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Yao R, Zhang Y, Yan Y, Wu X, Uddin MG, Wei D, Huang X, Tang L. Natural background level, source apportionment and health risk assessment of potentially toxic elements in multi-layer aquifers of arid area in Northwest China. JOURNAL OF HAZARDOUS MATERIALS 2024; 479:135663. [PMID: 39217931 DOI: 10.1016/j.jhazmat.2024.135663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2024] [Revised: 08/12/2024] [Accepted: 08/25/2024] [Indexed: 09/04/2024]
Abstract
Groundwater contaminated by potentially toxic elements has become an increasing global concern for human health. Therefore, it is crucial to identify the sources and health risks of potentially toxic elements, especially in arid areas. Despite the necessity, there is a notable research gap concerning the sources and risks of these elements within multi-layer aquifers in such regions. To address this gap, 54 phreatic and 24 confined groundwater samples were collected from an arid area in Northwest China. This study aimed to trace the sources and evaluate the human health risks of potentially toxic elements by natural background level (NBL), positive matrix factorization (PMF) model, and health risk model. Findings revealed exceeding levels of potentially toxic elements existed in phreatic and confined aquifers. Source apportionment and NBL results indicated that mineral dissolution, evaporation, redox reactions, and human activities were the main factors for elevated concentrations of potentially toxic elements. High Fe and Mn concentrations were attributed to reduction environments, while F accumulation resulted from slow runoff, and irrigation from the Yellow River. Due to high F levels, more than one-third of groundwater samples (phreatic: 33.14 %, confined: 56.22 %) posed non-carcinogenic health risks to population groups. Adults displayed higher carcinogenic risks (phreatic: 19.47 %, confined: 34.16 %) than infants (phreatic: 0 %, confined: 0 %) and children (phreatic: 1.26 %, confined: 7.97 %) owing to the toxic elements of Cr. The confined aquifer presented greater health risks than the phreatic aquifer. Consequently, controlling the levels of F and Cr in multi-layered aquifers is key to reducing health risks. These findings provide valuable insights into protecting groundwater from contamination by potentially toxic elements in multi-layered aquifers worldwide.
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Affiliation(s)
- Rongwen Yao
- Yibin Research Institute, Southwest Jiaotong University, Yibin 644000, China; Faculty of Geosciences and Engineering, Southwest Jiaotong University, Sichuan, Chengdu 611756, China
| | - Yunhui Zhang
- Yibin Research Institute, Southwest Jiaotong University, Yibin 644000, China; Faculty of Geosciences and Engineering, Southwest Jiaotong University, Sichuan, Chengdu 611756, China.
| | - Yuting Yan
- Yibin Research Institute, Southwest Jiaotong University, Yibin 644000, China; Faculty of Geosciences and Engineering, Southwest Jiaotong University, Sichuan, Chengdu 611756, China
| | - Xiangchuan Wu
- Yibin Research Institute, Southwest Jiaotong University, Yibin 644000, China; Faculty of Geosciences and Engineering, Southwest Jiaotong University, Sichuan, Chengdu 611756, China
| | - Md Galal Uddin
- School of Engineering, University of Galway, Ireland; Ryan Institute, University of Galway, Ireland; MaREI Research Centre, University of Galway, Ireland; Eco-HydroInformatics Research Group (EHIRG), Civil Engineering, National University of Ireland Galway, Ireland
| | - Denghui Wei
- Yibin Research Institute, Southwest Jiaotong University, Yibin 644000, China; Faculty of Geosciences and Engineering, Southwest Jiaotong University, Sichuan, Chengdu 611756, China
| | - Xun Huang
- Yibin Research Institute, Southwest Jiaotong University, Yibin 644000, China
| | - Lijun Tang
- Ningxia Survey and Monitoring Institute of Land and Resources, Yinchuan 750000, China
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Pasquetti F, Natali S, Luppichini M, Bini M, Del Seppia N, Delgado-Huertas A, Giannecchini R. Hydrodynamics and water quality of a highly anthropized wetland: the case study of the Massaciuccoli basin (Tuscany, Italy). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:43117-43137. [PMID: 38886272 PMCID: PMC11222230 DOI: 10.1007/s11356-024-33899-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Accepted: 05/31/2024] [Indexed: 06/20/2024]
