Difference between revisions of "1,2,3-Trichloropropane"

Latest revision as of 03:07, 28 April 2022

1,2,3-Trichloropropane (TCP) is a chlorinated volatile organic compound (CVOC) that has been used in chemical production processes, in agriculture, and as a solvent, resulting in point and non-point source contamination of soil and groundwater. TCP is mobile and highly persistent in soil and groundwater. TCP is not currently regulated at the national level in the United States, but maximum contaminant levels (MCLs) have been developed by some states. Current treatment methods for TCP are limited and can be cost prohibitive. However, some treatment approaches, particularly in situ chemical reduction (ISCR) with zero valent zinc (ZVZ) and in situ bioremediation (ISB), have recently been shown to have potential as practical remedies for TCP contamination of groundwater.

Introduction

Figure 1. Ball and stick representation of the molecular structure of TCP (Salter-Blanc and Tratnyek, unpublished)

1,2,3-Trichloropropane (TCP) (Figure 1) is a man-made chemical that was used in the past primarily as a solvent and extractive agent, as a paint and varnish remover, and as a cleaning and degreasing agent.^[3]. Currently, TCP is primarily used in chemical synthesis of compounds such as polysulfone liquid polymers used in the aerospace and automotive industries; hexafluoropropylene used in the agricultural, electronic, and pharmaceutical industries; polysulfide polymers used as sealants in manufacturing and construction; and 1,3-dichloropropene used in agriculture as a soil fumigant. TCP may also be present in products containing these chemicals as an impurity^[3]^[4]. For example, the 1,2-dichlropropane/1,3-dichloropropene soil fumigant mixture (trade name D-D), which is no longer sold in the United States, contained TCP as an impurity and has been linked to TCP contamination in groundwater^[5]^[4]. Soil fumigants currently in use which are composed primarily of 1,3-dichloropropene may also contain TCP as an impurity, for instance Telone II has been reported to contain up to 0.17 percent TCP by weight^[6].

TCP contamination is problematic because it is “reasonably anticipated to be a human carcinogen” based on evidence of carcinogenicity to animals^[7]. Toxicity to humans appears to be high relative to other chlorinated solvents^[6], suggesting that even low-level exposure to TCP could pose a significant human health risk.

Environmental Fate

TCP’s fate in the environment is governed by its physical and chemical properties (Table 1). TCP does not adsorb strongly to soil, making it likely to leach into groundwater and exhibit high mobility. In addition, TCP is moderately volatile and can partition from surface water and moist soil into the atmosphere. Because TCP is only slightly soluble and denser than water, it can form a dense non-aqueous phase liquid (DNAPL) as observed at the Tyson’s Dump Superfund Site^[8]. TCP is generally resistant to aerobic biodegradation, hydrolysis, oxidation, and reduction under naturally occurring conditions making it persistent in the environment^[1].

Table 1. Physical and chemical properties of TCP^[9]
Property	Value
Chemical Abstracts Service (CAS) Number	96-18-4
Physical Description (at room temperature)	Colorless to straw-colored liquid
Molecular weight (g/mol)	147.43
Water solubility at 25°C (mg/L)	1,750 (slightly soluble)
Melting point (°C)	-14.7
Boiling point (°C)	156.8
Vapor pressure at 25°C (mm Hg)	3.10 to 3.69
Density at 20°C (g/cm³)	1.3889
Octanol-water partition coefficient (logK_ow)	1.98 to 2.27 (temperature dependent)
Organic carbon-water partition coefficient (logK_oc)	1.70 to 1.99 (temperature dependent)
Henry’s Law constant at 25°C (atm-m³/mol)	3.17x10^-4^[3] to 3.43x10^-4^[10]

Occurrence

TCP has been detected in approximately 1% of public water supply and domestic well samples tested by the United States Geological Survey. More specifically, TCP was detected in 1.2% of public supply well samples collected between 1993 and 2007 by Toccalino et al^[11] and 0.66% of domestic supply well samples collected between 1991 and 2004 by DeSimone^[12]. TCP was detected at a higher rate in domestic supply well samples associated with agricultural land-use studies than samples associated with studies comparing primary aquifers (3.5% versus 0.2%)^[12].

Regulation

The United States Environmental Protection Agency (USEPA) has not established an MCL for TCP, although guidelines and health standards are in place^[9]. TCP was included in the Contaminant Candidate List 3^[13] and the Unregulated Contaminant Monitoring Rule 3 (UCMR 3)^[14]. The UCMR 3 specified that data be collected on TCP occurrence in public water systems over the period of January 2013 through December 2015 against a reference concentration range of 0.0004 to 0.04 μg/L^[15]. The reference concentration range was determined based on a cancer risk of 10-6 to 10-4 and derived from an oral slope factor of 30 mg/kg-day, which was determined by the EPA’s Integrated Risk Information System^[16]. Of 36,848 samples collected during UCMR 3, 0.67% exceeded the minimum reporting level of 0.03 µg/L. 1.4% of public water systems had at least one detection over the minimum reporting level, corresponding to 2.5% of the population^[15]. While these occurrence percentages are relatively low, the minimum reporting level of 0.03 µg/L is more than 75 times the USEPA-calculated Health Reference Level of 0.0004 µg/L. Because of this, TCP may occur in public water systems at concentrations that exceed the Health Reference Level but are below the minimum reporting level used during UCMR 3 data collection. These analytical limitations and lack of lower-level occurrence data have prevented the USEPA from making a preliminary regulatory determination for TCP^[17].

Some US states have established their own standards including Hawaii which has established an MCL of 0.6 μg/L^[18]. California has established an MCL of 0.005 μg/L^[19], a notification level of 0.005 μg/L, and a public health goal of 0.0007 μg/L^[20], and New Jersey has established an MCL of 0.03 μg/L^[21].

Transformation Processes

Figure 2. Figure 2. Summary of anticipated primary reaction pathways for degradation of TCP. Oxidation, hydrolysis, and hydrogenolysis are represented by the horizontal arrows. Elimination (dehydrochlorination) and reductive elimination are shown with vertical arrows. [O] represents oxygenation (by oxidation or hydrolysis), [H] represents reduction. Gray indicates products that appear to be of lesser significance^[1].

Potential TCP degradation pathways include hydrolysis, oxidation, and reduction (Figure 2). These pathways are expected to be similar overall for abiotic and biotic reactions^[22], but the rates of the reactions (and their resulting significance for remediation) depend on natural and engineered conditions.

The rate of hydrolysis of TCP is negligible under typical ambient pH and temperature conditions but is favorable at high pH and/or temperature^[1]^[22]. For example, ammonia gas can be used to raise soil pH and stimulate alkaline hydrolysis of chlorinated propanes including TCP^[23]. Thermal Conduction Heating (TCH) may also produce favorable conditions for TCP hydrolysis^[1]^[22].

Treatment Approaches

Compared to more frequently encountered CVOCs such as trichloroethene (TCE) and tetrachloroethene (PCE), TCP is relatively recalcitrant^[24]^[1]. TCP is generally resistant to hydrolysis, bioremediation, oxidation, and reduction under natural conditions^[1]. The moderate volatility of TCP makes air stripping, air sparging, and soil vapor extraction (SVE) less effective compared to other VOCs^[24]. Despite these challenges, both ex situ and in situ treatment technologies exist. Ex situ treatment processes are relatively well established and understood but can be cost prohibitive. In situ treatment methods are comparatively limited and less-well developed, though promising field-scale demonstrations of some in situ treatment technologies have been conducted.

Ex Situ Treatment

The most common ex situ treatment technology for groundwater contaminated with TCP is groundwater extraction and treatment^[25]. Extraction of TCP is generally effective given its relatively high solubility in water and low degree of partitioning to soil. After extraction, TCP is typically removed by adsorption to granular activated carbon (GAC)^[24]^[26].

TCP contamination in drinking water sources is typically treated using granular activated carbon (GAC)^[27].

In California, GAC is considered the best available technology (BAT) for treating TCP, and as of 2017 seven full-scale treatment facilities were using GAC to treat groundwater contaminated with TCP^[28]. Additionally, GAC has been used for over 30 years to treat 60 million gallons per day of TCP-contaminated groundwater in Hawaii^[29].

GAC has a low to moderate adsorption capacity for TCP, which can necessitate larger treatment systems and result in higher treatment costs relative to other organic contaminants^[9]. Published Freundlich adsorption isotherm parameters^[30] indicate that less TCP mass is adsorbed per gram of carbon compared to other volatile organic compounds (VOCs), resulting in increased carbon usage rate and treatment cost. Recent bench-scale studies indicate that subbituminous coal-based GAC and coconut shell-based GAC are the most effective types of GAC for treatment of TCP in groundwater^[29]^[31]. To develop more economical and effective treatment approaches, further treatability studies with site groundwater (e.g., rapid small-scale column tests) may be needed.

In Situ Treatment

In situ treatment of TCP to concentrations below current regulatory or advisory levels is difficult to achieve in both natural and engineered systems. However, several in situ treatment technologies have demonstrated promise for TCP remediation, including chemical reduction by zero-valent metals (ZVMs), chemical oxidation with strong oxidizers, and anaerobic bioremediation^[24]^[1].

In Situ Chemical Reduction (ISCR)

Reduction of TCP under conditions relevant to natural attenuation has been observed to be negligible. Achieving significant degradation rates of TCP requires the addition of a chemical reductant to the contaminated zone^[24]^[1]. Under reducing environmental conditions, some ZVMs have demonstrated the ability to reduce TCP all the way to propene. As shown in Figure 2, the desirable pathway for reduction of TCP is the formation of 3-chloro-1-propene (also known as allyl chloride) via dihaloelimination, which is then rapidly reduced to propene through hydrogenolysis ^[24]^[1]^[32]. ZVMs including granular zero-valent iron (ZVI), nano ZVI, palladized nano ZVI, and zero-valent zinc (ZVZ) have been evaluated by researchers^[24]^[1].

ZVI is a common reductant used for ISCR and, depending on the form used, has shown variable levels of success for TCP treatment. The Strategic Environmental Research and Development Program (SERDP) Project ER-1457 measured the TCP degradation rates for various forms of ZVI and ZVZ. Nano-scale ZVI and palladized ZVI increased the TCP reduction rate over that of natural attenuation, but the reaction is not anticipated to be fast enough to be useful in typical remediation applications^[22].

Commercial-grade zerovalent zinc (ZVZ) on the other hand is a strong reductant that reduces TCP relatively quickly under a range of laboratory and field conditions to produce propene without significant accumulation of intermediates^[22]^[33]^[34]^[24]. Of the ZVMs tested as part of SERDP Project ER-1457, ZVZ had the fastest degradation rates for TCP^[1]. In bench-scale studies, TCP was reduced by ZVZ to propene with 3-chloro-1-propene as the only detectable chlorinated intermediate, which was short-lived and detected only at trace concentrations^[32].

Navy Environmental Sustainability Development to Integration (NESDI) Project 434 conducted bench-scale testing which demonstrated that commercially available ZVZ was effective for treating TCP. Additionally, this project evaluated field-scale ZVZ column treatment of groundwater impacted with TCP at Marine Corps Base Camp Pendleton (MCBCP) in Oceanside, California. This study reported reductions of TCP concentrations by up to 95% which was maintained for at least twelve weeks with influent concentrations ranging from 3.5 to 10 µg/L, without any significant secondary water quality impacts detected^[34].

