1
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Hu Y, Deng Q, Kätterer T, Olesen JE, Ying SC, Ochoa-Hueso R, Mueller CW, Weintraub MN, Chen J. Depth-dependent responses of soil organic carbon under nitrogen deposition. Glob Chang Biol 2024; 30:e17247. [PMID: 38491798 DOI: 10.1111/gcb.17247] [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] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 02/06/2024] [Accepted: 03/05/2024] [Indexed: 03/18/2024]
Abstract
Emerging evidence points out that the responses of soil organic carbon (SOC) to nitrogen (N) addition differ along the soil profile, highlighting the importance of synthesizing results from different soil layers. Here, using a global meta-analysis, we found that N addition significantly enhanced topsoil (0-30 cm) SOC by 3.7% (±1.4%) in forests and grasslands. In contrast, SOC in the subsoil (30-100 cm) initially increased with N addition but decreased over time. The model selection analysis revealed that experimental duration and vegetation type are among the most important predictors across a wide range of climatic, environmental, and edaphic variables. The contrasting responses of SOC to N addition indicate the importance of considering deep soil layers, particularly for long-term continuous N deposition. Finally, the lack of depth-dependent SOC responses to N addition in experimental and modeling frameworks has likely resulted in the overestimation of changes in SOC storage under enhanced N deposition.
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Affiliation(s)
- Yuanliu Hu
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems/Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- South China National Botanical Garden, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
- Department of Agroecology, Aarhus University, Tjele, Denmark
| | - Qi Deng
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems/Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- South China National Botanical Garden, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Thomas Kätterer
- Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jørgen Eivind Olesen
- Department of Agroecology, Aarhus University, Tjele, Denmark
- Aarhus University Centre for Circular Bioeconomy, Aarhus University, Tjele, Denmark
| | - Samantha C Ying
- Department of Environmental Sciences, University of California, Riverside, California, USA
| | - Raúl Ochoa-Hueso
- Department of Biology, IVAGRO, University of Cádiz, Campus de Excelencia Internacional Agroalimentario (CeiA3), Cádiz, Spain
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Carsten W Mueller
- Institute of Ecology, Chair of Soil Science, Technische Universitaet Berlin, Berlin, Germany
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Michael N Weintraub
- Department of Environmental Sciences, University of Toledo, Toledo, Ohio, USA
| | - Ji Chen
- Department of Agroecology, Aarhus University, Tjele, Denmark
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China
- Institute of Global Environmental Change, Department of Earth and Environmental Science, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
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2
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Aiken M, Ying SC. Small Community Water Systems Have the Highest Prevalence of Mn in Drinking Water in California, USA. ACS ES T Water 2023; 3:2168-2178. [PMID: 37588804 PMCID: PMC10425977 DOI: 10.1021/acsestwater.3c00007] [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] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 04/12/2023] [Accepted: 04/13/2023] [Indexed: 08/18/2023]
Abstract
Manganese (Mn) is currently regulated as a secondary contaminant in California, USA; however, recent revisions of the World Health Organization drinking water guidelines have increased regulatory attention of Mn in drinking water due to increasing reports of neurotoxic effects in infants and children. In this study, Mn concentrations reported to California's Safe Drinking Water Information System were used to estimate the potentially exposed population within California based on system size. We estimate that between 2011 and 2021, over 525,000 users in areas with reported Mn data are potentially exposed to Mn concentrations exceeding the WHO health-based guideline (80 μg L-1), and over 34,000 users are potentially exposed to Mn concentrations exceeding the U.S. Environmental Protection Agency health-advisory limit (300 μg L-1). Water treatment significantly decreased Mn concentrations compared to intake concentrations for all system sizes. However, smaller water systems have a wider range and a higher skew of Mn concentrations in finished water than larger systems. Additionally, higher Mn concentrations were found in systems above the maximum contaminant levels for chromium and arsenic. The treatment of these primary contaminants appears to also remove Mn. Lastly, data missingness remains a barrier to accurately assess public exposure to Mn in very small, small, and medium community water system-delivered water.
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Affiliation(s)
- Miranda
L. Aiken
- School
of Earth and Environmental Sciences, Schmid College of Science and
Technology, Chapman University, Orange, California 92866, United States
| | - Samantha C. Ying
- Schmid
College of Science and Technology, Chapman
University, Orange, California 92866, United States
- Environmental
Sciences Department, University of California, Riverside, California 92521, United States
- Planetary
Health Center, University of California
Global Health Institute, San Francisco, California, 94158, United States
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3
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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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4
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Luo M, Moorhead DL, Ochoa‐Hueso R, Mueller CW, Ying SC, Chen J. Nitrogen loading enhances phosphorus limitation in terrestrial ecosystems with implications for soil carbon cycling. Funct Ecol 2022. [DOI: 10.1111/1365-2435.14178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Min Luo
- Academy of Geography and Ecological Environment Fuzhou University Fuzhou China
- College of Environment and Safety Engineering Fuzhou University Fuzhou China
| | - Daryl L. Moorhead
- Department of Environmental Sciences University of Toledo Toledo OH USA
| | - Raúl Ochoa‐Hueso
- Department of Biology, IVAGRO University of Cádiz, Campus de Excelencia Internacional Agroalimentario (CeiA3), Campus del Rio San Pedro, 11510 Puerto Real Cádiz Spain
- Department of Terrestrial Ecology Netherlands Institute of Ecology (NIOO‐KNAW) AB Wageningen the Netherlands
| | - Carsten W. Mueller
- Department of Geosciences and Natural Resource Management University of Copenhagen Copenhagen Denmark
| | - Samantha C. Ying
- Environmental Sciences Department University of California‐ Riverside CA USA
| | - Ji Chen
- Department of Agroecology Aarhus University Tjele Denmark
- Aarhus University Centre for Circular Bioeconomy, Aarhus University Tjele Denmark
- iCLIMATE Interdisciplinary Centre for Climate Change Aarhus University Roskilde Denmark
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5
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Abernathy M, Schaefer MV, Ramirez R, Garniwan A, Lee I, Zaera F, Polizzotto ML, Ying SC. Vanadate Retention by Iron and Manganese Oxides. ACS Earth Space Chem 2022; 6:2041-2052. [PMID: 36016759 PMCID: PMC9393891 DOI: 10.1021/acsearthspacechem.2c00116] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 07/04/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Anthropogenic emissions of vanadium (V) into terrestrial and aquatic surface systems now match those of geogenic processes, and yet, the geochemistry of vanadium is poorly described in comparison to other comparable contaminants like arsenic. In oxic systems, V is present as an oxyanion with a +5 formal charge on the V center, typically described as H x VO4 (3-x)-, but also here as V(V). Iron (Fe) and manganese (Mn) (oxy)hydroxides represent key mineral phases in the cycling of V(V) at the solid-solution interface, and yet, fundamental descriptions of these surface-processes are not available. Here, we utilize extended X-ray absorption fine structure (EXAFS) and thermodynamic calculations to compare the surface complexation of V(V) by the common Fe and Mn mineral phases ferrihydrite, hematite, goethite, birnessite, and pyrolusite at pH 7. Inner-sphere V(V) complexes were detected on all phases, with mononuclear V(V) species dominating the adsorbed species distribution. Our results demonstrate that V(V) adsorption is exergonic for a variety of surfaces with differing amounts of terminal -OH groups and metal-O bond saturations, implicating the conjunctive role of varied mineral surfaces in controlling the mobility and fate of V(V) in terrestrial and aquatic systems.
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Affiliation(s)
- Macon
J. Abernathy
- Stanford
Synchrotron Radiation Lightsource, SLAC
National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Michael V. Schaefer
- Department
of Earth and Environmental Science, New
Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, United States
| | - Roxana Ramirez
- Environmental
Sciences Department, University of California-Riverside, Riverside, California 92521, United States
| | - Abdi Garniwan
- Environmental
Sciences Department, University of California-Riverside, Riverside, California 92521, United States
| | - Ilkeun Lee
- Department
of Chemistry, University of California-Riverside, Riverside, California 92521, United States
| | - Francisco Zaera
- Department
of Chemistry, University of California-Riverside, Riverside, California 92521, United States
| | - Matthew L. Polizzotto
- Department
of Earth Sciences, University of Oregon, Eugene, Oregon 97403, United States
| | - Samantha C. Ying
- Environmental
Sciences Department, University of California-Riverside, Riverside, California 92521, United States
- Environmental
Toxicology Graduate Program, University
of California-Riverside, Riverside, California 92521, United States
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6
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Yang SY, Li SH, Liu JL, Sun XQ, Cen YY, Ren RY, Ying SC, Chen Y, Zhao ZH, Liao W. Histopathology-Based Diagnosis of Oral Squamous Cell Carcinoma Using Deep Learning. J Dent Res 2022; 101:1321-1327. [PMID: 35446176 DOI: 10.1177/00220345221089858] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Oral squamous cell carcinoma (OSCC) is prevalent around the world and is associated with poor prognosis. OSCC is typically diagnosed from tissue biopsy sections by pathologists who rely on their empirical experience. Deep learning models may improve the accuracy and speed of image classification, thus reducing human error and workload. Here we developed a custom-made deep learning model to assist pathologists in detecting OSCC from histopathology images. We collected and analyzed a total of 2,025 images, among which 1,925 images were included in the training set and 100 images were included in the testing set. Our model was able to automatically evaluate these images and arrive at a diagnosis with a sensitivity of 0.98, specificity of 0.92, positive predictive value of 0.924, negative predictive value of 0.978, and F1 score of 0.951. Using a subset of 100 images, we examined whether our model could improve the diagnostic performance of junior and senior pathologists. We found that junior pathologists were able to delineate OSCC in these images 6.26 min faster when assisted by the model than when working alone. When the clinicians were assisted by the model, their average F1 score improved from 0.9221 to 0.9566 in the case of junior pathologists and from 0.9361 to 0.9463 in the case of senior pathologists. Our findings indicate that deep learning can improve the accuracy and speed of OSCC diagnosis from histopathology images.
