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Brodersen KE, Mosshammer M, Bittner MJ, Hallstrøm S, Santner J, Riemann L, Kühl M. Seagrass-mediated rhizosphere redox gradients are linked with ammonium accumulation driven by diazotrophs. Microbiol Spectr 2024; 12:e0333523. [PMID: 38426746 DOI: 10.1128/spectrum.03335-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 01/24/2024] [Indexed: 03/02/2024] Open
Abstract
Seagrasses can enhance nutrient mobilization in their rhizosphere via complex interactions with sediment redox conditions and microbial populations. Yet, limited knowledge exists on how seagrass-derived rhizosphere dynamics affect nitrogen cycling. Using optode and gel-sampler-based chemical imaging, we show that radial O2 loss (ROL) from rhizomes and roots leads to the formation of redox gradients around below-ground tissues of seagrass (Zostera marina), which are co-localized with regions of high ammonium concentrations in the rhizosphere. Combining such chemical imaging with fine-scale sampling for microbial community and gene expression analyses indicated that multiple biogeochemical pathways and microbial players can lead to high ammonium concentration within the oxidized regions of the seagrass rhizosphere. Symbiotic N2-fixing bacteria (Bradyrhizobium) were particularly abundant and expressed the diazotroph functional marker gene nifH in Z. marina rhizosphere areas with high ammonium concentrations. Such an association between Z. marina and Bradyrhizobium can facilitate ammonium mobilization, the preferred nitrogen source for seagrasses, enhancing seagrass productivity within nitrogen-limited environments. ROL also caused strong gradients of sulfide at anoxic/oxic interfaces in rhizosphere areas, where we found enhanced nifH transcription by sulfate-reducing bacteria. Furthermore, we found a high abundance of methylotrophic and sulfide-oxidizing bacteria in rhizosphere areas, where O2 was released from seagrass rhizomes and roots. These bacteria could play a beneficial role for the plants in terms of their methane and sulfide oxidation, as well as their formation of growth factors and phytohormones. ROL from below-ground tissues of seagrass, thus, seems crucial for ammonium production in the rhizosphere via stimulation of multiple diazotrophic associations. IMPORTANCE Seagrasses are important marine habitats providing several ecosystem services in coastal waters worldwide, such as enhancing marine biodiversity and mitigating climate change through efficient carbon sequestration. Notably, the fitness of seagrasses is affected by plant-microbe interactions. However, these microscale interactions are challenging to study and large knowledge gaps prevail. Our study shows that redox microgradients in the rhizosphere of seagrass select for a unique microbial community that can enhance the ammonium availability for seagrass. We provide first experimental evidence that Rhizobia, including the symbiotic N2-fixing bacteria Bradyrhizobium, can contribute to the bacterial ammonium production in the seagrass rhizosphere. The release of O2 from rhizomes and roots also caused gradients of sulfide in rhizosphere areas with enhanced nifH transcription by sulfate-reducing bacteria. O2 release from seagrass root systems thus seems crucial for ammonium production in the rhizosphere via stimulation of multiple diazotrophic associations.
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Affiliation(s)
| | - Maria Mosshammer
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Meriel J Bittner
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Søren Hallstrøm
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Jakob Santner
- Department of Crop Sciences, Institute of Agronomy, University of Natural Resources and Life Sciences Vienna, Tulln an der Donau, Austria
| | - Lasse Riemann
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
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Zhang N, Liu Y, Wan Z, Zhang Y, Xie W, Zhang P, Tong M, Yuan S. Dependence of Biotic and Abiotic H 2O 2 and •OH Production on the Redox Conditions and Compositions of Sediment during Oxygenation. Environ Sci Technol 2024; 58:3849-3857. [PMID: 38349952 DOI: 10.1021/acs.est.3c10424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
Reactive oxygen species (ROS) production in O2-perturbed subsurface environments has been increasingly documented in recent years. However, the constraining conditions under which abiotic and/or biotic mechanisms predominate for ROS production remain ambiguous. Here, we demonstrate that the ROS production mechanism, biotic and abiotic, is determined by sediment redox properties and sediment compositions. Upon the oxygenation of 10 field sediments, the cumulative H2O2 concentrations reached up to 554 μmol/kg within 2 h. The autoclaving sterilization experiments showed that H2O2 could be produced by both biotic and abiotic processes depending on the redox conditions. However, only the abiotic process could produce significant levels of •OH, and the production yield was closely related to the sediment components, particularly sediment Fe(II) and organic matter. Fe(II) bound with organic matter led to high yields of H2O2 and •OH production. Sediment oxygenation contributed to the appearance of H2O2 in groundwater, with the abiotic mechanism producing higher instantaneous H2O2 concentrations than the biotic mechanism. These findings reveal that the redox conditions, compositions, and texture of sediments collectively control abiotic and biotic mechanisms for ROS production, which assists the identification of ROS production hotspots and the understanding of ROS distribution and utilization in the subsurface.