Following the column study, a 2014 pilot study at MCBCP evaluated direct injection of ZVZ with subsequent monitoring. Direct injection of ZVZ was reportedly effective for TCP treatment, with TCP reductions ranging from 90% to 99% in the injection area. Concentration reduction downgradient of the injection area ranged from 50 to 80%. TCP concentrations have continued to decrease, and reducing conditions have been maintained in the aquifer since injection, demonstrating the long-term efficacy of ZVZ for TCP reduction^[2].

Potential in situ applications of ZVZ include direct injection, as demonstrated by the MCBCP pilot study, and permeable reactive barriers (PRBs). Additionally, ZVZ could potentially be deployed in an ex situ flow-through reactor, but the economic feasibility of this approach would depend in part on the permeability of the aquifer and in part on the cost of the reactor volumes of ZVZ media necessary for complete treatment.

In Situ Chemical Oxidation (ISCO)

Chemical oxidation of TCP with mild oxidants such as permanganate or ozone is ineffective. However, stronger oxidants (e.g. activated peroxide and persulfate) can effectively treat TCP, although the rates are slower than observed for most other organic contaminants^[1]^[26]. Fenton-like chemistry (i.e., Fe(II) activated hydrogen peroxide) has been shown to degrade TCP in the laboratory with half-lives ranging from 5 to 10 hours^[1], but field-scale demonstrations of this process have not been reported. Treatment of TCP with heat-activated or base-activated persulfate is effective but secondary water quality impacts from high sulfate may be a concern at some locations.

Aerobic Bioremediation

No naturally occurring microorganisms have been identified that degrade TCP under aerobic conditions^[25]. Relatively slow aerobic cometabolism by the ammonia oxidizing bacterium Nitrosomonas europaea and other populations has been reported^[35]^[25], and genetic engineering has been used to develop organisms capable of utilizing TCP as a sole carbon source under aerobic conditions^[36]^[25]^[37].

Anaerobic Bioremediation

Like other CVOCs, TCP has been shown to undergo biodegradation under anaerobic conditions via reductive dechlorination by Dehalogenimonas (Dhg) species^[24]^[38]^[39]^[40]^[41]^[25]. However, the kinetics are slower than for other CVOCs. Bioaugmentation cultures containing Dehalogenimonas (KB-1 Plus, SiREM) are commercially available and have been implemented for remediation of TCP-contaminated groundwater^[42]. One laboratory study examined the effect of pH on biotransformation of TCP over a wide range of TCP concentrations (10 to 10,000 µg/L) and demonstrated that successful reduction occurred from a pH of 5 to 9, though optimal conditions were from pH 7 to 9^[42].

As with other microbial cultures capable of reductive dechlorination, coordinated amendment with a fermentable organic substrate (e.g. lactate or vegetable oil), also known as biostimulation, creates reducing conditions in the aquifer and provides a source of hydrogen which is required as the primary electron donor for reductive dechlorination.

A 2016 field demonstration of in situ bioremediation (ISB) was performed in California’s Central Valley at a former agricultural chemical site with relatively low TCP concentrations (2 µg/L). The site was first biostimulated by injecting amendments of emulsified vegetable oil (EVO) and lactate, which was followed by bioaugmentation with a microbial consortium containing Dhg. After an initial lag period of six months, TCP concentrations decreased to below laboratory detection limits (<0.005 µg/L)^[42].

Table 2. Advantages and limitations of TCP treatment technologies^[2]
Technology	Advantages	Limitations
ZVZ	Can degrade TCP at relatively high and low concentrations Faster reaction rates than ZVI Material is commercially available	Higher cost than ZVI Difficult to distribute in subsurface in situ applications
Groundwater Extraction and Treatment	Can cost-effectively capture and treat larger, more dilute groundwater plumes than in situ technologies Well understood and widely applied technology	Requires construction, operation and maintenance of aboveground treatment infrastructure Typical technologies (e.g. GAC) may be expensive due to treatment inefficiencies
ZVI	Can degrade TCP at relatively high and low concentrations Lower cost than ZVZ Material is commercially available	Lower reactivity than ZVZ, therefore may require higher ZVI volumes or thicker PRBs Difficult to distribute in subsurface in situ applications
ISCO	Can degrade TCP at relatively high and low concentrations Strategies to distribute amendments in situ are well established Material is commercially available	Most effective oxidants (e.g., base-activated or heat-activated persulfate) are complex to implement Secondary water quality impacts (e.g., high pH, sulfate, hexavalent chromium) may limit ability to implement
In Situ Bioremediation	Can degrade TCP at moderate to high concentrations Strategies to distribute amendments in situ are well established Materials are commercially available and inexpensive	Slower reaction rates than ZVZ or ISCO

The 2016 field demonstration was expanded to full-scale treatment in 2018 with biostimulation and bioaugmentation occurring over several months. The initial TCP concentration in performance monitoring wells ranged from 0.008 to 1.7 µg/L. As with the field demonstration, a lag period of approximately 6 to 8 months was observed before TCP was degraded, after which concentrations declined over fifteen months to non-detectable levels (less than 0.005 µg/L). TCP degradation was associated with increases in Dhg population and propene concentration. Long term monitoring showed that TCP remained at non-detectable levels for at least three years following treatment implementation^[24].

Treatment Comparisons and Considerations

When selecting a technology for TCP treatment, considerations include technical feasibility, ability to treat to regulated levels, potential secondary water quality impacts and relative costs. A comparison of some TCP treatment technologies is provided in Table 2.

Summary

The relatively high toxicity of TCP has led to the development of health-based drinking water concentration values that are very low. TCP is sometimes present in groundwater and in public water systems at concentrations that exceed these health based goals. While a handful of states have established MCLs for TCP, US federal regulatory determination is hindered by the lack of low concentration occurrence data. Because TCP is persistent in groundwater and resistant to typical remediation methods (or costly to treat), specialized strategies may be needed to meet drinking water based treatment goals. In situ chemical reduction (ISCR) with zero valent zinc (ZVZ) and in situ bioremediation have been demonstrated to be effective for TCP remediation.