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Affiliation(s)
- S Y Yang
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - S H Li
- National Key Laboratory of Fundamental Science on Synthetic Vision, College of Computer Science, Sichuan University, Chengdu, Sichuan, China
| | - J L Liu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - X Q Sun
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Y Y Cen
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - R Y Ren
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - S C Ying
- College of Computer Science, Sichuan University, Chengdu, Sichuan, China
| | - Y Chen
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Z H Zhao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - W Liao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
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7
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Abstract
Vanadium is a redox-active metal that has been added to the EPA's Contaminant Candidate List with a notification level of 50 μg L-1 due to mounting evidence that VV exposure can lead to adverse health outcomes. Groundwater V concentration exceeds the notification level in many locations, yet geochemical controls on its mobility are poorly understood. Here, we examined the redox interaction between VIV and birnessite (MnO2), a well-characterized oxidant and a scavenger of many trace metals. In our findings, birnessite quickly oxidized sparingly soluble VIV species such as häggite [V2O3(OH)2] into highly mobile and toxic vanadate (HnVO4(3-n)-) in continuously stirred batch reactors under neutral pH conditions. Synchrotron X-ray absorption spectroscopic (XAS) analysis of in situ and ex situ experiments showed that oxidation of VIV occurs in two stages, which are both rapid relative to the measured dissolution rate of the VIV solid. Concomitantly, the reduction of birnessite during VIV oxidation generated soluble MnII, which led to the formation of the MnIII oxyhydroxide feitknechtite (β-MnOOH) upon back-reaction with birnessite. XAS analysis confirmed a bidentate-mononuclear edge-sharing complex formed between VV and birnessite, although retention of VV was minimal relative to the aqueous quantities generated. In summary, we demonstrate that Mn oxides are effective oxidants of VIV in the environment with the potential to increase dissolved V concentrations in aquifers subject to redox oscillations.
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Affiliation(s)
- Macon J Abernathy
- Environmental Toxicology Program, University of California-Riverside, Riverside, California 92521, United States
| | - Michael V Schaefer
- Department of Environmental Science, University of California-Riverside, Riverside, California 92521, United States
- Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, United States
| | - Colton J Vessey
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Haizhou Liu
- Environmental Toxicology Program, University of California-Riverside, Riverside, California 92521, United States
- Department of Chemical and Environmental Engineering, University of California-Riverside, Riverside, California 92521, United States
| | - Samantha C Ying
- Environmental Toxicology Program, University of California-Riverside, Riverside, California 92521, United States
- Department of Environmental Science, University of California-Riverside, Riverside, California 92521, United States
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8
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Schaefer MV, Abernathy MJ, Nguyen D, Cornell T, Ying SC. Firing Increases Arsenic Leaching from Ceramic Water Filters via Arsenic and Iron Phase Transformations. Environ Sci Technol 2021; 55:9826-9835. [PMID: 34232034 PMCID: PMC8761037 DOI: 10.1021/acs.est.1c00169] [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] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Ceramic water filters (CWFs) are produced globally using local clay sources and can effectively remove bacterial pathogens during point-of-use water treatment. The ceramic production process involves firing clay mixed with burnout material at temperatures of 800-1100 °C, which induces mineralogical changes leading to increased arsenic (As) leaching from CWF material compared to source clay. Unfired clay and fired CWFs from Cambodia, Canada, and Mexico, CWF from Laos, and test-fired clay from the United States were analyzed to determine the extent of As leaching from CWFs that range in As (<1 to 16 mg kg-1) and iron (Fe) (0.6 to 5%) content. Deionized water, NaOH, HCl, and oxalate extractions showed that firing increased As solubility and decreased Fe solubility compared to unfired clay, with up to 8 mg kg-1 of water-soluble As in Cambodian CWFs. X-ray absorption spectra of the Cambodian clay and CWF showed a decrease in the Fe-O distance from 2.01 to 1.91 Å and decreased Fe coordination number from 6.3 to 4.6 after firing, indicating a decrease in Fe-O coordination. Arsenic(V) was the dominant species in Cambodia clay and CWF, existing primarily as a surface complex with average As-Fe distance of 3.28 Å in clay while in CWF As was either an outer-sphere As(V) phase or a discrete arsenate phase with no significant As-Fe scattering contribution within the resolution of the data. Improved understanding of molecular-scale processes that cause increased As leaching from CWFs provides a basis for assessing As leaching potential prior to CWF factory capital investment as well as engineered solutions (e.g., modified firing temperature, material amendments, and leaching prior to distribution) to mitigate As exposure from CWFs.
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Affiliation(s)
- Michael V Schaefer
- Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, United States
| | - Macon J Abernathy
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521, United States
| | - Dominique Nguyen
- Department of Environmental Sciences, University of California, Riverside, California 92521, United States
| | - Thida Cornell
- Department of Environmental Sciences, University of California, Riverside, California 92521, United States
| | - Samantha C Ying
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521, United States
- Department of Environmental Sciences, University of California, Riverside, California 92521, United States
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9
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Zhuang W, Liu M, Song J, Ying SC. Retention of thallium by natural minerals: A review. Sci Total Environ 2021; 777:146074. [PMID: 33676216 DOI: 10.1016/j.scitotenv.2021.146074] [Citation(s) in RCA: 6] [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] [Received: 12/23/2020] [Revised: 02/18/2021] [Accepted: 02/20/2021] [Indexed: 06/12/2023]
Abstract
Though thallium (Tl) is usually present in trace amounts in natural environments, its biotoxicity is extremely high. With the development of mining, the metallurgy industry, and the growing application of Tl in high-tech fields, the threat of Tl to ecological environments and human health is increasing. Natural minerals, such as clay minerals, iron oxides, and manganese oxides, are natural Tl adsorbents due to their mineralogy and crystal structures. In this review, we discuss the mechanisms of Tl adsorption by various natural minerals, compare the adsorption capacities of common soil minerals for Tl, and describe the limitations of traditional sequential extraction methods for identifying the chemical states of Tl on minerals and source of Tl. We also provide suggestions on future directions needed in Tl research including a) additional in-depth studies on the competitive adsorption of Tl by minerals; b) more direct comparison of Tl adsorption behavior from lab-based experiments with field observations to clarify the mechanisms of Tl adsorption by minerals under environmental conditions; c) more research data are needed to support the establishment and improvement of relevant research methods based on modern leading-edge technologies such as synchrotron radiation. Further, we suggest further research is needed in adsorption technologies used for Tl treatment. This is the first review on the research progress of Tl adsorption by natural minerals with the purpose of helping understanding the mechanisms of Tl migration and transformation controlled by natural minerals, and providing theoretical supports for the development of Tl adsorbents and the treatments of Tl pollution.
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Affiliation(s)
- Wen Zhuang
- Institute of Eco-environmental Forensics, Shandong University, Qingdao, Shandong 266237, China; Ministry of Justice Hub for Research and Practice in Eco-Environmental Forensics, Shandong University, Qingdao, Shandong 266237, China.
| | - Min Liu
- Institute of Eco-environmental Forensics, Shandong University, Qingdao, Shandong 266237, China; Ministry of Justice Hub for Research and Practice in Eco-Environmental Forensics, Shandong University, Qingdao, Shandong 266237, China
| | - Jinming Song
- Key Laboratory of Marine Ecology and Environmental Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong 266071, China.
| | - Samantha C Ying
- Department of Environmental Sciences, University of California, Riverside, California 92521, United States
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10
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Queiroz HM, Ying SC, Bernardino AF, Barcellos D, Nóbrega GN, Otero XL, Ferreira TO. Role of Fe dynamic in release of metals at Rio Doce estuary: Unfolding of a mining disaster. Mar Pollut Bull 2021; 166:112267. [PMID: 33752157 DOI: 10.1016/j.marpolbul.2021.112267] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [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: 11/13/2020] [Revised: 03/03/2021] [Accepted: 03/09/2021] [Indexed: 06/12/2023]
Abstract
The role of Fe oxyhydroxides dynamic on metal bioavailability was studied in the Rio Doce estuary after the largest mining disaster in the world. Soon after the disaster in 2015, metals were associated with Fe oxyhydroxides under a redox-active estuarine environment. Our results indicate that organic matter inputs from plant colonization on deposited tailings over estuarine soils led to a reductive dissolution of Fe oxyhydroxides within two years. Soil pseudo-total Fe content decreased by 70% between 2015 and 2017, while the total metal contents (Cr, Cu, Ni, Pb, and Zn) decreased by 79% in the soil. The losses of Fe and metals coupled to changes in Fe oxides crystallinity reveal a future ephemeral control of Fe oxyhydroxides over metal immobilization. Our results suggest a potential chronic contamination at the estuary and points to an aggravating scenario for the following years due to the increasing dominance of poorly crystalline Fe oxyhydroxides.
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Affiliation(s)
- Hermano M Queiroz
- Luiz de Queiroz College of Agriculture, University of São Paulo (ESALQ-USP), Av. Pádua Dias 11, CEP 13418-900 Piracicaba, São Paulo, Brazil
| | - Samantha C Ying
- Environmental Toxicology Graduate Program, University of California, Riverside, CA 92521, United States; Department of Environmental Sciences, University of California, Riverside, CA 92521, United States
| | - Angelo F Bernardino
- Departamento de Oceanografia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo 29075-910, Brazil
| | - Diego Barcellos
- Luiz de Queiroz College of Agriculture, University of São Paulo (ESALQ-USP), Av. Pádua Dias 11, CEP 13418-900 Piracicaba, São Paulo, Brazil
| | - Gabriel N Nóbrega
- CRETUS Institute, Department of Edaphology and Agricultural Chemistry - Faculty of Biology, Universidade de Santiago de Compostela, Campus Sur, 15782 Santiago de Compostela, Spain
| | - Xosé L Otero
- Graduate Program in Earth Sciences (Geochemistry), Department of Geochemistry Federal Fluminense University Niterói, Brazil
| | - Tiago O Ferreira
- Luiz de Queiroz College of Agriculture, University of São Paulo (ESALQ-USP), Av. Pádua Dias 11, CEP 13418-900 Piracicaba, São Paulo, Brazil.
