon and Building Pressure Differences as Environmental Indicators for Vapor Intrusion Assessment]
+*[https://pubs.acs.org/doi/10.1021/es4024767 Temporal Variability of Indoor Air Concentrations under Natural Conditions in a House Overlying a Dilute Chlorinated Solvent Groundwater Plume]
+*[https://serdp-estcp.mil/projects/details/e0d00662-c333-4560-8ae7-60f20b0e714b Integrated Field-Scale, Lab-Scale, and Modeling Studies for Improving Our Ability to Assess the Groundwater to Indoor Air Pathway at Chlorinated Solvent Impacted Sites]

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Latest revision as of 21:57, 22 July 2024

Munitions Constituents – Sample Extraction and Analytical Techniques

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