Search

Your search keyword '"Qafoku, Odeta"' showing total 210 results
Start Over Author "Qafoku, Odeta" Language english
210 results on '"Qafoku, Odeta"'

15. Evaluation of materials for iodine and technetium immobilization through sorption and redox-driven processes

Author

Pearce, Carolyn I., Cordova, Elsa A., Garcia, Whitney L., Saslow, Sarah A., Cantrell, Kirk J., Morad, Joseph W., Qafoku, Odeta, Matyáš, Josef, Plymale, Andrew E., Chatterjee, Sayandev, Kang, Jaehyuk, Colon, Ferdinan Cintron, Levitskaia, Tatiana G., Rigali, Mark J., Szecsody, Jim E., Heald, Steve M., Balasubramanian, Mahalingam, Wang, Shuao, Sun, Daniel T., Queen, Wendy L., Bontchev, Ranko, Moore, Robert C., and Freedman, Vicky L.

Published
2020
Full Text
View/download PDF

17. Costs of Dust Collection by Trichodesmium: Effect on Buoyancy and Toxic Metal Release.

Author

Siyuan Wang, Futing Zhang, Koedooder, Coco, Qafoku, Odeta, Basu, Subhajit, Krisch, Stephan, Visser, Anna-Neva, Eichner, Meri, Kessler, Nivi, Boiteau, Rene M., Gledhill, Martha, and Shaked, Yeala

Abstract

The marine cyanobacterium Trichodesmium has the remarkable ability to interact with and utilize air-borne dust as a nutrient source. However, dust may adversely affect Trichodesmium through buoyancy loss and exposure to toxic metals. Our study explored the effect of desert dust on buoyancy and mortality of natural Red Sea puff-shaped Trichodesmium thiebautii. Sinking velocities and ability of individual colonies to stay afloat with increasing dust loads were studied in sedimentation chambers. Low dust loads of up to ~400 ng per colony did not impact initial sinking velocity and colonies remained afloat in the chamber. Above this threshold, sinking velocity increased linearly with the colony dust load at a slope matching prediction based on Stoke's law. The potential toxicity of dust was assessed with regards to metal dissolution kinetics, differentiating between rapidly released metals, which may impact surface blooms, and gradually released metals that may impact dustcentering colonies. Incubations with increasing dust concentrations revealed colony death, but the observed lethal dose far exceeded dust concentrations measured in coastal and open ocean systems. Removal of toxic particles as a mechanism to reduce toxicity was explored using SEM-EDX imaging of colonies incubated with Cu-minerals, yet observations did not support this pathway. Combining our current and former experiments, we suggest that in natural settings the nutritional benefits gained by Trichodesmium via dust collection outweigh the risks of buoyancy loss and toxicity. Our data and concepts feed into the growing recognition of the significance of dust for Trichodesmium's ecology and subsequently to ocean productivity. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

32. One thousand soils for molecular understanding of belowground carbon cycling.

Author

Bowman, Maggie M., Heath, Alexis E., Varga, Tamas, Battu, Anil K., Chu, Rosalie K., Toyoda, Jason, Cheeke, Tanya E., Porter, Stephanie S., Moffett, Kevan B., LeTendre, Brittany, Qafoku, Odeta, Bargar, John R., Mans, Douglas M., Hess, Nancy J., and Graham, Emily B.

Abstract

While significant progress has been made in understanding global carbon (C) cycling, the mechanisms regulating belowground C fluxes and storage are still uncertain. New molecular technologies have the power to elucidate these processes, yet we have no widespread standardized implementation of molecular techniques. To address this gap, we introduce the Molecular Observation Network (MONet), a decadal vision from the Environmental Molecular Sciences Laboratory (EMSL), to develop a national network for understanding the molecular composition, physical structure, and hydraulic and biological properties of soil and water. These data are essential for advancing the next generation of multiscale Earth systems models. In this paper, we discuss the 1000 Soils Pilot for MONet, including a description of standardized sampling materials and protocols and a use case to highlight the utility of molecular-level and microstructural measurements for assessing the impacts of wildfire on soil. While the 1000 Soils Pilot generated a plethora of data, we focus on assessments of soil organic matter (SOM) chemistry via Fouriertransform ion cyclotron resonance-mass spectrometry and microstructural properties via X-ray computed tomography to highlight the effects of recent fire history in forested ecosystems on belowground C cycling. We observed decreases in soil respiration, microbial biomass, and potential enzyme activity in soils with high frequency burns. Additionally, the nominal oxidation state of carbon in SOM increased with burn frequency in surface soils. This results in a quantifiable shift in the molecular signature of SOM and shows that wildfire may result in oxidation of SOM and structural changes to soil pore networks that persist into deeper soils. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