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11
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Liu JL, Li SH, Cai YM, Lan DP, Lu YF, Liao W, Ying SC, Zhao ZH. Automated Radiographic Evaluation of Adenoid Hypertrophy Based on VGG-Lite. J Dent Res 2021; 100:1337-1343. [PMID: 33913367 DOI: 10.1177/00220345211009474] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Adenoid hypertrophy is a pathological hyperplasia of the adenoids, which may cause snoring and apnea, as well as impede breathing during sleep. The lateral cephalogram is commonly used by dentists to screen for adenoid hypertrophy, but it is tedious and time-consuming to measure the ratio of adenoid width to nasopharyngeal width for adenoid assessment. The purpose of this study was to develop a screening tool to automatically evaluate adenoid hypertrophy from lateral cephalograms using deep learning. We proposed the deep learning model VGG-Lite, using the largest data set (1,023 X-ray images) yet described to support the automatic detection of adenoid hypertrophy. We demonstrated that our model was able to automatically evaluate adenoid hypertrophy with a sensitivity of 0.898, a specificity of 0.882, positive predictive value of 0.880, negative predictive value of 0.900, and F1 score of 0.889. The comparison of model-only and expert-only detection performance showed that the fully automatic method (0.07 min) was about 522 times faster than the human expert (36.6 min). Comparison of human experts with or without deep learning assistance showed that model-assisted human experts spent an average of 23.3 min to evaluate adenoid hypertrophy using 100 radiographs, compared to an average of 36.6 min using an entirely manual procedure. We therefore concluded that deep learning could improve the accuracy, speed, and efficiency of evaluating adenoid hypertrophy from lateral cephalograms.
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Affiliation(s)
- J L Liu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - S H Li
- National Key Laboratory of Fundamental Science on Synthetic Vision, College of Computer Science, Sichuan University, Chengdu, Sichuan, China
| | - Y M Cai
- Department of Dental Technology, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - D P Lan
- Department of Dental Technology, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Y F Lu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - W Liao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - S C Ying
- College of Computer Science, Sichuan University, Chengdu, Sichuan, China
| | - Z H Zhao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
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12
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Affiliation(s)
- Maithili Ramachandran
- School of Public Policy, University of California, Riverside, Riverside, California United States
| | - Kurt A Schwabe
- School of Public Policy, University of California, Riverside, Riverside, California United States
- Water Policy Center, Public Policy Institute of California, San Francisco, California United States
| | - Samantha C Ying
- Environmental Sciences, University of California, Riverside, Riverside, California United States
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13
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Fakhreddine S, Prommer H, Scanlon BR, Ying SC, Nicot JP. Mobilization of Arsenic and Other Naturally Occurring Contaminants during Managed Aquifer Recharge: A Critical Review. Environ Sci Technol 2021; 55:2208-2223. [PMID: 33503373 DOI: 10.1021/acs.est.0c07492] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Population growth and climate variability highlight the need to enhance freshwater security and diversify water supplies. Subsurface storage of water in depleted aquifers is increasingly used globally to alleviate disparities in water supply and demand often caused by climate extremes including floods and droughts. Managed aquifer recharge (MAR) stores excess water supplies during wet periods via infiltration into shallow underlying aquifers or direct injection into deep aquifers for recovery during dry seasons. Additionally, MAR can be designed to improve recharge water quality, particularly in the case of soil aquifer treatment and riverbank filtration. While there are many potential benefits to MAR, introduction of recharge water can alter the native geochemical and hydrological conditions in the receiving aquifer, potentially mobilizing toxic, naturally occurring (geogenic) contaminants from sediments into groundwater where they pose a much larger threat to human and ecosystem health. On the basis of the present literature, arsenic poses the most widespread challenge at MAR sites due to its ubiquity in subsurface sediments and toxicity at trace concentrations. Other geogenic contaminants of concern include fluoride, molybdenum, manganese, and iron. Water quality degradation threatens the viability of some MAR projects with several sites abandoning operations due to arsenic or other contaminant mobilization. Here, we provide a critical review of studies that have uncovered the geochemical and hydrological mechanisms controlling mobilization of arsenic and other geogenic contaminants at MAR sites worldwide, including both infiltration and injection sites. These mechanisms were evaluated based on site-specific characteristics, including hydrological setting, native aquifer geochemistry, and operational site parameters (e.g., source of recharge water and recharge/recovery cycling). Observed mechanisms of geogenic contaminant mobilization during MAR via injection include shifting redox conditions and, to a lesser extent, pH-promoted desorption, mineral solubility, and competitive ligand exchange. The relative importance of these mechanisms depends on various site-specific, operational parameters, including pretreatment of injection water and duration of injection, storage, and recovery phases. This critical review synthesizes findings across case studies in various geochemical, hydrological, and operational settings to better understand controls on arsenic and other geogenic contaminant mobilization and inform the planning and design of future MAR projects to protect groundwater quality. This critical review concludes with an evaluation of proposed management strategies for geogenic contaminants and identification of knowledge gaps regarding fate and transport of geogenic contaminants during MAR.
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Affiliation(s)
- Sarah Fakhreddine
- Bureau of Economic Geology, University of Texas at Austin, Austin, Texas 78758, United States
| | - Henning Prommer
- CSIRO Land and Water, Wembley, Western Australia 6913, Australia
- School of Earth Sciences, University of Western Australia, Crawley, Western Australia 6913, Australia
| | - Bridget R Scanlon
- Bureau of Economic Geology, University of Texas at Austin, Austin, Texas 78758, United States
| | - Samantha C Ying
- Environmental Sciences, University of California Riverside, Riverside, California 92521, United States
| | - Jean-Philippe Nicot
- Bureau of Economic Geology, University of Texas at Austin, Austin, Texas 78758, United States
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14
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Queiroz HM, Ying SC, Abernathy M, Barcellos D, Gabriel FA, Otero XL, Nóbrega GN, Bernardino AF, Ferreira TO. Manganese: The overlooked contaminant in the world largest mine tailings dam collapse. Environ Int 2021; 146:106284. [PMID: 33264733 PMCID: PMC8382573 DOI: 10.1016/j.envint.2020.106284] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [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: 08/31/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 05/11/2023]
Abstract
Manganese (Mn) is an abundant element in terrestrial and coastal ecosystems and an essential micronutrient in the metabolic processes of plants and animals. Mn is generally not considered a potentially toxic element due to its low content in both soil and water. However, in coastal ecosystems, the Mn dynamic (commonly associated with the Fe cycle) is mostly controlled by redox processes. Here, we assessed the potential contamination of the Rio Doce estuary (SE Brazil) by Mn after the world's largest mine tailings dam collapse, potentially resulting in chronic exposure to local wildlife and humans. Estuarine soils, water, and fish were collected and analyzed seven days after the arrival of the tailings in 2015 and again two years after the dam collapse in 2017. Using a suite of solid-phase analyses including X-ray absorption spectroscopy and sequential extractions, our results indicated that a large quantity of MnII arrived in the estuary in 2015 bound to Fe oxyhydroxides. Over time, dissolved Mn and Fe were released from soils when FeIII oxyhydroxides underwent reductive dissolution. Due to seasonal redox oscillations, both Fe and Mn were then re-oxidized to FeIII, MnIII, and MnIV and re-precipitated as poorly crystalline Fe oxyhydroxides and poorly crystalline Mn oxides. In 2017, redox conditions (Eh: -47 ± 83 mV; pH: 6.7 ± 0.5) favorable to both Fe and Mn reduction led to an increase (~880%) of dissolved Mn (average for 2015: 66 ± 130 µg L-1; 2017: 582 ± 626 µg L-1) in water and a decrease (~75%, 2015: 547 ± 498 mg kg-1; 2017: 135 ± 80 mg kg-1) in the total Mn content in soils. The crystalline Fe oxyhydroxides content significantly decreased while the fraction of poorly ordered Fe oxides increased in the soils limiting the role of Fe in Mn retention. The high concentration of dissolved Mn found within the estuary two years after the arrival of mine tailings indicates a possible chronic contamination scenario, which is supported by the high levels of Mn in two species of fish living in the estuary. Our work suggests a high risk to estuarine biota and human health due to the rapid Fe and Mn biogeochemical dynamic within the impacted estuary.
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Affiliation(s)
- Hermano M Queiroz
- Luiz de Queiroz College of Agriculture, University of São Paulo (ESALQ-USP), Av. Pádua Dias 11, CEP 13418-900, Piracicaba, São Paulo, Brazil
| | - Samantha C Ying
- Environmental Toxicology Graduate Program, University of California, Riverside, CA 92521, United States; Department of Environmental Sciences, University of California, Riverside, CA, 92521, United States
| | - Macon Abernathy
- Environmental Toxicology Graduate Program, University of California, Riverside, CA 92521, United States
| | - Diego Barcellos
- Luiz de Queiroz College of Agriculture, University of São Paulo (ESALQ-USP), Av. Pádua Dias 11, CEP 13418-900, Piracicaba, São Paulo, Brazil
| | - Fabricio A Gabriel
- Grupo de Ecologia Bentônica, Departamento de Oceanografia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo 29075-910, Brazil
| | - Xosé L Otero
- Department of Edaphology and Agricultural Chemistry - CRETUS, Faculty of Biology, Universidade de Santiago de Compostela, Campus Sur, 15782, Santiago de Compostela, Spain
| | - Gabriel N Nóbrega
- Graduate Program in Earth Sciences (Geochemistry), Department of Geochemistry, Federal Fluminense University, Niterói, Brazil
| | - Angelo F Bernardino
- Grupo de Ecologia Bentônica, Departamento de Oceanografia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo 29075-910, Brazil
| | - Tiago O Ferreira
- Luiz de Queiroz College of Agriculture, University of São Paulo (ESALQ-USP), Av. Pádua Dias 11, CEP 13418-900, Piracicaba, São Paulo, Brazil.