References

^ ^1.00 ^1.01 ^1.02 ^1.03 ^1.04 ^1.05 ^1.06 ^1.07 ^1.08 ^1.09 ^1.10 ^1.11 ^1.12 ^1.13 Tratnyek, P.G., Sarathy, V., Salter, A.J., Nurmi, J.T., O’Brien Johnson, G., DeVoe, T., and Lee, P., 2010. Prospects for Remediation of 1,2,3-Trichloropropane by Natural and Engineered Abiotic Degradation Reactions. Strategic Environmental Research and Development Program (SERDP), Project ER-1457. Report pdf
^ ^2.0 ^2.1 ^2.2 Kane, L.Z., Suchomel, E.J., and Deeb, R.A., 2020. Verification Monitoring for In Situ Chemical Reduction Using Zero-Valent Zinc, A Novel Technology for Remediation of Chlorinated Alkanes. Strategic Environmental Research and Development Program (SERDP), Project ER-201628. Report pdf
^ ^3.0 ^3.1 ^3.2 Agency for Toxic Substances and Disease Registry (ATSDR), 2021. Toxicological Profile for 1,2,3-Trichloropropane. Report pdf
^ ^4.0 ^4.1 CH2M HILL, 2005. Interim Guidance for Investigating Potential 1,2,3-Trichloropropane Sources in San Gabriel Valley Area 3. Report pdf
^ Oki, D.S. and Giambelluca, T.W., 1987. DBCP, EDB, and TCP Contamination of Ground Water in Hawaii. Groundwater, 25(6), pp. 693-702. DOI: 10.1111/j.1745-6584.1987.tb02210.x
^ ^6.0 ^6.1 Kielhorn, J., Könnecker, G., Pohlenz-Michel, C., Schmidt, S. and Mangelsdorf, I., 2003. Concise International Chemical Assessment Document 56: 1,2,3-Trichloropropane. World Health Organization, Geneva. Report pdf
^ National Toxicology Program, 2016. Report on Carcinogens, 14th ed. U.S. Department of Health and Human Services, Public Health Service. Report pdf
^ United States Environmental Protection Agency (USEPA), 2019. Fifth Five-year Review Report, Tyson’s Dump Superfund Site, Upper Merion Township, Montgomery County, Pennsylvania. Report pdf
^ ^9.0 ^9.1 ^9.2 United States Environmental Protection Agency (USEPA), 2017. Technical Fact Sheet—1,2,3-Trichloropropane (TCP). EPA Project 505-F-17-007. 6 pp. Report pdf
^ Leighton Jr, D.T. and Calo, J.M., 1981. Distribution Coefficients of Chlorinated Hydrocarbons in Dilute Air-Water Systems for Groundwater Contamination Applications. Journal of Chemical and Engineering Data, 26(4), pp. 382-385. DOI: 10.1021/je00026a010
^ Toccalino, P.L., Norman, J.E., Hitt, K.J., 2010. Quality of Source Water from Public-Supply Wells in the United States, 1993–2007. Scientific Investigations Report 2010-5024. U.S. Geological Survey. DOI: 10.3133/sir20105024 Report pdf
^ ^12.0 ^12.1 DeSimone, L.A., 2009. Quality of Water from Domestic Wells in Principal Aquifers of the United States, 1991–2004. U.S. Geological Survey, Scientific Investigations Report 2008–5227. 139 pp. Report pdf
^ United States Environmental Protection Agency (US EPA), 2009. Drinking Water Contaminant Candidate List 3-Final. Federal Register 74(194), pp. 51850–51862, Document E9-24287. Register pdf
^ United States Environmental Protection Agency (US EPA), 2012. Revisions to the Unregulated Contaminant Mentoring Regulation (UCMR 3) for Public Water Systems. Federal Register 77(85) pp. 26072-26101. Register pdf
^ ^15.0 ^15.1 United States Environmental Protection Agency (USEPA), 2017. The Third Unregulated Contaminant Monitoring Rule (UCMR 3): Data Summary. EPA 815-S-17-001. Report.pdf
^ USEPA Integrated Risk Information System (IRIS), 2009. 1,2,3-Trichloropropane (CASRN 96-18-4). Summary pdf
^ USEPA, 2021. Announcement of Final Regulatory Determinations for Contaminants on the Fourth Drinking Water Contaminant Candidate List. Report pdf
^ Hawaii Department of Health, 2013. Amendment and Compilation of Chapter 11-20 Hawaii Administrative Rules. Report pdf
^ California Code of Regulations, 2021. Section 64444 Maximum Contaminant Levels – Organic Chemicals (22 CA ADC § 64444).
^ Office of Environmental Health Hazard Assessment (OEHHA), California Environmental Protection Agency, 2009. Final Public Health Goal for 1,2,3-Trichloropropane in Drinking Water.
^ New Jersey Administrative Code 7:10, 2020. Safe Drinking Water Act Rules.
^ ^22.0 ^22.1 ^22.2 ^22.3 ^22.4 Sarathy, V., Salter, A.J., Nurmi, J.T., O’Brien Johnson, G., Johnson, R.L., and Tratnyek, P.G., 2010. Degradation of 1, 2, 3-Trichloropropane (TCP): Hydrolysis, Elimination, and Reduction by Iron and Zinc. Environmental Science and Technology, 44(2), pp.787-793. DOI: 10.1021/es902595j
^ Medina, V.F., Waisner, S.A., Griggs, C.S., Coyle, C., and Maxwell, M., 2016. Laboratory-Scale Demonstration Using Dilute Ammonia Gas-Induced Alkaline Hydrolysis of Soil Contaminants (Chlorinated Propanes and Explosives). US Army Engineer Research and Development Center, Environmental Laboratory (ERDC/EL), Report TR-16-10. Report pdf
^ ^24.0 ^24.1 ^24.2 ^24.3 ^24.4 ^24.5 ^24.6 ^24.7 ^24.8 ^24.9 Merrill, J.P., Suchomel, E.J., Varadhan, S., Asher, M., Kane, L.Z., Hawley, E.L., and Deeb, R.A., 2019. Development and Validation of Technologies for Remediation of 1,2,3-Trichloropropane in Groundwater. Current Pollution Reports, 5(4), pp. 228–237. DOI: 10.1007/s40726-019-00122-7
^ ^25.0 ^25.1 ^25.2 ^25.3 ^25.4 Samin, G. and Janssen, D.B., 2012. Transformation and biodegradation of 1,2,3-trichloropropane (TCP). Environmental Science and Pollution Research International, 19(8), pp. 3067-3078. DOI: 10.1007/s11356-012-0859-3 Report pdf
^ ^26.0 ^26.1 California Environmental Protection Agency, 2017. Groundwater Information Sheet, 1,2,3-Trichloropropane (TCP). State Water Resources Control Board, Division of Water Quality, Groundwater Ambient Monitoring and Assessment (GAMA) Program, 8 pp. Report pdf
^ Hooker, E.P., Fulcher, K.G. and Gibb, H.J., 2012. Report to the Hawaii Department of Health, Safe Drinking Water Branch, Regarding the Human Health Risks of 1, 2, 3-Trichloropropane in Tap Water. Report pdf
^ California Environmental Protection Agency, 2017. Initial Statement of Reasons 1,2,3-Trichloropropane Maximum Contaminant Level Regulations. Water Resources Control Board, Title 22, California Code of Regulations (SBDDW-17-001). 36 pp.
^ ^29.0 ^29.1 Babcock Jr, R.W., Harada, B.K., Lamichhane, K.M., and Tsubota, K.T., 2018. Adsorption of 1, 2, 3-Trichloropropane (TCP) to meet a MCL of 5 ppt. Environmental Pollution, 233, 910-915. DOI: 10.1016/j.envpol.2017.09.085
^ Snoeyink, V.L. and Summers, R.S, 1999. Adsorption of Organic Compounds (Chapter 13), In: Water Quality and Treatment, 5th ed., Letterman, R.D., editor. McGraw-Hill, New York, NY. ISBN 0-07-001659-3
^ Knappe, D.R.U., Ingham, R.S., Moreno-Barbosa, J.J., Sun, M., Summers, R.S., and Dougherty, T., 2017. Evaluation of Henry’s Law Constants and Freundlich Adsorption Constants for VOCs. Water Research Foundation Project 4462 Final Report.
^ ^32.0 ^32.1 Torralba-Sanchez, T.L., Bylaska, E.J., Salter-Blanc, A.J., Meisenheimer, D.E., Lyon, M.A., and Tratnyek, P.G., 2020. Reduction of 1, 2, 3-trichloropropane (TCP): pathways and mechanisms from computational chemistry calculations. Environmental Science: Processes and Impacts, 22(3), 606-616. DOI: 10.1039/C9EM00557A Article pdf
^ Salter-Blanc, A.J. and Tratnyek, P.G., 2011. Effects of Solution Chemistry on the Dechlorination of 1,2,3-Trichloropropane by Zero-Valent Zinc. Environmental Science and Technology, 45(9), pp 4073–4079. DOI: 10.1021/es104081p Article pdf
^ ^34.0 ^34.1 Salter-Blanc, A.J., Suchomel, E.J., Fortuna, J.H., Nurmi, J.T., Walker, C., Krug, T., O'Hara, S., Ruiz, N., Morley, T. and Tratnyek, P.G., 2012. Evaluation of Zerovalent Zinc for Treatment of 1,2,3-Trichloropropane‐Contaminated Groundwater: Laboratory and Field Assessment. Groundwater Monitoring and Remediation, 32(4), pp.42-52. DOI: 10.1111/j.1745-6592.2012.01402.x
^ Vannelli, T., Logan, M., Arciero, D.M., and Hooper, A.B., 1990. Degradation of Halogenated Aliphatic Compounds by the Ammonia-Oxidizing Bacterium Nitrosomonas europaea. Applied and Environmental Microbiology, 56(4), pp. 1169–1171. DOI: 10.1128/aem.56.4.1169-1171.1990 Report pdf
^ Bosma, T., Damborsky, J., Stucki, G., and Janssen, D.B., 2002. Biodegradation of 1,2,3-Trichloropropane through Directed Evolution and Heterologous Expression of a Haloalkane Dehalogenase Gene. Applied and Environmental Microbiology, 68(7), pp. 3582–3587. DOI: 10.1128/AEM.68.7.3582-3587.2002 Report pdf
^ Janssen, D. B., and Stucki, G., 2020. Perspectives of genetically engineered microbes for groundwater bioremediation. Environmental Science: Processes and Impacts, 22(3), pp. 487-499. DOI: 10.1039/C9EM00601J Article pdf
^ Yan, J., B.A. Rash, F.A. Rainey, and W.M. Moe, 2009. Isolation of novel bacteria within the Chloroflexi capable of reductive dechlorination of 1,2,3-trichloropropane. Environmental Microbiology, 11(4), pp. 833–843. DOI: 10.1111/j.1462-2920.2008.01804.x
^ Bowman, K.S., Nobre, M.F., da Costa, M.S., Rainey, F.A., and Moe, W.M., 2013. Dehalogenimonas alkenigignens sp. nov., a chlorinated-alkane-dehalogenating bacterium isolated from groundwater. International Journal of Systematic and Evolutionary Microbiology, 63(Pt_4), pp. 1492-1498. DOI: 10.1099/ijs.0.045054-0 Article pdf
^ Loffler, F.E., Champine, J.E., Ritalahti, K.M., Sprague, S.J. and Tiedje, J.M., 1997. Complete Reductive Dechlorination of 1, 2-Dichloropropane by Anaerobic Bacteria. Applied and Environmental Microbiology, 63(7), pp.2870-2875. Article pdf
^ Moe, W.M., Yan, J., Nobre, M.F., da Costa, M.S. and Rainey, F.A., 2009. Dehalogenimonas lykanthroporepellens gen. nov., sp. nov., a reductively dehalogenating bacterium isolated from chlorinated solvent-contaminated groundwater. International Journal of Systematic and Evolutionary Microbiology, 59(11), pp.2692-2697. DOI: 10.1099/ijs.0.011502-0 Article pdf
^ ^42.0 ^42.1 ^42.2 Schmitt, M., Varadhan, S., Dworatzek, S., Webb, J. and Suchomel, E., 2017. Optimization and validation of enhanced biological reduction of 1,2,3-trichloropropane in groundwater. Remediation Journal, 28(1), pp.17-25. DOI: 10.1002/rem.21539

