Physical Sciences and Mathematics Commons^™

Dark Iron-Catalyzed Reactions In Acidic And Viscous Aerosol Systems Efficiently Form Secondary Brown Carbon, Hind A. Al-Abadleh, Md Sohel Rana, Wisam Mohammed, Marcelo I. Guzman

Chemistry Faculty Publications

Iron-driven secondary brown carbon formation reactions from water-soluble organics in cloud droplets and aerosols create insoluble and soluble products of emerging atmospheric importance. This work shows, for the first time, results on dark iron-catalyzed polymerization of catechol forming insoluble black polycatechol particles and colored water-soluble oligomers under conditions characteristic of viscous multicomponent aerosol systems with relatively high ionic strength (I = 1–12 m) and acidic pH (∼2). These systems contain ammonium sulfate (AS)/nitrate (AN) and C3–C5 dicarboxylic acids, namely, malonic, malic, succinic, and glutaric acids. Using dynamic light scattering (DLS) and ultra high pressure liquid chromatography-mass spectrometry (UHPLC-MS), …

Modeling Holocene Peatland Carbon Accumulation In North America, Qianlai Zhuang, Sirui Wang, Bailu Zhao, Filipe Aires, Catherine Prigent, Zicheng Yu, Jason K. Keller, Scott Bridgham

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Peatlands are a large carbon reservoir. Yet the quantification of their carbon stock still has a large uncertainty due to lacking observational data and well‐tested peatland biogeochemistry models. Here, a process‐based peatland model was calibrated using long‐term peat carbon accumulation data at multiple sites in North America. The model was then applied to quantify the peat carbon accumulation rates and stocks within North America over the last 12,000 years. We estimated that 85–174 Pg carbon was accumulated in North American peatlands over the study period including 0.37–0.76 Pg carbon in subtropical peatlands. During the period from 10,000 to 8,000 years …

Effect Of Carbon Hybridization In C—F Bond As An Electron Donor In Triel Bonds, Qingqing Yang, Zongqing Chi, Qingzhong Li, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The ability of the F atom of HC≡CF, H₂C=CHF and H₃CCH₂F to serve as an electron donor to the triel (Tr) atom of TrR₃ in the context of a triel bond is assessed by ab initio calculations. The triel bond formed by C_sp3—F is strongest, as high as 30 kcal/mol, followed by C_sp2—F, and then by C_sp—F whose triel bonds can be as small as 1 kcal/mol. The noncovalent bond strength diminishes in the order Tr = Al > Ga > B, consistent with the intensity of the π-hole …

The Post-Wildfire Impact Of Burn Severity And Age On Black Carbon Snow Deposition And Implications For Snow Water Resources, Cascade Range, Washington, Ted M. Uecker, Susan D. Kaspari, Keith N. Musselman, S. Mckenzie Skiles

Geological Sciences Faculty Scholarship

Wildfires in the snow zone affect ablation by removing forest canopy, which enhances surface solar irradiance, and depositing light absorbing particles [LAPs, such as black carbon (BC)] on the snowpack, reducing snow albedo. How variations in BC deposition affects post-wildfire snowmelt timing is poorly known and highly relevant to water resources. We present a field-based analysis of BC variability across five sites of varying burn age and burn severity in the Cascade Range, Washington State, United States. Single particle soot photometer (SP2) analyses of BC snow concentrations were used to assess the impact of BC on snow albedo, and radiative …

Diffuse Spectra Model Of Photoluminescence In Carbon Quantum Dots, S. E. Kumekov, N. K. Saitova, Karen S. Martirosyan

Physics and Astronomy Faculty Publications and Presentations

The attractive aspect of excitation related to fluorescence nature in carbon quantum dots (CQD) has guided to several assumptions correlated with clusters size distribution, shapes as well as presence of different emissive states. In this study, a dimer–excimer model of photoluminescence (PL) in CQD describing discrete multiple electronic states for the excitation-dependent emission is described. The functional dependence of the characteristic width of the diffuse spectra of PL on the size of a quantum dots are calculated. The effective width of PL spectrum can be tuned from 0.1 to 1 eV.