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15
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Jones ME, LaCroix RE, Zeigler J, Ying SC, Nico PS, Keiluweit M. Enzymes, Manganese, or Iron? Drivers of Oxidative Organic Matter Decomposition in Soils. Environ Sci Technol 2020; 54:14114-14123. [PMID: 33095570 DOI: 10.1021/acs.est.0c04212] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Oxidative decomposition of soil organic matter determines the proportion of carbon that is either stored or emitted to the atmosphere as CO2. Full conversion of organic matter to CO2 requires oxidative mechanisms that depolymerize complex molecules into smaller, soluble monomers that can be respired by microbes. Current models attribute oxidative depolymerization largely to the activity of extracellular enzymes. Here we show that reactive manganese (Mn) and iron (Fe) intermediates, rather than other measured soil characteristics, best predict oxidative activity in temperate forest soils. Combining bioassays, spectroscopy, and wet-chemical analysis, we found that oxidative activity in surface litters was most significantly correlated to the abundance of reactive Mn(III) species. In contrast, oxidative activity in underlying mineral soils was most significantly correlated to the abundance of reactive Fe(II/III) species. Positive controls showed that both Mn(III) and Fe(II/III) species are equally potent in generating oxidative activity, but imply conventional bioassays have a systematic bias toward Fe. Combined, our results highlight the coupled biotic-abiotic nature of oxidative mechanisms, with Mn-mediated oxidation dominating within Mn-rich organic soils and Fe-mediated oxidation dominating Fe-rich mineral soils. These findings suggest microbes rely on different oxidative strategies depending on the relative availability of Fe and Mn in a given soil environment.
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Affiliation(s)
- Morris E Jones
- School of Earth & Sustainability and Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Chemistry, Franklin Pierce University, Rindge, New Hampshire 03461, United States
| | - Rachelle E LaCroix
- School of Earth & Sustainability and Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Jacob Zeigler
- School of Earth & Sustainability and Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Samantha C Ying
- Department of Environmental Science, University of California-Riverside, Riverside, California 92521, United States
| | - Peter S Nico
- Environmental and Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Marco Keiluweit
- School of Earth & Sustainability and Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts 01003, United States
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16
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Tian S, Li K, Møller P, Ying SC, Wang L, Li Z, Roursgaard M, Liang T. Assessment of reactive oxygen species production and genotoxicity of rare earth mining dust: Implications for public health and mining management. Sci Total Environ 2020; 740:139759. [PMID: 32569908 DOI: 10.1016/j.scitotenv.2020.139759] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [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: 03/15/2020] [Revised: 05/24/2020] [Accepted: 05/25/2020] [Indexed: 06/11/2023]
Abstract
Mining rare earth elements (REEs) can release large amounts of metal(loid)-rich dust, which can pose significant health risks to local residents. However, compared to other types of particulates, toxicity of mining dust has been largely overlooked. To provide experimental evidence on toxicity of REE mine dust, the study assessed the oxidative stress potential and genotoxicity of inhalable particles collected in a REE mining area, and associated toxicological response with source compositions. Both source types (i.e., mine and tailing area) and distances from source (i.e., industrial and residential areas) were considered when selecting the 44 sampling sites. The particle samples contained 2.3-3.5 folds higher concentrations of tested metal(loid)s than background concentrations in soil. Specially, elevated Fe, REEs, Cd, Pb were found. In spite of low cytotoxicity in lung epithelial A549 cells, there was increased cellular ROS production by of particle exposure. Samples with higher mining-originated source contributions (Provenance Index <0.3) had higher cellular ROS production (1.72 fold, 95%CI: 1.66-1.79 fold) than samples with lower mining contributions (1.58 fold, 95%CI: 1.52-1.65 fold). The factors soil (~46%), mine (~22%), and heavy metal (~20%) sources were recognized by source apportionment analysis as the main contributors to cellular ROS production; importantly, mine and heavy metal sources counted more in industrial samples. While samples generated genotoxicity, there were no differences in DNA damage between the location groups of sampling. Collectively, the results indicate that particles in mining areas may cause ROS production and DNA damage in lung cells depending on mine dust. Coupled with the long-range transportation potential of mine dust, safety measures on open pit and dust disposal sites should be adopted.
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Affiliation(s)
- Shuhan Tian
- Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing 100101, China; Department of Public Health, Section of Environmental Health, Faculty of Health and Medical Sciences, University of Copenhagen, Øster Farimagsgade 5A, DK-1014 Copenhagen K, Denmark; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kexin Li
- Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peter Møller
- Department of Public Health, Section of Environmental Health, Faculty of Health and Medical Sciences, University of Copenhagen, Øster Farimagsgade 5A, DK-1014 Copenhagen K, Denmark
| | - Samantha C Ying
- Department of Environmental Sciences, University of California, Riverside, CA 92521, United States
| | - Lingqing Wang
- Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhiyi Li
- Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Martin Roursgaard
- Department of Public Health, Section of Environmental Health, Faculty of Health and Medical Sciences, University of Copenhagen, Øster Farimagsgade 5A, DK-1014 Copenhagen K, Denmark.
| | - Tao Liang
- Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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17
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Schaefer MV, Plaganas M, Abernathy MJ, Aiken ML, Garniwan A, Lee I, Ying SC. Manganese, Arsenic, and Carbonate Interactions in Model Oxic Groundwater Systems. Environ Sci Technol 2020; 54:10621-10629. [PMID: 32786605 PMCID: PMC8435213 DOI: 10.1021/acs.est.0c02084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Manganese and arsenic both threaten groundwater quality globally, but their chemical behavior leads to both co-contamination and separation of these contaminants from individual well to regional scales. Here we tested manganese and arsenic retention under conditions commonly found within aquifer redox fluctuating and transition zones where both arsenic and iron phases are present in oxidized forms, but manganese persists as reduced and soluble Mn(II). Analysis of column aqueous breakthrough data and characterization of solid-phase products using X-ray photoelectron (XPS) and absorption spectroscopies (XAS) show that the addition of bicarbonate increased manganese retention but decreased arsenic retention, while the presence of manganese and arsenic together increased both arsenic and manganese retention. In the presence of O2 arsenic remained oxidized as arsenate under all conditions measured; however, reduced Mn(II) was oxidized to an average Mn oxidation state of ∼3 in the absence of arsenate. The presence of arsenate partially inhibited Mn(II) oxidation likely by blocking ferrihydrite surfaces needed to catalyze Mn(II) oxidation by O2 and by stabilizing Mn(II) via ternary complex formation. These results highlight the interactions between reduced and oxidized contaminants that can contribute to the co-occurrence or physical separation of manganese and arsenic in groundwater systems under changing or stratified redox conditions.
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Affiliation(s)
- Michael V Schaefer
- Department of Environmental Sciences, University of California, Riverside, California 92521, United States
- Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, United States
| | - Mariejo Plaganas
- Department of Environmental Sciences, University of California, Riverside, California 92521, United States
| | - Macon J Abernathy
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521, United States
| | - Miranda L Aiken
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521, United States
| | - Abdi Garniwan
- Department of Environmental Sciences, University of California, Riverside, California 92521, United States
| | - Ilkeun Lee
- Analytical Chemistry Instrumentation Facility, Central Facility for Advanced Microscopy and Microanalysis, University of California, Riverside, California 92521, United States
| | - Samantha C Ying
- Department of Environmental Sciences, University of California, Riverside, California 92521, United States
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521, United States
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18
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Chen J, van Groenigen KJ, Hungate BA, Terrer C, van Groenigen JW, Maestre FT, Ying SC, Luo Y, Jørgensen U, Sinsabaugh RL, Olesen JE, Elsgaard L. Long-term nitrogen loading alleviates phosphorus limitation in terrestrial ecosystems. Glob Chang Biol 2020; 26:5077-5086. [PMID: 32529708 DOI: 10.1111/gcb.15218] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [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: 04/28/2020] [Accepted: 05/21/2020] [Indexed: 05/02/2023]
Abstract
Increased human-derived nitrogen (N) deposition to terrestrial ecosystems has resulted in widespread phosphorus (P) limitation of net primary productivity. However, it remains unclear if and how N-induced P limitation varies over time. Soil extracellular phosphatases catalyze the hydrolysis of P from soil organic matter, an important adaptive mechanism for ecosystems to cope with N-induced P limitation. Here we show, using a meta-analysis of 140 studies and 668 observations worldwide, that N stimulation of soil phosphatase activity diminishes over time. Whereas short-term N loading (≤5 years) significantly increased soil phosphatase activity by 28%, long-term N loading had no significant effect. Nitrogen loading did not affect soil available P and total P content in either short- or long-term studies. Together, these results suggest that N-induced P limitation in ecosystems is alleviated in the long-term through the initial stimulation of soil phosphatase activity, thereby securing P supply to support plant growth. Our results suggest that increases in terrestrial carbon uptake due to ongoing anthropogenic N loading may be greater than previously thought.