@@ Line 1: / Line 1: @@
-[[wikipedia: 1,2,3-Trichloropropane | 1,2,3-Trichloropropane]] is a probable human carcinogen that is present in the environment due to historic use as a solvent and current use as a precursor in chemical synthesis. TCP is mobile and highly persistent in soil and groundwater. TCP is not currently regulated at the national level in the United States, but maximum contaminant levels (MCLs) have been established or are proposed at the state level in Hawaii, California, and New Jersey. Treatment of TCP contamination using conventional groundwater and soil treatment methods is either ineffective or costly, but alternative remediation strategies are under development.
+[[Wikipedia: 1,2,3-Trichloropropane | 1,2,3-Trichloropropane (TCP)]] is a chlorinated volatile organic compound (CVOC) that has been used in chemical production processes, in agriculture, and as a solvent, resulting in point and non-point source contamination of soil and groundwater.  TCP is mobile and highly persistent in soil and groundwater. TCP is not currently regulated at the national level in the United States, but [[Wikipedia: Maximum contaminant level | maximum contaminant levels (MCLs)]] have been developed by some states.  Current treatment methods for TCP are limited and can be cost prohibitive. However, some treatment approaches, particularly [[Chemical Reduction (In Situ - ISCR) | ''in situ'' chemical reduction (ISCR)]] with [[Wikipedia: In_situ_chemical_reduction#Zero_valent_metals_%28ZVMs%29 | zero valent zinc (ZVZ)]] and [[Bioremediation - Anaerobic | ''in situ'' bioremediation (ISB)]], have recently been shown to have potential as practical remedies for TCP contamination of groundwater.
 <div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
 '''Related Article(s):'''
-*[[Soil & Groundwater Contaminants]]
+*[[Bioremediation - Anaerobic | Anaerobic Bioremediation]]
+*[[Chemical Oxidation (In Situ - ISCO) | ''In Situ'' Chemical Oxidation (ISCO)]]
+*[[Chemical Reduction (In Situ - ISCR) | ''In Situ'' Chemical Reduction (ISCR)]]
-'''Contributor(s):''' [[Dr. Alexandra Salter-Blanc]]
+'''Contributor(s):'''  [[Dr. Alexandra Salter-Blanc |Dr. Alexandra J. Salter-Blanc]], [[Dr. Paul Tratnyek |Dr. Paul G. Tratnyek]], John Merrill, Alyssa Saito, Lea Kane, Eric Suchomel, [[Dr. Rula Deeb |Dr. Rula Deeb]]
 '''Key Resource(s):'''
-*[https://serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Emerging-Issues/ER-1457/ER-1457/(language)/eng-US Prospects for Remediation of 1,2,3-Trichloropropane by Natural and Engineered Abiotic Degradation Reactions]<ref name= "Tratnyek2010P">Tratnyek, P.G., Sarathy, V., Salter, A.J., Nurmi, J.T., Johnson, G.O., DeVoe, T., Lee, P., 2010. Prospects for Remediation of 1,2,3-Trichloropropane by Natural and Engineered Abiotic Degradation Reactions. Project ER-1457. [https://serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Emerging-Issues/ER-1457/ER-1457/(language)/eng-US Report pdf]</ref>
+*Prospects for Remediation of 1,2,3-Trichloropropane by Natural and Engineered Abiotic Degradation Reactions. Strategic Environmental Research and Development Program (SERDP), Project ER-1457.<ref name="Tratnyek2010">Tratnyek, P.G., Sarathy, V., Salter, A.J., Nurmi, J.T., O’Brien Johnson, G., DeVoe, T., and Lee, P., 2010. Prospects for Remediation of 1,2,3-Trichloropropane by Natural and Engineered Abiotic Degradation Reactions. Strategic Environmental Research and Development Program (SERDP), [https://serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Emerging-Issues/ER-1457/ER-1457/(language)/eng-US Project ER-1457].  [//www.enviro.wiki/images/4/43/ER-1457-FR.pdf Report pdf]</ref>
+*Verification Monitoring for In Situ Chemical Reduction Using Zero-Valent Zinc, A Novel Technology for Remediation of Chlorinated Alkanes. Strategic Environmental Research and Development Program (SERDP), Project ER-201628.<ref name="Kane2020">Kane, L.Z., Suchomel, E.J., and Deeb, R.A., 2020. Verification Monitoring for In Situ Chemical Reduction Using Zero-Valent Zinc, A Novel Technology for Remediation of Chlorinated Alkanes. Strategic Environmental Research and Development Program (SERDP), [https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Persistent-Contamination/ER-201628 Project ER-201628]. [//www.enviro.wiki/images/d/dd/ER-201628.pdf Report pdf]</ref>
 ==Introduction==
-[[File:SalterBlanc-Article2-Figure1.jpg|thumbnail|300px|left|Figure 1. Ball and stick representation of TCP (courtesy of the [http://www.ebs.ieh.ohsu.edu/tratnyek Tratnyek Research Group]).]]
+[[File:123TCPFig1.png|thumb|left|Figure 1. Ball and stick representation of the molecular structure of TCP (Salter-Blanc and Tratnyek, unpublished)]]
-[[wikipedia: 1,2,3-Trichloropropane | 1,2,3-Trichloropropane]] is a man-made chemical that was used in the past primarily as a solvent and extractive agent, a paint and varnish remover, and as a cleaning and degreasing agent (Fig. 1)<ref name= "ATSDR1992"> Agency for Toxic Substances and Disease Registry, 1992. Toxicological Profile for 1,2,3-Trichloropropane. [[Media: atsdr toxprofile stp57.pdf| Report pdf]]</ref>. Currently, TCP is primarily used in chemical synthesis (e.g., synthesis of polysulfone liquid polymers used in the aerospace and automotive industries; [[wikipedia:: Hexafluoropropylene | hexafluoropropylene]] used in the agricultural, electronic, and pharmaceutical industries; [[wikipedia:: Polysulfide | polysulfide]] polymers used as sealants in manufacturing and construction; and [[wikipedia: 1,3-Dichloropropene | 1,3-dichloropropene]] used in agriculture as a soil fumigant)<ref name= "ATSDR1992" /><ref name= "CH2MHILL2005"> CH2M HILL, 2005. Interim Guidance for Investigating Potential 1,2,3-Trichloropropane Sources in San Gabriel Valley Area 3. [[Media:INTERIM_GUIDANCE_FOR_INVESTIGATING_POTENTIAL_1%2C2%2C3-TRICHLOROPROPANE_SOURCES.pdf|Report pdf]]</ref>. TCP may be present in products containing these chemicals as an impurity<ref name= "ATSDR1992" /><ref name= "CH2MHILL2005" />. For example, the 1,2-dichlropropane/1,3-dichlropropene soil fumigant mixture (trade name D-D), which is no longer sold in the United States, contained TCP as an impurity and has been linked to TCP contamination in groundwater<ref>Oki, D.S.,Giambelluca, T.W., 1987. DBCP, EDB, and TCP contamination of ground water in Hawaii. Ground Water, 25(6), 693-702. [https://doi.org/10.1111/j.1745-6584.1987.tb02210.x doi:10.1111/j.1745-6584.1987.tb02210.x]</ref><ref name= "CH2MHILL2005" />. Soil fumigants composed primarily of 1,3-dichlropropene, which are currently in use, may also contain TCP as an impurity (e.g., Telone II is reported to contain up to 0.17 percent TCP by weight<ref name= "Kielhorn2003">Kielhorn, J., G. Könnecker, C. Pohlenz-Michel, S. Schmidt, and I. Mangelsdorf, 2003. 1,2,3-Trichloropropane. Geneva: World Health Organization. Concise International Chemical Assessment, Document 56. [http://www.who.int/ipcs/publications/cicad/en/cicad56.pdf Report pdf]</ref>).
+,2,3-Trichloropropane (TCP) (Figure 1) is a man-made chemical that was used in the past primarily as a solvent and extractive agent, as a paint and varnish remover, and as a cleaning and degreasing agent.<ref name="ATSDR2021"> Agency for Toxic Substances and Disease Registry (ATSDR), 2021. Toxicological Profile for 1,2,3-Trichloropropane. [//www.enviro.wiki/images/6/6e/TCP2021ATSDR.pdf Report pdf]</ref>. Currently, TCP is primarily used in chemical synthesis of compounds such as [[Wikipedia: Polysulfone | polysulfone]] liquid polymers used in the aerospace and automotive industries; [[Wikipedia: Hexafluoropropylene | hexafluoropropylene]] used in the agricultural, electronic, and pharmaceutical industries; [[Wikipedia: Polysulfide | polysulfide]] polymers used as sealants in manufacturing and construction; and [[Wikipedia: 1,3-Dichloropropene | 1,3-dichloropropene]] used in agriculture as a soil fumigant. TCP may also be present in products containing these chemicals as an impurity<ref name="ATSDR2021" /><ref name="CH2M2005">CH2M HILL, 2005. Interim Guidance for Investigating Potential 1,2,3-Trichloropropane Sources in San Gabriel Valley Area 3. [//www.enviro.wiki/images/f/f4/INTERIM_GUIDANCE_FOR_INVESTIGATING_POTENTIAL_1%2C2%2C3-TRICHLOROPROPANE_SOURCES.pdf Report pdf]&nbsp;&nbsp;  </ref>. For example, the 1,2-dichlropropane/1,3-dichloropropene soil fumigant mixture (trade name D-D), which is no longer sold in the United States, contained TCP as an impurity and has been linked to TCP contamination in groundwater<ref name="OkiGiambelluca1987">Oki, D.S. and Giambelluca, T.W., 1987. DBCP, EDB, and TCP Contamination of Ground Water in Hawaii. Groundwater, 25(6), pp. 693-702.  [https://doi.org/10.1111/j.1745-6584.1987.tb02210.x DOI: 10.1111/j.1745-6584.1987.tb02210.x]</ref><ref name="CH2M2005" />. Soil fumigants currently in use which are composed primarily of 1,3-dichloropropene may also contain TCP as an impurity, for instance Telone II has been reported to contain up to 0.17 percent TCP by weight<ref name="Kielhorn2003">Kielhorn, J., Könnecker, G., Pohlenz-Michel, C., Schmidt, S. and Mangelsdorf, I., 2003. Concise International Chemical Assessment Document 56: 1,2,3-Trichloropropane. World Health Organization, Geneva. [//www.enviro.wiki/images/f/fe/WHOcicad56TCP.pdf Report pdf]</ref>.
-TCP contamination is problematic because it is "reasonably anticipated to be a human carcinogen" based on evidence of carcinogenicity to animals<ref>National Toxicology Program, 2016. Report on Carcinogens, 14th ed. U.S. Department of Health and Human Services, Public Health Service. [http://ntp.niehs.nih.gov/pubhealth/roc/index-1.html Report pdfs]</ref>. Toxicity to humans appears to be high relative to other chlorinated solvents<ref name= "Kielhorn2003" />, suggesting that even low-level exposure to TCP could pose a significant human health risk.
-==Environmental Fate, Occurrence, and Regulation==
+TCP contamination is problematic because it is “reasonably anticipated to be a human carcinogen” based on evidence of carcinogenicity to animals<ref name="NTP2016"> National Toxicology Program, 2016. Report on Carcinogens, 14th ed. U.S. Department of Health and Human Services, Public Health Service. [//www.enviro.wiki/images/c/cc/NTP2016trichloropropane.pdf Report pdf]</ref>. Toxicity to humans appears to be high relative to other chlorinated solvents<ref name="Kielhorn2003" />, suggesting that even low-level exposure to TCP could pose a significant human health risk.
-===Environmental Fate===
-[[File:SalterBlanc-Article2-Table1.jpg|thumbnail|650px|right|Table 1. Physical and chemical properties of TCP<ref name= "USEPA2014">United States Environmental Protection Agency, 2014. Technical Fact Sheet—1,2,3-Trichloropropane. EPA 505-F-14-007. [[Media:1_2_3_TCP_fact_sheet.pdf|Fact Sheet pdf]]</ref>. See also ASTDR (1992)<ref name= "ATSDR1992" /> and Dombeck and Borg (2005)<ref>Dombeck, G., Borg., C., 2005. Multicontaminant Treatment for 1,2,3 Trichloropropane Destruction Using the HiPOx Reactor.” Proceedings of the 2005 National Groundwater Association Conference on MTBE and Perchlorate: Assessment, Remediation, and Public Policy with permission of the NGWA Press. ISBN 1-56034-120-3 </ref>.]]
-TCP’s fate in the environment is governed by its physical and chemical properties (Table 1). TCP is not anticipated to sorb strongly to soil making it likely to leach into groundwater and exhibit high mobility. In addition, TCP is moderately volatile and can partition from surface water and moist soil into the atmosphere. Because TCP is only slightly soluble and denser than water, it is capable of forming a [[wikipedia: Dense non-aqueous phase liquid | dense non-aqueous phase liquid (DNAPL)]]. TCP is generally resistant to [[wikipedia:: Biodegradation | biodegradation]], [[wikipedia: Hydrolysis | hydrolysis]], oxidation, and reduction under naturally occurring conditions making it highly persistent in the environment<ref name= "Tratnyek2010P"/>.
