Chemistry Commons^™

Developing Consensus-Based Methods For The Examination And Interpretation Of Contemporary Vehicle, Architectural, And Portable Electronic Device Glasses By Micro-X-Ray Fluorescence Spectrometry, Zachary Bailey Andrews

Graduate Theses, Dissertations, and Problem Reports (ETD)

Glass is a trace material that is commonly encountered during investigations of violent crimes. When glass is recovered at crime scenes, it can be used to establish links between suspects, victims, and the scene itself. The most discriminatory form of analysis for glass evidence is elemental analysis, and micro-X-ray fluorescence spectrometry (µXRF) is becoming an increasingly common technique used for this purpose. Recent advances in µXRF technology, such as the introduction of silicon drift detectors (SDD) and improved polycapillary optics are promising in enhancing the capabilities for the examination of glass evidence in forensic investigations. However, along with these advances …

Explorations Of Dna-Single-Walled Carbon Nanotube Interactions To Develop Multiplexed Molecularly Specific Biosensors For Inflammation, Amelia K. Ryan

Dissertations and Theses

Inflammatory cytokines such as interleukin-6 (IL-6) and interleukin-12 (IL-12) are central regulators of immune signaling and key biomarkers of disease, yet existing assays for their detection remain slow, invasive, and lack multiplexing ability. This dissertation advances the development of single-walled carbon nanotube (SWCNT) optical nanosensors capable of real-time, multiplexed, and molecularly specific cytokine detection through innovative use of single-stranded DNA (ssDNA) interfaces.

First, an IL-6-specific DNA aptamer was employed as both a dispersing agent and recognition probe for SWCNT fluorescence sensing. Sequence modifications, including anchor domains, truncations, and thermally induced refolding, were systematically tested to optimize sensitivity and selectivity. The …

Multi-Attribute Characterization Of Polymeric And Lipid-Based Drug Delivery Systems By Column Switching Liquid Chromatography-Mass Spectrometry, Brady W. Drennan

Chemistry & Biochemistry Dissertations - Archive

Drug delivery systems (DDS) are an increasingly relevant technology, owing to their ability to provide controlled release and to enable the use of otherwise toxic or labile therapeutics. However, these modalities are complex, containing a multitude of species with diverse chemical and physical properties. Their characterization, which involves the assessment of critical quality attributes (CQAs), requires numerous analytical techniques. The high-throughput demands of the biopharmaceutical industry have driven the need to consolidate these characterizations into a single analytical method. Consequently, novel analytical technologies are needed to support multi-attribute characterization. A multimodal liquid chromatography–mass spectrometry (LC–MS) system was developed to facilitate …

Structure–Property Relationships Mediated By Lone Pairs And Vacancies In Oxychalcogenides: A Combined Experimental And Theoretical Study, Hoa Hn Nguyen

Chemistry & Biochemistry Dissertations - Archive

Structure–property relationships in some oxychalcogenide materials are strongly governed by the interplay between stereochemically active lone pairs and anion vacancy formation. Through a combination of density functional theory (DFT), synchrotron and neutron total scattering and optical characterization, this work elucidates how local symmetry breaking, chemical substitution, and vacancy dynamics influence electronic and optical behavior across several lone pair-containing systems. In crystalline TeO₂, all three polymorphs exhibit wide band gaps with Te⁴⁺ 5s² lone pairs contributing significantly near the valence band edge. Oxygen vacancy formation is thermodynamically favorable and induces asymmetric charge redistribution and enhanced polarizability, supporting …

Characterization And Leaching Feasibility Studies Of Copper Flue Dust For The Recovery Of Main And Trace Metals, Fardis Nakhaei, Marek Locmelis, Lana Alagha, Michael S. Moats, Carlos Eyzaguirre, Cory Smith

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Although copper smelter dust (CSD) is classified as hazardous waste, it also serves as a valuable secondary resource, offering potential for the recovery of critical elements. In this study, CSD samples were collected from the waste heat boiler (WHB) and electrostatic precipitator (ESP) units connected to the flash smelting furnace at a copper smelter. The representative samples were extensively characterized by particle size, and chemical and mineralogical analyses. Following sample characterization, leaching experiments were performed to evaluate the potential extraction of Cu, Fe, As, Zn, Pb, In, Ga, and Ge from the flue dusts. Distilled water, H2SO4, and HCl were …

