Accumulation of Insensitive Munition Compounds in the Earthworm Eisenia andrei from Amended Soil: Methodological Considerations for Determination of Bioaccumulation Factors.

The present study investigates the bioaccumulation of the insensitive munition compounds 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO), developed for future weapons systems to replace current munitions containing sensitive explosives. The earthworm Eisenia andrei was exposed to sublethal concentrations of DNAN or NTO amended in Sassafras sandy loam. Chemical analysis indicated that 2- and 4-amino-nitroanisole (2-ANAN and 4-ANAN, respectively) were formed in DNAN-amended soils. The SumDNAN (sum of DNAN, 2-ANAN, and 4-ANAN concentrations) in soil decreased by 40% during the 14-d exposure period. The SumDNAN in the earthworm body residue increased until day 3 and decreased thereafter. Between days 3 and 14, there was a 73% decrease in tissue uptake that was greater than the 23% decrease in the soil concentration, suggesting that the bioavailable fraction may have decreased over time. By day 14, the DNAN concentration accounted for only 45% of the SumDNAN soil concentration, indicating substantial DNAN transformation in the presence of earthworms. The highest bioaccumulation factor (BAF; the tissue-to-soil concentration ratio) was 6.2 ± 1.0 kg/kg (dry wt) on day 3 and decreased to 3.8 ± 0.8 kg/kg by day 14. Kinetic studies indicated a BAF of 2.3 kg/kg, based on the earthworm DNAN uptake rate of 2.0 ± 0.24 kg/kg/d, compared with the SumDNAN elimination rate of 0.87 d-1 (half-life = 0.79 d). The compound DNAN has a similar potential to bioaccumulate from soil compared with trinitrotoluene. The NTO concentration in amended soil decreased by 57% from the initial concentration (837 mg NTO/kg dry soil) during 14 d, likely due to the formation of unknown transformation products. The bioaccumulation of NTO was negligible (BAF ≤ 0.018 kg/kg dry wt). Environ Toxicol Chem 2021;40:1713-1725. © 2021 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Development of a reference material for analysing naturally occurring radioactive material from the steel industry.

Accurate measurement of naturally occurring radionuclides in blast furnace slag, a by-product of the steel industry, is required for compliance with building regulations where it is often used as an ingredient in cement. A matrix reference blast furnace slag material has been developed to support traceability in these measurements. Raw material provided by a commercial producer underwent stability and homogeneity testing, as well as characterisation of matrix constituents, to provide a final candidate reference material. The radionuclide content was then determined during a comparison exercise that included 23 laboratories from 14 countries. Participants determined the activity per unit mass for 226Ra, 232Th and 40K using a range of techniques. The consensus values obtained from the power-moderated mean of the reported participant results were used as indicative activity per unit mass values for the three radionuclides: A0(226Ra) = 106.3 (34) Bq·kg-1, A0(232Th) = 130.0 (48) Bq·kg-1 and A0(40K) = 161 (11) Bq·kg-1 (where the number in parentheses is the numerical value of the combined standard uncertainty referred to the corresponding last digits of the quoted result). This exercise helps to address the current shortage of NORM industry reference materials, putting in place infrastructure for production of further reference materials.

A feasibility study on the determination of 90Sr food-chain transfer using stable strontium as a surrogate and neutron activation analysis.

We evaluated the applicability of neutron activation analysis for investigating the potential mobility of 90Sr in a pasture area in Hungary. To measure strontium concentrations, we made use of the 84Sr(n,γ)85Sr radiative capture reaction using neutron activation analysis and performed gamma spectroscopy using Compton-suppression techniques on the resulting 514.0 keV gamma ray. Our values for soil-to-plant transfer factors value of 1.6 (2.2) kg kg-1 were in agreement with recommended values from the ICRP and IAEA, as well as similar studies performed by independent researchers. Our values for plant-to-animal transfer coefficients and concentration ratios varied from suggested values by several orders of magnitude to agreement with other values. Based on our results the utilized transfer of stable strontium could not be regarded as a convenient substitute to help clarify the long-term transfer of radioactive strontium in the environment, because short term dosing was applied. Neutron activation analysis provides a unique niche as a technique with very little chemical processing and short sample analysis times.

