Temporal Variations in Fire Impacts on Characteristics and Composition of Soil-Derived Dissolved Organic Matter at Qipan Mountain, China.

Dissolved organic matter (DOM), the most reactive fraction of forest soil organic matter, is increasingly impacted by wildfires worldwide. However, few studies have quantified the temporal changes in soil DOM quantity and quality after fire. Here, soil samples were collected after the Qipan Mountain Fire (3-36 months) from pairs of burned and unburned sites. DOM contents and characteristics were analyzed using carbon quantification and various spectroscopic and spectrometric techniques. Compared with the unburned sites, burned sites showed higher contents of bulk DOM and most DOM components 3 months after the fire but lower contents of them 6-36 months after the fire. During the sharp drop of DOM from 3 to 6 months after the fire, carboxyl-rich alicyclic molecule-like and highly unsaturated compounds had greater losses than condensed aromatics. Notably, the burned sites had consistently higher abundances of oxygen-poor dissolved black nitrogen and fluorescent DOM 3-36 months after the fire, particularly the abundance of pyrogenic C2 (excitation/emission maxima of <250/∼400 nm) that increased by 150% before gradually declining. This study advances the understanding of temporal variations in the effects of fire on different soil DOM components, which is crucial for future postfire environmental management.

Dissolved Organic Matter Contains Ketones Across a Wide Range of Molecular Formulas.

The carbonyl functionality of natural organic matter (NOM) is poorly constrained. Here, we treated Suwannee River NOM (SRNOM) with ammonium acetate and sodium cyanoborohydride to convert ketone-containing compounds by reductive amination to their corresponding primary amines. The total dissolved nitrogen content increased by up to 275% after amination. Up to 30% of the molecular formulas of SRNOM contained isomers with ketone functionalities as detected by ultrahigh-resolution mass spectrometry. Most of these isomers contained one or two keto groups. At least 3.5% of the oxygen in SRNOM was bound in ketone moieties. The conversion of reacted compounds increased linearly with O/H values of molecular formulas and was predictable from the elemental composition. The mean conversion rate of reacted compounds nearly followed a log-normal distribution. This distribution and the predictability of the proportion of ketone-containing isomers solely based on the molecular formula indicated a stochastic distribution of ketones across SRNOM compounds. We obtained isotopically labeled amines by using 15N-labeled ammonium acetate, facilitating the identification of reaction products and enabling NMR spectroscopic analysis. 1H,15N HSQC NMR experiments of derivatized samples containing less than 20 µg of nitrogen confirmed the predominant formation of primary amines, as expected from the reaction pathway.

Freeze-induced acceleration of iodide oxidation and consequent iodination of dissolved organic matter to form organoiodine compounds.

Freeze-induced acceleration of I- oxidation and the consequent iodination of dissolved organic matter (DOM) contribute to the formation of organoiodine compounds (OICs) in cold regions. The formed OICs may be a potentially important source of risk and are very closely with the environment and human health. Herein, we investigated the acceleration effects of the freeze process on I- oxidation and the formation of OICs. In comparison to reactive iodine species (RIS) formed in aqueous solutions, I- oxidation and RIS formation were greatly enhanced in frozen solution and were affected by pH, and the content of I- and O2. Freeze-thaw process further promoted I- oxidation and the concentration of RIS reached 45.7 µmol/L after 6 freeze-thaw cycles. The consequent products of DOM iodination were greatly promoted in terms of both concentration and number. The total content of OICs ranged from 0.02 to 2.83 µmol/L under various conditions. About 183-1197 OICs were detected by Fourier transform ion cyclotron resonance mass spectrometry, and more than 96.2% contained one or two iodine atoms. Most OICs had aromatic structures and were formed via substitution and addition reactions. Our findings reveal an important formation pathway for OICs and shed light on the biogeochemical cycling of iodine in the natural aquatic environment.

Humic-like Substances (HULIS) in Ship Engine Emissions: Molecular Composition Effected by Fuel Type, Engine Mode, and Wet Scrubber Usage.

