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Crop rotational diversity is an important part of sustainable agricultural and soil management to improve crop yield and soil fertility including enhancing soil organic matter (SOM) stabilization. Because of the physical protection via interactions with soil minerals, SOM in mineral-associated fractions is believed to be longer-lived and more stable relative to SOM in particulate (light) fractions. However, it is still unclear how crop rotational diversity alters soil carbon distribution, composition and stabilization in soil physical fractions. To address this, we studied a 37 years’ agricultural site with different crop rotational diversity (from continuous corn or alfalfa up to four species (corn, soybean, winter wheat, and red clover)). Soil carbon analysis, targeted compound analysis and nuclear magnetic resonance spectroscopy methods were used to obtain the distribution and degradation of SOM components in light and mineral-associated (F53–2000 µm, F2–53 µm, and F) fractions. Higher soil organic carbon (SOC) concentrations were observed in F with relatively high diversified crop rotations (three and four types of crops) compared to monoculture or two crops in the rotations, which suggests that carbon storage is enhanced in mineral-stabilized pools. Higher concentrations of long-chain aliphatic compounds as well as increased accumulation and preservation of lignin-derived compounds in fine aggregates (

Maternal exposure to polystyrene nanoplastics impact postnatal brain development in mouse offspring. This work motivates further studies to determine the levels of nanoplastics in the environment.

Environmental metabolomics provides insight into how anthropogenic activities have an impact on the health of an organism at the molecular level. Within this field, in vivo NMR stands out as a powerful tool for monitoring real-time changes in an organism’s metabolome. Typically, these studies use 2D 13C-1H experiments on 13C-enriched organisms. Daphnia are the most studied species, given their widespread use in toxicity testing. However, with COVID-19 and other geopolitical factors, the cost of isotope enrichment increased ~6–7 fold over the last two years, making 13C-enriched cultures difficult to maintain. Thus, it is essential to revisit proton-only in vivo NMR and ask, “Can any metabolic information be obtained from Daphnia using proton-only experiments?”. Two samples are considered here: living and whole reswollen organisms. A range of filters are tested, including relaxation, lipid suppression, multiple-quantum, J-coupling suppression, 2D 1H-1H experiments, selective experiments, and those exploiting intermolecular single-quantum coherence. While most filters improve the ex vivo spectra, only the most complex filters succeed in vivo. If non-enriched organisms must be used, then, DREAMTIME is recommended for targeted monitoring, while IP-iSQC was the only experiment that allowed non-targeted metabolite identification in vivo. This paper is critically important as it documents not just the experiments that succeed in vivo but also those that fail and demonstrates first-hand the difficulties associated with proton-only in vivo NMR.

Per- and polyfluoroalkyl substances (PFASs) have been widely used since the 1940s in industry and everyday household products. They also persist in the environment and bioaccumulate in humans and wildlife. Despite these concerns, the identities of most PFASs in environmental and biological samples are unknown. Herein, we describe a novel cyclic ion mobility mass spectrometer (cIMS), hyphenated with gas chromatography (GC) atmospheric pressure chemical ionization, that can reveal the presence of unknown PFASs on the basis of the ratio of their mass and collision cross section (CCS). Prediction of the CCS of ca. 20,000 chemicals used in industry and commerce indicates that most compounds characterized by CCS values that are less than the sum of 100 Å

Environmental metabolomics is a promising approach to study pollutant impacts to target organisms in both terrestrial and aquatic environments. To this end, both nuclear magnetic resonance (NMR)- and mass spectrometry (MS)-based methods are used to profile amino acids in different environmental metabolomic studies. However, these two methods have not been compared directly which is an important consideration for broader comparisons in the environmental metabolomics field. We compared the quantification of 18 amino acids in the tissue extracts of Daphnia magna, a common model organism used in both ecotoxicology and ecology, using both 1H NMR spectroscopy and liquid chromatography with tandem MS (LC-MS/MS). 1H NMR quantification of amino acids agreed with the LC-MS/MS quantification for 17 of 18 amino acids measured. We also tested both quantitative methods in a D. magna sub-lethal exposure study to copper and lithium. Again, both NMR and LC-MS/MS measurements showed agreement. We extended our analyses with extracts from the earthworm Eisenia fetida and the plant model Nicotiana tabacum. The concentrations of amino acids by both 1H NMR and LC-MS/MS, agreed and demonstrated the robustness of both techniques for quantitative metabolomics. These findings demonstrate the compatibility of these two analytical platforms for amino acid profiling in environmentally relevant model organisms and emphasizes that data from either method is robust for comparisons across studies to further build the knowledge base related to pollutant exposure impacts and toxic responses of diverse environmental organisms.