What Amino Acid Residue Is Responsible For The Interaction Of Atg11 With Its Autophagy Partner Atg9?, Patricia Omoyemwen Woghiren

Senior Honors Theses and Projects

Macroautophagy is a cellular function that involves the formation of a double membrane vesicle that isolates and transports cellular materials to the vacuole or lysosome for degradation and recycling. It is divided into selective and non-selective macroautophagy. Atg11 and Atg9 are two key proteins involved in selective macroautophagy, and their interaction is critical for selective macroautophagy. Specific residues on Atg9 critical for Atg11 binding have been identified, but similar residues on Atg11 have not been identified. The aim of my research was to identify a specific residue critical for Atg11’s interaction with Atg9. To this end, we carried out Yeast-twohybrid …

The Role Of Leptin In The Regulation Of The Soluble Amyloid Precursor Protein Alpha (Sappa) Levels In Non-Small Cell Lunch Cancer (Nsclc) Cell Media, Benjamin Haddad

Senior Honors Theses and Projects

We previously found that the levels of soluble amyloid precursor protein α (sAPPα) are partly regulated by acetylcholinesterase (AChE) in human non-small cell lung cancer cell lines A549 (p53 wild-type) and H1299 (p53-null). In this study, we hypothesize that sAPPα is partly regulated by leptin, a hormone classically recognized for its anorexigenic role in appetite regulation— yet recently shown to play a role in cancer cell signaling. It was observed that cells treated with leptin exhibited greater concentrations of sAPPα and lower concentrations of Aβ40/42 in the media compared to those of cells left untreated. An opposite effect was observed …

Tailoring Selected Aerogels To Targeted Applications, Stephen Yaw Owusu

Doctoral Dissertations

Aerogels are ultra-lightweight, porous solid materials characterized by a three-dimensional nanostructured network. Owing to their exceptional physical and chemical properties, aerogels have garnered considerable attention within the materials science community and were recognized by IUPAC in 2022 as one of the top ten emerging technologies in chemistry. Although numerous aerogels have been synthesized, only a few have been effectively tailored for specific applications. Optimizing the properties of known aerogels for targeted uses remains challenging. This dissertation investigates strategies for tailoring aerogels derived from isocyanate-benzoxazine, benzodiazine, and phenolic resins to meet the requirements of various advanced applications. The approaches employed include …

Development Of Dual-Scan Nuclear Magnetic Resonance (Nmr) Pulse Programs For Spin-Lattice Relaxation Measurements, Zachary Mayes

Doctoral Dissertations

This research develops and refines the Split Inversion Pulse and Recovery (SIP R) methodology for spin-lattice relaxation (T₁) measurements in NMR spectroscopy. SIP R introduces a two-scan difference technique using a split inversion pulse sequence, where the 180° pulse is split into two 90° pulses phase-shifted with respect to each other. This approach simplifies data fitting, requiring only two parameters to extract T₁ values, compared to the traditional inversion-recovery method, which needs three. The SIP-R-DS and SIP-R-S adaptations extend this framework by incorporating selective NMR resonance excitations, enhancing its applicability to cross-polarization experiments and enabling unobstructed NOE measurements. These adaptations …

Epitaxial Growth Of Metal-Organic Framwork Thin Films By Electro-Conversion And Electrodeposition, Xiaoting Zhang

Doctoral Dissertations

Electrochemical epitaxy is a facile and inexpensive soft-solution process to fabricate highly ordered thin films. This research focuses on the epitaxial growth of metal-organic framework (MOF) thin films by electrochemical methods which include electro-conversion and electrodeposition.

First, an electrochemical conversion pathway was invented to achieve epitaxial MOF thin films. Epitaxial single-domain Cu-BTC(111) thin films were manufactured by electrochemical oxidation of Cu₂O(111) films electrodeposited on single-crystal Au(111). The single-crystal-like Cu-BTC(111) thin films with out-of-plane and in-plane order provide well-aligned 3.5 Å triangular windows along the [111] direction. Cu-BTC(111) foils were fabricated from the Cu-BTC/Cu₂O system by electrochemical …

Polybenzodiazine Aerogels: All-Nitrogen Analogues Of Polybenzoxazines - Synthesis, Characterization, And Their Application In Carbon Dioxide Capture, Vaibhav Edlabadkar