Abstract
Owing to increasing anthropogenic impacts, wetlands have suffered a serious environmental decline in recent decades. The sustainable management of these natural resources is fundamental to maintain both the ecosystems and the economic activities. The Lake Massaciuccoli and nearby areas represent one of the largest residual coastal marshy areas in Tuscany (Italy). This wetland is characterized by large-scale and intensive agricultural use and affected by reclamation activities, with consequent problems of erosion, subsidence and lake eutrophication and siltation. In this context, an integrated study combining hydrochemical data (water levels, electrical conductivity, pH, turbidity, major ions, trace metals) and stable isotopes (H, O, S) has been performed in the southernmost part of the basin, to better disentangle processes and interactions between groundwater and surface water and to understand the origin of solutes and their evolution. Our results indicated that both groundwater and surface water have a meteoric origin and that geochemical composition of groundwater is mainly affected by local geological and biological processes. Moreover, surface water is affected by sea water mixing and evapotranspiration/precipitation processes. The impact of agricultural activity and the use of fertilizers on the water quality appears to be limited as regards nitrates, indicating that less intense agricultural practices implemented in recent years have been successful. As regards sulfates, Fe, and Mn, we cannot fully elucidate the mechanisms underlying human influence, but the oscillation of water level and degradation of peat enhanced by reclamation and agriculture activities likely played an important role in controlling the fate of these elements. Overall, these results underline the importance of integrated approaches to disentangle geochemical processes and will be useful in supporting policy implementation and environmental protection in this valuable area of Tuscany. Findings from this work suggest the need for policy-making authorities to take actions as soon as possible to mitigate risks. Closer co-operation is essential between authorities and farmers to reduce inputs of fertilizers and chemicals into the lake and the surrounding area. Also, additional policy measures should be enforced to reduce the mechanical soil tillage and limit erosion and runoff, such as the NBSs implemented within the Phusicos Project.
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Affiliation(s)
- Francesca Pasquetti
- Earth Science Department, University of Pisa, Via S. Maria 53, 56126, Pisa, Italy.
| | - Stefano Natali
- Earth Science Department, University of Pisa, Via S. Maria 53, 56126, Pisa, Italy
| | - Marco Luppichini
- Earth Science Department, University of Pisa, Via S. Maria 53, 56126, Pisa, Italy
| | - Monica Bini
- Earth Science Department, University of Pisa, Via S. Maria 53, 56126, Pisa, Italy
- CIRSEC - Centre for Climate Change Impact-University of Pisa, Via del Borghetto 80, 56124, Pisa, Italy
- Istituto Nazionale Di Geofisica E Vulcanologia (INGV), Via Di Vigna Murata 605, 00143, Rome, Italy
| | - Nicola Del Seppia
- Autorità Di Bacino Distrettuale Dell'Appennino Settentrionale, Via V. Veneto, 1, 55100, Lucca, Italy
| | - Antonio Delgado-Huertas
- Instituto Andaluz de Ciencias de La Tierra, CSIC-UGR, Av. de Las Palmeras, 4, 18100, Armilla, Spain
| | - Roberto Giannecchini
- Earth Science Department, University of Pisa, Via S. Maria 53, 56126, Pisa, Italy
- CIRSEC - Centre for Climate Change Impact-University of Pisa, Via del Borghetto 80, 56124, Pisa, Italy
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Monir MM, Sarker SC. Analyzing post-2000 groundwater level and rainfall changes in Rajasthan, India, using well observations and GRACE data. Heliyon 2024; 10:e24481. [PMID: 38312700 PMCID: PMC10835170 DOI: 10.1016/j.heliyon.2024.e24481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 01/09/2024] [Accepted: 01/09/2024] [Indexed: 02/06/2024] Open
Abstract