Humic-like substances (HULIS), known for their substantial impact on the atmosphere, are identified in marine diesel engine emissions obtained from five different fuels at two engine loads simulating real world scenarios as well as the application of wet sulfur scrubbers. The HULIS chemical composition is characterized by electrospray ionization (ESI) ultrahigh resolution mass spectrometry and shown to contain partially oxidized alkylated polycyclic aromatic compounds as well as partially oxidized aliphatic compounds, both including abundant nitrogen- and sulfur-containing species, and clearly different to HULIS emitted from biomass burning. Fuel properties such as sulfur content and aromaticity as well as the fuel combustion efficiency and engine mode are reflected in the observed HULIS composition. When the marine diesel engine is operated below the optimum engine settings, e.g., during maneuvering in harbors, HULIS-C emission factors are increased (262-893 mg kg-1), and a higher number of HULIS with a shift toward lower degree of oxidation and higher aromaticity is detected. Additionally, more aromatic and aliphatic CHOS compounds in HULIS were detected, especially for high-sulfur fuel combustion. The application of wet sulfur scrubbers decreased the HULIS-C emission factors by 4-49% but also led to the formation of new HULIS compounds. Overall, our results suggest the consideration of marine diesel engines as a relevant regional source of HULIS emissions.

Characterization of the Nonpolar and Polar Extractable Components of Glanded Cottonseed for Its Valorization.

Cottonseed is the second major product of cotton (Gossypium spp.) crops after fiber. Thus, the characterization and valorization of cottonseed are important parts of cotton utilization research. In this work, the nonpolar and polar fractions of glanded (Gd) cottonseed were sequentially extracted by 100% hexane and 80% ethanol aqueous solutions and subjected to 13C and 1H nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), respectively. The nonpolar (crude oil) extracts showed the characteristic NMR peak features of edible plant oils with the absence of ω-3 linolenic acid. Quantitative analysis revealed the percentage of polyunsaturated, monounsaturated, and saturated fatty acids as 48.7%, 16.9%, and 34.4%, respectively. Both general unsaturated fatty acid features and some specific olefinic compounds (e.g., oleic, linolenic, and gondonic acids) were found in the nonpolar fraction. In the polar extracts, FT-ICR MS detected 1673 formulas, with approximately 1/3 being potential phenolic compounds. Both the total and phenolic formulas fell mainly in the categories of lipid, peptide-like, carbohydrate, and lignin. A literature search and comparison further identifies some of these formulas as potential bioactive compounds. For example, one compound [2,5-dihydroxy-N'-(2,3,4-trihydroxybenzylidene) benzohydrazide] identified in the polar extracts is likely responsible for the anticancer function observed when used on human breast cancer cell lines. The chemical profile of the polar extracts provides a formulary for the exploration of bioactive component candidates derived from cottonseed for nutritive, health, and medical applications.

Discovery of Polar Ozonation Byproducts via Direct Injection of Effluent Organic Matter with Online LC-FT-ICR-MS.

Effluent organic matter (EfOM), a major ozone consumer during wastewater ozonation, is a complex mixture of natural and anthropogenic organic molecules. Ozonation of EfOM adds to molecular complexity by introducing polar and potentially mobile ozonation byproducts (OBPs). Currently, nontargeted direct infusion (DI) ultrahigh resolution mass spectrometry (e.g. FT-ICR-MS) is used to study OBPs but requires sample extraction, limiting the accessible polarity range of OBPs. To better understand the impact of ozonation on EfOM and the formation of polar OBPs, nonextracted effluent was analyzed by direct injection onto a reversed-phase liquid chromatography system (RP-LC) online hyphenated with an FT-ICR-MS. Over four times more OBPs were detected in nonextracted EfOM compared to effluent extracted with solid phase extraction and measured with DI-FT-ICR-MS (13817 vs 3075). Over 1500 highly oxygenated OBPs were detected exclusively in early eluting fractions of nonextracted EfOM, indicating polar OBPs. Oxygenation of these newly discovered OBPs is higher than previously found, with an average molecular DBE-O value of -3.3 and O/C ratio of 0.84 in the earliest eluting OBP fractions. These polar OBPs are consistently lost during extraction but may play an important role in understanding the environmental impact of ozonated EfOM. Moreover, 316 molecular formulas classified as nonreactive to ozone in DI-FT-ICR-MS can be identified with LC-FT-ICR-MS as isomers with varying degrees of reactivity, providing for the first time experimental evidence of differential reactivity of complex organic matter isomers with ozone.

Expansion of the composition library for chemodiversity of hardwood extractives at molecular level by ultrahigh-resolution mass spectrometry.