Synergism between different phases gives rise to chemical, biological or environmental reactivity, thus it is increasingly important to study samples intact. Here, SASSY (SimultAneous Solid and Solution spectroscopY) is introduced to simultaneously observe (and differentiate) all phases in multiphase samples using standard, solid-state NMR equipment. When monitoring processes, the traditional approach of studying solids and liquids sequentially, can lead to information in the non-observed phase being missed. SASSY solves this by observing the full range of materials, from crystalline solids, through gels, to pure liquids, at full sensitivity in every scan. Results are identical to running separate 13C CP-MAS solid-state and 13C solution-state experiments back-to-back but requires only a fraction of the spectrometer time. After its introduction, SASSY is applied to process monitoring and finally to detect all phases in a living freshwater shrimp. SASSY is simple to implement and thus should find application across all areas of research.

The various climate scenarios consistently predict warming and drying of forests in Hungary. Soils play a significant role in the long-term sequestration of atmospheric CO2, while in other cases they can also become net carbon emitters. Therefore, it is important to know what can be expected regarding future changes in the carbon storage capacity of soils in forests. We used precipitation gradient studies to solve this problem, using a type of “space–time” substitution. In this research, we primarily examined the quality parameters of soil organic matter (SOM) to investigate how climate change transforms the ratio of the main SOM compound groups in soils. For our studies, we applied elemental and 13C and 15N isotopic ratio analysis, NMR analysis, FT-IR spectra analysis, thermogravimetric and differential thermal analyses to measure SOM chemistry in samples from different oak forests with contrasting mean annual precipitation from Central Europe. Our results showed that soil organic carbon (SOC) was lower in soils of humid forests due to the enhanced decomposition processes and the leaching of Ca, which stabilizes SOM; however, in particular, the amount of easily degradable SOM compounds (e.g., thermolabile SOM, O-alkyl carbon, carboxylic and carbonyl carbon) decreased. In dry forest soils, the amount of recalcitrant SOM (e.g., thermostable SOM, alkyl carbon, aromatic and phenolic carbon and organo–mineral complexes stabilized by Ca increased, but the amount of easily degradable SOM increased further. The main conclusion of our study is that SOC can increase in forests that become drier, compensating somewhat for the decrease in forest plant biomass.

Per- and polyfluoroalkyl substances (PFAS) are a class of persistent organic pollutants used in industrial applications due to their physicochemical properties that results in their ubiquitous presence across environmental matrices. To date, legacy PFAS have been well-studied, however, the concentration of alternative PFAS may exceed the concentration of legacy pollutants and more information is needed regarding the sub-lethal toxicity at the molecular-level of aquatic model organisms, such as Daphnia magna. Perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorohexanesulfonic acid (PFHxS), and perfluorononanoic acid (PFNA), are four widely detected PFAS alternatives of varying chain length and polar functionality that are quantified in aquatic environments. This study examines the metabolic perturbations of PFAS with varying chemistries to D. magna using targeted mass spectrometry -based metabolomics. Daphnia were acutely exposed to sub-lethal concentrations of PFBA, PFHxA, PFHxS, and PFNA before the polar metabolite profile was extracted from single organisms. Multivariate analysis demonstrated significant separation between the sub-lethal concentrations of PFHxA, PFHxS, and PFNA relative to the controls; in sum, longer chain lengths demonstrated greater overall perturbations to the extracted metabolic profiles. Univariate statistics revealed significant perturbations in the concentrations of several amino acids, nucleotides/nucleosides, and neurotransmitters with exposure to PFAS. These metabolic perturbations are consistent with disruptions in energy metabolism (pantothenate and Coenzyme A metabolism, histidine metabolism) and protein synthesis (aminoacyl-tRNA biosynthesis and amino acid metabolism) which were identified through biochemical pathway analysis. These results provide evidence that while PFAS chemistry (chain length and polar functional group) invokes unique metabolic responses there is also an underlying toxic mode of action that is common with select PFAS exposure. Overall, this work highlights the capabilities of environmental metabolomics to elucidate the molecular-level perturbations of pollutants within the same chemical class to model aquatic organisms which can be used to prioritize risk assessment of substituted PFAS alternatives. This article is protected by copyright. All rights reserved. Environ Toxicol Chem 2022;00:0-0. © 2022 SETAC.

Forest soils are an important carbon (C) sink and critical component of the global C cycle. Warmer temperatures and increased atmospheric nitrogen (N) deposition are altering the biogeochemistry in forest soils and disrupting the intricate balance between C storage and C respired across the globe. The molecular biogeochemistry of soil organic matter (SOM) with warming, N-addition, and simultaneous warming and N-addition was analyzed in soil samples from the Soil Warming × Nitrogen Addition Study at the Harvard Forest Long-term Ecological Research Site using advanced techniques. The results unequivocally demonstrate that warming and N-addition alter the molecular composition of SOM as individual stressors uniquely and in combination. Warming alone and in combination with N-addition accelerated SOM decomposition while N-addition alone slowed SOM degradation. The two-factor N-addition and warming plots contain SOM more like the warming only plots but exhibited unique changes over time (from 4 to 10 years) that could not be predicted by studying N-addition or warming alone. The specific SOM components and the overall SOM decomposition suggests that N-addition and warming impacts are not additive. N-addition may hinder warming impacts antagonistically over time but not to the extent where advanced SOM decomposition from warming is supplanted. As such, the results from warming alone and N-addition alone are not necessarily additive compared to the observed SOM molecular compositional changes when these treatments are applied simultaneously. Marked evolution in the molecular biogeochemistry of SOM demonstrates the sensitivity of SOM trajectories to multiple interactive global environmental changes and the continued need to study long-term impacts more holistically.