Research on groundwater and water resources is essential for preserving viable environments. Although the arid area has been identified as a significant hotspot for groundwater depletion, the Indian desert region was not included in the initial analysis. This study intends to evaluate Rajasthan's groundwater level (GWL) and rainfall trends from 2000 to 2021 and how variations in GWLs are related to long-term rainfall. Annual GWL and rainfall data time series were collected from 921 monitoring stations for 33 districts of Rajasthan. The GWL trends and rainfall were identified using non-parametric modified Mann-Kendall test and Spearman rho techniques. Pearson's, Kendall's (tau b), and Spearman's analyses were used to determine the correlation between GWL and rainfall. The results from the modified Mann-Kendall and Spearman rho methods reveal that GWL has a significant declining trend in 38 % of districts, where 13 % have no trend, and the rest of 49 % have a rising trend. The yearly rainfall trend at 70 % and 30 % of the districts are rising and stable, respectively. A negative correlation between GWL depth and rainfall was discovered in each district, where 15 % are firm, 58 % are moderate, and 27 % are weak negative correlations. Also, the regression analysis estimates the effect of rainfall on GWL, which was observed: rainfall negatively influenced the depth of GWL at 58 % of the districts, had a positive impact at 33 %, and others had no effect. GRACE TWS anomaly shows a decreasing trend of -1.22 cm/yr, and GRACE and GWL anomalies have a positive relationship (r = 0.471). Results conclude that rainfall is the primary influencer on GWL in this semi-arid region vulnerable to drought.
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Affiliation(s)
- Md. Moniruzzaman Monir
- Department of Geography and Environmental Science, Begum Rokeya University, Rangpur-5400, Bangladesh
| | - Subaran Chandra Sarker
- Department of Geography and Environmental Science, Begum Rokeya University, Rangpur-5400, Bangladesh
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Fernández-Ayuso A, Kohfahl C, Aguilera H, Rodríguez-Rodríguez M, Ruiz-Bermudo F, Serrano-Hidalgo C, Romero-Álvarez C. Control of trace metal distribution and variability in an interdunal wetland. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 857:159409. [PMID: 36243073 DOI: 10.1016/j.scitotenv.2022.159409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/04/2022] [Accepted: 10/09/2022] [Indexed: 06/16/2023]
Abstract
Trace elements are serious pollutants in the natural environment and are of increasing concern due to the adverse effects at global scale. To refine the current understanding of trace metal distribution and variability in natural environments, concentrations of dissolved trace metals (Ag, Al, As, B, Ba, Be, Co, Cr, Cd, Cu, Fe, Hg, Mo, Ni, Pb, Sb, Se, Th,Tl, U, V, Mn, Zn), major ions, inorganic nutrients (NO3, PO4), TOC and stable isotopes of water were determined in water samples from rainwater, seven piezometers and a pond in the coastal Doñana wetland during four sampling campaigns between 2017 and 2019. Results show clear evaporation signatures of stable isotopes in the pond but not in the groundwater. Hydrochemical analyses yield significant, systematic changes in groundwater trace metal and nutrient composition along the flowpath from the dune belt to the pond, controlled by organic matter in the sediments. Whereas major ions reached maximum concentrations in the pond due to evapoconcentration, most trace metals showed highest concentrations at sites with lower redox levels, except for B, As and U, which showed very high concentrations in the pond. Cu, Zn, Ni, Sb and Tl yielded higher median concentrations in rainwater than in most of the groundwater points and in case of Cu and Zn higher even than in surface water which points to an atmospheric input source of these elements. Temporal variability of trace metals was related to lower hydraulic heads after an elongated dry period which led to lower redox levels and higher concentrations of most of the trace elements whereas major ions showed more constant concentration levels. This is of special concern regarding climate change and the predicted higher frequency of prolonged dry periods, which could modify the natural hydrochemical patterns in undisturbed wetlands systems.