Determination of cesium transfer factors by instrumental neutron activation analysis.

Food-chain models are used to predict radionuclide ingestion after fallout deposition. These models include those transfer processes (soil-to-plant transfer factor(s) [TF], plant-to-animal transfer coefficient(s) [TC] and concentration ratio [CR]) that are likely to be important for radiological assessment. The range of variability for transfer factors for the same plant groups is great, about 4-5 orders of magnitude, which limits their applicability. A better way to determine the best estimate the factors for radiocaesium and other important radionuclides is if the site-specific data are available. Soil, plant and animal samples were collected from a pasture area in Hungary during the vegetation period in 2016. Stable 133Cs concentration was analysed by comparative method with neutron activation analysis (NAA). The comparator and the samples were irradiated in thermal neutron flux 2.55 × 1012 ncm-2s-1 for 2 h (soil) and 6 h (vegetation, animal samples) in the TRIGA Mark II research reactor at the Nuclear Engineering Teaching Laboratory. After an appropriate decay time (12 days) the samples were measured by gamma-spectrometry and analysed. The observed stable caesium TCpm (0.48-0.53) and CRpm (0.41-0.45) were very close to 137Cs factors in the IAEA 2009 Report of 0.49 and 0.54, respectively. This methodology is particularly suitable for the simultaneous study of natural caesium in ecosystem compartments. Consequently, the transfer of stable caesium in a pasture field may be regarded as a useful analogy in predicting the long-term changes of 137Cs affected by site-specific environmental factors.

Analysis of munitions constituents in IMX formulations by HPLC and HPLC-MS.

The use of Insensitive Munitions eXplosives (IMX) is increasing as the Army seeks to replace certain conventional munitions constituents, such as 2,4,6-trinitrotolene (TNT), for improved safety. The IMX formulations are more stable and therefore less prone to accidental detonation while designed to match the performance of legacy materials. Two formulations, IMX 101 and 104 are being investigated as a replacement for TNT in artillery rounds and composition B Army mortars, respectively. The chemical formulations of IMX-101 and 104 are comprised of four constituents;2,4-dinitroanisole (DNAN), 3-nitro-1,2,4-triazol-5-one (NTO), 1-nitroguanidine (NQ), and Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) which are mixed in various ratios to achieve the desired performance. The current work details the analysis of the IMX constituents by single column HPLC-UV-ESI-MS. Detection limits determined are in agreement with similar HPLC analysis of compounds, ranging from 7 to 9µg/L. Gradient mobile phases are used to allow separation of the 4 target compounds in more complex mixture of other concomitant compounds. Mass spectra are used to confirm analyte identity with chromatographic retention time.

Characterization of metals released from coal fly ash during dredging at the Kingston ash recovery project.

A storage-pond dike failure occurred on December 22, 2008 at the Tennessee Valley Authority Kingston Fossil Plant resulting in the release of over 4million cubic meters (5million cubic yards) of fly ash. Approximately half of the released ash was deposited in the main channel of the Emory River, Tennessee, USA. Remediation efforts of the Emory River focused on hydraulic dredging, as well as mechanical excavation in targeted areas. However, agitation of the submerged fly ash during hydraulic dredging introduces river water into the fly ash material, which could promote dissolution and desorption of metals from the solid fly ash material. Furthermore, aeration of the dredge slurry could alter the redox state of metals in the fly ash material and thereby change their sorption, mobility, and toxicity properties. The research presented here focuses on the concentrations and speciation of metals during the fly ash recovery from the Emory River. Our results indicate that arsenite [As(III)] released from the fly ash material during dredging was slowly oxidized to arsenate [As(V)] in the slurry recovery system with subsequent removal through precipitation or sorption reactions with suspended fly ash material. Concentrations of other dissolved metals, including iron and manganese, also generally decreased in the ash recovery system prior to water discharge back to the river.

Comparison of on-line detectors for field flow fractionation analysis of nanomaterials.