+==Environmental Fate==
+TCP’s fate in the environment is governed by its physical and chemical properties (Table 1). TCP does not adsorb strongly to soil, making it likely to leach into groundwater and exhibit high mobility. In addition, TCP is moderately volatile and can partition from surface water and moist soil into the atmosphere. Because TCP is only slightly soluble and denser than water, it can form a [[Wikipedia: Dense non-aqueous phase liquid | dense non-aqueous phase liquid (DNAPL)]] as observed at the Tyson’s Dump Superfund Site<ref name="USEPA2019"> United States Environmental Protection Agency (USEPA), 2019. Fifth Five-year Review Report, Tyson’s Dump Superfund Site, Upper Merion Township, Montgomery County, Pennsylvania. [//www.enviro.wiki/images/7/7c/USEPA2019.pdf Report pdf]</ref>. TCP is generally resistant to aerobic biodegradation, hydrolysis, oxidation, and reduction under naturally occurring conditions making it persistent in the environment<ref name="Tratnyek2010" />.
-===Occurrence===
+{| class="wikitable" style="float:right; margin-left:10px;text-align:center;"
-TCP has been detected in ~1% percent of United States Geological Survey tested public supply and domestic well samples. More specifically, TCP was detected in 1.2% of public supply well samples collected between 1993 and 2007<ref name= "Toccalino 2010">Toccalino, P.L., Norman, J.E., Hitt, K.J., 2010. Quality of source water from public-supply wells in the United States, 1993-2007. U. S. Geological Survey. Scientific Investigations Report 2010-5024. [[Media:Quality_of_source_water_from_public-supply_wells_in_the_United_States%2C_1993-2007.pdf|Report pdf]]</ref> and 0.66% of domestic supply well samples collected between 1991 and 2004<ref name= "DeSimone2009">DeSimone, L.A., 2009. Quality of water from domestic wells in principal aquifers of the United States, 1991–2004: U.S. Geological Survey. Scientific Investigations Report 2008–5227. [[Media:Quality_of_Water_from_Domestic_wells.pdf|Report pdf]]</ref>. TCP was detected at a higher rate in domestic supply well samples associated with agricultural land-use studies than samples associated with aquifer studies (3.5% versus 0.2%)<ref name= "DeSimone2009" />.
+|+Table 1.  Physical and chemical properties of TCP<ref name="USEPA2017">United States Environmental Protection Agency (USEPA), 2017. Technical Fact Sheet—1,2,3-Trichloropropane (TCP). EPA Project 505-F-17-007. 6 pp. [//www.enviro.wiki/images/e/e8/Epa_tcp_2017.pdf Report pdf]</ref>
+|-
+!Property
+!Value
+|-
+|Chemical Abstracts Service (CAS) Number||96-18-4
+|-
+|Physical Description<br>(at room temperature)||Colorless to straw-colored liquid
+|-
+|Molecular weight  (g/mol)||147.43
+|-
+|Water solubility at 25°C  (mg/L)||1,750 (slightly soluble)
+|-
+|Melting point  (°C)||-14.7
+|-
+|Boiling point  (°C)||156.8
+|-
+|Vapor pressure at 25°C  (mm Hg)||3.10 to 3.69
+|-
+|Density at 20°C (g/cm<sup>3</sup>)||1.3889
+|-
+|Octanol-water partition coefficient<br>(log''K<sub>ow</sub>'')||1.98 to 2.27<br>(temperature dependent)
+|-
+|Organic carbon-water partition coefficient<br>(log''K<sub>oc</sub>'')||1.70 to 1.99<br>(temperature dependent)
+|-
+|Henry’s Law constant at 25°C<br>(atm-m<sup>3</sup>/mol)||3.17x10<sup>-4</sup><ref name="ATSDR2021" /> to 3.43x10<sup>-4</sup><ref name="LeightonCalo1981">Leighton Jr, D.T. and Calo, J.M., 1981. Distribution Coefficients of Chlorinated Hydrocarbons in Dilute Air-Water Systems for Groundwater Contamination Applications. Journal of Chemical and Engineering Data, 26(4), pp. 382-385.  [https://doi.org/10.1021/je00026a010 DOI: 10.1021/je00026a010]</ref>
+|}
-===Regulation===
+==Occurrence==
-The United States Environmental Protection Agency (EPA) has not established a MCL for TCP, although guidelines and health standards are in place<ref name= "USEPA2014" />. TCP was included in the Contaminant Candidate List 3<ref name= "EPA2009">United States Environmental Protection Agency (US EPA), 2009. Drinking water contaminant candidate list 3-final. Federal Register 74(194), 51850–51862. [[Media:drinking_water_contaminant_candidate_list.pdf|Report pdf]]</ref> and the Unregulated Contaminant Monitoring Rule 3 (UCMR 3)<ref name= "EPA2009" />. The UCMR 3 specified that data be collected on TCP occurrence in public water systems over the period of January 2013 to December 2015 against a reference concentration range of 0.0004 to 0.04 μg/L<ref name= "USEPA2016">United States Environmental Protection Agency, 2016. The Third Unregulated Contaminant Monitoring Rule (UCMR 3): Data Summary. EPA 815-S-16-004. [[Media:third_unregulated_contaminant_monitoring_rule_july_2016.pdf|Report pdf]]</ref>. The reference concentration range was determined based on a cancer risk of 10<sup>-6</sup> to 10<sup>-4</sup><ref name= "USEPA2016" /> and derived from an oral slope factor of 30 mg/kg-day determined for the EPA’s Integrated Risk Information System<ref>United States Environmental Protection Agency and Integrated Risk Information System, 2009. 1,2,3-Trichloropropane (CASRN 96-18-4). [[Media:123-TRICHLOROPROPANE_ERD.PDF|Report pdf]]</ref>. Available partial UCMR 3 data published as of July 2016 indicate that TCP has been detected above the UCMR-specified minimum reporting level of 0.03 μg/L at 1.3% of monitored public water systems<ref name= "USEPA2016" />.
+TCP has been detected in approximately 1% of public water supply and domestic well samples tested by the United States Geological Survey. More specifically, TCP was detected in 1.2% of public supply well samples collected between 1993 and 2007 by Toccalino ''et al''<ref name="ToccalinoHopple2010">Toccalino, P.L., Norman, J.E., Hitt, K.J., 2010. Quality of Source Water from Public-Supply Wells in the United States, 1993–2007. Scientific Investigations Report 2010-5024. U.S. Geological Survey. [https://doi.org/10.3133/sir20105024 DOI: 10.3133/sir20105024]  [//www.enviro.wiki/images/6/6b/Quality_of_source_water_from_public-supply_wells_in_the_United_States%2C_1993-2007.pdf Report pdf]</ref> and 0.66% of domestic supply well samples collected between 1991 and 2004 by DeSimone<ref name="DeSimone2009">DeSimone, L.A., 2009. Quality of Water from Domestic Wells in Principal Aquifers of the United States, 1991–2004. U.S. Geological Survey, Scientific Investigations Report 2008–5227. 139 pp. [//www.enviro.wiki/images/2/2e/Quality_of_Water_from_Domestic_wells.pdf Report pdf]</ref>. TCP was detected at a higher rate in domestic supply well samples associated with agricultural land-use studies than samples associated with studies comparing primary aquifers (3.5% versus 0.2%)<ref name="DeSimone2009" />.
-At the state level, Hawaii is the only state that has established a MCL for TCP in drinking water. This MCL is 0.6 μg/L<ref>Hawaii Department of Health, 2013. Amendment and Compilation of Chapter 11-20 Hawaii Administrative Rules. September 5. [[Media:Amendment_and_Compilation_of_Chapter_11-20_Hawaii_Administrative_Rules.pdf|Report pdf]]</ref>. California has established a notification level of 0.005 μg/L and a public health goal of 0.0007 μg/L<ref>Office of Environmental Health and Hazard Assessment, California Environmental Protection Agency (OEHHA), 2009. Public Health Goals for 1,2,3-Trichloropropane in Drinking Water. August.</ref>. The state is currently in the process of developing a MCL for TCP and a preliminary recommendation of 0.005 μg/L was made public July 2016. Up-to-date information can be found at the [http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/123TCP.shtml California Environmental Protection Agency State Water Resources Control Board]. In October 2016, the New Jersey Drinking Water Quality Institute recommended proposition and adoption of a 0.03-μg/L MCL based on a practical quantitation limit of the same value (a health based MCL of 0.0005 μg/L was recommended<ref>New Jersey Drinking Water Quality Institute, 2016. Maximum contaminant level recommendations for 1,2,3-trichloroporpane in drinking water. [[Media:Maximum_contaminant_level_recommendations_for_1%2C2%2C3-trichloroporpane_in_drinking_water.pdf|Report pdf]]</ref>).
+==Regulation==
+The United States Environmental Protection Agency (USEPA) has not established an MCL for TCP, although guidelines and health standards are in place<ref name="USEPA2017" />. TCP was included in the Contaminant Candidate List 3<ref name="USEPA2009">United States Environmental Protection Agency (US EPA), 2009. Drinking Water Contaminant Candidate List 3-Final. Federal Register 74(194), pp. 51850–51862, Document E9-24287. &nbsp;&nbsp; [//www.enviro.wiki/images/5/5b/FR74-194DWCCL3.pdf Register pdf]</ref> and the Unregulated Contaminant Monitoring Rule 3 (UCMR 3)<ref name="USEPA2012">United States Environmental Protection Agency (US EPA), 2012. Revisions to the Unregulated Contaminant Mentoring Regulation (UCMR 3) for Public Water Systems. Federal Register 77(85) pp. 26072-26101. [//www.enviro.wiki/images/f/fd/FR77-85UCMR3.pdf Register pdf]</ref>. The UCMR 3 specified that data be collected on TCP occurrence in public water systems over the period of January 2013 through December 2015 against a reference concentration range of 0.0004 to 0.04 μg/L<ref name="USEPA2017a">United States Environmental Protection Agency (USEPA), 2017. [https://www.epa.gov/dwucmr/data-summary-third-unregulated-contaminant-monitoring-rule The Third Unregulated Contaminant Monitoring Rule (UCMR 3)]: Data Summary. EPA 815-S-17-001. [//www.enviro.wiki/images/d/d7/Ucmr3-data-summary-january-2017.pdf Report.pdf]</ref>. The reference concentration range was determined based on a cancer risk of 10-6 to 10-4 and derived from an oral slope factor of 30 mg/kg-day, which was determined by the EPA’s Integrated Risk Information System<ref name="IRIS2009">USEPA Integrated Risk Information System (IRIS), 2009. [https://cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=200 1,2,3-Trichloropropane (CASRN 96-18-4)]. [//www.enviro.wiki/images/f/ff/TCPsummaryIRIS.pdf Summary pdf]</ref>. Of 36,848 samples collected during UCMR 3, 0.67% exceeded the minimum reporting level of 0.03 µg/L. 1.4% of public water systems had at least one detection over the minimum reporting level, corresponding to 2.5% of the population<ref name="USEPA2017a" />. While these occurrence percentages are relatively low, the minimum reporting level of 0.03 µg/L is more than 75 times the USEPA-calculated Health Reference Level of 0.0004 µg/L. Because of this, TCP may occur in public water systems at concentrations that exceed the Health Reference Level but are below the minimum reporting level used during UCMR 3 data collection. These analytical limitations and lack of lower-level occurrence data have prevented the USEPA from making a preliminary regulatory determination for TCP<ref name="USEPA2021">USEPA, 2021. Announcement of Final Regulatory Determinations for Contaminants on the Fourth Drinking Water Contaminant Candidate List. [//www.enviro.wiki/images/d/d2/CCL4.pdf Report pdf]</ref>.
-==Prospects for Remediation==