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Affiliation(s)
- Na Zhang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
- Hebei Key Laboratory of Wetland Ecology and Conservation, Hengshui University, 1088 Heping West Road, Hengshui 053000, P. R. China
| | - Ying Liu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Zhenchen Wan
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Yanting Zhang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Wenjing Xie
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Peng Zhang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Man Tong
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
| | - Songhu Yuan
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
- Hubei Key Laboratory of Yangze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, No. 68 Jincheng Street, East Lake High-Tech Development Zone, Wuhan 430078, P. R. China
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3
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Li C, Chen R, Ouyang W, Xue C, Liu M, Liu H. The response of C/N/S cycling functional microbial communities to redox conditions in shallow aquifers using in-situ sediment as bio-trap matrix. Environ Technol 2023:1-37. [PMID: 37323025 DOI: 10.1080/09593330.2023.2225704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Microbial communities are fundamental components driving critical biogeochemical carbon (C), nitrogen (N) and sulfur (S) cycles in groundwater ecosystems. The reduction-oxidation (redox) potential is one important environmental factor influencing the microbial community composition. Here, we developed a bio-trap method using in-situ sediment as a matrix to collect aquifer sediment samples and evaluate the response of microbial composition and C/N/S cycling functions to redox variations created by providing sole O2, joint O2 and H2, and sole H2 to three wells. Illumina sequencing analyses showed that the microbial communities in the bio-trap sediment could respond quickly to redox changes in the wells, demonstrating that this bio-trap method is promising for detecting microbial variation in the aquifer sediment. The microbial metabolic functions related to C, N and S cyclings and organic pollutants degradation were predicted by the Kyoto Encyclopedia of Genes and Genomes (KEGG) approach. It was found that the joint O2 and H2 injection produced medium oxidation-reduction potential (ORP -346 and -614 mV) and enhanced more microbial functions than sole O2 or H2, which mainly include oxidative phosphorylation, most carbon source metabolism, various pollutants degradation, and nitrogen and sulfur metabolism. Moreover, the functional genes encoding phenol monooxygenase, dioxygenase, nitrogen fixation, nitrification, aerobic and anaerobic nitrate reductase, nitrite reductase, nitric oxide reductase, and sulfur oxidation increased. These findings tell us the contaminant bioremediation and N, S metabolism can be promoted by adjusting ORP realised by injecting joint O2 and H2.
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Affiliation(s)
- Cui Li
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei 430078, PR China
- Hubei Ecology Polytechnic College, Wuhan, Hubei 430200, PR China
| | - Rong Chen
- School of Environmental and Biological Engineering, Wuhan Technology and Business University, Wuhan, Hubei 430065, PR China
| | - Weiwei Ouyang
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei 430078, PR China
| | - Chen Xue
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei 430078, PR China
| | - Minghui Liu
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei 430078, PR China
| | - Hui Liu
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei 430078, PR China
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, Hubei 430078, PR China
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Yu W, Chu C, Chen B. Pyrogenic Carbon Improves Cd Retention during Microbial Transformation of Ferrihydrite under Varying Redox Conditions. Environ Sci Technol 2023; 57:7875-7885. [PMID: 37171251 DOI: 10.1021/acs.est.3c01008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Fe(III) (oxyhydr)oxides are ubiquitous in paddy soils and play a key role in Cd retention. Recent studies report that pyrogenic carbon (PC) may largely affect the microbial transformation processes of Fe(III) (oxyhydr)oxides, yet the impact of PC on the fate of Fe(III) (oxyhydr)oxide-associated Cd during redox fluctuations remains unclear. Here, we investigated the effects of PC on Cd retention during microbial (Shewanella oneidensis MR-1) transformation of Cd(II)-bearing ferrihydrite under varying redox conditions. The results showed that in the absence of PC, microbial reduction of ferrihydrite resulted in Cd release under anoxic conditions and Fe(II) oxidation by oxygen resulted in Cd retention under subsequent oxic conditions. The presence of PC facilitated microbial ferrihydrite reductive dissolution under anoxic conditions, promoted Fe(II) oxidative precipitation under oxic conditions, and inhibited Cd release under both anoxic and oxic conditions. The presence of PC and frequent shifts in redox conditions (i.e., redox cycling) inhibited the transformation of ferrihydrite to highly crystalline goethite and magnetite that exhibited less Cd adsorption. As a result, PC enhanced Cd retention by 41-59% and 55-77% after the redox shift and redox cycling, respectively, while in the absence of PC, Cd retention decreased by 5% after the redox shift and increased by 11% after redox cycling. Sequential extraction analysis revealed that 63-78% of Cd was associated with Fe minerals, while 3-12% of Cd was bound to PC, indicating that PC promoted Cd retention mainly through inhibiting ferrihydrite transformation. Our results demonstrate the great impacts of PC on improving Cd retention under dynamic redox conditions, which is essential for applying PC in remediating Cd-contaminated paddy soils.