Characterization of nanomaterials must include analysis of both size and chemical composition. Many analytical techniques, such as dynamic light scattering (DLS), are capable of measuring the size of suspended nanometer-sized particles, yet provide no information on the composition of the particle. While field flow fractionation (FFF) is a powerful nanoparticle sizing technique, common detectors used in conjunction with the size separation, including UV, light-scattering, and fluorescence spectroscopy, do not provide the needed particle compositional information. Further, these detectors do not respond directly to the mass concentration of nanoparticles. The present work describes the advantages achieved when interfacing sensitive and elemental specific detectors, such as inductively coupled plasma atomic emission spectroscopy and mass spectrometry, to FFF separation analysis to provide high resolution nanoparticle sizing and compositional analysis at the µg/L concentration level, a detection at least 10-100-fold lower than DLS or FFF-UV techniques. The full benefits are only achieved by utilization of all detector capabilities, such as dynamic reaction cell (DRC) ICP-MS. Such low-level detection and characterization capability is critical to nanomaterial investigations at biologically and environmentally relevant concentrations. The techniques have been modified and applied to characterization of all four elemental constituents of cadmium selenide-zinc sulfide core-shell quantum dots, and silver nanoparticles with gold seed cores. Additionally, sulfide coatings on silver nanoparticles can be detected as a potential means to determine environmental aging of nanoparticles.

Analysis of munitions constituents in groundwater using a field-portable GC-MS.

The use of munitions constituents (MCs) at military installations can produce soil and groundwater contamination that requires periodic monitoring even after training or manufacturing activities have ceased. Traditional groundwater monitoring methods require large volumes of aqueous samples (e.g., 2-4 L) to be shipped under chain of custody, to fixed laboratories for analysis. The samples must also be packed on ice and shielded from light to minimize degradation that may occur during transport and storage. The laboratory's turn-around time for sample analysis and reporting can be as long as 45 d. This process hinders the reporting of data to customers in a timely manner; yields data that are not necessarily representative of current site conditions owing to the lag time between sample collection and reporting; and incurs significant shipping costs for samples. The current work compares a field portable Gas Chromatograph-Mass Spectrometer (GC-MS) for analysis of MCs on-site with traditional laboratory-based analysis using High Performance Liquid Chromatography with UV absorption detection. The field method provides near real-time (within ~1 h of sampling) concentrations of MCs in groundwater samples. Mass spectrometry provides reliable confirmation of MCs and a means to identify unknown compounds that are potential false positives for methods with UV and other non-selective detectors.

Characterization of silver nanoparticles using flow-field flow fractionation interfaced to inductively coupled plasma mass spectrometry.

The ability to detect and identify the physiochemical form of contaminants in the environment is important for degradation, fate and transport, and toxicity studies. This is particularly true of nanomaterials that exist as discrete particles rather than dissolved or sorbed contaminant molecules in the environment. Nanoparticles will tend to agglomerate or dissolve, based on solution chemistry, which will drastically affect their environmental properties. The current study investigates the use of field flow fractionation (FFF) interfaced to inductively coupled plasma-mass spectrometry (ICP-MS) as a sensitive and selective method for detection and characterization of silver nanoparticles. Transmission electron microscopy (TEM) is used to verify the morphology and primary particle size and size distribution of precisely engineered silver nanoparticles. Subsequently, the hydrodynamic size measurements by FFF are compared to dynamic light scattering (DLS) to verify the accuracy of the size determination. Additionally, the sensitivity of the ICP-MS detector is demonstrated by fractionation of µg/L concentrations of mixed silver nanoparticle standards. The technique has been applied to nanoparticle suspensions prior to use in toxicity studies, and post-exposure biological tissue analysis. Silver nanoparticles extracted from tissues of the sediment-dwelling, freshwater oligochaete Lumbriculus variegatus increased in size from approximately 31-46nm, indicating a significant change in the nanoparticle characteristics during exposure.

Geochemical investigations of metals release from submerged coal fly ash using extended elutriate tests.