To enhance the characterization of wood extractives at molecular level, a detailed ultrahigh-resolution mass spectrometry (UHRMS)-based analytical methodology was developed in this work. The analytical strategies, including selection of compatible solvent for extraction, evaluation of ionization solvent for effective electrospray ionization, and multi-dimensional data analysis, were established to ensure a comprehensive characterization of complex compositions in wood extractives. Extraction capability of seven solvents with varied polarities was examined by a standard reference material of hardwood biomass and evaluated based on thousands of compounds which were much more than those discovered before. With a variety of data-processing approaches, including compound type distribution, double bond equivalent versus carbon number plot, and van Krevelen diagram, the chemodiversity of the extractives was fully explored from different perspectives. This work greatly expanded the compound library of wood extractives and could also provide guidance for the integrated composition analysis of other biomass materials.

Molecular Diversity and Biochemical Content in Two Invasive Alien Species: Looking for Chemical Similarities and Bioactivities.

The biochemical composition, molecular diversity, and two different bioactivities of Asparagopsis armata and Rugulopteryx okamurae (two alien species with different invasive patterns in the southern Iberian Peninsula) were analyzed through spectrophotometric methods and Fourier transform ion cyclotron mass spectroscopy (FT-ICR-MS). A total of 3042 molecular formulas were identified from the different extracts. The dH2O extracts were the most molecularly different. A. armata presented the highest content of nitrogenous compounds (proteins, CHON) and sulphur content, whereas R. okamurae was rich in carbonated compounds (total carbon, lipids, CHO, and CHOP). Antioxidant capacity and phenolic content were higher in R. okamurae than in A. armata. Antimicrobial activity was detected from both species. A. armata showed capacity to inhibit human and fish pathogens (e.g., Staphylococcus aureus or Vibrio anguillarum), whereas R. okamurae only showed inhibition against human bacteria (Staphylococcus aureus and Cutibacterium acnes). In R. okamurae, molecules with a great number of pharmaceutical activities (e.g., anti-inflammatory or antitumoral), antibacterial, biomaterial, and other utilities were found. The main molecules of A. armata had also pharmaceutical applications (e.g., antimalarian, antithrombotic, anti-inflammatory, or antiarthritis). The valorization of these species can help to counteract the environmental effects of the bioinvasions.

How Well Do We Handle the Sample Preparation, FT-ICR Mass Spectrometry Analysis, and Data Treatment of Atmospheric Waters?

FT-ICR MS (Fourier-transform ion cyclotron resonance mass spectrometry) analysis has shown great potential to aid in the understanding of the extremely high molecular diversity of cloud water samples. The main goal of this work was to determine the differences in terms of formula assignment for analytical (i.e., measurement replicates) and experimental replicates of a given cloud water sample. The experimental replicates, obtained by solid phase extraction, were also compared to the results obtained for freeze-dried samples to evaluate whether the presence of salts interferes with the analysis. Two S/N ratios, generally adopted for atmospheric samples, were evaluated, and three different algorithms were used for assignment: DataAnalysis 5.3 (Bruker), Composer (Sierra Analytics), and MFAssignR (Chemical Advanced Resolution Methods Lab). In contrast to other works, we wanted to treat this comparison from the point of view of users, who usually must deal with a simple list of m/z ratios and intensity with limited access to the mass spectrum characteristics. The aim of this study was to establish a methodology for the treatment of atmospheric aqueous samples in light of the comparison of three different software programs, to enhance the possibility of data comparison within samples.

An Automated Methodology for Non-targeted Compositional Analysis of Small Molecules in High Complexity Environmental Matrices Using Coupled Ultra Performance Liquid Chromatography Orbitrap Mass Spectrometry.

The life-critical matrices of air and water are among the most complex chemical mixtures that are ever encountered. Ultrahigh-resolution mass spectrometers, such as the Orbitrap, provide unprecedented analytical capabilities to probe the molecular composition of such matrices, but the extraction of non-targeted chemical information is impractical to perform via manual data processing. Automated non-targeted tools rapidly extract the chemical information of all detected compounds within a sample dataset. However, these methods have not been exploited in the environmental sciences. Here, we provide an automated and (for the first time) rigorously tested methodology for the non-targeted compositional analysis of environmental matrices using coupled liquid chromatography-mass spectrometric data. First, the robustness and reproducibility was tested using authentic standards, evaluating performance as a function of concentration, ionization potential, and sample complexity. The method was then used for the compositional analysis of particulate matter and surface waters collected from worldwide locations. The method detected >9600 compounds in the individual environmental samples, arising from critical pollutant sources, including carcinogenic industrial chemicals, pesticides, and pharmaceuticals among others. This methodology offers considerable advances in the environmental sciences, providing a more complete assessment of sample compositions while significantly increasing throughput.