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Affiliation(s)
- Ji Chen
- Department of Agroecology, Aarhus University, Tjele, Denmark
- Aarhus University Center for Circular Bioeconomy, Aarhus University, Tjele, Denmark
- iCLIMATE Interdisciplinary Centre for Climate Change, Aarhus University, Roskilde, Denmark
| | - Kees J van Groenigen
- Department of Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Bruce A Hungate
- Center for Ecosystem Science and Society and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - César Terrer
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory (LLNL), Livermore, CA, USA
| | | | - Fernando T Maestre
- Instituto Multidisciplinar para el Estudio del Medio "Ramon Margalef", Universidad de Alicante, Alicante, Spain
- Departamento de Ecología, Universidad de Alicante, Alicante, Spain
| | - Samantha C Ying
- Department of Environmental Sciences, University of California, Riverside, CA, USA
| | - Yiqi Luo
- Center for Ecosystem Science and Society and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Uffe Jørgensen
- Department of Agroecology, Aarhus University, Tjele, Denmark
- Aarhus University Center for Circular Bioeconomy, Aarhus University, Tjele, Denmark
| | | | - Jørgen E Olesen
- Department of Agroecology, Aarhus University, Tjele, Denmark
- iCLIMATE Interdisciplinary Centre for Climate Change, Aarhus University, Roskilde, Denmark
| | - Lars Elsgaard
- Department of Agroecology, Aarhus University, Tjele, Denmark
- iCLIMATE Interdisciplinary Centre for Climate Change, Aarhus University, Roskilde, Denmark
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19
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Frie AL, Garrison AC, Schaefer MV, Bates SM, Botthoff J, Maltz M, Ying SC, Lyons T, Allen MF, Aronson E, Bahreini R. Dust Sources in the Salton Sea Basin: A Clear Case of an Anthropogenically Impacted Dust Budget. Environ Sci Technol 2019; 53:9378-9388. [PMID: 31339712 DOI: 10.1021/acs.est.9b02137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The Salton Sea Basin in California suffers from poor air quality, and an expanding dry lakebed (playa) presents a new potential dust source. In 2017-18, depositing dust was collected approximately monthly at five sites in the Salton Sea Basin and analyzed for total elemental and soluble anion content. These data were analyzed with Positive Matrix Factorization (PMF). The PMF method resolved seven dust sources with distinct compositional markers: Playa (Mg, SO42-, Na, Ca, Sr), Colorado Alluvium (U, Ca), Local Alluvium (Al, Fe, Ti), Agricultural Burning (K, PO43-), Sea Spray (Na, Cl-, Se), Anthropogenic Trace Metals (Sb, As, Zn, Cd, Pb, Na), and Anthropogenic Copper (Cu). All sources except Local Alluvium are influenced or caused by current or historic anthropogenic activities. PMF attributed 55 to 80% of the measured dust flux to these six sources. The dust fluxes at the site where the playa source was dominant (89 g m-2 yr-1) were less than, but approaching the scale of, those observed at Owens Lake playas in the late 20th century. Playa emissions in the Salton Sea region were most intense during the late spring to early summer and contain high concentrations of evaporite mineral tracers, particularly Mg, Ca, and SO42-.
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Affiliation(s)
- Alexander L Frie
- Department of Environmental Sciences , University of California , Riverside , California 92521 , United States
| | - Alexis C Garrison
- Department of Environmental Sciences , University of California , Riverside , California 92521 , United States
| | - Michael V Schaefer
- Department of Environmental Sciences , University of California , Riverside , California 92521 , United States
| | - Steve M Bates
- Department of Earth Sciences , University of California , Riverside , California 92521 , United States
| | - Jon Botthoff
- Center for Conservation Biology , University of California , Riverside , California 92521 , United States
| | - Mia Maltz
- Center for Conservation Biology , University of California , Riverside , California 92521 , United States
| | - Samantha C Ying
- Department of Environmental Sciences , University of California , Riverside , California 92521 , United States
| | - Timothy Lyons
- Department of Earth Sciences , University of California , Riverside , California 92521 , United States
| | - Michael F Allen
- Center for Conservation Biology , University of California , Riverside , California 92521 , United States
- Department of Microbiology and Plant Pathology , University of California , Riverside , California 92521 , United States
| | - Emma Aronson
- Center for Conservation Biology , University of California , Riverside , California 92521 , United States
- Department of Microbiology and Plant Pathology , University of California , Riverside , California 92521 , United States
| | - Roya Bahreini
- Department of Environmental Sciences , University of California , Riverside , California 92521 , United States
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20
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Zhuang W, Ying SC, Frie AL, Wang Q, Song J, Liu Y, Chen Q, Lai X. Distribution, pollution status, and source apportionment of trace metals in lake sediments under the influence of the South-to-North Water Transfer Project, China. Sci Total Environ 2019; 671:108-118. [PMID: 30928740 DOI: 10.1016/j.scitotenv.2019.03.306] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 03/19/2019] [Accepted: 03/20/2019] [Indexed: 06/09/2023]
Abstract
In an effort to combat the threat of drought, China constructed the South-to-North Water Transfer Project (SNWTP), the biggest water transfer project in terms of volume with the largest beneficiary population in the world. Reports have shown that massive water diversion projects have had detrimental environmental consequences including water quality decline and freshwater habitat degradation. However, few reports have assessed the impact of the transfer project on sediment quality, which is highly susceptible to allogenic and local anthropogenic pollution. We examined the distribution characteristics of Cd, Cr, Cu, Ni, Pb and Zn in surface sediment of the largest reservoir along the East Route of SNWTP, Nansihu Lake, followed by positive matrix factorization (PMF) to determine their potential sources. We utilized enrichment factor, multiple sediment quality guidelines (SQGs), and potential ecological risk index (RI) to determine metal accumulation or pollution risk. The results show the mean concentrations of Cr, Cu, Pb, Zn were slightly lower than in samples collected in 2003, 2010 and 2012, while the mean concentrations of Cr and Ni were significantly higher than samples from previous years. Among the six metals, Cr, Cu and Ni are of higher ecological risk according to SQGs; but Cd is of higher ecological risk according to RI. PMF analysis shows that industrial production and shipping are important sources of Cr, Cu, and Ni. PMF analysis also shows that a considerable amount of trace metals, especially Cd, Cr, Pb and Zn, mainly comes from the use of pesticide fertilizers and biomass sources in farmland, and may partly enter Nansihu Lake from SNWTP. This study reveals the possible sources of trace metals to the Nansihu Lake which is part of SNWTP; the results of the study may serve as a reference for better understanding the impact of future water diversion projects on metals distribution.
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Affiliation(s)
- Wen Zhuang
- Key Laboratory of Marine Ecology and Environmental Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong 266071, China; Department of Environmental Sciences, University of California, Riverside, CA 92521, United States; College of City and Architecture Engineering, Zaozhuang University, Zaozhuang, Shandong 277160, China.
| | - Samantha C Ying
- Department of Environmental Sciences, University of California, Riverside, CA 92521, United States
| | - Alexander L Frie
- Department of Environmental Sciences, University of California, Riverside, CA 92521, United States
| | - Qian Wang
- College of City and Architecture Engineering, Zaozhuang University, Zaozhuang, Shandong 277160, China
| | - Jinming Song
- Key Laboratory of Marine Ecology and Environmental Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong 266071, China
| | - Yongxia Liu
- College of City and Architecture Engineering, Zaozhuang University, Zaozhuang, Shandong 277160, China
| | - Qing Chen
- College of Life Sciences, Zaozhuang University, Zaozhuang, Shandong 277160, China
| | - Xiaoying Lai
- National Engineering and Technology Research Center for Development & Utilization of Phosphorous Resources, Wuhan Institute of Technology, Wuhai, Hubei 430073, China
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Cong W, Meng J, Ying SC. Impact of soil properties on the soil methane flux response to biochar addition: a meta-analysis. Environ Sci Process Impacts 2018; 20:1202-1209. [PMID: 30178797 DOI: 10.1039/c8em00278a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In an effort to optimize soil management practices that can help mitigate terrestrial carbon emissions, biochar has been applied to a wide range of soil environments to examine its effect on soil greenhouse gas emissions. Such studies have shown that the soil methane (CH4) flux response can vary widely leading to both increase and decrease in CH4 flux upon biochar amendment. To address this discrepancy, multiple meta-analysis studies have been performed in recent years to determine the key factors that may control the direction of CH4 flux upon biochar treatment. However, even comparing across conclusions from meta-analyses reveals disagreement upon which factors ultimately determine the change in direction and magnitude of CH4 flux due to biochar addition. Furthermore, using multiple observations from a single study can lead to misinterpretation of the influence of a factor within a meta-analysis due to non-independence. In this study, we use a multivariate meta-regression approach that allows factor interactions to investigate which biochar, soil, and management practice factors in combination or individually best explain the CH4 flux response in past biochar amendment studies. Our results show that the interaction of multiple soil factors (i.e., water saturation, soil texture, and soil organic carbon content) best explains the soil CH4 flux response to biochar addition (minimum deviance information criterion (DIC) value along with lowest heterogeneity) as compared to all models utilizing individual factors alone. These findings provide insight into the specific soil factors that should be taken into account simultaneously when optimizing the CH4 flux response to biochar amendments and building empirical models to quantitatively predict soil CH4 flux.
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Affiliation(s)
- Weiwei Cong
- College of Agronomy, Shenyang Agricultural University, Shenyang, 110161, China.
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22
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Ying SC, Schaefer MV, Cock-Esteb A, Li J, Fendorf S. Depth Stratification Leads to Distinct Zones of Manganese and Arsenic Contaminated Groundwater. Environ Sci Technol 2017; 51:8926-8932. [PMID: 28695739 DOI: 10.1021/acs.est.7b01121] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Providing access to safe drinking water is a global challenge, for which groundwater is increasingly being used throughout the world. However, geogenic contaminants limit the suitability of groundwater for domestic purposes over large geographic areas across most continents. Geogenic contaminants in groundwater are often evaluated individually, but here we demonstrate the need to evaluate multiple contaminants to ensure that groundwater is safe for human consumption and agricultural usage. We compiled groundwater chemical data from three aquifer regions across the world that have been reported to have widespread As and Mn contamination including the Glacial Aquifer in the U.S., the Ganges-Brahmaputra-Mehta Basin within Bangladesh, and the Mekong Delta in Cambodia, along with newly sampled wells in the Yangtze River Basin of China. The proportion of contaminated wells increase by up to 40% in some cases when both As and Mn contaminants are considered. Wilcoxon rank-sum analysis indicates that Mn contamination consistently occurs at significantly shallower depths than As contaminated wells in all regions. Arsenic concentrations in groundwater are well predicted by redox indicators (Eh and dissolved oxygen) whereas Mn shows no significant relationship with either parameter. These findings illustrate that the number of safe wells may be drastically overestimated in some regions when Mn contamination is not taken into account and that depth may be used as a distinguishing variable in efforts to predict the presence of groundwater contaminants regionally.