Doctoral Dissertations

"The rapidly risen concentration of carbon dioxide in the atmosphere over recent years contributed to global warming and ocean acidification. Carbon capture is viewed as an essential tool from keeping atmospheric CO₂ levels from rising further. This thesis focuses on the development of new materials for high capacity and selective adsorption of CO₂. One such material was based on a newly synthesized tetrahydroquinazoline (THQ), which was designed as an all-nitrogen analogue of main-stream benzoxazine monomers. THQ solutions in DMF gelled at 100 °C via HCl-catalyzed ring opening polymerization to polybenzodiazine (PBDAZ) wet gels, which were dried in …

Applications Of Tetramethyl-Guanidine Supported Cationic Transition Metal Sites Towards C─N Bond Construction Methodologies And [3+2] Cycloaddition Reactions, Suraj Kumar Sahoo

Doctoral Dissertations

"We present a family of divalent cationic bipodal and tripodal M(II) reagents (M = Mn, Fe, Co) supported by superbasic tetramethyl-guanidinyl (TMG) residue framework with applications towards C─N bond construction methodologies. These cationic reagents possess unique characteristics since their enhanced Lewis acidity facilitates in situ elaboration of the primary nitrene-transfer product (aziridine). Indeed, further aziridine-ring opening and cycloaddition of several dipolarophiles (nitriles, alkenes, ketones) permits the three-component synthesis of valuable five-membered N-heterocycles, commonly found in pharmaceuticals and agrochemicals.

We undertake a more systematic study to unravel parameters that make certain divalent metal sites more suitable as catalysts for the in-situ …

Development Of Ligands And Metal Complexes With Weakly Coordinating Apical Elements And Their Application To Nitrene Insertion And Addition To C‒H And C=C Bonds, Meenakshi Sharma

Doctoral Dissertations

"We present a family of triangular coinage metal M₃Cl₃ complexes [M = Cu (I), Ag (I)] supported by antimony [Sb (III)], and bismuth [Bi (III)]-centered highly basic tetramethyl-guanidinyl [TMG₃trphen-E] (E = Sb, Bi) ligand frameworks with their applications as catalysts toward the construction of C‒N bond through aziridination and amination reaction methodologies.

The [(TMG₃trphen-Sb)Cu₃(µ-Cl)₃] catalyst gives better yields of aziridines with styrenes than [(TMG3trphen-Bi)Cu₃(µ-Cl)₃] with PhINTs as a nitrene source. However, the catalytic reactivity of both catalysts is enhanced by an electrophilic nitrene, PhINTces for …

Development Of Catalytic Membranes And Composites For Energy Storage Devices And Nonenzymatic Biosensors, Harish Singh

Doctoral Dissertations

The excessive use of fossil fuels has led to their rapid depletion, causing an energy crisis and environmental issues. Consequently, there's a growing focus on sustainable energy conversion. Electrocatalysts are pivotal in this development, particularly for fuel cells and solar fuel generators, necessitating high-efficiency, cost-effective catalysts for large-scale adoption. Transition metal chalcogenides have emerged as promising electrocatalysts due to their high efficiency, electrochemical tunability, and abundant active sites. This work is divided in two parts. In Part A, we have investigated transition metal chalcogenide and few atom clusters FACs as electrocatalysts for oxygen evolution and reduction, highlighting their structure-property relationships …

Products Of Laser Ablated Actinides And Actinide Comparators In The Presence Of Carbonyl Sulfide Characterized By Rotational Spectroscopy, Joshua Edward Isert

Doctoral Dissertations

As the consumption of energy continues to rise globally, so too has interest in alternative energy sources such as nuclear power. However, a fundamental understanding of the actinide series is needed in order to safely and efficiently utilize these elements. Rotational or microwave spectroscopy, depending on if one is speaking of the physical outcome of the experiment or the region of the electromagnetic spectrum being operated in, is a gas phase molecular study utilized for structural determination. This technique can be utilized to gain an in depth understanding of bonding within the actinide series. However, when studying species that are …

Atmospheric Chemistry Experiment (Ace) Winds, Matthew Wyatt, Peter F. Bernath, Chris Boone, Léo Lavy, Ryan Johnson