Macromolecular Characterization of Compound Selectivity for Oxidation and Oxidative Alterations of Dissolved Organic Matter by Manganese Oxide.

Manganese (Mn) oxides can oxidize dissolved organic matter (DOM) and alter its chemical properties and microbial degradability, but the compound selectivity for oxidation and oxidative alterations remain to be determined. We applied ultrahigh mass spectrometry to catalog the macromolecular composition of Suwannee River fulvic acid (SRFA) before and after oxidation by a Mn oxide (δ-MnO2) at pH 4 or 6. Polycyclic aromatic hydrocarbons, polyphenols, and carbohydrates were more reactive in reducing δ-MnO2 than highly unsaturated and phenolic (HuPh) compounds and aliphatics, but highly abundant HuPh contributed the most (∼50%) to the overall reduction of δ-MnO2. On average, oxidized species had higher molecular weights, aromaticity, carbon unsaturation degree, nominal oxidation state of carbon, and oxygen and nitrogen contents but were lower in hydrogen content compared to unoxidized species. The oxidation decreased these molecular indices and oxygen and nitrogen contents but increased the hydrogen content, with stronger changes at the lower pH. This DOM oxidation on polar mineral surfaces was more selective but shared similar selectivity rules to adsorption. The abiotic oxidation resembles microbial oxidative degradation of organic matter, and Mn oxide-oxidizable carbon may be a useful index for detection and identification of labile organic carbon.

Marine dissolved organic matter: a vast and unexplored molecular space.

Marine dissolved organic matter (DOM) comprises a vast and unexplored molecular space. Most of it resided in the oceans for thousands of years. It is among the most diverse molecular mixtures known, consisting of millions of individual compounds. More than 1 Eg of this material exists on the planet. As such, it comprises a formidable source of natural products promising significant potential for new biotechnological purposes. Great emphasis has been placed on understanding the role of DOM in biogeochemical cycles and climate attenuation, its lifespan, interaction with microorganisms, as well as its molecular composition. Yet, probing DOM bioactivities is in its infancy, largely because it is technically challenging due to the chemical complexity of the material. It is of considerable interest to develop technologies capable to better discern DOM bioactivities. Modern screening technologies are opening new avenues allowing accelerated identification of bioactivities for small molecules from natural products. These methods diminish a priori the need for laborious chemical fractionation. We examine here the application of untargeted metabolomics and multiplexed high-throughput molecular-phenotypic screening techniques that are providing first insights on previously undetectable DOM bioactivities. KEY POINTS: • Marine DOM is a vast, unexplored biotechnological resource. • Untargeted bioscreening approaches are emerging for natural product screening. • Perspectives for developing bioscreening platforms for marine DOM are discussed.

Application of silver-assisted laser desorption ionization ultrahigh-resolution mass spectrometry for the speciation of sulfur compounds.

We herein report the optimization and application of silver cationization (Ag+) in combination with laser desorption ionization (LDI) ultrahigh-resolution mass spectrometry (UHR-MS) to determine the structures of the sulfur-containing compounds present in heavy crude oil. A number of sulfur-containing model compounds were used to optimize the positive-ion mode LDI-MS conditions in the presence of a silver-complexing agent. Under the optimized LDI conditions, sulfur-rich heavy oil fractions were treated with the silver salt, where Ag+ coordinated with the sulfur atoms to speciate the sulfur species. The obtained results suggested that benzothiophenic, naphtheno-non-aromatic sulfides, and non-aromatic thiols were the major components present in the analyzed oil sample. Graphical abstract.

MFAssignR: Molecular formula assignment software for ultrahigh resolution mass spectrometry analysis of environmental complex mixtures.

Ultrahigh resolution mass spectrometry is widely used for nontargeted analysis of complex environmental and biological mixtures, such as dissolved organic matter, due to its unparalleled ability to provide accurate mass measurements. Accurate and efficient characterization of these mixtures is critical to being better able to evaluate their effect on human health and climate. This characterization requires accurate mass signals free from isobaric interferences, instrument noise, and mass measurement biases, allowing for molecular formula identification. To address this need, an open source post-processing pipeline for ultrahigh resolution mass spectra of environmental complex mixtures software was developed. MFAssignR contains functions that perform noise estimation, 13C and 34S polyisotopic mass filtering, mass measurement recalibration, and molecular formula assignment as part of a consistent data processing environment. Novel applications of mass defect analysis were used in the functions for noise estimation and isotope pair identification. Using formula extensions, exact mass measurements are converted to unambiguous molecular formulas via data dependent pathways, reducing a priori decisions. Optional molecular formula ambiguity and multiple non-oxygen heteroatoms are provided for custom user applications, including isotopically labeled reactive species, halogen-containing species, or tandem ultrahigh resolution mass spectrometry. This represents uncommon flexibility for an open-source software package. To evaluate the performance of MFAssignR, it was used to characterize a sample of biomass burning influenced organic aerosol and the results were compared to those from other available methods of molecular formula assignment and noise estimation. The differences between the methods are described here. Overall, the inclusion of a full pipeline of data preparation functions and the data-dependent ambiguity reductions in MFAssignR render excellent results and make MFAssignR well-suited for the consistent and efficient analysis of environmental complex mixtures. MFAssignR is publicly available via GitHub.