Comprehensive multiphase-nuclear magnetic resonance (CMP-NMR) is a non-invasive approach designed to observe all phases (solutions, gels, and solids) in intact samples using a single NMR probe. Studies of dead and living organisms are important to understand processes ranging from biological growth to environmental stress. Historically, such studies have utilized

Organic pollutants can be identified by comparing their electron ionization (EI) mass spectra with those in libraries or obtained from authentic standards. Nevertheless, libraries are incomplete; standards may be unavailable or too costly, or their synthesis may be too time-consuming. This study evaluates the performance of quantum chemical electron ionization mass spectrometry (QCEIMS) vis-a-vis competitive fragmentation modeling (CFM) for suspect screening and unknown identification. EI mass spectra of 35 compounds, including halogenated organics, organophosphorus flame retardants (OPFRs), and disinfection byproducts were computed. Computational results were compared with EI mass spectra compiled in the NIST Library as well as collision-induced dissociation (CID) mass spectra obtained from radical cations M•+ generated by charge-exchange atmospheric pressure chemical ionization (APCI). The results indicate that QCEIMS performs equivalently or better than CFM. Average match factors between computed and experimental (NIST) EI mass spectra were 656 vs 503 for the halogenated organics, and on average, QCEIMS predicted 55% of the products generated by CID vs 17% predicted by CFM. QCEIMS predicted 37% of the OPFR CID products whereas CFM predicted 29%. QCEIMS performed comparably to a commercial combinatorial fragmentation method for suspect screening of a dust sample, identifying 19/20 targets. Examples of unknown pollutants, whose reference spectra were unavailable at the time of discovery, are also presented. The computational results suggest that QCEIMS can help guide the analyst in obtaining authentic standards and raise the possibility that, with advances in computing, an unknown may eventually be confirmed in hours as opposed to the days or months required to obtain authentic standards.

Conserving soil carbon (C) and harnessing the potential for soil C sequestration requires an improved understanding of the processes through which organic material accumulates in soil. Currently, competing hypotheses exist regarding the dominant mechanisms that control soil C accumulation and transfers to mineral-associated pools. Long-standing hypotheses rely upon an assumed strong relationship between the quantity of organic inputs and soil C accumulation, while more recent hypotheses have shifted the focus towards the more complex controls of root activity, microbial processing and priming, and organo-mineral complexation. The Detrital Input and Removal Treatment (DIRT) experiment can test these competing hypotheses through field manipulations of detrital inputs. After 20 years of detrital manipulations in the wet, temperate forest of the H.J. Andrews Experimental Station, we found that with the termination of live root activity, the significant influx of dead root material and absence of soil priming by roots led to decreases in particulate organic matter (POM), but increases in stable mineral associated organic matter (MAOM). This suggests that soil mineral particles in undisturbed soils are not saturated with C in the presence of live roots and that pools of MAOM are sensitive to the balance between microbial-induced stabilization and microbial-induced priming and destabilization. Twenty years of aboveground litter removal did not change bulk soil C stocks or pools. Soil C stabilization did not increase in response to increases in high quality litter inputs, in contrast to recent theory, but in accordance with other empirical results. In contrast, increases in low quality wood litter led to a large increase in bulk soil C, with gains over 20 years confined to increases in POM. These findings offer insight into the pathways controlling soil C contents and provide potential explanations for the often-limited potential to increase mineral associated soil C in many vegetated soils and observed buffered responses of soil C stocks to disturbances such as drought, fire, and timber harvest.

Endocrine disruption is intimately linked to controlling the population of pollutant-exposed organisms through reproduction and development dysregulation. This study investigated how endocrine disruption in a predator organism could affect prey species biology through infochemical communication. Daphnia magna and Chlorella vulgaris were chosen as model prey and predator planktons, respectively, and fenoxycarb was used for disrupting the endocrine system of D. magna. Hormones as well as endo- and exometabolomes were extracted from daphnids and algal cells and their culture media and analyzed using liquid chromatography with tandem mass spectrometry. Biomolecular perturbations of D. magna under impaired offspring production and hormone dysregulation were observed. Differential biomolecular responses of the prey C. vulgaris, indicating changes in methylation and infochemical communication, were subsequently observed under the exposure to predator culture media, containing infochemicals released from the reproducibly normal and abnormal D. magna, as results of fenoxycarb exposure. The observed cross-species transfer of the endocrine disruption consequences, initiated from D. magna, and mediated through infochemical communication, demonstrates a novel discovery and emphasizes the broader ecological risk of endocrine disruptors beyond reproduction disruption in target organisms.