Synergistic Use Of Remote Sensing And Modeling For Estimating Net Primary Productivity In The Red Sea With Vgpm, Eppley-Vgpm, And Cbpm Models Intercomparison, Wenzhao Li, Surya Prakash Tiwari, Hesham El-Askary, Mohamed Ali Qurban, Vassilis Amiridis, K. P. Manikandan, Michael J. Garay, Olga V. Kalashnikova, Thomas C. Piechota, Daniele C. Struppa

Mathematics, Physics, and Computer Science Faculty Articles and Research

Primary productivity (PP) has been recently investigated using remote sensing-based models over quite limited geographical areas of the Red Sea. This work sheds light on how phytoplankton and primary production would react to the effects of global warming in the extreme environment of the Red Sea and, hence, illuminates how similar regions may behave in the context of climate variability. study focuses on using satellite observations to conduct an intercomparison of three net primary production (NPP) models--the vertically generalized production model (VGPM), the Eppley-VGPM, and the carbon-based production model (CbPM)--produced over the Red Sea domain for the 1998-2018 time period. …

Organic Sulfur: A Spatially Variable And Understudied Component Of Marine Organic Matter, Krista Longnecker, Lisa Oswald, Melissa C. Kido Soule, Gregory A. Cutter, Elizabeth B. Kujawinski

OES Faculty Publications

Sulfur (S) is a major heteroatom in organic matter. This project evaluated spatial variability in the concentration and molecular-level composition of organic sulfur along gradients of depth and latitude. We measured the concentration of total organic sulfur (TOS) directly from whole seawater. Our data reveal high variability in organic sulfur, relative to established variability in total organic carbon or nitrogen. The deep ocean contained significant amounts of organic sulfur, and the concentration of TOS in North Atlantic Deep Water (NADW) decreased with increasing age while total organic carbon remained stable. Analysis of dissolved organic matter extracts by ultrahigh resolution mass …

Green Edge Ice Camp Campaigns: Understanding The Processes Controlling The Under-Ice Arctic Phytoplankton Spring Bloom, Philippe Massicotte, Rémi Amiraux, Marie-Pier Amyot, Philippe Archambault, Mathieu Ardyna, Laurent Arnaud, Lise Artigue, Cyril Aubry, Pierre Ayotte, Guislain Bécu, Simon Bélanger, Ronald Benner, Henry C. Bittig, Annick Bricaud, Éric Brossier, Flavienne Bruyant, Et. Al.

Faculty Publications

The Green Edge initiative was developed to investigate the processes controlling the primary productivity and fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797∘ N, 63.7895∘ W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea-ice cover from the surface to the bottom (at 360 m depth) to better understand the factors driving the …

Carbon And Nitrogen Recycling During Cyanohabs In Dreissenid-Invaded And Non-Invaded Us Midwestern Lakes And Reservoirs, Trinity L. Hamilton, Jessica Corman, Jeff R. Havig

School of Natural Resources: Faculty Publications

Lakes and reservoirs play key roles in global carbon cycling, especially as a carbon sink. Enrichment of nutrients in lakes and reservoirs (eutrophication) and rising global temperatures favors the proliferation of bloom-forming cyanobacteria. Harmful blooms of cyanobacteria (cyanoHABs) alter carbon and nutrient cycling in freshwater ecosystems. Some evidence suggests the introduction or establishment of invasive mussel species (i.e., Dreissena spp.) also favor cyanoHAB formation through selective filter feeding, a process through which they may also impact biogeochemical processes including carbon cycling and sequestration. However, few studies have considered the combined effects of invasive mussels and cyanoHABs on carbon and nitrogen …

Geochemical Flux Analysis Of Glacial River Runoff For Sólheimajökull, Iceland, Jessica Garrison