Super Secondary Structures of Proteins with Post-Translational Modifications in Colon Cancer.

New advances in protein post-translational modifications (PTMs) have revealed a complex layer of regulatory mechanisms through which PTMs control cell signaling and metabolic pathways, contributing to the diverse metabolic phenotypes found in cancer. Using conformational templates and the three-dimensional (3D) environment investigation of proteins in patients with colorectal cancer, it was demonstrated that most PTMs (phosphorylation, acetylation, and ubiquitination) are localized in the supersecondary structures (helical pairs). We showed that such helical pairs are represented on the outer surface of protein molecules and characterized by a largely accessible area for the surrounding solvent. Most promising and meaningful modifications were observed on the surface of vitamin D-binding protein (VDBP), complement C4-A (CO4A), X-ray repair cross-complementing protein 6 (XRCC6), Plasma protease C1 inhibitor (IC1), and albumin (ALBU), which are related to colorectal cancer developing. Based on the presented data, we propose the impact of the observed modifications in immune response, inflammatory reaction, regulation of cell migration, and promotion of tumor growth. Here, we suggest a computational approach in which high-throughput analysis for identification and characterization of PTM signature, associated with cancer metabolic reprograming, can be improved to prognostic value and bring a new strategy to the targeted therapy.

Molecular profiling of naphthenic acids in technical mixtures and oil sands process-affected water using polar reversed-phase liquid chromatography-mass spectrometry.

In this work, a reversed-phase ultra-HPLC (UHPLC) ultrahigh resolution MS (UHRMS) method was evaluated for the comprehensive profiling of NAs containing two O atoms in each molecule (O2NAs; general formula Cn H2n + z O2 , where n is the number of carbon atoms and z represents hydrogen deficiency). Using a polar cyanopropyl-bonded phase column and negative-ion electrospray ionization mass spectrometric detection at 120,000 FWHM (m/z 400), 187 and 226 O2NA species were found in two naphthenic acid technical mixtures, and 424 and 198 species with molecular formulas corresponding to O2NAs were found in two oil sands process-affected water samples (one from a surface mining operation and the other from a steam-assisted gravity drainage operation), respectively. To our knowledge, these are the highest numbers of molecular compositions of O2NAs that have been profiled thus far in environmental samples. Assignments were based on accurate mass measurements (≤3 ppm) combined with rational molecular formula generation, correlation of chromatographic behavior of O2NA homologues with their elemental compositions, and confirmation with carboxyl group-specific chemical derivatization using 3-nitrophenylhydrazine. Application of this UHPLC-UHRMS method to the quantitation of O2NAs in the surface mining operation-derived water sample showed excellent linearity (R2 = 0.9999) with external calibration, a linear range of 256-fold in concentration, and quantitation accuracies of 64.9 and 69.4% at two "standard substance" spiking levels.

Comparative study of organic matter chemical characterization using negative and positive mode electrospray ionization ultrahigh-resolution mass spectrometry.

The chemical characterization of dissolved organic matter (DOM) is critical for understanding carbon sequestration processes in soils. This work evaluated the use of electrospray ionization in both negative ion mode (ESI-) and positive ion mode (ESI+) for the characterization of DOM extracted from nine terrestrial sources using Fourier transform ion cyclotron mass spectrometry (FT-ICR-MS). The compositing of the peaks from ESI- to ESI+ modes increased the total assigned formulas from 23 to 63 % as compared to the traditional use of ESI- alone for DOM characterization. In general, there was a preferential increase in the number of assignments for the aliphatic and carbohydrate-like DOM components in the ESI+ mode. The soil-extracted DOM specifically exhibited greater increases in the aliphatic and carbohydrate-like DOM components with the combined use of ESI- and ESI+ modes likely due to the greater presence of aromatic DOM molecules that suppressed the ionization of these entities in ESI- mode. On the basis of these findings, we show that improved characterization of DOM is possible through the combined use of ESI- and ESI+ modes for FT-ICR-MS analysis, especially for samples rich in condensed aromatic and aromatic molecules.