Comprehensive multiphase NMR combines the ability to study and differentiate all phases (solids, gels, and liquids) using a single NMR probe. The general goal of CMP-NMR is to study intact environmental and biological samples to better understand conformation, organization, association, and transfer between and across phases/interfaces that may be lost with conventional sample preparation such as drying or solubilization. To date, all CMP-NMR studies have used 4 mm probes and rotors. Here, a larger 7 mm probehead is introduced which provides ∼3 times the volume and ∼2.4 times the signal over a 4 mm version. This offers two main advantages: (1) the additional biomass reduces experiment time, making 13C detection at natural abundance more feasible; (2) it allows the analysis of larger samples that cannot fit within a 4 mm rotor. Chicken heart tissue and Hyalella azteca (freshwater shrimp) are used to demonstrate that phase-based spectral editing works with 7 mm rotors and that the additional biomass from the larger volumes allows detection with 13C at natural abundance. Additionally, a whole pomegranate seed berry (aril) and an intact softgel capsule of hydroxyzine hydrochloride are used to demonstrate the analysis of samples too large to fit inside a conventional 4 mm CMP probe. The 7 mm version introduced here extends the range of applications and sample types that can be studied and is recommended when 4 mm CMP probes cannot provide adequate signal-to-noise (S/N), or intact samples are simply too big for 4 mm rotors.

Forest ecosystems are important global soil carbon (C) reservoirs, but their capacity to sequester C is susceptible to climate change factors that alter the quantity and quality of C inputs. To better understand forest soil C responses to altered C inputs, we integrated three molecular composition published data sets of soil organic matter (SOM) and soil microbial communities for mineral soils after 20 years of detrital input and removal treatments in two deciduous forests: Bousson Forest (BF), Harvard Forest (HF), and a coniferous forest: H.J. Andrews Forest (HJA). Soil C turnover times were estimated from radiocarbon measurements and compared with the molecular-level data (based on nuclear magnetic resonance and specific analysis of plant- and microbial-derived compounds) to better understand how ecosystem properties control soil C biogeochemistry and dynamics. Doubled aboveground litter additions did not increase soil C for any of the forests studied likely due to long-term soil priming. The degree of SOM decomposition was higher for bacteria-dominated sites with higher nitrogen (N) availability while lower for the N-poor coniferous forest. Litter exclusions significantly decreased soil C, increased SOM decomposition state, and led to the adaptation of the microbial communities to changes in available substrates. Finally, although aboveground litter determined soil C dynamics and its molecular composition in the coniferous forest (HJA), belowground litter appeared to be more influential in broadleaf deciduous forests (BH and HF). This synthesis demonstrates that inherent ecosystem properties regulate how soil C dynamics change with litter manipulations at the molecular-level. Across the forests studied, 20 years of litter additions did not enhance soil C content, whereas litter reductions negatively impacted soil C concentrations. These results indicate that soil C biogeochemistry at these temperate forests is highly sensitive to changes in litter deposition, which are a product of environmental change drivers.

The rapid growth in the worldwide use of plastics has resulted in a vast accumulation of microplastics in the air, soil and water. The impact of these microplastics on pregnancy and fetal development remains largely unknown. In pregnant mice, we recently demonstrated that exposure to micro- and nanoplastics throughout gestation resulted in significant fetal growth restriction. One possible explanation for reduced fetal growth is abnormal placental metabolism.To evaluate the effect of maternal exposure to microplastics on placental metabolism.In the present study, CD-1 pregnant mice were exposed to 5 μm polystyrene microplastics in filtered drinking water at one of four concentrations (0 ng/L (controls), 10The relative concentration of lysine (p = 0.003) and glucose (p 0.0001) in the placenta were found to decrease with increasing microplastic concentrations, with a significant reduction at the highest exposure concentration. Multivariate analysis identified shifts in the metabolic profile with MP exposure and pathway analysis identified perturbations in the biotin metabolism, lysine degradation, and glycolysis/gluconeogenesis pathways.Maternal exposure to microplastics resulted in significant alterations in placental metabolism. This study highlights the potential impact of microplastic exposure on pregnancy outcomes and that efforts should be made to minimize exposure to plastics, particularly during pregnancy.

Sulphate and dissolved organic matter (DOM) in freshwater systems may regulate the formation of methylmercury (MeHg), a potent neurotoxin that biomagnifies in aquatic ecosystems. While many boreal lakes continue to recover from decades of elevated atmospheric sulphate deposition, little research has examined whether historically high sulphate concentrations can result in persistently elevated MeHg production and accumulation in aquatic systems. This study used sediment from a historically sulphate-impacted lake and an adjacent reference lake in northwestern Ontario, Canada to investigate the legacy effects of sulphate pollution, as well as the effects of newly added sulphate, natural organic matter (NOM) of varying sulphur content and a sulphate reducing bacteria (SRB) inhibitor on enhancing or inhibiting the Hg methylation and demethylation activity (

