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Abstract Coastal marine habitats become contaminated with the munitions constituent, Hexahydro-1,3,5-trinitro-1,3,5-trazine (RDX), via military training, weapon testing and leakage of unexploded ordnance. This study used 15N labeled RDX in simulated aquarium-scale coastal marine habitat containing seawater, sediment, and biota to track removal pathways from surface water including sorption onto particulates, degradation to nitroso-triazines and mineralization to dissolved inorganic nitrogen (DIN). The two aquaria received continuous RDX inputs to maintain a steady state concentration (0.4 mg L−1) over 21 days. Time series RDX and nitroso-triazine concentrations in dissolved (surface and porewater) and sorbed phases (sediment and suspended particulates) were analyzed. Distributions of DIN species (ammonium, nitrate + nitrite and dissolved N 2) in sediments and overlying water were also measured along with geochemical variables in the aquaria. Partitioning of RDX and RDX-derived breakdown products onto surface sediment represented 13% of the total added 15N as RDX (15N-[RDX]) equivalents after 21 days. Measured nitroso-triazines in the aquaria accounted for 6–13% of total added 15N-[RDX]. 15N-labeled DIN was found both in the oxic surface water and hypoxic porewaters, showing that RDX mineralization accounted for 34% of the 15N-[RDX] added to the aquaria over 21 days. Labeled ammonium (15NH 4 +, found in sediment and overlying water) and nitrate + nitrite (15NO X , found in overlying water only) together represented 10% of the total added 15N-[RDX]. The production of 15N labeled N 2 (15N 2), accounted for the largest individual sink during the transformation of the total added 15N-[RDX] (25%). Hypoxic sediment was the most favorable zone for production of N 2 , most of which diffused through porous sediments into the water column and escaped to the atmosphere. Graphical abstract Unlabelled Image Highlights • RDX transforms to inorganic nitrogen via series of organic derivatives. • Coupled oxic and anoxic degradation help to transform RDX in marine environments. • Major breakdown product of RDX is N 2 that majority escapes to the atmosphere. • The low redox conditions in porewaters were likely important for RDX mineralization. • RDX breakdown products can adsorb onto the sandy sediment in marine settings. [ABSTRACT FROM AUTHOR]

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is globally one of the most commonly used military explosives and environmental contaminant. 15 N labeled RDX was added into a mesocosm containing 9 different coastal marine species in a time series experiment to quantify the uptake of RDX and assess the RDX derived 15 N retention into biota tissue. The 15 N attributed to munitions compounds reached steady state concentrations ranging from 0.04 to 0.67 μg 15 N g dw −1 , the bulk 15 N tissue concentration for all species was 1–2 orders of magnitude higher suggesting a common mechanism or pathway of RDX biotransformation and retention of 15 N. A toxicokinetic model was created that described the 15 N uptake, elimination, and transformation rates. While modeled uptake rates were within previous published values, elimination rates were several orders of magnitude smaller than previous studies ranging from 0.05 to 0.7 days −1 . These small elimination rates were offset by high rates of retention of 15 N previously not measured. Bioconcentration factors and related aqueous:organism ratios of compounds and tracer calculated using different tracer and non-tracer methods yielded a broad range of values (0.35–101.6 mL g −1 ) that were largely method dependent. Despite the method-derived variability, all values were generally low and consistent with little bioaccumulation potential. The use of 15 N labeled RDX in this study indicates four possible explanations for the observed distribution of compounds and tracer; each with unique potential implications for possible toxicological impacts in the coastal marine environment. [ABSTRACT FROM AUTHOR]

This original paper, based on data from the Erasmus+Blurred Lives Project, presents a new multi-dimensional categorisation model to describe negative online experiences, including forms of cyberbullying, based on a study of internet usage among over N = 2,500 adolescents with lower socio-economic status (SES) backgrounds across five European countries. The paper first sets out the rationale for the development of a new coding system, before describing the current study and nature of the survey data collected. There follows a description of the development of the new system and the series of reliability checks undertaken by the research team (N= 11, from 5 countries) and of the refinements made to the categories and codes. The resulting coding system is presented with consideration of the strengths and limitations, and description of two early pilot studies which have successfully adopted the new system. [ABSTRACT FROM AUTHOR]