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Affiliation(s)
- A Fernández-Ayuso
- Instituto Geológico y Minero de España (IGME-CSIC), C/Rios Rosas 23, 28003 Madrid, Spain; Universidad Autonoma de Madrid-Campus de Cantoblanco, C/Francisco Tomás y Valiente, 7, 28049 Madrid, Spain
| | - C Kohfahl
- Instituto Geológico y Minero de España (IGME-CSIC), Plaza de España, Torre Norte, 41013 Sevilla, Spain.
| | - H Aguilera
- Instituto Geológico y Minero de España (IGME-CSIC), C/Rios Rosas 23, 28003 Madrid, Spain
| | - M Rodríguez-Rodríguez
- Department of Physical, Chemical and Natural Systems, University Pablo de Olavide, 41013 Seville, Spain
| | - F Ruiz-Bermudo
- Instituto Geológico y Minero de España (IGME-CSIC), Plaza de España, Torre Norte, 41013 Sevilla, Spain
| | - C Serrano-Hidalgo
- Escuela Técnica Superior de Ingenieros de Minas, Universidad Politécnica de Madrid, C/Ríos Rosas, 21, 28003 Madrid, Spain
| | - C Romero-Álvarez
- Department of Physical, Chemical and Natural Systems, University Pablo de Olavide, 41013 Seville, Spain
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Pensky J, Fisher AT, Gorski G, Schrad N, Dailey H, Beganskas S, Saltikov C. Enhanced cycling of nitrogen and metals during rapid infiltration: Implications for managed recharge. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:156439. [PMID: 35660593 DOI: 10.1016/j.scitotenv.2022.156439] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 05/12/2022] [Accepted: 05/30/2022] [Indexed: 06/15/2023]
Abstract
We present results from a series of plot-scale field experiments to quantify physical infiltration dynamics and the influence of adding a carbon-rich, permeable reactive barrier (PRB) for the cycling of nitrogen and associated trace metals during rapid infiltration for managed aquifer recharge (MAR). Recent studies suggest that adding a bio-available carbon source to soils can enhance denitrification rates and associated N load reduction during moderate-to-rapid infiltration (≤1 m/day). We examined the potential for N removal during faster infiltration (>1 m/day), through coarse and carbon-poor soils, and how adding a carbon-rich PRB (wood chips) affects subsurface redox conditions and trace metal mobilization. During rapid infiltration, plots amended with a carbon-rich PRB generally demonstrated modest increases in subsurface loads of dissolved organic carbon, nitrite, manganese and iron, decreases in loads of nitrate and ammonium, and variable changes in arsenic. These trends differed considerably from those seen during infiltration through native soil without a carbon-rich PRB. Use of a carbon-rich soil amendment increased the fraction of dissolved N species that was removed at equivalent inflowing N loads. There is evidence that N removal took place primarily via denitrification. Shifts in microbial ecology following infiltration in all of the plots included increases in the relative abundances of microbes in the families Comamonadaceae, Pseudomonadaceae, Methylophilaceae, Rhodocyclaceae and Sphingomonadaceae, all of which contain genera capable of carrying out denitrification. These results, in combination with studies that have tested other soil types, flow rates, and system scales, show how water quality can be improved during infiltration for managed recharge, even during rapid infiltration, with a carbon-rich soil amendment.