Chemistry & Biochemistry Faculty Publications

The Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) uses limb geometry to measure transmittance spectra of Earth's atmosphere by solar occultation. Line-of-sight wind speeds can be derived via Doppler shifts of molecular lines in infrared spectra. The wind look direction angles relative to geodetic North are derived from geometry. We validate the new ACE version 5.3 (v.5.3) line-of-sight winds with MIGHTI and meteor radar vector wind observations and find a ±15 m/s sunrise/sunset shift above 80 km. We also compare line-of-sight winds from ACE-FTS v.5.2 and v.5.3 with vector winds from the MERRA-2, HWM14, and WACCM-X models. A ±15 m/s …

Synthesis And Luminescence Studies Of Europium Doped Zinc Lead Germanate Phosphors, Anika Nawar Chowdhury

Dissertations and Theses

Phosphors are luminescent materials that emit light upon excitation, which have significant uses in optoelectronics, bioimaging, sensors, security, and other fields. Inorganic luminescent materials are well known for their stability and broad applications. Among these, germanate based phosphors have recently caught attention because of their inertness, excellent chemical and thermal stability, structural flexibility, and unique properties. For optimizing the properties of the materials, impurities are added to the host intentionally, which are known as dopants. Rare earth elements are often applied as dopants because of their unique f-f transitions. Eu3+ is one of the broadly studied rare-earth dopants among these, …

Demystifying Misconceptions In Introductory Undergraduate Chemistry Education With 3d Printed Molecular Orbitals, Hiwot Endeshaw, Daniel J. O'Leary

Pomona Senior Theses

Spatial abilities are invaluable skills for the science, technology, engineering, and mathematics (STEM) subjects. However, women, people from low socioeconomic backgrounds, and ethnic minorities are more likely to have less developed spatial abilities, which is one of the many contributing factors for the lack of diversity in STEM subjects like chemistry. Teaching spatial skills to undergraduate chemistry students may address this issue and help increase the diversity of students who go on to continue their education in the subject. 3D printing technology in higher education has exploded in recent years, presenting a unique opportunity to teach “hard to grasp” concepts …

Modified N-Heterocyclic Carbene Catalysts For Polyurethane Synthesis, Charise D. Young

Pomona Senior Theses

Polyurethanes are widely used polymers synthesized from diisocyanate and diol molecules. They are ubiquitous polymeric materials with important industrial applications. Their increasing market value prompts the need for selective and efficient production which can be achieved through N-Heterocyclic carbene (NHC) catalysis. N-heterocyclic carbenes are heterocyclic molecules containing a carbene atom and at least one nitrogen adjacent to the carbene center. The nitrogen substituents on the adjacent nitrogen play an important role in influencing their steric and electronic properties and resultant reactivity.^1,2 There is a lack of a comprehensive understanding of the steric and electronic properties of NHCs and how …

Optimizing And Scaling Up Tcfh–Nmi Pyrrole Acylation For Organic Syntheses, Grant H. Miller

Pomona Senior Theses

Traditional ketone synthesis often depends on toxic reagents and hazardous solvents, which limits its scalability and environmental compatibility. The TCFH–NMI method has shown strong potential for amide, ester, and thioester formation, but its use in ketone synthesis has only been recently described, and only on small scales. This thesis addresses that gap by optimizing a scalable synthesis of 2-(monomethyl succinyl)-3,5-dimethylpyrrole using monomethyl succinate and 2,4-dimethylpyrrole as model substrates. Key reaction parameters were systematically refined to improve yield, reproducibility, and sustainability. The final protocol avoids chromatography, operates at room temperature, and consistently delivers high yields. These features position it as a …

Rwanda's Natural Remedies: A Fresh Look At The Fight Against Malaria, Leandre Nsabimana Ndisanze

Pomona Senior Theses

Malaria remains one of the most devastating parasitic diseases globally, disproportionately affecting sub-Saharan Africa, where Rwanda continues to face high transmission rates and rising resistance to conventional interventions. Despite decades of control efforts, the emergence of drug-resistant Plasmodium falciparum and insecticide-resistant Anopheles mosquitoes threatens to reverse recent gains. This research responds to the urgent need for sustainable and culturally relevant alternatives by exploring the therapeutic potential of Rwandan traditional medicinal plants. These indigenous remedies, long used by local healers, offer an underexplored reservoir of bioactive compounds that may provide the basis for novel antimalarial drugs.