Use of three-dimensional (3D) printing in industrial and residential settings has grown exponentially with the development of less expensive equipment. However, understanding of particle emissions from these machines is limited, particularly when additives are integrated into the printable filament feedstocks. In this work, we assessed emissions from a fused filament fabrication (FFF) printer that used two common thermoplastics, acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA), and variants of these materials doped with metal additives PLA-copper (PLA-Cu) and ABS-tungsten (ABS-W), the latter of which has not been reported in literature until now. Experiments were performed inside a custom enclosure and emissions were monitored with a fast mobility particle sizer (FMPS). Mean particle emission rates were higher for ABS (2.06 × 107 #/cm3) than PLA (1.64 × 106 #/min). Feedstocks with metal additives were observed to have higher mean emission rates of 3.05 × 108 #/min for ABS-W and 4.43 × 105 #/min for PLA-Cu when printed at the same temperature as their respective neat thermoplastics. Median particle diameter by number concentration during printing was greatest for neat PLA (57.2 nm), with PLA-Cu (22.7 nm), ABS (29.7), and ABS-W (26.7) significantly lower. Our results demonstrate that polymer filaments containing metal additives have particle emissions rates an order of magnitude higher than neat polymers printed at the same temperature and emphasize the variability that can occur based on sampling methods and build parameters. [ABSTRACT FROM AUTHOR]

Hundreds of explosive-contaminated marine sites exist globally, many of which contain the common munitions constituent hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Quantitative information about RDX transformation in coastal ecosystems is essential for management of many of these sites. Isotopically labelled RDX containing 15N in all 3 nitro groups was used to track the fate of RDX in three coastal ecosystem types. Flow-through mesocosms representing subtidal vegetated (silt/eel grass), subtidal non-vegetated (sand) and intertidal marsh ecosystems were continuously loaded with isotopically labelled RDX for 16–17 days. Sediment, pore-water and overlying surface water were analyzed to determine the distribution of RDX, nitroso-triazine transformation products (NXs) and nitrogen containing complete mineralization products, including ammonium, nitrate+nitrite, nitrous oxide and nitrogen gas. The marsh, silt, and sand ecotypes transformed 94%, 90% and 76% of supplied RDX, respectively. Total dissolved NXs accounted for 2%–4% of the transformed 15N-RDX. The majority of RDX transformation in the water column was by mineralization to inorganic N (dissolved and evaded; 64%–78% of transformed 15N-RDX). RDX was mineralized primarily to N 2 O (62–74% of transformed 15N-RDX) and secondarily to N 2 (1–2% of transformed 15N-RDX) which exchanged with the atmosphere. Transformation of RDX was favored in carbon-rich lower redox potential sediments of the silt and marsh mesocosms where anaerobic processes of iron and sulfate reduction were most prevalent. RDX was most persistent in the carbon-poor sand mesocosm. Partitioning of 15N derived from RDX onto sediment and suspended particulates was negligible in the overall mass balance of RDX transformation (2%–3% of transformed 15N-RDX). The fraction of 15N derived from RDX that was sorbed or assimilated in sediment was largest in the marsh mesocosm (most organic carbon), and smallest in the sand mesocosm (largest grain size and least organic carbon). Sediment redox conditions and available organic carbon stores affect the fate of RDX in different coastal marine habitats. Unlabelled Image • Majority of RDX transforms to inorganic nitrogen via a series of organic derivatives. • RDX is mineralized primarily to N 2 O which then exchanges with the atmosphere. • Sorption of RDX breakdown products account for a negligible portion of RDX transformation. • Silt/eel grass and marsh ecotypes transformed more RDX than non-vegetated sand. • Redox status and organic matter of sediment affects the fate of RDX in coastal habitats. [ABSTRACT FROM AUTHOR]