35. Scientific Reports

Author

Lybrand, Rebecca A, Qafoku, Odeta, Bowden, Mark E, Hochella, Michael F, Kovarik, Libor, Perea, Daniel E, Qafoku, Nikolla P, Schroeder, Paul A, Wirth, Mark G, and Zaharescu, Dragos G

Subjects
Multidisciplinary, weathering rinds, biomass, volcanic glass, ectomycorrhizal fungi, Silicates, growth, Hyphae, Forests, alteration textures, soil, Soil, mineral interactions, impact, dissolution rates
Abstract

Nutrient foraging by fungi weathers rocks by mechanical and biochemical processes. Distinguishing fungal-driven transformation from abiotic mechanisms in soil remains a challenge due to complexities within natural field environments. We examined the role of fungal hyphae in the incipient weathering of granulated basalt from a three-year field experiment in a mixed hardwood-pine forest (S. Carolina) to identify alteration at the nanometer to micron scales based on microscopy-tomography analyses. Investigations of fungal-grain contacts revealed (i) a hypha-biofilm-basaltic glass interface coinciding with titanomagnetite inclusions exposed on the grain surface and embedded in the glass matrix and (ii) native dendritic and subhedral titanomagnetite inclusions in the upper 1-2 mu m of the grain surface that spanned the length of the fungal-grain interface. We provide evidence of submicron basaltic glass dissolution occurring at a fungal-grain contact in a soil field setting. An example of how fungal-mediated weathering can be distinguished from abiotic mechanisms in the field was demonstrated by observing hyphal selective occupation and hydrolysis of glass-titanomagnetite surfaces. We hypothesize that the fungi were drawn to basaltic glass-titanomagnetite boundaries given that titanomagnetite exposed on or very near grain surfaces represents a source of iron to microbes. Furthermore, glass is energetically favorable to weathering in the presence of titanomagnetite. Our observations demonstrate that fungi interact with and transform basaltic substrates over a three-year time scale in field environments, which is central to understanding the rates and pathways of biogeochemical reactions related to nuclear waste disposal, geologic carbon storage, nutrient cycling, cultural artifact preservation, and soil-formation processes. Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility - Biological and Environmental Research program [49828, 51465, DE-AC05-76RL01830]; NSF [CAREER EAR-1945659, EAR-GEO-1331846]; [EAR-1023215] Published version A portion of this research was performed on project award no. 49828 and 51465 from the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility sponsored by the Biological and Environmental Research program under Contract No. DE-AC05-76RL01830. This work was partially supported by NSF Grant CAREER EAR-1945659 to R.A.L. and NSF grant EAR-GEO-1331846 to P.A.S. The granular basalt and granite used in our study was produced during an earlier project funded by EAR-1023215 that was awarded to Katerina Dontsova, Jon D. Chorover, Travis E. Huxman, and Raina M. Maier to whom we are very grateful. The CZO SAVI program also provided a valuable training opportunity with members of the Mineral Weathering Consortium, and the authors specifically thank Steven Banwart, Jonathan Leake, Liane Benning, and Joe Quirk for advice on the use of the in-soil mesh bag approach. The authors also thank Jay Austin, Andrew Martinez, Emma Talbot, Erica Flores, Stephan Hlohowskyj, Katarena Matos, Julia Perdrial, Nate Abramson, Jake Kelly, Vanessa Yubeta, Lauren Guthridge, Mathew Clark, James Olmid, Guillermo Molano, Andrew Toriello, Arturo Jacobo, Carmen Burghelea, Ed Hunt, Jennifer Presler, Viktor Polyakov, and Kenneth Kanipe for laboratory, logistical, and field support.

Published
2022

36. Nanoscale characterization of the sequestration and transformation of silver and arsenic in soil organic matter using atom probe tomography and transmission electron microscopy.

Author

Akbari Alavijeh, Mozhgan, Schindler, Michael, Wirth, Mark G., Qafoku, Odeta, Kovarik, Libor, and Perea, Daniel E.