Mahurin Honors College Capstone Experience/Thesis Projects

Geochemical fluxes in aqueous studies are an essential component of research to understand weathering and changes in a hydrologic system. These data can indicate any discrepancies, outliers, or gradual changes in a water environment to gain information on pollutants, carbon cycles, biological input, etc. Glacial melt is the majority of the surface water present throughout the country. The melting amount is increasing with the temperatures, which can be monitored by the changes in geochemical flux during increased discharge in glacial rivers. A high-resolution data set of Sόlheimajökull Glacier in Iceland was used to determine how changing climatic conditions for the …

A Synthesis Of The Effects Of Cheatgrass Invasion On The Us Great Basin Carbon Storage, R. Chelsea Nagy, Emily J. Fusco, Jennifer K. Balch, John T. Finn, Adam Mahood, Jenica M. Allen, Bethany A. Bradley

Environmental Conservation Faculty Publication Series

1. Non‐native, invasive Bromus tectorum (cheatgrass) is pervasive in sagebrush ecosystems in the Great Basin ecoregion of the western United States, competing with native plants and promoting more frequent fires. As a result, cheatgrass invasion likely alters carbon (C) storage in the region. Many studies have measured C pools in one or more common vegetation types: native sagebrush, invaded sagebrush and cheatgrass‐dominated (often burned) sites, but these results have yet to be synthesized.
2. We performed a literature review to identify studies assessing the consequences of invasion on C storage in above‐ground biomass (AGB), below‐ground biomass (BGB), litter, organic soil and total …

S/N-Doped Carbon Nanofibers Affording Fe7s8 Particles With Superior Sodium Storage, Xiu Li, Tao Liu, Yunxiao Wang, Shulei Chou, Xun Xu, Anmin Cao, Libao Chen

Australian Institute for Innovative Materials - Papers

2020 Iron sulfides draw much attention as electrode candidates for sodium-ion batteries (SIBs) due to the rich chemical stoichiometries and high capacity. However, they usually exhibit poor cycling performance due to the large volume change during sodiation/desodiation process. In this work, we embed Fe7S8 nanoparticles into sulfur, nitrogen-doped carbon (S/N-C) nanofibers through electrospinning/sulfurization processes. The heteroatom doped carbon matrixes could effectively protect the Fe7S8 from structural collapse, obtaining a stable cycling performance. Moreover, the conductive matrixes with 1D structure can facilitate the diffusion of electrons, leading to good rate capability. As results, the as-designed Fe7S8@S/N-C nanofibers present a discharge capacity …

The Importance Of Catchments To Mine-Pit Lakes: Implications For Closure, Mark Lund, Eddie Van Etten, Jonas Polifka, Marylin Quintero Vasquez, Ravish Ramessur, Dechen Yangzom, Melanie L. Blanchette

Research outputs 2014 to 2021

Despite the large body of riparian literature for rivers and lakes, there are few studies on the catchments of mine pit lakes. Therefore, the broad objective of this research was to determine if catchment characteristics were related to pit lake nutrient concentrations. We hypothesised that: (1) catchment characteristics would vary among pit lakes, (2) pit lake catchments would differ from co-occurring naturally-forested catchments, and (3) connecting a pit lake (Kepwari) to a naturally-forested catchment via a river flow-through would increase C accumulation in the lake. The research was conducted in pit lakes of the Collie lake district in Western Australia …

Global Database Of Ratios Of Particulate Organic Carbon To Thorium-234 In The Ocean: Improving Estimates Of The Biological Carbon Pump, Viena Puigcorbe, Pere Masque, Frederic A.C. Le Moigne

Research outputs 2014 to 2021

The ocean's biological carbon pump (BCP) plays a major role in the global carbon cycle. A fraction of the photosynthetically fixed organic carbon produced in surface waters is exported below the sunlit layer as settling particles (e.g., marine snow). Since the seminal works on the BCP, global estimates of the global strength of the BCP have improved but large uncertainties remain (from 5 to 20 Gt C yr−1 exported below the euphotic zone or mixed-layer depth). The 234Th technique is widely used to measure the downward export of particulate organic carbon (POC). This technique has the advantage of allowing a …