Molecular characteristics of halogenated disinfection byproducts elucidated by Fourier transform ion cyclotron resonance mass spectrometry.

Dissolved organic matter is the main precursor for the formation of halogenated disinfection by-products (X-DBPs) during the disinfection of drinking water. However, the majority of the X-DBPs identified based on the artificially prepared water using the Suwannee River Natural Organic Matter (SRNOM) will bias the assessment of X-DBP formation potential in actual natural water. Herein, the non-targeted analysis based on ultrahigh-resolution mass spectrometry was employed to reveal the discrepancy in the molecular composition of X-DBPs and their precursors in SRNOM solution and actual authentic samples during disinfection.

Significant enhancement of photoproduced reactive intermediates in liquid-like region in frozen surface water for micropollutant degradation.

Freezing enhancing the photochemistry of dissolved organic matter (DOM), yet the mechanism of reactive intermediate (RIs) generation influenced by DOM property and structure remain elusive. Here, we demonstrate that freezing induces exceptional amplification of RIs, with steady-state concentrations in ice (-10 °C) surpassing aqueous solutions by 5-41 times. Laser scanning confocal microscopy first visualized cryo-concentration of DOM and RIs in liquid-like regions (LLR).

Effects of Eluate Drying on the Chemodiversity of Dissolved Organic Matter Revealed by Ultrahigh-Resolution Mass Spectrometry.

The drying treatment of dissolved organic matter (DOM) eluate was often used to prepare DOM solutions for chemodiversity analysis using Fourier transform ion cyclotron resonance mass spectrometry. However, the effects of drying treatment on the chemodiversity of DOM have not been thoroughly investigated. In this study, vacuum freeze-drying and vacuum centrifuge drying resulted in approximately half and 10% loss of DOM mass loss, respectively.

Unveiling Molecular Constraints on the Formation and Fate of Organoiodine Compounds under Aquifer Conditions.

The interaction between dissolved organic matter (DOM) and iodine, as well as the complexation of organoiodine compounds (OICs) with Fe (hydr)oxides, is significantly influenced by their respective molecular characteristics. However, molecular constraints governing the formation and mobility of OICs within aquifer systems remain inadequately understood. Here, we employed ultrahigh-resolution mass spectrometry to investigate the molecular fractionation of organic compounds induced by DOM (humic acid (HA) and fulvic acid (FA)) iodination and by the subsequent formation of OICs complexation with Fe oxides under aquifer conditions.

Deciphering the Effects of Quenching on the Chemodiversity of Low- and Non-volatile Disinfection Byproducts in Drinking Source Water Using ESI(-)-FT-ICR MS.

Quenching is essential for terminating chlorination and preserving halogenated disinfection byproducts (X-DBPs) in disinfected waters. However, the effects of quenchers on the chemodiversity and stability of low- and non-volatile X-DBPs are still poorly understood. Four quenchers─sodium sulfite (SS), sodium thiosulfate (STS), ascorbic acid (AA), and 1,3,5-trimethoxybenzene (TMB)─were employed to elucidate their influences on the non-targeted analysis of X-DBPs using Fourier transform ion cyclotron resonance mass spectrometry under negative electrospray ionization mode (ESI(-)-FT-ICR MS).

Molecular Humification Mechanisms of Dissolved Organic Matter during Maize Straw Composting Enhanced by Humus Soil Biomaterial: Paired-Molecule Mass Difference Reactomics Analysis Based on FT-ICR MS.

This study investigated molecular humification mechanisms of dissolved organic matter during maize straw composting enhanced by humus soil biomaterial using paired-molecule mass difference reactomics analysis and high-throughput sequencing. Results indicated that the composting process predominantly involved three molecular humification pathways, namely, the phenol-protein reaction, polyphenol self-condensation, and Maillard reaction, with N-containing molecules showing the highest reactivity. Proteins were hydrolyzed into N-containing intermediates in the initial composting stage, which rapidly polymerized with phenol from humus soil biomaterial to form humic acids, improving organic nitrogen retention.

Simultaneous Elucidation of the Chemodiversity of Dissolved Organic Matter and Quantitation of Trace Organic Contaminant Sucralose by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry.

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has become a cutting-edge technique for molecular characterization of dissolved organic matter (DOM) and trace organic contaminants. Nevertheless, FT-ICR MS is rarely applied to simultaneously elucidate DOM chemodiversity and quantify the concentrations of trace organic contaminants. Compared to conventional solid-phase extraction (SPE), pH-dependent fractionation of DOM molecules using a sequential SPE strategy significantly enhanced the recovery of dissolved organic carbon and yielded more chemical formulas for DOM from environmental samples ( < 0.