Abstract

This study investigates the sequestration and transformation of silver (Ag) and arsenic (As) ions in soil organic matter (OM) at the nanoscale using the combination of atom probe tomography (APT), transmission electron microscopy (TEM), focused ion beam (FIB), ion mill thinning and scanning electron microscopy (SEM). Silver-arsenic contaminated organic-rich soils were collected along the shore of Cobalt Lake, a former mining and milling site of the famous Ag deposits at Cobalt, Ontario, Canada. SEM examinations show that particulate organic matter (OM grains) contains mineral inclusions composed of mainly Fe, S, and Si with minor As and traces of Ag. Four OM grains with detectable concentrations of Ag (by SEM-EDS) were further characterized with either a combination of TEM and APT or TEM alone. These examinations show that As is predominantly sequestered by OM through either co-precipitation with Fe-(hydr)oxide inclusions or adsorption on Fe-(hydr)oxides and their subsequent transformation into scorodite (FeAsO4·2H2O)/amorphous Fe-arsenate (AFA). Silver nanoparticles (NPs) with diameters in the range of ∼5–20 nm occur in the organic matrix as well as on the surface of Fe-rich inclusions (Fe-hydroxides, Fe-arsenates, Fe-sulfides), whereas Ag sulfide NPs were only observed on the surfaces of the Fe-rich inclusions. Rims of Ag-sulfides on Ag NPs (TEM data), accumulation of S atoms within and around Ag NPs (APT data), and the occurrence of dendritic as well as euhedral acanthite NPs with diameters in the range of ∼100–400 nm (TEM data) indicate that the sulfidation of the Ag NPs occurred via a mineral-replacement reaction (rims) or a complete dissolution of the Ag NPs, the subsequent precipitation of acanthite NPs and their aggregation (dendrites) and Ostwald ripening (euhedral crystals). These results show the importance of OM and, specifically the mineral inclusions in the sequestration of Ag and As to less bioavailable forms such as acanthite and scorodite, respectively. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

38. A Mineral-Doped Micromodel Platform Demonstrates Fungal Bridging of Carbon Hot Spots and Hyphal Transport of MineralDerived Nutrients.

Author

Bhattacharjee, Arunima, Qafoku, Odeta, Richardson, Jocelyn A., Anderson, Lindsey N., Schwarz, Kaitlyn, Bramer, Lisa M., Lomas, Gerard X., Orton, Daniel J., Zihua Zhu, Engelhard, Mark H., Bowden, Mark E., Nelson, William C., Jumpponen, Ari, Jansson, Janet K., Hofmockel, Kirsten S., and Anderton, Christopher R.

Published
2022
Full Text
View/download PDF

40. Atom probe tomography and transmission electron microscopy: a powerful combination to characterize the speciation and distribution of Cu in organic matter.

Author

Jadoon, Sarib, Schindler, Michael, Wirth, Mark G., Qafoku, Odeta, Kovarik, Libor, and Perea, Daniel E.

Abstract

The large surface areas in porous organic matter (OM) and on the surface of altered minerals control the sequestration of metal(loid)s in contaminated soils and sediments. This study explores the sequestration of Cu by OM in surficial forest soil in close proximity to the Horne smelter, Rouyn-Noranda, Quebec, Canada. The organic-rich soils have elevated concentrations of Cu (Cu = 〈0.75〉 wt%) but lack associations between organic matter (OM) and Cu-sulfides, commonly observed in organic-rich Cu-contaminated soils. This provides a unique opportunity to study the sequestration of Cu by OM in a sulfur-depleted environment using a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atom probe tomography (APT). In two examined OM particles, Cu is predominantly sequestered as (I) nano- to micrometer-size Cu-bearing spinels, (II) as cuprite (Cu2O) nanoparticles or (III) finely dispersed Cu in association with clusters of magnetite (Fe3O4) nanoparticles embedded in amorphous silica-rich pockets and (IV) in the OM matrix. The occurrence of euhedral crystals and nanoparticles in the single-digit range within the OM matrix indicate that the majority of the nanoparticles formed in situ within the OM particles. A model is developed which proposes that the sequestration of Cu in OM is promoted by (I) the partial mineralization of the OM matrix by amorphous silica; (II) the nucleation of magnetite nanoparticles on highly reactive silanol groups; (III) the diffusion of Cu within mineralized and altered areas of the OM; (IV) the availability of Cu-bearing species, which in turn is controlled by the hydrodynamic properties of the pore channels; (V) the formation of precursors and nucleation of Cu-bearing nanoparticles. This study shows that the combination of SEM, TEM and APT provides new insights into the sequestration of metal contaminants by OM at various scales ranging from the single-digit nano- to micrometer scale. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results