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Affiliation(s)
- Samantha C Ying
- Environmental Sciences Department, University of California-Riverside , 900 University Ave, Riverside, California 92521, United States
| | - Michael V Schaefer
- Environmental Sciences Department, University of California-Riverside , 900 University Ave, Riverside, California 92521, United States
| | - Alicea Cock-Esteb
- Earth System Science Department Stanford University , 473 Via Ortega, Stanford, California 94305, United States
| | - Jun Li
- Statistics Department, University of California-Riverside , 900 University Ave, Riverside, California 92521, United States
| | - Scott Fendorf
- Earth System Science Department Stanford University , 473 Via Ortega, Stanford, California 94305, United States
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23
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Frie AL, Dingle JH, Ying SC, Bahreini R. The Effect of a Receding Saline Lake (The Salton Sea) on Airborne Particulate Matter Composition. Environ Sci Technol 2017; 51:8283-8292. [PMID: 28697595 DOI: 10.1021/acs.est.7b01773] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The composition of ambient particulate matter (PM) and its sources were investigated at the Salton Sea, a shrinking saline lake in California. To investigate the influence of playa exposure on PM composition, PM samples were collected during two seasons and at two sites around the Salton Sea. To characterize source composition, soil samples were collected from local playa and desert surfaces. PM and soil samples were analyzed for 15 elements using mass spectrometry and X-ray diffraction. The contribution of sources to PM mass and composition was investigated using Al-referenced enrichment factors (EFs) and source factors resolved from positive matrix factorization (PMF). Playa soils were found to be significantly enriched in Ca, Na, and Se relative to desert soils. PMF analysis resolved the PM10 data with four source factors, identified as Playa-like, Desert-like, Ca-rich, and Se. Playa-like and desert-like sources were estimated to contribute to a daily average of 8.9% and 45% of PM10 mass, respectively. Additionally, playa sources were estimated to contribute to 38-68% of PM10 Na. PM10 Se concentrations showed strong seasonal variations, suggesting a seasonal cycle of Se volatilization and recondensation. These results support the importance of playas as a source of PM mass and a controlling factor of PM composition.
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Affiliation(s)
- Alexander L Frie
- Department of Environmental Sciences, University of California , Riverside, California 92521, United States
| | - Justin H Dingle
- Environmental Toxicology Graduate Program, University of California , Riverside, California 92521, United States
| | - Samantha C Ying
- Department of Environmental Sciences, University of California , Riverside, California 92521, United States
- Environmental Toxicology Graduate Program, University of California , Riverside, California 92521, United States
| | - Roya Bahreini
- Department of Environmental Sciences, University of California , Riverside, California 92521, United States
- Environmental Toxicology Graduate Program, University of California , Riverside, California 92521, United States
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24
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Schaefer MV, Ying SC, Benner SG, Duan Y, Wang Y, Fendorf S. Aquifer Arsenic Cycling Induced by Seasonal Hydrologic Changes within the Yangtze River Basin. Environ Sci Technol 2016; 50:3521-3529. [PMID: 26788939 DOI: 10.1021/acs.est.5b04986] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Consumption of groundwater containing >10 μg L(-1) arsenic (As) adversely impacts more than 100 million people worldwide. Multiyear trends in aquifer As concentrations have been documented, but strong seasonal variations are not commonly observed. Here we report dramatic seasonal changes in As concentrations and aquifer chemistry within the Jianghan Plain of the Yangtze River, China. At some wells, concentrations fluctuate by more than an order of magnitude within a single year (100-1200 μg L(-1)). Groundwater extraction and sustained water levels of surface channels during the dry season induces a strong downward hydraulic gradient, seasonally supplying oxidizing (oxygen, nitrate) water to the otherwise anoxic aquifer. Oxygen and/or nitrate addition promotes a transient drop in As concentrations for 1-3 months. When recharge ceases, reducing, low-arsenic conditions are reestablished by reactive, endogenous organic carbon. Temporal variability in As concentrations is especially problematic because it increases the probability of false-negative well testing during low-arsenic seasons. However, periods of low As may also provide a source of less toxic water for irrigation or other uses. Our results highlight the vulnerability and variability of groundwater resources in the Jianghan Plain and other inland basins within Asia to changing geochemical conditions, both natural and anthropogenic, and reinforce that continued monitoring of wells in high-risk regions is essential.
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Affiliation(s)
- Michael V Schaefer
- Earth System Science Department, Stanford University , Stanford, California 94305, United States
| | - Samantha C Ying
- Environmental Sciences Department, University of California - Riverside , Riverside, California 92521, United States
| | - Shawn G Benner
- Department of Geosciences, Boise State University , Boise, Idaho 83725, United States
| | - Yanhua Duan
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences , Wuhan, Hubei 430074, People's Republic of China
| | - Yanxin Wang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences , Wuhan, Hubei 430074, People's Republic of China
| | - Scott Fendorf
- Earth System Science Department, Stanford University , Stanford, California 94305, United States
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Ying SC, Damashek J, Fendorf S, Francis CA. Indigenous arsenic(V)-reducing microbial communities in redox-fluctuating near-surface sediments of the Mekong Delta. Geobiology 2015; 13:581-587. [PMID: 26466963 DOI: 10.1111/gbi.12152] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/10/2015] [Indexed: 06/05/2023]
Abstract
Arsenic (As) cycling within soils and sediments of the Mekong Delta of Cambodia is affected by drastic redox fluctuations caused by seasonal monsoons. Extensive flooding during monsoon seasons creates anoxic soil conditions that favor anaerobic microbial processes, including arsenate [As(V)] respiration-a process contributing to the mobilization of As. Repeated oxidation and reduction in near-surface sediments, which contain 10-40 mg kg(-1) As, lead to the eventual downward movement of As to the underlying aquifer. Amplification of a highly conserved functional gene encoding dissimilatory As(V) reductase, arrA, can be used as a molecular marker to detect the genetic potential for As(V) respiration in environmental samples. However, few studies have successfully amplified arrA from sediments without prior enrichment, which can drastically shift community structure. In the present study, we examine the distribution and diversity of arrA genes amplified from multiple sites within the Cambodian Mekong Delta as a function of near-surface depth (10, 50, 100, 200, and 400 cm), where sediments undergo seasonal redox fluctuations. We report successful amplification of 302 arrA gene sequences (72 OTUs) from near-surface Cambodian soils (without prior enrichment or stimulation with carbon amendments), where a large majority (>70%) formed a well-supported clade that is phylogenetically distinct from previously reported sequences from Cambodia and other South and Southeast Asian sediments, with highest sequence similarity to known Geobacter species capable of As(V) respiration, further supporting the potentially important role of Geobacter sp. in arsenic mobilization in these regions.
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Affiliation(s)
- S C Ying
- Department of Environmental Sciences, University of California-Riverside, Riverside, CA, USA
| | - J Damashek
- Earth System Science Department, Stanford University, Stanford, CA, USA
| | - S Fendorf
- Earth System Science Department, Stanford University, Stanford, CA, USA
| | - C A Francis
- Earth System Science Department, Stanford University, Stanford, CA, USA
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Granato E, Ying SC, Elder KR, Ala-Nissila T. Anomalous fast dynamics of adsorbate overlayers near an incommensurate structural transition. Phys Rev Lett 2013; 111:126102. [PMID: 24093278 DOI: 10.1103/physrevlett.111.126102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Indexed: 06/02/2023]
Abstract
We investigate the dynamics of a compressively strained adsorbed layer on a periodic substrate via a simple two-dimensional model that admits striped and hexagonal incommensurate phases. We show that the mass transport is superfast near the striped-hexagonal phase boundary and in the hexagonal phase. For an initial step profile separating a bare substrate region (or "hole") from the rest of a striped incommensurate phase, the superfast domain wall dynamics leads to a bifurcation of the initial step profile into two interfaces or profiles propagating in opposite directions with a hexagonal phase in between. This yields a theoretical understanding of the recent experiments for the Pb/Si(111) system.
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Affiliation(s)
- Enzo Granato
- Laboratório Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, 12245-970 São José dos Campos, São Paulo, Brazil and Department of Physics, Post Office Box 1843, Brown University, Providence, Rhode Island 02912-1843, USA
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Masue-Slowey Y, Ying SC, Kocar BD, Pallud CE, Fendorf S. Dependence of arsenic fate and transport on biogeochemical heterogeneity arising from the physical structure of soils and sediments. J Environ Qual 2013; 42:1119-1129. [PMID: 24216363 DOI: 10.2134/jeq2012.0253] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Reduction of As(V) and Fe(III) is commonly the dominant process controlling the fate and transport of As in soils and sediments. However, the physical structure of such environments produces complex heterogeneity in biogeochemical processes controlling the fate and transport of As. To resolve the role of soil and sediment physical structure on the distribution of biogeochemical processes controlling the fate and transport of As, we examined the biogeochemical transformations of As and Fe within constructed aggregates-a fundamental unit of soil structure. Spherical aggregates were made with As(V)- or As(III)-bearing, ferrihydrite-coated quartz that was fused with agarose and placed in a cylindrical reactor; advective flow of anoxic solutes was then initiated around the aggregates to examine As release from a dual-pore domain system. To examine the impact of biotic As(V) and Fe(III) reduction, constructed aggregates having As(V)-bearing, ferrihydrite-coated quartz inoculated with sp. ANA-3 were placed in flow-through reactors under anoxic and aerated advective flow. Consistent with desorption from advective columns, As(III) is released to advecting water more prevalently than As(V) within abiotic aggregate systems, indicating a greater lability and concomitant enhanced propensity for transport of As(III) relative to As(V). During reaction with , As release to advecting water was similar between anoxic and aerated systems for the first 20 d; thereafter, the anoxic advecting solutes increased As release relative to the aerated counterpart. With aerated advecting solutes, Fe remained oxidized (or was oxidized) in the aggregate exterior, forming a protective barrier that limited As release to the advective channel. However, anaerobiosis within the aggregate interior, even with aerated advective flow, promotes internal repartitioning of As to the exterior region.