Improved identification of chlorinated disinfection byproducts by the sequential elution and absorption mode.

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been extensively employed to characterize the chemodiversty of dissolved organic matter (DOM) including chlorinated disinfection byproducts (Cl-DBPs). However, little is known about the combined effects of the sequential solid phase extraction (SPE) and absorption mode of Fourier transform data processing on the identification of Cl-DBPs. In this study, the identification of Cl-DBPs by the sequential SPE extraction and absorption mode were systematically compared using a typical swimming pool water.

Accurate detection and high throughput profiling of unknown PFAS transformation products for elucidating degradation pathways.

The accurate detection of unknown per- and polyfluoroalkyl substances (PFAS) transformation products (TPs) is essential for elucidating degradation pathways and advancing remediation strategies. Herein, we developed a workflow that combined Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with a paired mass distance (PMD) network. This study achieved high throughput profiling of PFAS TPs with mDa resolving power and sub-ppm mass error.

A molecular transformation study on the humus soil biomaterial promoting effects on the humification process in an anaerobic digestate composting system.

Biopolymers with different biodegradability result in the asynchronous production of humus precursors during anaerobic digestate composting, which hinders humus formation. This study aimed to improve the humification process of digestate composting with Humus Soil Biomaterial (HSB) as ameliorant, and unveiled corresponding humification mechanisms. Results indicated that HSB containing pumice stone, phenolics, and native microbes promoted the humification process of digestate composting and contributed to higher aromaticity and humification degree.

Development of a Nontargeted Algorithm for Per- and Polyfluoroalkyl Substances in the FT-ICR Mass Spectra of Complex Organic Mixtures.

The unrivaled mass resolving power and subppm mass error enable the application of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for nontargeted screening of per- and polyfluoroalkyl substances (PFAS). Few automated FT-ICR MS methods exist for nontargeted analysis of PFAS in solutions containing other dissolved organic matter. In this study, isotopic pattern analysis and dynamic homologous series inspection were complementarily employed in the FTMSDeu algorithm to simultaneously assign chemical formulas for PFAS and other organic molecules, with an overall assignment accuracy of 91.

Qualitatively elucidating the molecular characteristics of precursors for saturated halogenated disinfection byproducts in chlorinated urban eutrophic lake water by ultrahigh-resolution mass spectrometry.

Lake eutrophication affects the molecular composition of aquatic dissolved organic matter (DOM) and halogenated disinfection byproducts (X-DBPs). However, the effects of autochthonous DOM on the X-DBPs formation during disinfection of natural eutrophic water from the perspective of biological metabolism are still poorly revealed. Herein, the natural urban eutrophic lake (UEL) water with slight eutrophication was employed to elucidate the discrepancies in X-DBPs formation between autochthonous and allochthonous DOM based on the ultrahigh-resolution mass spectrometry.

Iron(II/III) Alters the Relative Roles of the Microbial Byproduct and Humic Acid during Chromium(VI) Reduction and Fixation by Soil-Dissolved Organic Matter.

Though reduction of hexavalent chromium (Cr(VI)) to Cr(III) by dissolved organic matter (DOM) is critical for the remediation of polluted soils, the effects of DOM chemodiversity and underlying mechanisms are not fully elucidated yet. Here, Cr(VI) reduction and immobilization mediated by microbial byproduct (MBP)- and humic acid (HA)-like components in (hot) water-soluble organic matter (WSOM), (H)WSOM, from four soil samples in tropical and subtropical regions of China were investigated. It demonstrates that Cr(VI) reduction capacity decreases in the order WSOM > HWSOM and MBP-enriched DOM > HA-enriched DOM due to the higher contents of low molecular weight saturated compounds and CHO molecules in the former.

Irradiation and DOM mediate lead release from polyvinyl chloride microplastics in natural surface water.

Polyvinyl chloride (PVC) is a widely used plastic, but the potential risk of heavy metal additive release from PVC microplastics (MPs) has not been fully explored. This study evaluates the release of lead (Pb) from recycled PVC MPs under natural conditions. The released Pb concentration in the dark was 1079.

Molecular composition difference of electron donating moieties between natural organic matter and effluent organic matter probed by chlorine dioxide.

Lignin- and tannin-like phenolic compounds are shown to be the major compositions of electron donating moieties (EDM) of aquatic natural organic matter (NOM). However, little is known about the compositions of EDMs within effluent organic matter (EfOM). In the present study, chlorine dioxide (ClO) was used as a selectively oxidative probe to investigate the difference in the molecular composition of EDM between NOM and EfOM due to its high selectivity towards electron-rich compounds.

Transformation of Natural Organic Matter in Simulated Abiotic Redox Dynamic Environments: Impact on Fe Cycling.