A storage pond dike failure occurred at the Tennessee Valley Authority Kingston Fossil Plant that resulted in the release of over 3.8 million cubic meters (5 million cubic yards) of fly ash. Approximately half of this material deposited in the main channel of the Emory River, 3.5 km upstream of the confluence of the Emory and Clinch Rivers, Tennessee, USA. Remediation efforts to date have focused on targeted removal of material from the channel through hydraulic dredging, as well as mechanical excavation in some areas. The agitation of the submerged fly ash during hydraulic dredging introduces river water into the fly ash material, which could alter the redox state of metals present in the fly ash and thereby change their sorption and mobility properties. A series of extended elutriate tests were used to determine the concentration and speciation of metals released from fly ash. Results indicated that arsenic and selenium species released from the fly ash materials during elutriate preparation were redox stable over the course of 10d, with dissolved arsenic being present as arsenate, and dissolved selenium being present as selenite. Concentrations of certain metals, such as arsenic, selenium, vanadium, and barium, increased in the elutriate waters over the 10d study, whereas manganese concentrations decreased, likely due to oxidation and precipitation reactions.

A modified acid digestion procedure for extraction of tungsten from soil.

Interest in tungsten occurrence and geochemistry is increasing due to increased use of tungsten compounds and its unknown biochemical effects. Tungsten has a complex geochemistry, existing in most environmental matrices as the soluble and mobile tungstate anion, as well as poly- and heteropolytungstates. Because the geochemistry of tungsten is substantially different than most trace metals, including the formation of insoluble species under acidic conditions, it is not extracted from soil matrices using standard acid digestion procedures. Therefore, the current work describes a modification to a commonly used acid digestion procedure to facilitate quantification of tungsten in soil matrices. Traditional soil digestion procedures, using nitric and hydrochloric acids with hydrogen peroxide yield <1 up to 50% recovery on soil matrix spike samples, whereas the modified method reported here, which includes the addition of phosphoric acid, yields spike recoveries in the 76-98% range. Comparison of the standard and modified digestion procedures on National Institute of Standards and Technology Standard Reference Materials yielded significantly improved tungsten recoveries for the phosphoric acid modified method. The modified method also produces comparable results for other acid extractable metals as the standard methods, and therefore can be used simultaneously for tungsten and other metals of interest.

Mobility and sorption of bis-2-chloroethyl ether in an aquifer material.

Active treatment of BCEE (bis-2-chloroethyl ether) is being currently performed in the on-site Cohansey Aquifer at the Lipari Superfund Site. Remediation of BCEE in the underlying Kirkwood aquifer is being considered, necessitating investigations of BCEE geochemistry in aquifer material from the site. It is currently unknown to what extent BCEE is present in the dissolved, sorbed, or free-product phase in the Kirkwood Sand aquifer material. A series of partition coefficient sorption, column leach, and column loading tests were conducted to determine BCEE sorption to, and mobility in, the Kirkwood Sand aquifer material. The leach studies indicated that up to 50% of BCEE spiked (as free-phase product) onto two aquifer material column designs could be leached in approximately 18h, due to the high aqueous solubility of BCEE. Dissolved BCEE concentrations then began to plateau as sorption reactions hindered further leaching, resulting in up to 80% removal after 48h. Column loading and batch sorption experiments suggest that BCEE mobility is limited by sorption rather than solubility factors. Tracer tests in both column loading and batch sorption tests indicate sorption hinders leaching of BCEE from the Kirkwood Sand material.

Determination of vanadium by reaction cell inductively coupled plasma mass spectrometry.