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Affiliation(s)
- Jennifer Pensky
- Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, United States.
| | - Andrew T Fisher
- Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, United States
| | - Galen Gorski
- Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, United States
| | - Nicole Schrad
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA 95064, United States
| | - Hannah Dailey
- Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, United States
| | - Sarah Beganskas
- Water Resource Management, Delaware River Basin Commission, West Trenton, NJ 08628, United States
| | - Chad Saltikov
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA 95064, United States
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Wang Z, Su Q, Wang S, Gao Z, Liu J. Spatial distribution and health risk assessment of dissolved heavy metals in groundwater of eastern China coastal zone. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 290:118016. [PMID: 34428698 DOI: 10.1016/j.envpol.2021.118016] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/11/2021] [Accepted: 08/19/2021] [Indexed: 05/12/2023]
Abstract
Environmental changes and human activities have deteriorated the quality of groundwater, which is an important source of freshwater in coastal areas. The Jiangsu Coastal Zone (JCZ), which is a typical area of the eastern China coastal zone (ECCZ), has a great demand for clean water resources due to its dense population. The groundwater in the JCZ is affected by both human activities and seawater intrusion. However, research on heavy metals in the groundwater of the JCZ is limited. This study investigated the spatial distribution characteristics and influencing factors of heavy metals in coastal groundwater of Jiangsu Province and conducted a health risk assessment (HRA). Relatively high concentrations of Cu, Cd, Pb, Co, Zn, and Ba existed in the northern JCZ, while As and B predominated in the central JCZ. The main heavy metal pollutants in the groundwater are B and As, with mean values at 0.61 mg/L and 0.02 mg/L, exceeding the standard rate reaching 48.28% and 18.07% respectively. The HRA results showed that B had the largest hazard quotient (HQ), accounting for 50.22% of the total HQs, and As was attributed to the pollutant with the largest cancer risk (CR), accounting for 99.74% of the total CRs. According to the results of the correlation analysis, heavy metals in the groundwater of JCZ mainly originated from industrial pollution, seawater intrusion, and mineral dissolution. Seawater intrusion increases the content of As and B in groundwater, leading to higher health risks. Therefore, the government should strengthen the supervision of seawater intrusion by implementing more effective water resource management policies, or adopting engineering measures such as installing subsurface physical barriers to prevent and control seawater intrusion.
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Affiliation(s)
- Zhenyan Wang
- College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, 266510, China; Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, Ministry of Natural Resources of the People's Republic of China, Qingdao, 266061, China; Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266061, China
| | - Qiao Su
- Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, Ministry of Natural Resources of the People's Republic of China, Qingdao, 266061, China; Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266061, China
| | - Shu Wang
- College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, 266510, China; Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, Ministry of Natural Resources of the People's Republic of China, Qingdao, 266061, China; Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266061, China
| | - Zongjun Gao
- College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, 266510, China.
| | - Jiutan Liu
- College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, 266510, China
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Mora A, Torres-Martínez JA, Moreau C, Bertrand G, Mahlknecht J. Mapping salinization and trace element abundance (including As and other metalloids) in the groundwater of north-central Mexico using a double-clustering approach. WATER RESEARCH 2021; 205:117709. [PMID: 34601358 DOI: 10.1016/j.watres.2021.117709] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 09/16/2021] [Accepted: 09/21/2021] [Indexed: 06/13/2023]
Abstract
This study aimed to determine the reliability of the double-clustering method to understand the spatial association and distribution of major and minor constituents in the groundwater of an arid endorheic basin in central Mexico (Comarca Lagunera Region). The results of the double-clustering approach were compared with well-known spatial statistics such as spatial autocorrelations (Moran index) and the local indicator of spatial association (LISA). Fifty-five groundwater samples were collected from diverse wells within the basin, and the major ions, metalloids, and trace elements were determined. Overall, the double-clustering analysis was an effective tool for identifying lithogenic/anthropogenic processes occurring in the basin and for establishing zones with high or low abundance of major ions and trace elements, even where processes affecting the groundwater quality were spatially dispersed. Although 89% of the samples showed As higher than the threshold value of 10 μg/L proposed by the World Health Organization for drinking water, both the double-clustering and LISA analyses identified As hotspots in the alluvial aquifer, where the extraction of deeper and warmer groundwater might promote the concomitant release of the metalloids As, Sb, and Ge and the trace elements V and W. Similarly, both statistical analyses identified mountainous sectors where the weathering of silicates and carbonates plays a key role in the abundance of HCO3-, Ga, and Ba. However, the LISA analysis failed to identify hotspots of carbonate-derived elements such as Ca, Mg, Sr, and U and silicate-derived elements such as Ca, Mg, K, Sr, Rb, Cs, Pb, Ni, and Y. Otherwise, the double-clustering analysis clearly defined high- and low-concentration zones for all these elements in the study region. Unlike the LISA analysis, the double-clustering approach was also successful in determining alluvial areas with high concentrations of Si and Ti and areas where the concentrations of Na, Cl-, SO42-, NO3-, B, Li, Cu, Re, and Se in groundwater were elevated, increasing the groundwater salinity. Overall, this study demonstrated that the double-clustering is an easy-to-apply approach, capable of visualizing disperse zones where specific anthropogenic processes may threaten the groundwater quality.