+Some US states have established their own standards including Hawaii which has established an MCL of 0.6 μg/L<ref name="HDOH2013">Hawaii Department of Health, 2013. Amendment and Compilation of Chapter 11-20 Hawaii Administrative Rules. [//www.enviro.wiki/images/c/cb/Amendment_and_Compilation_of_Chapter_11-20_Hawaii_Administrative_Rules.pdf Report pdf]</ref>. California has established an MCL of 0.005 μg/L<ref name="CCR2021">California Code of Regulations, 2021. [https://govt.westlaw.com/calregs/Document/IA7B3800D18654ABD9E2D24A445A66CB9?transitionType=Default&contextData=%28sc.Default%29 Section 64444 Maximum Contaminant Levels – Organic Chemicals (22 CA ADC § 64444)].</ref>,  a notification level of 0.005 μg/L, and a public health goal of 0.0007 μg/L<ref name="OEHHA2009">Office of Environmental Health Hazard Assessment (OEHHA), California Environmental Protection Agency, 2009. [https://oehha.ca.gov/water/public-health-goal/final-public-health-goal-123-trichloropropane-drinking-water Final Public Health Goal for 1,2,3-Trichloropropane in Drinking Water].</ref>, and New Jersey has established an MCL of 0.03 μg/L<ref name="NJAC2020">New Jersey Administrative Code 7:10, 2020. [https://www.nj.gov/dep/rules/rules/njac7_10.pdf Safe Drinking Water Act Rules].</ref>.
-===Physical Removal===
+==Transformation Processes==
-TCP contamination in drinking water is typically treated using granular activated carbon (GAC)<ref>TetraTech, 2012. Report to the Hawaii Department of Health, Safe Drinking Water Branch, Regarding the Human Health Risks of 1,2,3-Trichloropropane in Tap Water.</ref><ref>Ozekin, K., 2016. 1,2,3-Trichloropropane State of the Science. Water Research Foundation. [[Media:1%2C2%2C3-Trichloropropane_state_of_science.pdf|Report pdf]]</ref>. GAC is also applied for groundwater treatment in pump and treat scenarios<ref>California Environmental Protection Agency, 2016. State Water Resources Control Board. Groundwater Information Sheet: 1,2,3-Trichloropropane. [[Media:waterboards.ca.govgamadocscoc_tcp123.pdf|Report pdf]]</ref>. However, based on published [[wikipedia: Freundlich equation | Freundlich adsorption isotherm]] parameters<ref>Snoeyink, V.L., Summers, R.S, 1990. Adsorption of Organic Compounds, In: Pontius, F.W. (ed.). Water Quality and Treatment. New York, NY. McGraw-Hill.</ref>, less TCP mass is adsorbed per gram of carbon compared to other volatile organic compounds (VOCs) such as [[wikipedia: Tetrachloroethylene | tetrachloroethene]] and [[wikipedia:: Trichloroethylene | trichloroethene]]. This results in an increased carbon usage rate and treatment cost compared to these contaminants. Air stripping, air sparging, and soil vacuum extraction are also less effective compared to other VOCs because of TCP’s relatively low [[wikipedia:: Henry's law | Henry’s Law]] constant.
+[[File:123TCPFig2.png|thumb|600px|left|Figure 2. Figure 2. Summary of anticipated primary reaction pathways for degradation of TCP. Oxidation, hydrolysis, and hydrogenolysis are represented by the horizontal arrows. Elimination (dehydrochlorination) and reductive elimination are shown with vertical arrows. [O] represents oxygenation (by oxidation or hydrolysis), [H] represents reduction. Gray indicates products that appear to be of lesser significance<ref name="Tratnyek2010" />.]]
+Potential TCP degradation pathways include hydrolysis, oxidation, and reduction (Figure 2). These pathways are expected to be similar overall for abiotic and biotic reactions<ref name="Sarathy2010">Sarathy, V., Salter, A.J., Nurmi, J.T., O’Brien Johnson, G., Johnson, R.L., and Tratnyek, P.G., 2010. Degradation of 1, 2, 3-Trichloropropane (TCP): Hydrolysis, Elimination, and Reduction by Iron and Zinc. Environmental Science and Technology, 44(2), pp.787-793.  [https://doi.org/10.1021/es902595j DOI: 10.1021/es902595j]</ref>, but the rates of the reactions (and their resulting significance for remediation) depend on natural and engineered conditions.
-===Transformation===
+The rate of hydrolysis of TCP is negligible under typical ambient pH and temperature conditions but is favorable at high pH and/or temperature<ref name="Tratnyek2010" /><ref name="Sarathy2010" />. For example, ammonia gas can be used to raise soil pH and stimulate alkaline hydrolysis of chlorinated propanes including TCP<ref name="Medina2016">Medina, V.F., Waisner, S.A., Griggs, C.S., Coyle, C., and Maxwell, M., 2016. Laboratory-Scale Demonstration Using Dilute Ammonia Gas-Induced Alkaline Hydrolysis of Soil Contaminants (Chlorinated Propanes and Explosives). US Army Engineer Research and Development Center, Environmental Laboratory (ERDC/EL), [https://erdc-library.erdc.dren.mil/jspui/handle/11681/20312 Report TR-16-10]. [//www.enviro.wiki/images/2/2a/ERDC_EL_TR_16_10.pdf Report pdf]</ref>. [[Thermal Conduction Heating (TCH)]] may also produce favorable conditions for TCP hydrolysis<ref name="Tratnyek2010" /><ref name="Sarathy2010" />.
-[[File:SalterBlanc-Article2-Figure2.jpg|thumbnail|650px|left|Figure 2. Summary of anticipated, primary reaction pathways for degradation of TCP. Oxidation, hydrolysis, and hydrogenolysis are represented by the horizontal arrows. Elimination (dehydrochlorination) and reductive elimination are shown with vertical arrows. [O] represents oxygenation (by oxidation or hydrolysis), [H] represents reduction. Gray indicates products that appear to be of lesser significance. Reprinted with permission from Sarathy et al. (2010)<ref name= "Sarathy2010" /> (Copyright 2010, American Chemical Society).]]
-Potential TCP degradation pathways include hydrolysis, oxidation, and reduction (Fig. 2). These overall pathways are expected to be similar for abiotic and biotic reactions<ref name= "Sarathy2010">Sarathy, V., Salter, A.J., Nurmi, J.T., O’Brien Johnson, G., Johnson, R.L., Tratnyek, P.G., 2010. Degradation of 1, 2, 3-trichloropropane (TCP): Hydrolysis, elimination, and reduction by iron and zinc. Environmental Science & Technology, 44(2), 787-793. [https://doi.org/10.1021/es902595j doi:10.1021/es902595j]</ref>, but the rates of the reactions (and their resulting significance) are dependent on natural and engineered conditions.
-Hydrolysis of TCP is negligible under ambient pH and temperature conditions, but is favorable at high pH and/or temperature<ref name= "Tratnyek2010P" /><ref name= "Sarathy2010" />. For example, ammonia gas can be used to raise soil pH and stimulate alkaline hydrolysis of chlorinated propanes including TCP<ref>Medina, V.F., S.A. Waisner, C. Coyle, C. Griggs, M. Maxwell, 2016. Laboratory-Scale Demonstration Using Dilute Ammonia Gas-Induced Alkaline Hydrolysis of Soil Contaminants (Chlorinated Propanes and Explosives). ERDC/EL TR-16-10. [[Media:ERDC_EL_TR_16_10.pdf|Report pdf]]</ref>. In situ thermal remediation may also produce favorable conditions for TCP hydrolysis<ref name= "Tratnyek2010P"/><ref name= "Sarathy2010" />. Oxidation using mild/specific oxidants like [[wikipedia:: Permanganate | permanganate]] is negligible, but stronger oxidants like those used in [[Chemical Oxidation (In Situ - ISCO)|in situ chemical oxidation (ISCO)]] (especially hydroxyl and sulfate radicals) do oxidize TCP<ref name= "Tratnyek2010P" />. Reduction by naturally occurring reductants (i.e., those associated with natural attenuation) is negligible and granular [[Zerovalent Iron (ZVI) (Chemical Reduction - ISCR)| zerovalent iron (ZVI)]] produces only slow reduction<ref name= "Tratnyek2010P"/><ref name= "Sarathy2010" />. Nano-scale ZVI and palladized ZVI produce faster reduction, but the reaction is not anticipated to be fast enough to be useful in typical remediation applications<ref name= "Sarathy2010" />. Commercial-grade zerovalent zinc (ZVZ) reduces TCP relatively quickly under a range of laboratory and field conditions to produce propene without significant accumulation of intermediates<ref name= "Sarathy2010" /><ref>Salter-Blanc, A.J., Tratnyek, P.G., 2011. Effects of solution chemistry on the dechlorination of 1, 2, 3-trichloropropane by zero-valent zinc. Environmental Science & Technology, 45(9), 4073-4079. [https://doi.org/10.1021/es104081p doi:10.1021/es104081p]</ref><ref>Salter‐Blanc, A.J., Suchomel, E.J., Fortuna, J.H., Nurmi, J.T., Walker, C., Krug, T., O'Hara, S., Ruiz, N., Morley, T., Tratnyek, P.G., 2012. Evaluation of Zerovalent Zinc for Treatment of 1, 2, 3‐Trichloropropane‐Contaminated Groundwater: Laboratory and Field Assessment. Groundwater Monitoring & Remediation, 32(4), 42-52. [https://doi.org/10.1111/j.1745-6592.2012.01402.x doi:10.1111/j.1745-6592.2012.01402.x]</ref>.
+==Treatment Approaches==
+Compared to more frequently encountered CVOCs such as [[Wikipedia: Trichloroethylene | trichloroethene (TCE)]] and [[Wikipedia: Tetrachloroethylene | tetrachloroethene (PCE)]], TCP is relatively recalcitrant<ref name="Merrill2019">Merrill, J.P., Suchomel, E.J., Varadhan, S., Asher, M., Kane, L.Z., Hawley, E.L., and Deeb, R.A., 2019. Development and Validation of Technologies for Remediation of 1,2,3-Trichloropropane in Groundwater. Current Pollution Reports, 5(4), pp. 228–237.  [https://doi.org/10.1007/s40726-019-00122-7 DOI: 10.1007/s40726-019-00122-7]</ref><ref name="Tratnyek2010" />. TCP is generally resistant to hydrolysis, bioremediation, oxidation, and reduction under natural conditions<ref name="Tratnyek2010" />.  The moderate volatility of TCP makes air stripping, air sparging, and soil vapor extraction (SVE) less effective compared to other VOCs<ref name="Merrill2019" />. Despite these challenges, both ''ex situ'' and ''in situ'' treatment technologies exist. ''Ex situ'' treatment processes are relatively well established and understood but can be cost prohibitive. ''In situ'' treatment methods are comparatively limited and less-well developed, though promising field-scale demonstrations of some ''in situ'' treatment technologies have been conducted.
-Aerobic biodegradation is not favorable as no naturally-occurring microorganisms have been identified that degrade TCP under aerobic conditions<ref name= "Samin2012">Samin, G., Janssen, D.B., 2012. Transformation and biodegradation of 1, 2, 3-trichloropropane (TCP). Environmental Science and Pollution Research, 19(8), 3067-3078. [https://doi.org/10.1007/s11356-012-0859-3 doi:10.1007/s11356-012-0859-3]</ref>. Relatively slow aerobic cometabolism by the ammonia oxidizing bacterium [[wikipedia:: Nitrosomonas europaea | ''Nitrosomonas europaea'']] and other populations has been reported<ref>Vannelli, T.O.D.D., Logan, M.Y.K.E., Arciero, D.M., Hooper, A.B., 1990. Degradation of halogenated aliphatic compounds by the ammonia-oxidizing bacterium Nitrosomonas europaea. Applied and Environmental Microbiology, 56(4), 1169-1171. [http://aem.asm.org/content/56/4/1169.short Journal Article]</ref><ref name= "Samin2012"/> and genetic engineering has been used to develop organisms capable of utilizing TCP as a sole carbon source under aerobic conditions<ref>Bosma, T., Damborský, J., Stucki, G., Janssen, D.B., 2002. Biodegradation of 1, 2, 3-trichloropropane through directed evolution and heterologous expression of a haloalkane dehalogenase gene. Applied and Environmental Microbiology, 68(7), 3582-3587. [https://doi.org/10.1007/s002530051263 doi: 10.1007/s002530051263]</ref><ref name= "Samin2012" />. Anaerobic reductive dechlorination has been reported in enrichment cultures<ref>Löffler F.E., J.E. Champine, K.M Ritalahti, S.J. Sprague, J.M. Tiedje, 1997. Complete reductive dechlorination of 1,2-dichloropropane by anaerobic bacteria. Applied and Environmental Microbiology, 63, 2870–2875. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1389209/ PMC1389209]</ref><ref name= "Samin2012" /> and multiple species within the genus [[wikipedia:: Dehalogenimonas | ''Dehalogenimonas'']] capable of anaerobic reductive dechlorination of TCP have been isolated from contaminated groundwater<ref>Moe, W.M., Yan, J., Nobre, M.F., da Costa, M.S., Rainey, F.A., 2009. Dehalogenimonas lykanthroporepellens gen. nov., sp. nov., a reductively dehalogenating bacterium isolated from chlorinated solvent-contaminated groundwater. International Journal of Systematic and Evolutionary Microbiology, 59(11), 2692-2697. [https://doi.org/10.1099/ijs.0.011502-0 doi:10.1099/ijs.0.011502-0]</ref><ref>Yan, J., Rash, B.A., Rainey, F.A., Moe, W.M., 2009. Isolation of novel bacteria within the Chloroflexi capable of reductive dechlorination of 1, 2, 3‐trichloropropane. Environmental Microbiology, 11(4), 833-843. [https://doi.org/10.1111/j.1462-2920.2008.01804.x doi:10.1111/j.1462-2920.2008.01804.x]</ref><ref>Bowman, K.S., M.F. Nobre, M.S. da Costa, F.A. Rainy, Moe, W.M.,  2013. Dehalogenimonas alkenigignens sp. nov., a chlorinated-alkane-dehalogenating bacterium isolated from groundwater. International Journal of Systematic and Evolutionary Microbiology, 63, 1492-1498. [https://www.ncbi.nlm.nih.gov/pubmed/22888191 doi: 10.1099/ijs.0.045054-0]</ref>. A bioaugmentation culture containing ''Dehalogenimonas'' (KB-1 Plus, SiREM) is commercially available and has been implemented for remediation of TCP-contaminated groundwater<ref>Schmitt, M., Suchomel, E., 2016. 1,2,3-TCP Remediation in Groundwater: Biological Reduction and Chemical Reduction using ZVZ. Emerging Contaminants Summit. Westminster, CO.</ref>.