Redox fluctuations within redox dynamic environments influence the redox state of natural organic matter (NOM) and its interaction with redox-active elements, such as iron. In this work, we investigate the changes in the molecular composition of NOM during redox fluctuations as well as the impact of these changes on the Fe-NOM interaction employing Suwannee River Dissolved Organic Matter (SRDOM) as a representative NOM. Characterization of SRDOM using X-ray photoelectron spectroscopy and Fourier transform infrared spectrometry showed that irreversible changes occurred following electrochemical reduction and reoxidation of SRDOM in air.

PBAT biodegradable microplastics enhanced organic matter decomposition capacity and CO emission in soils with and without straw residue.

Recent studies show that biodegradable microplastics (BMPs) could increase soil CO emission, but whether altered carbon emission results from modified soil organic matter (SOM) decomposition remains underexplored. In this study, the effect and mechanisms of BMPs on CO emission from soil were investigated, using poly(butylene adipate-co-terephthalate) (PBAT, the main component of agricultural film) as an example. Considering that straw returning is a common agronomic measure which may interact with microplastics through affecting microbial activity, both soils with and without wheat straw were included.

Hidden Role of Organic Matter in the Immobilization and Transformation of Iodine on Fe-OM Associations.

The biogeochemical processes of iodine are typically coupled with organic matter (OM) and the dynamic transformation of iron (Fe) minerals in aquifer systems, which are further regulated by the association of OM with Fe minerals. However, the roles of OM in the mobility of iodine on Fe-OM associations remain poorly understood. Based on batch adsorption experiments and subsequent solid-phase characterization, we delved into the immobilization and transformation of iodate and iodide on Fe-OM associations with different C/Fe ratios under anaerobic conditions.

New insights into the influences of firework combustion on molecular composition and formation of sulfur- and halogen-containing organic compounds.

Firework (FW) events occur during various festivals worldwide and substantially negatively influence both air quality and human health. However, the effects of FWs on the chemical properties and formation of organic aerosols are far from clear. In this study, fine particulate matter (PM) samples were collected in a suburban area in Qingdao, China during the Chinese Spring Festival.

Activated Carbon Application Simultaneously Alleviates Paddy Soil Arsenic Mobilization and Carbon Emission by Decreasing Porewater Dissolved Organic Matter.

Flooding of paddy fields during the rice growing season enhances arsenic (As) mobilization and greenhouse gas (e.g., methane) emissions.

Formation of reactive intermediates in paddy water from different temperature zones for the promotion of abiotic ammonification.

The paddy field is a hot area of biogeochemical process. The paddy water has a large capacity in photo-generation of reactive intermediates (RIs) due to abundant photosensitive dissolved organic matter (DOM), which is influenced by the spatial heterogeneity of paddy soils but rarely been explored. Our work presents the first investigation of the role of soil properties on photochemistry in paddy water.

Enrichment of Geogenic Organoiodine Compounds in Alluvial-Lacustrine Aquifers: Molecular Constraints by Organic Matter.

Organoiodine compounds (OICs) are the dominant iodine species in groundwater systems. However, molecular mechanisms underlying the geochemical formation of geogenic OICs-contaminated groundwater remain unclear. Based upon multitarget field monitoring in combination with ultrahigh-resolution molecular characterization of organic components for alluvial-lacustrine aquifers, we identified a total of 939 OICs in groundwater under reducing and circumneutral pH conditions.

FT-ICR MS Spectral Improvement of Dissolved Organic Matter by the Absorption Mode: A Comparison of the Electrospray Ionization in Positive-Ion and Negative-Ion Modes.

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) in the absorption mode has a superior performance over the conventional magnitude mode. However, this improved performance for the analysis of dissolved organic matter (DOM) in negative-ion and positive-ion modes of electrospray ionization [ESI(-) and ESI(+), respectively] remains unknown. This study systemically compared the improved performance by the absorption mode for DOM FT-ICR MS spectra acquired with the low-field and high-field magnet instruments between two charge modes.

Interpretable Machine Learning and Reactomics Assisted Isotopically Labeled FT-ICR-MS for Exploring the Reactivity and Transformation of Natural Organic Matter during Ultraviolet Photolysis.

Isotopically labeled FT-ICR-MS combined with multiple post-analyses, including interpretable machine learning (IML) and a paired mass distance (PMD) network, was employed to unravel the reactivity and transformation of natural organic matter (NOM) during ultraviolet (UV) irradiation. FT-ICR-MS analysis was used to assign formulas, which were classified on the basis of their molecular compositions and structural categories. Isotope (deuterium, D) labeling was utilized to unequivocally determine the photochemical products and examine the development of OD radical-mediated NOM transformation.