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Affiliation(s)
- Abrahan Mora
- Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey, Campus Puebla, Atlixcáyotl 5718, Puebla de Zaragoza, 72453, Puebla, Mexico
| | - Juan Antonio Torres-Martínez
- Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey, Campus Monterrey, Eugenio Garza Sada 2501, Monterrey, 64849, Nuevo León, Mexico
| | - Cristina Moreau
- Facultad de Ingeniería Civil, Universidad Autónoma de Nuevo León, Av. Universidad, San Nicolás de Los Garza, Nuevo León, Mexico
| | - Guillaume Bertrand
- University of Bourgogne Franche-Comté, UMR UFC CNRS 6249 Chrono-Environnement, 16 route de Gray 25000 Besançon, 4 place Tharradin, 25200 Montbéliard, France
| | - Jürgen Mahlknecht
- Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey, Campus Monterrey, Eugenio Garza Sada 2501, Monterrey, 64849, Nuevo León, Mexico.
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LaRowe DE, Carlson HK, Amend JP. The Energetic Potential for Undiscovered Manganese Metabolisms in Nature. Front Microbiol 2021; 12:636145. [PMID: 34177823 PMCID: PMC8220133 DOI: 10.3389/fmicb.2021.636145] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 05/03/2021] [Indexed: 11/13/2022] Open
Abstract
Microorganisms are found in nearly every surface and near-surface environment, where they gain energy by catalyzing reactions among a wide variety of chemical compounds. The discovery of new catabolic strategies and microbial habitats can therefore be guided by determining which redox reactions can supply energy under environmentally-relevant conditions. In this study, we have explored the thermodynamic potential of redox reactions involving manganese, one of the most abundant transition metals in the Earth's crust. In particular, we have assessed the Gibbs energies of comproportionation and disproportionation reactions involving Mn2+ and several Mn-bearing oxide and oxyhydroxide minerals containing Mn in the +II, +III, and +IV oxidation states as a function of temperature (0-100°C) and pH (1-13). In addition, we also calculated the energetic potential of Mn2+ oxidation coupled to O2, NO2 -, NO3 -, and FeOOH. Results show that these reactions-none of which, except O2 + Mn2+, are known catabolisms-can provide energy to microorganisms, particularly at higher pH values and temperatures. Comproportionation between Mn2+ and pyrolusite, for example, can yield 10 s of kJ (mol Mn)-1. Disproportionation of Mn3+ can yield more than 100 kJ (mol Mn)-1 at conditions relevant to natural settings such as sediments, ferromanganese nodules and crusts, bioreactors and suboxic portions of the water column. Of the Mn2+ oxidation reactions, the one with nitrite as the electron acceptor is most energy yielding under most combinations of pH and temperature. We posit that several Mn redox reactions represent heretofore unknown microbial metabolisms.
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Affiliation(s)
- Douglas E LaRowe
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
| | - Harold K Carlson
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
| | - Jan P Amend
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States.,Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
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