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Granato E, Ramos JAP, Achim CV, Lehikoinen J, Ying SC, Ala-Nissila T, Elder KR. Glassy phases and driven response of the phase-field-crystal model with random pinning. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 84:031102. [PMID: 22060323 DOI: 10.1103/physreve.84.031102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 07/10/2011] [Indexed: 05/31/2023]
Abstract
We study the structural correlations and the nonlinear response to a driving force of a two-dimensional phase-field-crystal model with random pinning. The model provides an effective continuous description of lattice systems in the presence of disordered external pinning centers, allowing for both elastic and plastic deformations. We find that the phase-field crystal with disorder assumes an amorphous glassy ground state, with only short-ranged positional and orientational correlations, even in the limit of weak disorder. Under increasing driving force, the pinned amorphous-glass phase evolves into a moving plastic-flow phase and then, finally, a moving smectic phase. The transverse response of the moving smectic phase shows a vanishing transverse critical force for increasing system sizes.
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Affiliation(s)
- E Granato
- Laboratório Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, 12227-010 São José dos Campos, SP, Brazil
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29
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Ikonen T, Khandkar MD, Chen LY, Ying SC, Ala-Nissila T. Diffusion in periodic potentials with path integral hyperdynamics. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 84:026703. [PMID: 21929140 PMCID: PMC3177431 DOI: 10.1103/physreve.84.026703] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 06/07/2011] [Indexed: 05/31/2023]
Abstract
We consider the diffusion of brownian particles in one-dimensional periodic potentials as a test bench for the recently proposed stochastic path integral hyperdynamics (PIHD) scheme [Chen and Horing, J. Chem. Phys. 126, 224103 (2007)]. First, we consider the case where PIHD is used to enhance the transition rate of activated rare events. To this end, we study the diffusion of a single brownian particle moving in a spatially periodic potential in the high-friction limit at low temperature. We demonstrate that the boost factor as compared to straight molecular dynamics (MD) has nontrivial behavior as a function of the bias force. Instead of growing monotonically with the bias, the boost attains an optimal maximum value due to increased error in the finite path sampling induced by the bias. We also observe that the PIHD method can be sensitive to the choice of numerical integration algorithm. As the second case, we consider parallel resampling of multiple bias force values in the case of a brownian particle in a periodic potential subject to an external ac driving force. We confirm that there is no stochastic resonance in this system. However, while the PIHD method allows one to obtain data for multiple values of the ac bias, the boost with respect to MD remains modest due to the simplicity of the equation of motion in this case.
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Affiliation(s)
- T Ikonen
- Department of Applied Physics and Centre of Excellence in Computational Nanoscience (COMP), Aalto University School of Science, P.O. Box 11000, FI-00076 Aalto, Espoo, Finland
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30
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Ying SC, Kocar BD, Griffis SD, Fendorf S. Competitive microbially and Mn oxide mediated redox processes controlling arsenic speciation and partitioning. Environ Sci Technol 2011; 45:5572-9. [PMID: 21648436 DOI: 10.1021/es200351m] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The speciation and partitioning of arsenic (As) in surface and subsurface environments are controlled, in part, by redox processes. Within soils and sediments, redox gradients resulting from mass transfer limitations lead to competitive reduction-oxidation reactions that drive the fate of As. Accordingly, the objective of this study was to determine the fate and redox cycling of As at the interface of birnessite (a strong oxidant in soil with a nominal formula of MnO(x), where x ≈ 2) and dissimilatory As(V)-reducing bacteria (strong reductant). Here, we investigate As reduction-oxidation dynamics in a diffusively controlled system using a Donnan reactor where birnessite and Shewanella sp. ANA-3 are isolated by a semipermeable membrane through which As migrates. Arsenic(III) injected into the reaction cell containing birnessite is rapidly oxidized to As(V). Arsenic(V) diffusing into the Shewanella chamber is then reduced to As(III), which subsequently diffuses back to the birnessite chamber, undergoing oxidation, and establishing a continuous cycling of As. However, we observe a rapid decline in the rate of As(III) oxidation owing to passivation of the birnessite surface. Modeling and experimental results show that high [Mn(II)] combined with increasing [CO(3)(2-)] from microbial respiration leads to the precipitation of rhodochrosite, which eventually passivates the Mn oxide surface, inhibiting further As(III) oxidation. Our results show that despite the initial capacity of birnessite to rapidly oxidize As(III), the synergistic effect of intense As(V) reduction by microorganisms and the buildup of reactive metabolites capable of passivating reactive mineral surfaces-here, birnessite-will produce (bio)geochemical conditions outside of those based on thermodynamic predictions.
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Affiliation(s)
- Samantha C Ying
- Department of Environmental & Earth System Science, Stanford University, Stanford, California 94305, United States
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Ramos JAP, Granato E, Ying SC, Achim CV, Elder KR, Ala-Nissila T. Dynamical transitions and sliding friction of the phase-field-crystal model with pinning. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:011121. [PMID: 20365337 DOI: 10.1103/physreve.81.011121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Indexed: 05/11/2023]
Abstract
We study the nonlinear driven response and sliding friction behavior of the phase-field-crystal (PFC) model with pinning including both thermal fluctuations and inertial effects. The model provides a continuous description of adsorbed layers on a substrate under the action of an external driving force at finite temperatures, allowing for both elastic and plastic deformations. We derive general stochastic dynamical equations for the particle and momentum densities including both thermal fluctuations and inertial effects. The resulting coupled equations for the PFC model are studied numerically. At sufficiently low temperatures, we find that the velocity response of an initially pinned commensurate layer shows hysteresis with dynamical melting and freezing transitions for increasing and decreasing applied forces at different critical values. The main features of the nonlinear response in the PFC model are similar to the results obtained previously with molecular dynamics simulations of particle models for adsorbed layers.
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Affiliation(s)
- J A P Ramos
- Departamento de Ciências Exatas, Universidade Estadual do Sudoeste da Bahia, Vitória da Conquista, BA, Brazil
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Trushin O, Jalkanen J, Granato E, Ying SC, Ala-Nissila T. Atomistic studies of strain relaxation in heteroepitaxial systems. J Phys Condens Matter 2009; 21:084211. [PMID: 21817363 DOI: 10.1088/0953-8984/21/8/084211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a review of recent theoretical studies of different atomistic mechanisms of strain relaxation in heteroepitaxial systems. We explore these systems in two and three dimensions using different semi-empirical interatomic potentials of Lennard-Jones and many-body embedded atom model type. In all cases we use a universal molecular static method for generating minimum energy paths for transitions from the coherent epitaxial (defect free) state to the state containing an isolated defect (localized or extended). This is followed by a systematic search for the minimum energy configuration as well as self-organization in the case of a periodic array of islands. In this way we are able to understand many general features of the atomic mechanisms and energetics of strain relaxation in these systems. Finally, for the special case of Pd/Cu(100) and Cu/Pd(100) heteroepitaxy we also use conventional molecular dynamics simulation techniques to compare the compressively and tensilely strained cases. The results for this case are in good agreement with the existing experimental data.
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Affiliation(s)
- O Trushin
- Institute of Physics and Technology, Yaroslavl Branch, Academy of Sciences of Russia, Yaroslavl 150007, Russia
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Achim CV, Ramos JAP, Karttunen M, Elder KR, Granato E, Ala-Nissila T, Ying SC. Nonlinear driven response of a phase-field crystal in a periodic pinning potential. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 79:011606. [PMID: 19257044 DOI: 10.1103/physreve.79.011606] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 12/22/2008] [Indexed: 05/27/2023]
Abstract
We study numerically the phase diagram and the response under a driving force of the phase field crystal model for pinned lattice systems introduced recently for both one- and two-dimensional systems. The model describes the lattice system as a continuous density field in the presence of a periodic pinning potential, allowing for both elastic and plastic deformations of the lattice. We first present results for phase diagrams of the model in the absence of a driving force. The nonlinear response to a driving force on an initially pinned commensurate phase is then studied via overdamped dynamic equations of motion for different values of mismatch and pinning strengths. For large pinning strength the driven depinning transitions are continuous, and the sliding velocity varies with the force from the threshold with power-law exponents in agreement with analytical predictions. Transverse depinning transitions in the moving state are also found in two dimensions. Surprisingly, for sufficiently weak pinning potential we find a discontinuous depinning transition with hysteresis even in one dimension under overdamped dynamics. We also characterize structural changes of the system in some detail close to the depinning transition.
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Affiliation(s)
- C V Achim
- Department of Applied Physics, Helsinki University of Technology, P.O. Box 1100, FIN-02015 TKK, Espoo, Finland
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Ramos JAP, Granato E, Achim CV, Ying SC, Elder KR, Ala-Nissila T. Thermal fluctuations and phase diagrams of the phase-field crystal model with pinning. Phys Rev E Stat Nonlin Soft Matter Phys 2008; 78:031109. [PMID: 18850995 DOI: 10.1103/physreve.78.031109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Indexed: 05/26/2023]
Abstract
We study the influence of thermal fluctuations in the phase diagram of a recently introduced two-dimensional phase field crystal model with an external pinning potential. The model provides a continuum description of pinned lattice systems allowing for both elastic deformations and topological defects. We introduce a nonconserved version of the model and determine the ground-state phase diagram as a function of lattice mismatch and strength of the pinning potential. Monte Carlo simulations are used to determine the phase diagram as a function of temperature near commensurate phases. The results show a rich phase diagram with commensurate, incommensurate, and liquidlike phases with a topology strongly dependent on the type of ordered structure. A finite-size scaling analysis of the melting transition for the c(2x2) commensurate phase shows that the thermal correlation length exponent nu and specific heat behavior are consistent with the Ising universality class as expected from analytical arguments.