The US Army is replacing traditional munitions with insensitive munitions resistant to accidental detonation. Although the parent insensitive munition compound nitroguanidine (NQ) is generally not acutely toxic at concentrations >1000 mg/L in aquatic exposures, products formed by intensive ultraviolet (UV) degradation resulted in multiple‐order of magnitude increases in toxicity. A methylated congener of NQ, 1‐methyl‐3‐nitroguanidine (MeNQ), is also being assessed for potential use in insensitive munition explosive formulations; therefore, the present study investigated the hazard of parent versus UV‐degraded MeNQ using fathead minnows (Pimephales promelas). Although up to 716 mg/L parent MeNQ caused no significant mortality or effects on growth in larval P. promelas fish in 7‐d exposures, a similar concentration of MeNQ subjected to UV treatment resulted in 85% mortality. The UV treatment degraded only 3.3% of the MeNQ (5800 mg/L stock, UV‐treated for 6 h), indicating that MeNQ degradation products have potentially high toxicity. The parent MeNQ exposure caused significantly decreased transcriptional expression of genes within the significantly enriched insulin metabolic pathway, suggesting antagonism of bioenergetics pathways, which complements observed, although nonsignificant, decreases in body weight. Significant differential transcriptional expression in the UV‐degraded MeNQ treatments resulted in significant enrichment of pathways and functions related to the cell cycle, as well as erythrocyte function involved in O2/CO2 exchange. These functions represent potential mechanistic sources of increased toxicity observed in the UV‐degraded MeNQ exposures, which are distinct from previously observed mechanisms underlying increased toxicity of UV‐degraded NQ in fish. Environ Toxicol Chem 2020;39:612–622. © 2019 SETAC [ABSTRACT FROM AUTHOR]

[Display omitted] • Photocatalyst-enabled selective harmful algal bloom mitigation. • 3D printing provides photocatalyst immobilization and accessibility. • Photocatalyst (TiO 2) structures are deployable, retrievable for in situ treatment. • Printed PLA-TiO 2 photocatalytic and pH control to treat toxic microcystin. • Workflow for attainable, sustainable emerging contaminant treatment. Novel and sustainable solutions are needed for surface water treatment. Photocatalytic TiO 2 is studied but is not directly deployable into natural water bodies due to settling and poor recoverability. This research capitalizes on a convergence of the emerging technologies of 3D printing biocompatible polymer (polylactic acid, PLA) composites, nanotechnology, and advanced oxidative processes to immobilize TiO 2 into customizable, high surface area, deployable, and retrievable structures with localized kinetic specificity for harmful algal blooms (HAB). PLA-TiO 2 composites at varying loadings (3–34 %) were extruded as feedstock for fused filament fabrication (FFF) enabling low cost printing design freedom of photocatalyst structures (disks, lattices). Large surface area, 3D lattices were printed as PLA composites with highly loaded (34 % w/w) TiO 2. Prior to HAB cyanotoxin experiments, the photocatalytic performance of the 3D printed PLA-TiO 2 lattice composites (t 1/2 = 0.8 h) under UV light were confirmed comparable to free TiO 2 (t 1/2 = 0.9 h). Under environmentally relevant solar simulation, photocatalysis by printed lattices successfully reduced microcystin (MC) cyanotoxin (t 1/2 = 3 h) faster than photolysis alone (t 1/2 = 36 h). Lattice mediated photocatalysis of MC in presence of cyanobacteria cells (t 1/2 = 11 h) was faster than photolysis (t 1/2 = 58 h) but slower than water-only treatment due to cell activity and light attenuation. PLA-TiO 2 reduces local pH, promoting MC adsorption and degradation. This research is foundational to novel photocatalytic composite optimization for reactive surface area prototyping enabled by 3D printing and scale-up for sustainable water treatment structures, with applicability to traditional and emerging contaminants. [ABSTRACT FROM AUTHOR]

It is critical to thoroughly investigate, characterize, and understand the unique emission profiles of common and novel polymer feedstocks used in fused filament fabrication (FFF) 3D printers as these products become increasingly ubiquitous in consumer and industrial environments. This work contributes unique insights regarding the effects of polymer composite feedstocks with metal, ceramic, or carbonaceous particle additives on particulate emissions in a variety of filaments under various print conditions, including print temperature. In addition to active characterization of particulate size and concentration following the ANSI/CAN/UL 2904 method, particulate sampling and subsequent analysis by scanning electron microscopy revealed agglomeration behavior that may have important health implications. Specifically, fine particles (0.3–2.5 μm) generated by certain filaments including acrylonitrile butadiene styrene (ABS) and glycol‐modified poly(ethylene terephthalate) (PETG) are shown to be formed via agglomeration of emitted ultrafine particles rather than composed of coherent primary particles; accordingly, transport and behavior of these particulates after inhalation may not follow expected patterns for micrometer‐sized particles. Structures resembling carbonaceous additives (e.g., graphene and nanotubes) were also captured by airborne sampling during printing of filaments containing carbonaceous advanced materials. [ABSTRACT FROM AUTHOR]