Per- and polyfluoroalkyl substances (PFAS) are a class of pollutants of concern due to their ubiquitous presence, persistence, and toxicity in aquatic environments. Legacy PFAS pollutants such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) have been more widely studied in aquatic environments. However, replacement PFAS, such as ammonium perfluoro (2-methyl-3-oxahexanoate; GenX) are increasingly being detected with little known information surrounding their toxicity. Here, Daphnia magna, a model organism for freshwater ecotoxicology was used to compare the acute sub-lethal toxicity of PFOS, PFOA, GenX, and PFAS mixtures. Using liquid chromatography with tandem mass spectrometry (LC-MS/MS), the targeted polar metabolic profile extracted from single Daphnia was quantified to investigate perturbations in the exposure groups versus the unexposed organisms. Multivariate statistical analyses demonstrated significant non-monotonic separation in PFOA, GenX, and PFAS mixture exposures. Sub-lethal exposure to concentrations of PFOS did not lead to significant separation in multivariate analyses. Univariate statistics and pathway analyses were used to elucidate the mode of action of PFAS exposure. Exposure to all individual PFAS led to significant perturbations in many amino acids including cysteine, histidine, tryptophan, glycine, and serine. These perturbations are consistent with biochemical pathway disruptions in the pantothenate and Coenzyme A (CoA) biosynthesis, thiamine metabolism, histidine metabolism, and aminoacyl-tRNA biosynthesis pathways. Overall, the collected metabolomic data is consistent with disruptions in energy metabolism and protein synthesis as the primary mode of action of sub-lethal PFAS exposure. Secondary modes of action among individual pollutant exposures demonstrated that the structural properties (carboxylic acid vs. sulfonic acid group) may play a role in the metabolic perturbations observed. Sub-lethal exposure to PFAS mixtures highlighted a mixed response when compared to the individual pollutants (PFOS, PFOA, and GenX). Overall, this study emphasizes the niche capability of environmental metabolomics to differentiate secondary modes of action from metabolic perturbations in both single pollutant and pollutant mixtures within the same chemical class.

Considered as a promising source of sustainable energy, biofuel produced from algae holds many advantages. However, to truly understand the production process and assess the potential for further o...

The interactions of the different components of soils, such as living biomass and organic matter, with mineral surfaces are of considerable interest due to their environmental reactivity and potent...

Evaluate crop rotation diversity, perenniality, carbon (C) inputs, and C input quality as predictors of soil organic carbon (SOC) concentration and aggregate mean weight diameter (MWD). At a crop rotation trial in its 37th year in Ontario, Canada, species in rotations included corn (C, Zea mays L.), alfalfa (A, Medicago sativa L.), soybean (S, Glycine max (L.) Merr.), winter wheat (W, Triticum aestivum L.), and red clover (rc, Trifolium pratense L.). Rotations were: CC, CCAA, CCSS, CCSW, CCSWrc, AA. Soils (0–20 cm) were analyzed for aggregate MWD, aggregate C, and SOC concentrations. We estimated C inputs from historical yields and C input quality (C:N, lignin: N, or NMR-derived index) from structural plant tissues. C stabilization efficiency was estimated as the ratio of SOC stock per unit total or root C input. Crop rotation diversity failed to increase SOC concentrations or aggregate MWD. Perennialized rotations (CCSWrc, CCAA, AA) maintained the numerically highest SOC concentrations, and root C input increased SOC concentration. Out of 12 statistical tests relating C input quality to C stabilization efficiency, only 3 indicated a positive effect and 6 tests indicated a negative effect. Including a perennial forage such as alfalfa and limiting soybean frequency promotes aggregate MWD and SOC concentration more so than optimizing crop rotation diversity. Quality of structural plant inputs does not explain differences in C stabilization efficiency, possibly due to overriding influence of living root inputs.

The environment has many anthropogenic chemicals which, in sublethal concentrations, can alter the biochemical function of organisms. Environmental metabolomics uses analytical techniques such as nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) to uncover how the presence of environmental contaminants may alter the metabolic profile of organisms. Metabolomic experiments follow a typical workflow and can be applied to a gamut of organisms and contaminants or other environmental stressors. Following sublethal exposure, metabolic shifts and the contaminant toxic mode of action can be elucidated. Environmental metabolomics is a useful tool in ecotoxicology and may have a future role within environmental risk assessment strategies.

Daphnia (freshwater fleas) are among the most widely used organisms in regulatory aquatic toxicology/ecology, while their recent listing as an NIH model organism is stimulating research for understanding human diseases and processes. Daphnia are small enough to fit inside high field NMR spectrometers and can be kept alive indefinitely using flow systems that deliver food and oxygen. As such, in vivo NMR holds the potential to monitor when/if environmental stress is occurring, understand "why" chemicals are toxic (biochemical pathways impacted and toxic-mode-of-action), and differentiate between a temporary flux response (i.e. return to homeostasis) and a permanent change in biochemistry (likely a precursor to disease). At present however, such studies are limited as the in vivo NMR data of Daphnia are highly complex and the lack of spectral assignments makes extracting metabolic information difficult. In this study, Daphnia are 13C enriched to >97% 13C and numerous 1H and 13C 1D, 2D, and 3D NMR approaches are combined to provide, as complete as possible, an assignment of the Daphnia magna metabolome in vivo. Assignments are transferred (where possible) back to line narrowed susceptibility suppressed 1H 1D NMR spectra in order to permit the maximum amount of information to be gained in the future without the need for 13C enrichment. To our knowledge, this work represents the first time a comprehensive metabolic assignment of any small living organism has been performed using high field flow-based NMR.