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Affiliation(s)
- Wentao Yu
- Department of Environmental Science, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou 310058, China
| | - Chiheng Chu
- Department of Environmental Science, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou 310058, China
| | - Baoliang Chen
- Department of Environmental Science, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou 310058, China
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Aiken M, Pace CE, Ramachandran M, Schwabe KA, Ajami H, Link BG, Ying SC. Disparities in Drinking Water Manganese Concentrations in Domestic Wells and Community Water Systems in the Central Valley, CA, USA. Environ Sci Technol 2023; 57:1987-1996. [PMID: 36696271 PMCID: PMC9910038 DOI: 10.1021/acs.est.2c08548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/05/2023] [Accepted: 01/06/2023] [Indexed: 06/17/2023]
Abstract
Over 1.3 million Californians rely on unmonitored domestic wells. Existing probability estimates of groundwater Mn concentrations, population estimates, and sociodemographic data were integrated with spatial data delineating domestic well communities (DWCs) to predict the probability of high Mn concentrations in extracted groundwater within DWCs in California's Central Valley. Additional Mn concentration data of water delivered by community water systems (CWSs) were used to estimate Mn in public water supply. We estimate that 0.4% of the DWC population (2342 users) rely on groundwater with predicted Mn > 300 μg L-1. In CWSs, 2.4% of the population (904 users) served by small CWSs and 0.4% of the population (3072 users) served by medium CWS relied on drinking water with mean point-of-entry Mn concentration >300 μg L-1. Small CWSs were less likely to report Mn concentrations relative to large CWSs, yet a higher percentage of small CWSs exceed regulatory standards relative to larger systems. Modeled calculations do not reveal differences in estimated Mn concentration between groundwater from current regional domestic well depth and 33 m deeper. These analyses demonstrate the need for additional well-monitoring programs that evaluate Mn and increased access to point-of-use treatment for domestic well users disproportionately burdened by associated costs of water treatment.
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Affiliation(s)
- Miranda
L. Aiken
- Environmental
Toxicology Graduate Program, University
of California, Riverside, California 92521, United States
- Schmid
College of Science and Technology, Chapman
University, Orange, CA 92866, United
States
| | - Clare E. Pace
- Environmental
Science, Policy, and Management, University
of California, Berkeley, California 94704, United States
| | - Maithili Ramachandran
- School
of Public Policy, University of California, Riverside, California 92521, United States
| | - Kurt A. Schwabe
- School
of Public Policy, University of California, Riverside, California 92521, United States
| | - Hoori Ajami
- Environmental
Sciences Department, University of California, Riverside, California 92521, United States
| | - Bruce G. Link
- School
of Public Policy, University of California, Riverside, California 92521, United States
| | - Samantha C. Ying
- Environmental
Toxicology Graduate Program, University
of California, Riverside, California 92521, United States
- Environmental
Sciences Department, University of California, Riverside, California 92521, United States
- Health
Disparities Research Center, University
of California, Riverside, California 92521, United States
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Bełdowski J, Miotk M, Pempkowiak J. Methylation index as means of quantification of the compliance of sedimentary mercury to be methylated. Environ Monit Assess 2015; 187:498. [PMID: 26160740 PMCID: PMC4498312 DOI: 10.1007/s10661-015-4716-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 06/29/2015] [Indexed: 05/15/2023]
Abstract
Methylmercury (MeHg) is the most bioavailable and toxic mercury species in the marine environment. MeHg concentration levels, methylation rates leading to MeHg formation, and methylation index (MI) are all used to assess the compliance of mercury to be methylated in the marine sedimentary environment. This paper reports on the works conducted on the MI upgrade. This paper proposes a new formula for calculating MI. Apart from labile mercury(II) and organic matter, it includes redox potential and abundance of sulfur-reducing bacteria (SRB), both essential factors for MeHg generation. The obtained MI is validated against actual sedimentary MeHg concentrations proving the potential usefulness of MI as a factor characterizing status of sedimentary environment regarding possible occurrence of MeHg. Moreover, values of the methylation index in particular regions show that MI values correspond well to environmental conditions in those areas. The values calculated correlate well with MeHg concentrations; however, the correlation coefficients vary between different regions. This has been attributed to the lack of empirical coefficients. Thus, MI could be used as a characteristic of the sedimentary environment indicating the potential presence of MeHg. It could also be used in methylation rate modeling, provided that empirical constants are applied to improve model performance.