Vitamin D signaling modulates a variety of immune responses. Here, we assessed the role of vitamin D in immunity to experimental leishmaniasis infection in vitamin D receptor-deficient mice (VDRKO). We observed that VDRKO mice on a genetically resistant background have decreased Leishmania major-induced lesion development compared to wild-type (WT) mice; additionally, parasite loads in infected dermis were significantly lower at the height of infection. Enzymatic depletion of the active form of vitamin D mimics the ablation of VDR resulting in an increased resistance to L. major. Conversely, VDRKO or vitamin D-deficient mice on the susceptible Th2-biased background had no change in susceptibility. These studies indicate vitamin D deficiency, either through the ablation of VDR or elimination of its ligand, 1,25D3, leads to an increase resistance to L. major infection but only in a host that is predisposed for Th-1 immune responses. [ABSTRACT FROM AUTHOR]

Fused filament fabrication (FFF) 3D printers are increasingly used in industrial, academic, military, and residential sectors, yet their emissions and associated user exposure scenarios are not fully described. Characterization of potential user exposure and environmental releases requires robust investigation. During operation, common FFF 3D printers emit varying amounts of ultrafine particles (UFPs) depending upon feedstock material and operation procedures. Volatile organic compounds associated with these emissions exhibit distinct odors; however, the UFP portion is largely imperceptible by humans. This investigation presents straightforward computational modeling as well as experimental validation to provide actionable insights for the proactive design of lower exposure spaces where 3D printers may be used. Specifically, data suggest that forced clean airflows may create lower exposure spaces, and that computational modeling might be employed to predict these spaces with reasonable accuracy to assist with room design. The configuration and positioning of room air ventilation diffusers may be a key factor in identifying lower exposure spaces. A workflow of measuring emissions during a printing process in an ANSI/CAN/UL 2904 environmental chamber was used to provide data for computational fluid dynamics (CFD) modeling of a 6 m2 room. Measurements of the particle concentrations in a Class 1000 clean room of identical geometry were found to pass the Hanna test for agreement between model and experimental data, validating the findings. [ABSTRACT FROM AUTHOR]

2,4,6-Trinitrotoluene (TNT) has been used as a military explosive for over a hundred years. Contamination concerns have arisen as a result of manufacturing and use on a large scale; however, despite decades of work addressing TNT contamination in the environment, its fate in marine ecosystems is not fully resolved. Here we examine the cycling and fate of TNT in the coastal marine systems by spiking a marine mesocosm containing seawater, sediments, and macrobiota with isotopically labeled TNT (15N-[TNT]), simultaneously monitoring removal, transformation, mineralization, sorption, and biological uptake over a period of 16 days. TNT degradation was rapid, and we observed accumulation of reduced transformation products dissolved in the water column and in pore waters, sorbed to sediments and suspended particulate matter (SPM), and in the tissues of macrobiota. Bulk δ15N analysis of sediments, SPM, and tissues revealed large quantities of 15N beyond that accounted for in identifiable derivatives. TNT-derived N was also found in the dissolved inorganic N (DIN) pool. Using multivariate statistical analysis and a 15N mass balance approach, we identify the major transformation pathways of TNT, including the deamination of reduced TNT derivatives, potentially promoted by sorption to SPM and oxic surface sediments. [ABSTRACT FROM AUTHOR]