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Affiliation(s)
- J A P Ramos
- Departamento de Ciências Exatas, Universidade Estadual do Sudoeste da Bahia, 45000-000 Vitória da Conquista, Ba, Brasil
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35
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Achim CV, Karttunen M, Elder KR, Granato E, Ala-Nissila T, Ying SC. Phase diagram and commensurate-incommensurate transitions in the phase field crystal model with an external pinning potential. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 74:021104. [PMID: 17025390 DOI: 10.1103/physreve.74.021104] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Indexed: 05/12/2023]
Abstract
We study the phase diagram and the commensurate-incommensurate transitions in a phase field model of a two-dimensional crystal lattice in the presence of an external pinning potential. The model allows for both elastic and plastic deformations and provides a continuum description of lattice systems, such as for adsorbed atomic layers or two-dimensional vortex lattices. Analytically, a mode expansion analysis is used to determine the ground states and the commensurate-incommensurate transitions in the model as a function of the strength of the pinning potential and the lattice mismatch parameter. Numerical minimization of the corresponding free energy shows reasonable agreement with the analytical predictions and provides details on the topological defects in the transition region. We find that for small mismatch the transition is of first order, and it remains so for the largest values of mismatch studied here. Our results are consistent with results of simulations for atomistic models of adsorbed overlayers.
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Affiliation(s)
- C V Achim
- Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, FIN-02015 TKK, Finland
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Lu Y, Przybylski M, Trushin O, Wang WH, Barthel J, Granato E, Ying SC, Ala-Nissila T. Strain relief in Cu-Pd heteroepitaxy. Phys Rev Lett 2005; 94:146105. [PMID: 15904083 DOI: 10.1103/physrevlett.94.146105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2004] [Indexed: 05/02/2023]
Abstract
We present experimental and theoretical studies of Pd/Cu(100) and Cu/Pd(100) heterostructures in order to explore their structure and misfit strain relaxation. Ultrathin Pd and Cu films are grown by pulsed laser deposition at room temperature. For Pd/Cu, compressive strain is released by networks of misfit dislocations running in the [100] and [010] directions, which appear after a few monolayers (ML) already. In striking contrast, for Cu/Pd the tensile overlayer remains coherent up to about 9 ML, after which multilayer growth occurs. The strong asymmetry between tensile and compressive cases is in contradiction with continuum elasticity theory and is also evident in the structural parameters of the strained films. Molecular dynamics calculations based on classical many-body potentials confirm the pronounced tensile-compressive asymmetry and are in good agreement with the experimental data.
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Affiliation(s)
- Yafeng Lu
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
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Abstract
We present density functional theory calculations for atomic hydrogen interacting with a stepped surface, the Pt(211) surface. The calculations have been performed at the generalized gradient approximation level, using a slab representation of the surface. This is the state-of-the-art method for calculating the interaction of atoms or molecules with metal surfaces, nevertheless only few studies have used it to study atoms or molecules interacting with stepped surfaces, and none, to the best of our knowledge, have considered hydrogen interacting with stepped platinum surfaces. Our goal has been to initiate a systematic study of this topic. We have calculated the full three-dimensional potential energy surface (PES) for the H/Pt(211) system together with the vibrational band structure and vibrational eigenfunctions of H. A deep global minimum of the PES is found for bridge-bonded hydrogen on the step edge, in agreement with experimental results for the similar H/Pt(533) system. All the local vibrational excitations at the global minimum have been identified, and this will serve as a helpful guide to the interpretation of future experiments on this (or similar) system(s). Furthermore, from the calculated PES and vibrational band structure, we identify a number of consequences for the interpretation or modelling of diffusion experiments studying the coverage and directional dependence of atomic hydrogen diffusion on stepped platinum surfaces.
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Affiliation(s)
- R A Olsen
- Theoretische Chemie, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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Cai L, Altman MS, Granato E, Ala-Nissila T, Ying SC, Xiao X. Surface diffusion anomaly near a substrate phase transition: H on W(100). Phys Rev Lett 2002; 88:226105. [PMID: 12059435 DOI: 10.1103/physrevlett.88.226105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2002] [Indexed: 05/23/2023]
Abstract
Using a linear optical diffraction method, we have experimentally studied the long predicted diffusion anomalous behavior for H/W(100) near the reconstructive phase transition of the W(100) substrate. This anomaly manifests itself in the form of a strong dip in the diffusion coefficient D at the transition temperature T(C). We interpret the strong reduction of D as a result of the diverging friction damping near the transition. The finite dip in D instead of a vanishing D at T(C) also demonstrates the importance of the non-Markovian (memory) deviation from the simple instantaneous damping picture.
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Affiliation(s)
- Lei Cai
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, SAR, China
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Chen LY, Ying SC, Ala-Nissila T. Finding transition paths and rate coefficients through accelerated Langevin dynamics. Phys Rev E Stat Nonlin Soft Matter Phys 2002; 65:042101. [PMID: 12005894 DOI: 10.1103/physreve.65.042101] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2001] [Indexed: 05/23/2023]
Abstract
We present a technique to resolve the rare event problem for a Langevin equation describing a system with thermally activated transitions. A transition event within a given time interval (0,t(f)) can be described by a transition path that has an activation part during (0,t(M)) and a deactivation part during (t(M),t(f))(0<t(M)<t(f)). The activation path is governed by a Langevin equation with negative friction while the deactivation path by the standard Langevin equation with positive friction. Each transition path carries a given statistical weight from which rate constants and related physical quantities can be obtained as averages over all possible paths. We demonstrate how this technique can be used to calculate activation rates of a particle in a two dimensional potential for a wide range of temperatures where standard molecular dynamics techniques are inefficient.
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Affiliation(s)
- L Y Chen
- Department of Physics, University of Texas at San Antonio, San Antonio, Texas 78249, USA
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Bădescu SC, Salo P, Ala-Nissila T, Ying SC, Jacobi K, Wang Y, Bedürftig K, Ertl G. Energetics and vibrational states for hydrogen on Pt(111). Phys Rev Lett 2002; 88:136101. [PMID: 11955109 DOI: 10.1103/physrevlett.88.136101] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2001] [Revised: 03/04/2002] [Indexed: 05/23/2023]
Abstract
We present a combination of theoretical calculations and experiments for the low-lying vibrational excitations of H and D atoms adsorbed on the Pt(111) surface. The vibrational band states are calculated based on the full three-dimensional adiabatic potential energy surface obtained from first-principles calculations. For coverages less than three quarters of a monolayer, the observed experimental high-resolution electron peaks at 31 and 68 meV are in excellent agreement with the theoretical transitions between selected bands. Our results convincingly demonstrate the need to go beyond the local harmonic oscillator picture to understand the dynamics of this system.
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Affiliation(s)
- S C Bădescu
- Helsinki Institute of Physics and Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, FIN-02015 HUT, Espoo, Finland
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Badescu SC, Ying SC, Ala-Nissila T. Quantum diffusion of H/Ni(111) through a Monte Carlo wave function formalism. Phys Rev Lett 2001; 86:5092-5095. [PMID: 11384429 DOI: 10.1103/physrevlett.86.5092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2000] [Indexed: 05/23/2023]
Abstract
We consider a quantum system coupled to a dissipative background with many degrees of freedom using the Monte Carlo wave function method. Instead of dealing with a density matrix which can be very highly dimensional, the method consists of integrating a stochastic Schrödinger equation with a non-Hermitian damping term in the evolution operator, and with random quantum jumps. The method is applied to the diffusion of hydrogen on the Ni(111) surface below 100 K. We show that the recent experimental diffusion data for this system can be understood through an interband activation process, followed by quantum tunneling.
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Affiliation(s)
- S C Badescu
- Department of Physics, Box 1843, Brown University, Providence, Rhode Island 02912-1843, USA
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Abstract
We study the response of an adsorbed monolayer under a driving force as a model of sliding friction phenomena between two crystalline surfaces with a boundary lubrication layer. Using Langevin-dynamics simulation, we determine the nonlinear response in the direction transverse to a high symmetry direction along which the layer is already sliding. We find that below a finite transition temperature there exist a critical depinning force and hysteresis effects in the transverse response in the dynamical state when the adlayer is sliding smoothly along the longitudinal direction.
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Affiliation(s)
- E Granato
- Laboratório Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, 12201-190 São José dos Campos, São Paulo, Brazil
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Chen LY, Baldan MR, Ying SC. Surface diffusion in the low-friction limit: Occurrence of long jumps. Phys Rev B Condens Matter 1996; 54:8856-8861. [PMID: 9984567 DOI: 10.1103/physrevb.54.8856] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Cucchetti A, Ying SC. Memory effects in the frictional damping of diffusive and vibrational motion of adatoms. Phys Rev B Condens Matter 1996; 54:3300-3310. [PMID: 9986229 DOI: 10.1103/physrevb.54.3300] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Gewurz H, Ying SC, Jiang H, Lint TF. Nonimmune activation of the classical complement pathway. Behring Inst Mitt 1993:138-47. [PMID: 8172561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- H Gewurz
- Department of Immunology/Microbiology, Rush Medical College, Chicago, Illinois
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Han WK, Ying SC. Condensation energy and high-temperature phase of the W(100) reconstruction. Phys Rev B Condens Matter 1993; 48:14524-14528. [PMID: 10007874 DOI: 10.1103/physrevb.48.14524] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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