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Affiliation(s)
- Jacek Bełdowski
- Institute of Oceanology PAN, ul. Powstańców Warszawy 55, 81-712, Sopot, Poland,
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7
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Willinger M, Rupp E, Barbaris B, Gao S, Arnolda R, Betterton E, Sáez AE. Thermocatalytic destruction of gas-phase perchloroethylene using propane as a hydrogen source. J Hazard Mater 2009; 167:770-6. [PMID: 19217713 PMCID: PMC2693271 DOI: 10.1016/j.jhazmat.2009.01.059] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 01/13/2009] [Accepted: 01/14/2009] [Indexed: 05/06/2023]
Abstract
The use of propane in combination with oxygen to promote the destruction of perchloroethylene (PCE) over a platinum (Pt)/rhodium (Rh) catalyst on a cerium/zirconium oxide washcoat supported on an alumina monolith was explored. Conversions of PCE were measured in a continuous flow reactor with residence times less than 0.5s and temperatures ranging from 200 to 600 degrees C. The presence of propane was shown to increase significantly the conversion of PCE over oxygen-only conditions. Conversions close to 100% were observed at temperatures lower than 450 degrees C with 20% oxygen and 2% propane in the feed, which makes this process attractive from a practical standpoint. In the absence of oxygen, PCE conversion is even higher, but the catalyst suffers significant deactivation in less than an hour. Even though results show that oxygen competes with reactants for active sites on the catalyst, the long-term stability that oxygen confers to the catalyst makes the process an efficient alternative to PCE oxidation. A Langmuir-Hinshelwood competitive adsorption model is proposed to quantify PCE conversion.
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Affiliation(s)
- Marty Willinger
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721
| | - Erik Rupp
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721
| | - Brian Barbaris
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721
- Department of Atmospheric Sciences, The University of Arizona, Tucson, AZ 85721
| | - Song Gao
- Department of Atmospheric Sciences, The University of Arizona, Tucson, AZ 85721
| | - Robert Arnolda
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721
| | - Eric Betterton
- Department of Atmospheric Sciences, The University of Arizona, Tucson, AZ 85721
| | - A. Eduardo Sáez
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721
- Corresponding author. E-mail:
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Orbay Ö, Gao S, Barbaris B, Rupp E, Sáez AE, Arnold RG, Betterton EA. Catalytic Dechlorination of Gas-phase Perchloroethylene under Mixed Redox Conditions. Appl Catal B 2008; 79:43-52. [PMID: 19234593 PMCID: PMC2390786 DOI: 10.1016/j.apcatb.2007.09.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The validity of a new method to destroy gas-phase perchloroethylene (PCE) is demonstrated at bench scale using a fixed-bed reactor that contains a Pt/Rh catalyst. Hydrogen and oxygen were simultaneously fed to the reactor together with PCE. The conversion efficiencies of PCE were sensitive to H(2)/O(2) ratio and reactor temperature. When the temperature was >/= 400 degrees C and H(2)/O(2) was >/= 2.15, PCE conversion efficiency was maintained at >/= 90%. No catalyst deactivation was observed for over two years, using only mild, convenient regeneration procedures. It is likely that PCE reduction steps precede oxidation reactions and that the importance of oxidation lies in its elimination of intermediates that would otherwise lead to catalyst poisoning. In practice, this catalytic dechlorination method holds potential for low-cost, large-scale field operation.
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Affiliation(s)
- Özer Orbay
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721
| | - Song Gao
- Department of Atmospheric Sciences, The University of Arizona, Tucson, AZ 85721
- Corresponding author. E-mail:
| | - Brian Barbaris
- Department of Atmospheric Sciences, The University of Arizona, Tucson, AZ 85721
| | - Erik Rupp
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721
| | - A. Eduardo Sáez
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721
| | - Robert G. Arnold
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721
| | - Eric A. Betterton
- Department of Atmospheric Sciences, The University of Arizona, Tucson, AZ 85721
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