The central hypothesis of this …

Moderate Heating Renders 7.8-Million-Year-Old Sedimentary Organic Matter Bioavailable, Shuchai Gan, Verena B. Heuer, Frauke Schmidt, Lars Wormer, Faming Wang, Rishi R. Adhikari, Patrick Hatcher, Ann Pearson, Kai-Uwe Hinrichs

Chemistry & Biochemistry Faculty Publications

Marine sediments are a large reservoir of recalcitrant organic matter and host microbes at subsurface depths exceeding 2.4 kilometers and temperatures up to 120°C, yet the mechanisms supplying bioavailable substrates remain unclear. Here, we investigated 7.8-million-year-old sediment from IODP Site C0012 off the Nankai Trough, Japan, through incubations at 20°, 35°, 55°, and 85°C to simulate burial temperatures. Using 3D fluorescence spectroscopy and ultrahigh-resolution mass spectrometry, we tracked changes in dissolved organic matter (DOM). At 35°C, humic-like DOM was released alongside metal ions, exhibiting low bioavailability. At 55°C, abiotic decomposition of humic compounds generated smaller, more bioavailable DOM, promoting fermentation. …

Amorphous Quininium Aspirinate From Neat Mechanochemistry: Diffracting Nanocrystalline Domains And Quick Recrystallization Upon Exposure To Solvent Vapours, Silvina Pagola, James Howard, Johannes Merkelbach, Danny Stam

Chemistry & Biochemistry Faculty Publications

Quininium aspirinate is mechanochemically prepared as a crystalline solid by liquid-assisted grinding, or as an amorphous phase (as determined by X-ray powder diffraction), by neat grinding or neat ball milling. Our previous work demonstrated using FT-IR spectroscopy that a mechanochemical reaction had occurred in the mechanically treated neat mixtures. Herein is reported that microcrystal electron diffraction (microED) afforded the discovery of two diffracting micron-size particles in the amorphous powder synthesized by manual grinding, among a majority of non-diffracting particles. Remarkably, microED data of one of them led to the known lattice parameters of quininium aspirinate. Furthermore, this so-called 'X-ray amorphous' …

A Comparison Of Microcrystal Electron Diffraction And X-Ray Powder Diffraction For The Structural Analysis Of Metal-Organic Frameworks, Erik Biehler, Silvana Pagola, Daniel Stam, Johannes Merkelbach, Christian Jandl, Tarek M. Abdel-Fattah

Chemistry & Biochemistry Faculty Publications

This study successfully implemented microcrystal electron diffraction (microED) and X-ray powder diffraction (XRPD) for the crystal structure determination of a new phase, TAF-CNU-1, Ni(C₈H₄O₄)·3H₂O, solved by microED from single microcrystals in the powder and refined at the kinematic and dynamic electron diffraction theory levels. This nickel metal–organic framework (MOF), together with its cobalt and manganese analogues with formula M (C₈H₄O₄)·2H₂O with M = Mn ^II or Co^II, were synthesized in aqueous media as one-pot preparations from the corresponding hydrated metal chlorides and sodium terephthalate, as a promising `green' synthetic route to moisture-stable MOFs. The crystal structures of the …

Co₂ Isotopologues From The Ace Satellite, D. English, P. Bernath, C. Boone

Chemistry & Biochemistry Faculty Publications

Carbon dioxide isotopologues have been studied thoroughly in the troposphere. In the stratosphere, the minor oxygen CO₂ isotopologues have anomalous abundances due to their exchange reactions with isotopically fractionated ozone, differentiating them from tropospheric CO₂. Previously a model predicted that this anomalous isotopic abundance continues into the mesosphere but lacked verification from experimental observations. Here we use the Atmospheric Chemistry Experiment Fourier Transform Spectrometer which records infrared transmittance spectra of the Earth's limb from low Earth orbit using solar occultation. These infrared spectra provide measurements of global CO₂ isotopologue volume mixing ratios (VMRs) from the upper troposphere to the lower …

Metathesis Or Isomerization: Counteranion Directed Reactivity Of Grubbs I, Paul D. Miller, Joe B. Calkins, Craig A. Bayse, Trandon A. Bender