The Role of Ultrahigh Resolution Fourier Transform Mass Spectrometry (FT-MS) in Astrobiology-Related Research: Analysis of Meteorites and Tholins.

It is an important but also a challenging analytical problem to understand the chemical composition and structure of prebiotic organic matter that is present in extraterrestrial materials. Its formation, evolution and content in the building blocks ("seeds") for more complex molecules, such as proteins and DNA, are key questions in the field of exobiology. Ultrahigh resolution mass spectrometry is one of the best analytical techniques that can be applied because it provides reliable information on the chemical composition and structure of individual components of complex organic mixtures. Prebiotic organic material is delivered to Earth by meteorites or generated in laboratories in simulation (model) experiments that mimic space or atmospheric conditions. Recent representative examples for ultrahigh resolution mass spectrometry studies using Fourier-transform (FT) mass spectrometers such as Orbitrap and ion cyclotron resonance (ICR) mass spectrometers are shown and discussed in the present article, including: (i) the analysis of organic matter of meteorites; (ii) modeling atmospheric processes in ICR cells; and (iii) the structural analysis of laboratory made tholins that might be present in the atmosphere and surface of Saturn's largest moon, Titan.

Accessing the Low-Polar Molecular Composition of Boreal and Arctic Peat-Burning Organic Aerosol via Thermal Analysis and Ultrahigh-Resolution Mass Spectrometry: Structural Motifs and Their Formation.

Peatland fires emit organic carbon-rich particulate matter into the atmosphere. Boreal and Arctic peatlands are becoming more vulnerable to wildfires, resulting in a need for better understanding of the emissions of these special fires. Extractable, nonpolar, and low-polar organic aerosol species emitted from laboratory-based boreal and Arctic peat-burning experiments are analyzed by direct-infusion atmospheric pressure photoionization (APPI) ultrahigh-resolution mass spectrometry (UHRMS) and compared to time-resolved APPI UHRMS evolved gas analysis from the thermal analysis of peat under inert nitrogen (pyrolysis) and oxidative atmosphere. The chemical composition is characterized on a molecular level, revealing abundant aromatic compounds that partially contain oxygen, nitrogen, or sulfur and are formed at characteristic temperatures. Two main structural motifs are identified, single core and multicore, and their temperature-dependent formation is assigned to the thermal degradation of the lignocellulose building blocks and other parts of peat.

Biodegradation in oil sands process-affected water: A comprehensive laboratory analysis of the in situ biodegradation of dissolved organic acids.

Oil sands process-affected water (OSPW) is a by-product of the extraction of bitumen, and volumes of OSPW have accumulated across the Alberta oil sands region due to the governments zero-discharge policy. Some dissolved organics in OSPW, including toxic naphthenic acids (NAs), can be biodegraded in oxic conditions, thereby reducing the toxicity of OSPW. While there has been much focus on degradation of NAs, the biodegradation of other dissolved organic chemicals by endogenous organisms remains understudied. Here, using the HPLC-ultrahigh resolution Orbitrap mass spectrometry, we examined the microbial biodegradation of dissolved organic acids in OSPW. Non-targeted analysis enabled the estimation of biodegradation rates for unique heteroatomic chemical classes detected in negative ion mode. The microcosm experiments were conducted with and without nutrient supplementation, and the changes in the microbial community over time were investigated. Without added nutrients, internal standard-adjusted intensities of all organics, including NAs, were largely unchanged. The addition of nutrients increased the biodegradation rate of O2- and SO2- chemical classes. While anoxic biodegradation can occur in tailings ponds and end pit lakes, microbial community analyses confirmed that the presence of oxygen stimulated biodegradation of the OSPW samples studied. We detected several aerobic hydrocarbon-degrading microbes (e.g., Pseudomonas and Brevundimonas), and microbes capable of degrading sulfur-containing hydrocarbons (e.g., Microbacterium). Microbial community diversity decreased over time with nutrient addition. Overall, the results from this study indicate that toxic dissolved organics beyond NAs can be biodegraded by endogenous organisms in OSPW, but reaffirms that biological treatment strategies require careful consideration of how nutrients and dissolved oxygen may impact efficacy.