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a common constituent of military explosives. Despite RDX contamination at numerous U.S. military facilities and its mobility to aquatic systems, the fate of RDX in marine systems remains largely unknown. Here, we provide RDX mineralization pathways and rates in seawater and sediments, highlighting for the first time the importance of the denitrification pathway in determining the fate of RDX-derived N. 15N nitro group labeled RDX (15N-[RDX], 50 atom %) was spiked into a mesocosm simulating shallow marine conditions of coastal Long Island Sound, and the 15N enrichment of N2 (δ15N2) was monitored via gas bench isotope ratio mass spectrometry (GB-IRMS) for 21 days. The 15N tracer data were used to model RDX mineralization within the context of the broader coastal marine N cycle using a multicompartment time-stepping model. Estimates of RDX mineralization rates based on the production and gas transfer of 15N2O and 15N2 ranged from 0.8 to 10.3 μmol d-1. After 22 days, 11% of the added RDX had undergone mineralization, and 29% of the total removed RDX-N was identified as N2. These results demonstrate the important consideration of sediment microbial communities in management strategies addressing cleanup of contaminated coastal sites by military explosives. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sediments dramatically increase removal kinetics of dissolved RDX and TNT. [•] Removal rates very widely among published studies due to experimental setups. [•] Sediment characteristics are proxies for explosive contamination persistence. [Copyright &y& Elsevier]

Natural communities of microbes inhabiting amphibian skin, the skin microbiome, are critical to supporting amphibian health and disease resistance. To enable the pro-active health assessment and management of amphibians on Army installations and beyond, we investigated the effects of acute (96h) munitions exposures to Rana pipiens (leopard frog) tadpoles and the associated skin microbiome, integrated with RNAseq-based transcriptomic responses in the tadpole host. Tadpoles were exposed to the legacy munition 2,4,6-trinitrotoluene (TNT), the new insensitive munition (IM) formulation, IMX-101, and the IM constituents nitroguinidine (NQ) and 1-methyl-3-nitroguanidine (MeNQ). The 96h LC50 values and 95% confidence intervals were 2.6 (2.4, 2.8) for ΣTNT and 68.2 (62.9, 73.9) for IMX-101, respectively. The NQ and MeNQ exposures caused no significant impacts on survival in 96h exposures even at maximum exposure levels of 3560 and 5285 mg/L, respectively. However, NQ and MeNQ, as well as TNT and IMX-101 exposures, all elicited changes in the tadpole skin microbiome profile, as evidenced by significantly increased relative proportions of the Proteobacteria with increasing exposure concentrations, and significantly decreased alpha-diversity in the NQ exposure. The potential for direct effects of munitions exposure on the skin microbiome were observed including increased abundance of munitions-tolerant phylogenetic groups, in addition to possible indirect effects on microbial flora where transcriptional responses suggestive of changes in skin mucus-layer properties, antimicrobial peptide production, and innate immune factors were observed in the tadpole host. Additional insights into the tadpole host's transcriptional response to munitions exposures indicated that TNT and IMX-101 exposures significantly enriched transcriptional expression within type-I and type-II xenobiotic metabolism pathways, where dose-responsive increases in expression were observed. Significant enrichment and increased transcriptional expression of heme and iron binding functions in the TNT exposures served as likely indicators of known mechanisms of TNT toxicity including hemolytic anemia and methemoglobinemia. The significant enrichment and dose-responsive decrease in transcriptional expression of cell cycle pathways in the IMX-101 exposures was consistent with previous observations in fish, while significant enrichment of immune-related function in response to NQ exposure were consistent with potential immune suppression at the highest NQ exposure concentration. Finally, the MeNQ exposures elicited significantly decreased transcriptional expression of keratin 16, type I, a gene likely involved in keratinization processes in amphibian skin. Overall, munitions showed the potential to alter tadpole skin microbiome composition and affect transcriptional profiles in the amphibian host, some suggestive of potential impacts on host health and immune status relevant to disease susceptibility. • Munitions exposures elicited changes in the Rana pipiens tadpole skin microbiome. • Potential for direct & indirect effects of munitions exposures on skin microbiome. • TNT and IMX-101 exposures caused mortality in Rana pipiens tadpoles, not NQ or MeNQ. • RNAseq results identified potential detoxification mechanisms for munitions. • RNAseq suggests munitions tox mechanisms in R. pipiens similar to other vertebrates. [ABSTRACT FROM AUTHOR]