Chemistry & Biochemistry Faculty Publications

Catalytic isomerization of alkenes has garnered interest for many years, but there are remaining challenges when it comes to thermodynamic selectivity and uncontrolled isomerization. Nonbiased substrates, be it sterically or thermodynamically, remain challenging for many catalysts, with a few examples available in the more modern literature. Herein, we present the controlled isomerization of linear alkenes with a cocatalytic mixture of commercially available catalyst and reagents: Grubbs I, tris(pentafluorophenyl)borane, and triethylsilane. DFT calculations indicate that an observed alkylidyne hydride intermediate is in rapid equilibrium with an alkylidene that binds the alkene substrate. This combination results in a pi-acidic metal and a …

Protonic Capacitor Cell Energetics: Transmembrane-Electrostatically Localized Protons/Cations, James Weifu Lee

Chemistry & Biochemistry Faculty Publications

The transmembrane-electrostatically localized protons/cations charges (TELPs/TELCs) theory can serve as a theoretical framework to better explain cell electrophysiology and elucidate bioenergetic systems including both delocalized and localized protonic coupling. According to the TELCs model, the excess positive charges of TELCs at one side of the membrane are balanced by the excess negative charges of transmembrane-electrostatically localized hydroxides anions (TELAs) at the other side of the membrane. Through the TELCs-membrane-TELAs capacitor model, the energetics of oxidative phosphorylation have recently been better elucidated in mitochondria and alkalophilic bacteria, leading to the identification of a novel Type-B energetic process. Both the TELCs model …

Formation Of Pyramidal Palladium Enhanced By B(C₆F₅)₃ Additive Enabling Selective Alkene Monoisomerization, Paul D. Miller, Trandon A. Bender

Chemistry & Biochemistry Faculty Publications

The addition of a strong Lewis acid, tris(pentafluorophenyl)borane, facilitates the reduction of Pd(cod)Cl₂ with Et₃SiH to form palladium nanoparticles in organic solvents. It was found that these palladium nanoparticles are capable of selective monoisomerization of linear alkenes. This heterogeneous palladium catalyst is tolerant of a wide variety of functional groups, confirmed by substrate and robustness screenings. It is also possible to utilize poly(methylhydro)siloxane, an industrial waste byproduct, as the reductant to enable similar isomerization chemistry.

The B³Π–A³Δ And B³Π–X¹Σ+ Band Systems Of Zro, Manish Bhusal, Peter F. Bernath, Jacques Liévin, Léo Lavy

Chemistry & Biochemistry Faculty Publications

The zirconium oxide (ZrO) b³Π–a³Δ system is a prominent source of opacity in the atmospheres of S-type stars in the near-infrared region. The emission spectra of ZrO, obtained at the National Solar Observatory located at Kitt Peak in Arizona, have been utilized to analyze this band system. A reanalysis of the 0–0 vibrational band of the b³Π–a³Δ transition has been carried out. For the first time, the vibrational bands with 1 ⩽ v ′ ⩽ 3 and v″ ≤ 4 for the same electronic transition have been rotationally analyzed using PGOPHER. Additionally, the 0–0 and 1–1 bands of the spin-forbidden …

Oxidation Camouflages Terrestrial Organic Matter To Appear Marine-Like, Aleksandar I. Goranov, Susan J. Carter, Ann Pearson, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

The export of terrestrial organic matter (TOM) to the ocean has been traditionally viewed to be minimal or only of significance in near-coastal continental margins. The broadly accepted explanation for the widespread loss of terrestrial lignin biomarkers and apparent disappearance of the <-25‰ stable carbon isotopic signature (δ¹³C) of TOM is that TOM is almost fully degraded before reaching the open ocean. Oceanic carbon (δ¹³C value ≥ -22‰) is therefore thought to be derived primarily from algae. However, an alternative explanation for the different molecular and δ¹³C signatures in terrestrial and marine environments may be that oxidative processing transforms TOM to appear marine-like. To test this hypothesis, we subjected eight TOM samples to a strong oxidation gradient. At carbon losses typical of TOM degradation during transport and sedimentation (above 60%), the differentiators of provenance disappeared, leaving a residue that was marine-like both chemically (aliphatic- and nitrogen-rich) and isotopically (δ¹³C enrichment of 4 to 9‰). This challenges the validity of conventional two-endmember mixing models, suggesting that a much larger fraction than previously estimated of the organic matter found in the ocean may originate from terrestrial sources, impacting global models of carbon cycling and sequestration.