Recent advances in inductively coupled plasma mass spectrometry (ICP-MS) have included the addition of interference reduction technologies, such as collision and reaction cells, to improve its detection capability for certain elements that suffer from polyatomic interferences. The principle behind reaction cell (RC)-ICP-MS is to remove a particular polyatomic interference by dissociation or formation of a different polyatomic species that no longer interferes with the analyte of interest. However, some interferences cannot be removed by commonly reported reaction gases, such as hydrogen, oxygen, or methane, necessitating using more reactive and hazardous gases, such as ammonia. The current study investigates oxygen as a reaction gas in RC-ICP-MS to specifically react with vanadium analyte ions, rather than the interferents, to produce a polyatomic analyte species and thereby provide a way to analyze for vanadium in complex environmental matrices. The technique has been tested on a series of river water, tap water, and synthetic laboratory samples, and shown to be successful in vanadium analyses in high chloride and sulfate matrices. The zinc isobaric interference on the new vanadium oxide analyte at m/z 67 is also investigated, and can be corrected by using a standard mathematical correction equation. The results of this study further increase the utility of RC-ICP-MS analytical techniques for complex environmental matrices.

Investigations of tungsten mobility in soil using column tests.

The geochemistry of tungsten has recently gained attention in the scientific and regulatory communities. Tungsten has a complex geochemistry, existing in many environmental matrices as the soluble and mobile tungstate anion, as well as a series of ill-defined polymeric species. Previous work has shown that soluble tungsten leached from a metallic tungsten-spiked Grenada Loring soil will reach an equilibrium concentration >150 mgL(-1), and the concentration is greatly influenced by co-occurring analytes in the matrix, such as calcium and phosphate. In the present work, the mobility of tungsten compounds was investigated in a model soil with a range of aqueous leach solutions using column experiments. The relative column leachate concentrations measured followed trends from previously reported tungstate and polytungstate partition coefficients determined in the model soil under identical aqueous matrix conditions. Neutral to alkaline conditions produced maximum effluent tungsten concentrations >40 mgL(-1), whereas acid leach eluents produced concentrations in the <1-3 mgL(-1) range. The change in leached tungsten speciation over time was also measured as monomeric and polymeric tungsten species have different sorptive behaviors.

Tungsten effects on microbial community structure and activity in a soil.

Tungsten, once deposited onto a soil as a result of private, industrial, and military activities, may persist as tungstate anion or, via polymerization, as a variety of poly-tungstate species, each with varying solubility and soil sorption characteristics. In this study, the impact of weathered tungsten on a soil microbial community was measured. Fatty acid analyses indicated that weathered tungsten at < or =2500 mg kg(-1) was associated with a significant increase in microbial biomass and that concentrations up to 6500 mg kg(-1) did not result in a significant decrease in measured biomass, relative to the control. Analysis of cellular fatty acids also identified significant microbial community shifts between 0 and 325, 1300 and 2600, and 3900 and 6500 mg W kg(-1) soil. In general, the positive effect of tungsten on microbial biomass coincided with an increase in Gram-negative bacterial fatty acids, whereas fatty acids indicative of actinomycetes and Gram-positive bacteria were more abundant at the highest soil tungsten concentrations. The weathered tungsten also inhibited N2 fixing activity of a free living diazotroph at > or =1300 mg W kg(-1) soil. These results indicate that tungsten in soil can alter both the structure and the function of an indigenous soil microbial community.

Comparison of standard and reaction cell inductively coupled plasma mass spectrometry in the determination of chromium and selenium species by HPLC-ICP-MS.

Elemental speciation is becoming a common analytical procedure for geochemical investigations. The various redox species of environmentally relevant metals can have vastly different biogeochemical properties, including sorption, solubility, bioavailability, and toxicity. The use of high performance liquid chromatography (HPLC) coupled to elemental specific detectors, such as inductively coupled plasma mass spectrometry (ICP-MS), has become one of the most important speciation methods employed. This is due to the separation versatility of HPLC and the sensitive and selective detection capabilities of ICP-MS. The current study compares standard mode ICP-MS to recently developed reaction cell (RC) ICP-MS, which has the ability to remove or reduce many common polyatomic interferences that can limit the ability of ICP-MS to quantitate certain analytes in complex matrices. Determination of chromium and selenium redox species is achieved using ion-exchange chromatography with elemental detection by standard and RC-ICP-MS, using various chromium and selenium isotopes. In this study, method performance and detection limits for the various permutations of the method (isotope monitored or ICP-MS detection mode) were found to be comparable and generally less than 1 microg L(-1). The method was tested on synthetic laboratory samples, surface water, groundwater, and municipal tap water matrices.