+===''Ex Situ'' Treatment===
+The most common ''ex situ'' treatment technology for groundwater contaminated with TCP is groundwater extraction and treatment<ref name="SaminJanssen2012">Samin, G. and Janssen, D.B., 2012. Transformation and biodegradation of 1,2,3-trichloropropane (TCP). Environmental Science and Pollution Research International, 19(8), pp. 3067-3078. [https://doi.org/10.1007/s11356-012-0859-3 DOI: 10.1007/s11356-012-0859-3]&nbsp;&nbsp;[//www.enviro.wiki/images/2/2b/SaminJanssen2012.pdf Report pdf]</ref>. Extraction of TCP is generally effective given its relatively high solubility in water and low degree of partitioning to soil. After extraction, TCP is typically removed by adsorption to granular activated carbon (GAC)<ref name="Merrill2019" /><ref name="CalEPA2017">California Environmental Protection Agency, 2017. Groundwater Information Sheet, 1,2,3-Trichloropropane (TCP). State Water Resources Control Board, Division of Water Quality, Groundwater Ambient Monitoring and Assessment (GAMA) Program, 8 pp. [//www.enviro.wiki/images/5/53/CalEPA2017tcp123.pdf Report pdf]</ref>.
+TCP contamination in drinking water sources is typically treated using granular activated carbon (GAC)<ref name="Hooker2012">Hooker, E.P., Fulcher, K.G. and Gibb, H.J., 2012. Report to the Hawaii Department of Health, Safe Drinking Water Branch, Regarding the Human Health Risks of 1, 2, 3-Trichloropropane in Tap Water. [//www.enviro.wiki/images/b/ba/Hooker2012.pdf Report pdf]</ref>.
+In California, GAC is considered the best available technology (BAT) for treating TCP, and as of 2017 seven full-scale treatment facilities were using GAC to treat groundwater contaminated with TCP<ref name="CalEPA2017a">California Environmental Protection Agency, 2017. [https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/documents/123-tcp/sbddw17_001/isor.pdf Initial Statement of Reasons 1,2,3-Trichloropropane Maximum Contaminant Level Regulations]. Water Resources Control Board, Title 22, California Code of Regulations (SBDDW-17-001). 36 pp.</ref>. Additionally, GAC has been used for over 30 years to treat 60 million gallons per day of TCP-contaminated groundwater in Hawaii<ref name="Babcock2018">Babcock Jr, R.W., Harada, B.K., Lamichhane, K.M., and Tsubota, K.T., 2018. Adsorption of 1, 2, 3-Trichloropropane (TCP) to meet a MCL of 5 ppt. Environmental Pollution, 233, 910-915. [https://doi.org/10.1016/j.envpol.2017.09.085 DOI: 10.1016/j.envpol.2017.09.085]</ref>.
+GAC has a low to moderate adsorption capacity for TCP, which can necessitate larger treatment systems and result in higher treatment costs relative to other organic contaminants<ref name="USEPA2017" />.  Published Freundlich adsorption isotherm parameters<ref name="SnoeyinkSummers1999">Snoeyink, V.L. and Summers, R.S, 1999. Adsorption of Organic Compounds (Chapter 13), In: Water Quality and Treatment, 5th ed., Letterman, R.D., editor.  McGraw-Hill, New York, NY. ISBN 0-07-001659-3</ref> indicate that less TCP mass is adsorbed per gram of carbon compared to other volatile organic compounds (VOCs), resulting in increased carbon usage rate and treatment cost.  Recent bench-scale studies indicate that subbituminous coal-based GAC and coconut shell-based GAC are the most effective types of GAC for treatment of TCP in groundwater<ref name="Babcock2018" /><ref name="Knappe2017">Knappe, D.R.U., Ingham, R.S., Moreno-Barbosa, J.J., Sun, M., Summers, R.S., and Dougherty, T., 2017. Evaluation of Henry’s Law Constants and Freundlich Adsorption Constants for VOCs. [https://www.waterrf.org/research/projects/evaluation-henrys-law-constant-and-freundlich-adsorption-constant-vocs Water Research Foundation Project 4462 Final Report].</ref>. To develop more economical and effective treatment approaches, further treatability studies with site groundwater (e.g., rapid small-scale column tests) may be needed.
+===''In Situ'' Treatment===
+''In situ'' treatment of TCP to concentrations below current regulatory or advisory levels is difficult to achieve in both natural and engineered systems. However, several ''in situ'' treatment technologies have demonstrated promise for TCP remediation, including chemical reduction by zero-valent metals (ZVMs), chemical oxidation with strong oxidizers, and anaerobic bioremediation<ref name="Merrill2019" /><ref name="Tratnyek2010" />.
+===''In Situ'' Chemical Reduction (ISCR)===
+Reduction of TCP under conditions relevant to natural attenuation has been observed to be negligible. Achieving significant degradation rates of TCP requires the addition of a chemical reductant to the contaminated zone<ref name="Merrill2019" /><ref name="Tratnyek2010" />.  Under reducing environmental conditions, some ZVMs have demonstrated the ability to reduce TCP all the way to [[wikipedia:Propene | propene]]. As shown in Figure 2, the desirable pathway for reduction of TCP is the formation of [[Wikipedia: Allyl_chloride | 3-chloro-1-propene (also known as allyl chloride)]] via [[Biodegradation_-_Reductive_Processes#Dihaloelimination | dihaloelimination]], which is then rapidly reduced to propene through [[Wikipedia:Hydrogenolysis |  hydrogenolysis]] <ref name="Merrill2019" /><ref name="Tratnyek2010" /><ref name="Torralba-Sanchez2020">Torralba-Sanchez, T.L., Bylaska, E.J., Salter-Blanc, A.J., Meisenheimer, D.E., Lyon, M.A., and Tratnyek, P.G., 2020. Reduction of 1, 2, 3-trichloropropane (TCP): pathways and mechanisms from computational chemistry calculations. Environmental Science: Processes and Impacts, 22(3), 606-616. [https://doi.org/10.1039/C9EM00557A DOI: 10.1039/C9EM00557A] [//www.enviro.wiki/images/c/c3/Torralba-Sanchez2020.pdf Article pdf]</ref>.  ZVMs including granular zero-valent iron (ZVI), nano ZVI, [[wikipedia: In_situ_chemical_reduction#Bimetallic%20materials | palladized nano ZVI]], and [[wikipedia: In_situ_chemical_reduction#Zero_valent_metals_%28ZVMs%29 | zero-valent zinc (ZVZ)]] have been evaluated by researchers<ref name="Merrill2019" /><ref name="Tratnyek2010" />.
+ZVI is a common reductant used for ISCR and, depending on the form used, has shown variable levels of success for TCP treatment. The Strategic Environmental Research and Development Program (SERDP) Project ER-1457 measured the TCP degradation rates for various forms of ZVI and ZVZ.  Nano-scale ZVI and palladized ZVI increased the TCP reduction rate over that of natural attenuation, but the reaction is not anticipated to be fast enough to be useful in typical remediation applications<ref name="Sarathy2010" />.
+Commercial-grade zerovalent zinc (ZVZ) on the other hand is a strong reductant that reduces TCP relatively quickly under a range of laboratory and field conditions to produce propene without significant accumulation of intermediates<ref name="Sarathy2010" /><ref name="Salter-BlancTratnyek2011">Salter-Blanc, A.J. and Tratnyek, P.G., 2011. Effects of Solution Chemistry on the Dechlorination of 1,2,3-Trichloropropane by Zero-Valent Zinc. Environmental Science and Technology, 45(9), pp 4073–4079. [https://doi.org/10.1021/es104081p DOI: 10.1021/es104081p] [//www.enviro.wiki/images/0/09/Salter-BlancTratnyek2011.pdf Article pdf]</ref><ref name="Salter-Blanc2012">Salter-Blanc, A.J., Suchomel, E.J., Fortuna, J.H., Nurmi, J.T., Walker, C., Krug, T., O'Hara, S., Ruiz, N., Morley, T. and Tratnyek, P.G., 2012. Evaluation of Zerovalent Zinc for Treatment of 1,2,3-Trichloropropane‐Contaminated Groundwater: Laboratory and Field Assessment. Groundwater Monitoring and Remediation, 32(4), pp.42-52. [https://doi.org/10.1111/j.1745-6592.2012.01402.x DOI: 10.1111/j.1745-6592.2012.01402.x]</ref><ref name="Merrill2019" />. Of the ZVMs tested as part of SERDP Project ER-1457, ZVZ had the fastest degradation rates for TCP<ref name="Tratnyek2010" />. In bench-scale studies, TCP was reduced by ZVZ to propene with 3-chloro-1-propene as the only detectable chlorinated intermediate, which was short-lived and detected only at trace concentrations<ref name="Torralba-Sanchez2020" />.
+Navy Environmental Sustainability Development to Integration (NESDI) Project 434 conducted bench-scale testing which demonstrated that commercially available ZVZ was effective for treating TCP. Additionally, this project evaluated field-scale ZVZ column treatment of groundwater impacted with TCP at Marine Corps Base Camp Pendleton (MCBCP) in Oceanside, California. This study reported reductions of TCP concentrations by up to 95% which was maintained for at least twelve weeks with influent concentrations ranging from 3.5 to 10 µg/L, without any significant secondary water quality impacts detected<ref name="Salter-Blanc2012" />.
+Following the column study, a 2014 pilot study at MCBCP evaluated direct injection of ZVZ with subsequent monitoring. Direct injection of ZVZ was reportedly effective for TCP treatment, with TCP reductions ranging from 90% to 99% in the injection area. Concentration reduction downgradient of the injection area ranged from 50 to 80%. TCP concentrations have continued to decrease, and reducing conditions have been maintained in the aquifer since injection, demonstrating the long-term efficacy of ZVZ for TCP reduction<ref name="Kane2020" />.
+Potential ''in situ'' applications of ZVZ include direct injection, as demonstrated by the MCBCP pilot study, and permeable reactive barriers (PRBs). Additionally, ZVZ could potentially be deployed in an ''ex situ'' flow-through reactor, but the economic feasibility of this approach would depend in part on the permeability of the aquifer and in part on the cost of the reactor volumes of ZVZ media necessary for complete treatment.
+===''In Situ'' Chemical Oxidation (ISCO)===
+Chemical oxidation of TCP with mild oxidants such as permanganate or ozone is ineffective. However, stronger oxidants (e.g. activated peroxide and persulfate) can effectively treat TCP, although the rates are slower than observed for most other organic contaminants<ref name="Tratnyek2010" /><ref name="CalEPA2017" />. [[Wikipedia: Fenton's reagent | Fenton-like chemistry]] (i.e., Fe(II) activated hydrogen peroxide) has been shown to degrade TCP in the laboratory with half-lives ranging from 5 to 10 hours<ref name="Tratnyek2010" />, but field-scale demonstrations of this process have not been reported. Treatment of TCP with heat-activated or base-activated persulfate is effective but secondary water quality impacts from high sulfate may be a concern at some locations.