Concerns regarding the persistence, bioaccumulation behaviour, and toxicity of perfluorooctanoic acid and perfluorooctane sulfonic acid have resulted in the creation of thousands of replacement perfluoroalkyl substances (PFAS). This study reports on the discovery of fluorotelomer ethoxylates (FTEO) in indoor dust (9/15 samples), and industrial effluents (14/37 samples) using gas chromatographic cyclic ion mobility mass spectrometry (GC-cIMS). By filtering the detected unknowns by mass and collision-cross section, a series of FTEO homologues were revealed with the formula F-(CF

Forest soil dissolved organic matter (DOM) is a major source of terrigenous dissolved organic carbon (DOC) that is an important component of biogeochemical cycles. While many studies have shown tha...

Short-chain polychlorinated n-alkanes are ubiquitous industrial chemicals widely recognized as persistent organic pollutants. They represent only a small fraction of the 184,600 elemental compositions (C10-25) and the myriad isomers of all possible (mixed) halogenated n-alkanes (PXAs). This study prioritizes the PXAs on the basis of their potential to persist, bioaccumulate, and undergo long-range transport guided by quantitative structure-property relationships (QSPRs), density functional theory (DFT), chemical fate models, and partitioning space. The QSPR results narrow the list to 966 elemental compositions, of which 352 (23 Br, 83 Cl/F, 119 Br/Cl, and 127 Br/F) are likely constituents of substances used as lubricants, plasticizers, and flame retardants. Complementary DFT calculations suggest that an additional 1367 elemental compositions characterized by a greater number of carbon and fluorine atoms but fewer chlorine and bromine atoms may also pose a risk. The results of this study underline the urgent need to identify and monitor these suspected pollutants, most appropriately using mass spectrometry. We estimate that the resolving power required to distinguish ∼74% of the prioritized elemental compositions from the most likely interferents, i.e., chlorinated alkanes, is approximately 60,000 (full width at half-maximum). This indicates that accurate identification of the PXAs is achievable using most high-resolution mass spectrometers.

Gas chromatography–high-resolution mass spectrometry (GC–HRMS) is a powerful nontargeted screening technique that promises to accelerate the identification of environmental pollutants. Currently, most GC–HRMS instruments are equipped with electron ionization (EI), but atmospheric pressure ionization (API) ion sources have attracted renewed interest because: (i) collisional cooling at atmospheric pressure minimizes fragmentation, resulting in an increased yield of molecular ions for elemental composition determination and improved detection limits; (ii) a wide range of sophisticated tandem (ion mobility) mass spectrometers can be easily adapted for operation with GC–API; and (iii) the conditions of an atmospheric pressure ion source can promote structure diagnostic ion–molecule reactions that are otherwise difficult to perform using conventional GC–MS instrumentation. This literature review addresses the merits of GC–API for nontargeted screening while summarizing recent applications using various GC–API techniques. One perceived drawback of GC–API is the paucity of spectral libraries that can be used to guide structure elucidation. Herein, novel data acquisition, deconvolution and spectral prediction tools will be reviewed. With continued development, it is anticipated that API may eventually supplant EI as the de facto GC–MS ion source used to identify unknowns.

During pregnancy, appropriate placental metabolism is essential for fetuses to reach their growth potential. However, metabolic mechanisms during pregnancy remain poorly understood. Determination of the levels of placental metabolites in healthy pregnancy and how they change throughout gestation is critical for understanding placental function.To determine the effects of gestational age on placental metabolites using healthy pregnant mice.In the present study, we collected placental tissue samples from healthy pregnant mice at three timepoints in late gestation (n = 16 placentas per gestational age). Metabolite profiles were determined usingUsing HRMAS MRS, we identified 14 metabolites in murine placental tissue samples. The relative concentration of 12 of the 14 metabolites remains unchanged throughout late gestation. Lysine was found to decrease significantly (p = 0.04) and glucose showed an inverted U-shape relationship (p = 0.03) with gestational age.This study demonstrated the feasibility of HRMAS MRS to determine relative metabolite concentrations in murine placental tissue. These findings establish baseline levels of placental tissue metabolite profiles and will serve as reference ranges for future studies using mouse models of fetal distress.

Bisphenols are used in the production of polycarbonate plastics and epoxy resins. Bisphenol A (BPA) has been widely studied and is believed to act as an endocrine disruptor. Bisphenol F (BPF) and bisphenol S (BPS) have increasingly been employed as replacements for BPA, although previous studies suggested that they yield similar physiological responses to several organisms. Daphnia magna is a common model organism for ecotoxicology and was exposed to sub-lethal concentrations of BPA, BPF, and BPS to investigate disruption to metabolic profiles. Targeted metabolite analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to measure polar metabolites extracted from D. magna, which are linked to a range of biochemical pathways. Multivariate analyses and individual metabolite changes showed similar non-monotonic concentration responses for all three bisphenols (BPA, BPF, and BPS). Pathway analyses indicated the perturbation of similar and distinct pathways, mostly associated with protein synthesis, amino acid metabolism, and energy metabolism. Overall, we observed responses that can be linked to a chemical class (bisphenols) as well as distinct responses that can be related to each individual bisphenol type (A, F, and S). These findings further demonstrate the need for using metabolomic analyses in exposure assessment, especially for chemicals within the same class which may disrupt the biochemistry uniquely at the molecular-level.