Geochemical parameters influencing tungsten mobility in soils.

The biogeochemistry of tungsten and its effects on mobility have recently gained attention due to the existence of human cancer clusters, such as in Fallon, NV. Tungsten exists in many environmental matrices as the soluble and mobile tungstate anion. However, tungsten can polymerize with itself and other anions, creating poly- and heteropoly-tungstates with variable geochemical and toxicological properties. In the present work, geochemical parameters are determined for tungstate species in a model soil that describe the potential for tungsten mobility. Soluble tungsten leached from a metallic tungsten-spiked soil after six to twelve months aging reached an equilibrium concentration >150 mg/L within 4 h of extraction with deionized water. Partition coefficients determined for various tungstate and polytungstate compounds in the model soil suggest a dynamic system in which speciation changes over time affect tungsten geochemical behavior. Partition coefficients for tungstate and some poly-species have been observed to increase by a factor of 3 to 6 over a four month period, indicating decreased mobility with soil aging.

Effects of organic matter on the distribution of uranium in soil and plant matrices.

This work studied interactions of uranium with pure organic compounds, such as glutathione, and more complex mixtures, such as humic acid and aqueous plant extracts. High performance liquid chromatography with UV absorption interfaced to inductively coupled plasma mass spectrometry sequential detection was used to detect organouranium complexes in a variety of soils and plant materials, indicating that nearly 100% of the uranium extracted from certain plant tissues was bound to organic ligands. In addition, soil sorption experiments indicated that humic acid generally decreased uranium sorption to soils and promoted subsequent desorption of uranium because of uranium partitioning to the organic phase. These experiments demonstrate that organic compounds influence the mobility and chemistry of uranium in the environment.

The determination of tungsten, molybdenum, and phosphorus oxyanions by high performance liquid chromatography inductively coupled plasma mass spectrometery.

The toxic properties of tungsten compounds have recently been brought to the forefront with clusters of human cancer cases, such as in Fallon, NV. Such instances have made the determination of tungsten in natural water supplies vitally important. Tungsten exists in most environmental matrices as the soluble and mobile tungstate anion, although it can polymerize with itself and other anions, such as molybdate and phosphate. Because the geochemical and toxicological properties of these polymer species will vary from the monomeric tungstate parent, determination of tungstate speciation is as critical as determination of total dissolved tungsten concentration. Use of chromatographic separations, followed by element-specific detection is a proven technology for elemental speciation. In the present work, anion exchange chromatography has been coupled to inductively coupled plasma mass spectrometry to determine tungstate, molybdate, and phosphate species at the sub-microg l(-1) and microg l(-1) levels. The method provides quantitative determination of these species in about 10 min with the capability to simultaneously determine other oxyanion species. The method has been applied to groundwater and extracts of soils amended with tungsten powder. The water soluble tungsten in 1-h deionized water extracts after six months of soil aging was >15 mg l(-1), however, only approximately 50% of the tungsten was present as monomeric tungstate.

Characterization of a military training site containing 232Thorium.

Understanding contaminant distribution is critical to selection and implementation of effective and affordable containment and remediation efforts. This article describes the characterization of soil containing thorium at a training site on Kirtland Air Force Base, Albuquerque, NM. The site has been used by the Defense Nuclear Weapons School since the early 1960's to train personnel in emergency response to nuclear weapons accidents and for characterization and containment of radioactive contamination. The purpose of work reported herein is to describe the primary location and migration pattern of 232Thorium (232Th) and 232Th progeny (decay products) at the site. Soil containing thorium oxide (ThO2) was applied to the site for approximately 30 years (early 1960-1990) and was used to simulate a plutonium release from a nuclear weapons accident. Data presented indicate that surface 232Th and 232Th progeny at approximately 5 times background levels are approaching test site boundaries. However, the data also indicate that vertical migration has not exceeded 0.9 m because of the insoluble nature of ThO2. The major mechanisms of 232Th mobility appear to be surface migration mediated by precipitation runoff and wind-blown soil.