+===Aerobic Bioremediation===
+No naturally occurring microorganisms have been identified that degrade TCP under aerobic conditions<ref name="SaminJanssen2012" />. Relatively slow aerobic cometabolism by the ammonia oxidizing bacterium [[Wikipedia: Nitrosomonas europaea | Nitrosomonas europaea]] and other populations has been reported<ref name="Vanelli1990">Vannelli, T., Logan, M., Arciero, D.M., and Hooper, A.B., 1990. Degradation of Halogenated Aliphatic Compounds by the Ammonia-Oxidizing Bacterium Nitrosomonas europaea. Applied and Environmental Microbiology, 56(4), pp. 1169–1171. [https://doi.org/10.1128/aem.56.4.1169-1171.1990 DOI: 10.1128/aem.56.4.1169-1171.1990] [//www.enviro.wiki/images/2/2f/Vannelli1990.pdf Report pdf]</ref><ref name="SaminJanssen2012" />, and genetic engineering has been used to develop organisms capable of utilizing TCP as a sole carbon source under aerobic conditions<ref name="Bosma2002">Bosma, T., Damborsky, J., Stucki, G., and Janssen, D.B., 2002. Biodegradation of 1,2,3-Trichloropropane through Directed Evolution and Heterologous Expression of a Haloalkane Dehalogenase Gene. Applied and Environmental Microbiology, 68(7), pp. 3582–3587. [https://doi.org/10.1128/AEM.68.7.3582-3587.2002 DOI: 10.1128/AEM.68.7.3582-3587.2002] [//www.enviro.wiki/images/1/16/Bosma2002.pdf Report pdf]</ref><ref name="SaminJanssen2012" /><ref name="JanssenStucki2020">Janssen, D. B., and Stucki, G., 2020. Perspectives of genetically engineered microbes for groundwater bioremediation. Environmental Science: Processes and Impacts, 22(3), pp. 487-499. [https://doi.org/10.1039/C9EM00601J DOI: 10.1039/C9EM00601J] [//www.enviro.wiki/images/2/2c/JanssenStucki2020.pdf Article pdf]</ref>.
+===Anaerobic Bioremediation===
+Like other CVOCs, TCP has been shown to undergo biodegradation under anaerobic conditions via reductive dechlorination by [[Wikipedia:Dehalogenimonas | Dehalogenimonas (Dhg)]] species<ref name="Merrill2019" /><ref name="Yan2009">Yan, J., B.A. Rash, F.A. Rainey, and W.M. Moe, 2009. Isolation of novel bacteria within the Chloroflexi capable of reductive dechlorination of 1,2,3-trichloropropane. Environmental Microbiology, 11(4), pp. 833–843. [https://doi.org/10.1111/j.1462-2920.2008.01804.x DOI: 10.1111/j.1462-2920.2008.01804.x]</ref><ref name="Bowman2013">Bowman, K.S., Nobre, M.F., da Costa, M.S., Rainey, F.A., and Moe, W.M., 2013. Dehalogenimonas alkenigignens sp. nov., a chlorinated-alkane-dehalogenating bacterium isolated from groundwater. International Journal of Systematic and Evolutionary Microbiology, 63(Pt_4), pp. 1492-1498. [https://doi.org/10.1099/ijs.0.045054-0 DOI: 10.1099/ijs.0.045054-0] [//www.enviro.wiki/images/b/b5/Bowman2013.pdf Article pdf]</ref><ref name="Loffler1997">Loffler, F.E., Champine, J.E., Ritalahti, K.M., Sprague, S.J. and Tiedje, J.M., 1997. Complete Reductive Dechlorination of 1, 2-Dichloropropane by Anaerobic Bacteria. Applied and Environmental Microbiology, 63(7), pp.2870-2875. [//www.enviro.wiki/images/4/4f/Loffler1997.pdf Article pdf]</ref><ref name="Moe2019">Moe, W.M., Yan, J., Nobre, M.F., da Costa, M.S. and Rainey, F.A., 2009. Dehalogenimonas lykanthroporepellens gen. nov., sp. nov., a reductively dehalogenating bacterium isolated from chlorinated solvent-contaminated groundwater. International Journal of Systematic and Evolutionary Microbiology, 59(11), pp.2692-2697. [https://doi.org/10.1099/ijs.0.011502-0 DOI: 10.1099/ijs.0.011502-0] [//www.enviro.wiki/images/9/94/Moe2009.pdf Article pdf]</ref><ref name="SaminJanssen2012" />. However, the kinetics are slower than for other CVOCs.  Bioaugmentation cultures containing Dehalogenimonas (KB-1 Plus, SiREM) are commercially available and have been implemented for remediation of TCP-contaminated groundwater<ref name="Schmitt2017">Schmitt, M., Varadhan, S., Dworatzek, S., Webb, J. and Suchomel, E., 2017. Optimization and validation of enhanced biological reduction of 1,2,3-trichloropropane in groundwater. Remediation Journal, 28(1), pp.17-25. [https://doi.org/10.1002/rem.21539 DOI: 10.1002/rem.21539]</ref>. One laboratory study examined the effect of pH on biotransformation of TCP over a wide range of TCP concentrations (10 to 10,000 µg/L) and demonstrated that successful reduction occurred from a pH of 5 to 9, though optimal conditions were from pH 7 to 9<ref name="Schmitt2017" />.
+As with other microbial cultures capable of reductive dechlorination, coordinated amendment with a fermentable organic substrate (e.g. lactate or vegetable oil), also known as biostimulation,  creates reducing conditions in the aquifer and provides a source of hydrogen which is required as the primary electron donor for reductive dechlorination.
+A 2016 field demonstration of ''in situ'' bioremediation (ISB) was performed in California’s Central Valley at a former agricultural chemical site with relatively low TCP concentrations (2 µg/L). The site was first biostimulated by injecting amendments of emulsified vegetable oil (EVO) and lactate, which was followed by bioaugmentation with a microbial consortium containing Dhg. After an initial lag period of six months, TCP concentrations decreased to below laboratory detection limits (<0.005 µg/L)<ref name="Schmitt2017" />.
+{| class="wikitable" style="float:right; margin-left:10px;text-align:center;"
+|+Table 2.  Advantages and limitations of TCP treatment technologies<ref name="Kane2020" />
+|-
+!Technology
+!Advantages
+!Limitations
+|-
+|ZVZ
+| style="text-align:left;" |
+*Can degrade TCP at relatively high and low concentrations
+*Faster reaction rates than ZVI
+*Material is commercially available
+| style="text-align:left;" |
+*Higher cost than ZVI
+*Difficult to distribute in subsurface ''in situ'' applications
+|-
+|Groundwater<br>Extraction and<br>Treatment
+| style="text-align:left;" |
+*Can cost-effectively capture and treat larger, more dilute<br>groundwater plumes than ''in situ'' technologies
+*Well understood and widely applied technology
+| style="text-align:left;" |
+*Requires construction, operation and maintenance of<br>aboveground treatment infrastructure
+*Typical technologies (e.g. GAC) may be expensive due<br>to treatment inefficiencies
+|-
+|ZVI
+| style="text-align:left;" |
+*Can degrade TCP at relatively high and low concentrations
+*Lower cost than ZVZ
+*Material is commercially available
+| style="text-align:left;" |
+*Lower reactivity than ZVZ, therefore may require higher<br>ZVI volumes or thicker PRBs
+*Difficult to distribute in subsurface ''in situ'' applications
+|-
+|ISCO
+| style="text-align:left;" |
+*Can degrade TCP at relatively high and low concentrations
+*Strategies to distribute amendments ''in situ'' are well established
+*Material is commercially available
+| style="text-align:left;" |
+*Most effective oxidants (e.g., base-activated or heat-activated<br>persulfate) are complex to implement
+*Secondary water quality impacts (e.g., high pH, sulfate, <br>hexavalent chromium) may limit ability to implement
+|-
+|''In Situ''<br>Bioremediation
+| style="text-align:left;" |
+*Can degrade TCP at moderate to high concentrations
+*Strategies to distribute amendments ''in situ'' are well established
+*Materials are commercially available and inexpensive
+| style="text-align:left;" |
+*Slower reaction rates than ZVZ or ISCO
+|}
+The 2016 field demonstration was expanded to full-scale treatment in 2018 with biostimulation and bioaugmentation occurring over several months. The initial TCP concentration in performance monitoring wells ranged from 0.008 to 1.7 µg/L. As with the field demonstration, a lag period of approximately 6 to 8 months was observed before TCP was degraded, after which concentrations declined over fifteen months to non-detectable levels (less than 0.005 µg/L). TCP degradation was associated with increases in Dhg population and propene concentration. Long term monitoring showed that TCP remained at non-detectable levels for at least three years following treatment implementation<ref name="Merrill2019" />.
+==Treatment Comparisons and Considerations==
+When selecting a technology for TCP treatment, considerations include technical feasibility, ability to treat to regulated levels, potential secondary water quality impacts and relative costs. A comparison of some TCP treatment technologies is provided in Table 2.
 ==Summary==
-The relatively high toxicity of TCP has led to the development of low health-based drinking water concentration goals. TCP is present in groundwater and in public water systems at concentrations that exceed these health-based goals. While the EPA has not established a MCL for TCP, a handful of states have either established MCLs or are in the process of doing so. Because TCP is persistent in groundwater and it is resistant to typical remediation methods (or costly to treat), specialized strategies may be needed to meet drinking-water-based treatment goals. Research into TCP treatment is ongoing.
+The relatively high toxicity of TCP has led to the development of health-based drinking water concentration values that are very low. TCP is sometimes present in groundwater and in public water systems at concentrations that exceed these health based goals. While a handful of states have established MCLs for TCP, US federal regulatory determination is hindered by the lack of low concentration occurrence data. Because TCP is persistent in groundwater and resistant to typical remediation methods (or costly to treat), specialized strategies may be needed to meet drinking water based treatment goals.  ''In situ'' chemical reduction (ISCR) with zero valent zinc (ZVZ) and ''in situ'' bioremediation have been demonstrated to be effective for TCP remediation.
 ==References==
+<references />
+==See Also==
+ATSDR Toxicological Profile: https://www.atsdr.cdc.gov/ToxProfiles/TP.asp?id=912&tid=186
-<references/>
+EPA Technical Fact Sheet: https://www.epa.gov/sites/production/files/2014-03/documents/ffrrofactsheet_contaminant_tcp_january2014_final.pdf
-==See Also==
+Cal/EPA State Water Resources Control Board Groundwater Information Sheet: http://www.waterboards.ca.gov/gama/docs/coc_tcp123.pdf
-*[https://www.atsdr.cdc.gov/ToxProfiles/TP.asp?id=912&tid=186 ATSDR Toxicological Profile]
-*[https://www.epa.gov/sites/production/files/2014-03/documents/ffrrofactsheet_contaminant_tcp_january2014_final.pdf EPA Technical Fact Sheet]
+California Water Boards Fact Sheet: http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/documents/123-tcp/123tcp_factsheet.pdf
-*[http://www.waterboards.ca.gov/gama/docs/coc_tcp123.pdf Cal/EPA State Water Resources Control Board Groundwater Information Sheet]
-*[http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/documents/123-tcp/123tcp_factsheet.pdf California Water Boards Fact Sheet]
-*[https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Emerging-Issues/ER-1457  Prospects for Remediation of 1,2,3-Trichloropropane by Natural and Engineered Abiotic Degradation Reactions]

Difference between revisions of "1,2,3-Trichloropropane"

Latest revision as of 03:07, 28 April 2022

Contents

Introduction

Environmental Fate

Occurrence

Regulation

Transformation Processes

Treatment Approaches

Ex Situ Treatment

In Situ Treatment

In Situ Chemical Reduction (ISCR)

In Situ Chemical Oxidation (ISCO)

Aerobic Bioremediation

Anaerobic Bioremediation

Treatment Comparisons and Considerations

Summary

References

See Also

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