Bisphenols are used in the production of polycarbonate plastics and epoxy resins. Bisphenol A (BPA) has been widely studied and is believed to act as an endocrine disruptor. Bisphenol F (BPF) and bisphenol S (BPS) have increasingly been employed as replacements for BPA, although previous studies suggested that they yield similar physiological responses to several organisms. Daphnia magna is a common model organism for ecotoxicology and was exposed to sub-lethal concentrations of BPA, BPF, and BPS to investigate disruption to metabolic profiles. Targeted metabolite analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to measure polar metabolites extracted from D. magna, which are linked to a range of biochemical pathways. Multivariate analyses and individual metabolite changes showed similar non-monotonic concentration responses for all three bisphenols (BPA, BPF, and BPS). Pathway analyses indicated the perturbation of similar and distinct pathways, mostly associated with protein synthesis, amino acid metabolism, and energy metabolism. Overall, we observed responses that can be linked to a chemical class (bisphenols) as well as distinct responses that can be related to each individual bisphenol type (A, F, and S). These findings further demonstrate the need for using metabolomic analyses in exposure assessment, especially for chemicals within the same class which may disrupt the biochemistry uniquely at the molecular-level.

Comprehensive multiphase (CMP) NMR, first described in 2012, combines all of the hardware components necessary to analyze all phases (solid, gel, and solution) in samples in their natural state. In combination with spectral editing experiments, it can fully differentiate phases and study the transfer of chemical species across and between phases, providing unprecedented molecular-level information in unaltered natural systems. However, many natural samples, such as swollen soils, plants, and small organisms, contain water, salts, and ionic compounds, making them electrically lossy and susceptible to RF heating, especially when using high-strength RF fields required to select the solid domains. While dedicated reduced-heating probes have been developed for solid-state NMR, to date, all CMP-NMR probes have been based on solenoid designs, which can lead to problematic sample heating. Here, a new prototype CMP probe was developed, incorporating a loop gap resonator (LGR) for decoupling. Temperature increases are monitored in salt solutions analogous to those in small aquatic organisms and then tested in vivo on Hyalella azteca (freshwater shrimp). In the standard CMP probe (solenoid), 80% of organisms died within 4 h under high-power decoupling, while in the LGR design, all organisms survived the entire test period of 12 h. The LGR design reduced heating by a factor of ∼3, which allowed 100 kHz decoupling to be applied to salty samples with generally ≤10 °C sample heating. In addition to expanding the potential for in vivo research, the ability to apply uncompromised high-power decoupling could be beneficial for multiphase samples containing true crystalline solids that require the strongest possible decoupling fields for optimal detection.

In vivo Nuclear magnetic resonance (NMR) is rapidly evolving as a critical tool as it offers real-time metabolic information, which is crucial for delineating complex toxic response pathways in living systems. Organisms such as D. magna (water fleas) and H.azteca (freshwater shrimps) are commonly 13C enriched to increase signal in NMR experiments. A key goal of in vivo NMR is to monitor how molecules (nutrients, contaminants, or drugs) are metabolized. Conventionally, these studies would normally involve using a 13C enriched probe molecule and feeding this to an organism at natural abundance, in turn allowing the fate of the probe molecule to be selectively analyzed. The setback of such an approach is that there is a limited range of 13C enriched probe molecules, and if available, are extremely cost prohibitive. Uniquely, when utilizing 13C organisms a reverse strategy of isotopic filtering becomes possible. The concept described here uses 1H detection in combination with a 13C filter on living organisms....

Daphnia magna is a keystone indicator zooplankton used in environmental quality assessments. Comparative metabolomics, which contrasts small biomolecular regulations under different conditions, has emerged as a sensitive and informative investigation tool for the assessment of environmental stressors on D. magna. Baseline metabolomic variation is likely impacted by the asexual reproduction cycle of D. magna; however, the relationship between metabolite concentration regulation and reproduction cycle has not been investigated. This study investigated the time-course regulation of 51 metabolites during different reproduction stages to determine how the reproduction cycle controlled the metabolite profile of D. magna. Two-way analysis of variance (ANOVA) results reveal that most metabolites show significantly differentiated concentrations by individual or a combination of reproduction stages and sampling time. On the basis of the partial least-squares-discriminant analysis (PLS-DA) and ANOVA-simultaneous component analysis (ANOVA-SCA), stages 2 and 3 of reproduction show similarity in metabolite abundance regulation compared to stage 1. Metabolites were classified as being either dependent or independent of reproduction in the pairwise concentration correlation based on Pearson correlation coefficients. This study observed that the D. magna reproduction stage is an important consideration and potential variable and should be considered carefully when conducting metabolomic experiments using D. magna.

NMR applied to living organisms is arguably the ultimate tool for understanding environmental stress responses and can provide desperately needed information on toxic mechanisms, synergistic effects, sublethal impacts, recovery, and biotransformation of xenobiotics. To perform in vivo NMR spectroscopy, a flow cell system is required to deliver oxygen and food to the organisms while maintaining optimal line shape for NMR spectroscopy. In this tutorial, two such flow cell systems and their constructions are discussed: (a) a single pump high-volume flow cell design is simple to build and ideal for organisms that do not require feeding (i.e., eggs) and (b) a more advanced low-volume double pump flow cell design that permits feeding, maintains optimal water height for water suppression, improves locking and shimming, and uses only a small recirculating volume, thus reducing the amount of xenobiotic required for testing. In addition, key experimental aspects including isotopic enrichment, water suppression, and 2D experiments for both 13 C enriched and natural abundance organisms are discussed.

The pharmaceutical 17α-ethynylestradiol (EE2) and the industrial chemical perfluorooctane sulfonate (PFOS) are organic contaminants frequently detected in freshwater environments. It is hypothesized that hydrophobic organic contaminants can sorb to dissolved organic matter (DOM) and this may reduce the toxicity of these contaminants by reducing the contaminants’ bioavailability. To investigate this hypothesis, 1H nuclear magnetic resonance (NMR)-based metabolomics was used to determine how the metabolome of Daphnia magna changes when a range of DOM concentrations are added during EE2 and PFOS exposure experiments. D. magna were exposed for 48 h to sub-lethal concentrations of 1 mg/L EE2 or 30 mg/L PFOS in the presence of 0, 1, 2, 3 and 4 mg dissolved organic carbon (DOC)/L. EE2 exposure resulted in increased amino acids and decreased glucose in D. magna. All DOM concentrations were able to lessen these metabolite disturbances from EE2 exposure, likely due to reductions in the bioavailability of EE2 through interactions with DOM. Exposure to PFOS resulted in decreased amino acids, and the presence of 1 mg DOC/L did not alter this metabolic response. However, PFOS exposure with the higher DOM concentrations resulted in a different pattern of metabolite changes which may be due to combined impacts of PFOS and DOM on the metabolome or due to an increase in PFOS bioavailability and uptake in D. magna. These results suggest that the concentration of DOM influences the sensitive biochemical changes in organisms that occur during acute sub-lethal exposure to organic contaminants.

In vivo Nuclear Magnetic Resonance (NMR) spectroscopy has great potential to interpret the biochemical response of organisms to their environment, thus making it an essential tool in understanding toxic mechanisms. However, magnetic susceptibility distortions lead to 1D NMR spectra of living organisms with lines that are too broad to identify and quantify metabolites, necessitating the use of 2D 1H-13C Heteronuclear Single Quantum Coherence (HSQC) as a primary tool. While quantitative 2D HSQC is well established, to our knowledge it has yet to be applied in vivo. This study represents a simple pilot study that compares two of the most popular quantitative 2D HSQC approaches to determine if quantitative results can be directly obtained in vivo in isotopically enriched Daphnia magna (water flea). The results show the perfect-HSQC experiment performs very well in vivo, but the decoupling scheme used is critical for accurate quantitation. An improved decoupling approach derived using optimal control theory is presented here that improves the accuracy of metabolite concentrations that can be extracted in vivo down to micromolar concentrations. When combined with 2D Electronic Reference To access In vivo Concentrations (ERETIC) protocols, the protocol allows for the direct extraction of in vivo metabolite concentrations without the use of internal standards that can be detrimental to living organisms. Extracting absolute metabolic concentrations in vivo is an important first step and should, for example, be important for the parameterization as well as the validation of metabolic flux models in the future.

Forest soil organic carbon (SOC) is one of the largest reservoirs of terrestrial carbon (C) and is a major component of the global C cycle. Yet there is still uncertainty regarding how ecosystems, and the SOC they store, will respond to changes due to anthropogenic processes. Current and future reactive nitrogen (N) deposition to forest soils may alter biogeochemical processes and shift both the quantity and quality of stored SOC. We studied SOC storage and molecular-level composition after 22 years of N additions (100 kg N ha−1 y−1) in a temperate deciduous forest. SOC storage in surface soils increased by 0.93 kg m−2 due to a decline in microbial biomass (phospholipid fatty acids) and litter decomposition. N additions resulted in the selective preservation of a range of plant-derived compounds including steroids, lignin-derived, cutin-derived, and suberin-derived compounds that have anti-microbial properties or are non-preferred microbial substrates. This overall shift in SOC composition suggests limited sustainability and a decline in soil health. The reduction in microbial biomass and increase in specific SOC components demonstrate that long-term N fertilization negatively alters fundamental C cycling in forest soils. This study also demonstrates unequivocally that anthropogenic impacts on C and N cycling in forests at the molecular-level must be considered more holistically.