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Ekwonna T, Akindeju O, Amos B, Lin ZQ. Selenium Removal from Wastewater by Microbial Transformation and Volatilization. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2024. [PMID: 38337076 DOI: 10.1007/10_2023_242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
Selenium (Se) is a naturally occurring trace element that is nutritionally essential for humans and animals, but becomes toxic at high concentrations. This laboratory study explored the role of microbes in Se removal from contaminated wastewater via biological transformation and volatilization processes. Microbes could immobilize water-soluble selenate (SeO42-) and selenite (SeO32-) to water-insoluble elemental Se (Se0) and transform Se into volatile Se compounds found in the atmosphere. Results of this laboratory study showed that Bacillus cereus, a bacterial strain isolated from wheat straw and biosolid-WTR-sand substrates showed a significant biotransformation ability of reducing selenate and selenite to elemental Se and forming volatile Se organic compounds in wastewater. Overall, microbial Se chemical reduction, methylation, and volatilization are important processes in bioremediation of Se-contaminated wastewater.
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Affiliation(s)
- Tochukwu Ekwonna
- Department of Environmental Sciences, Southern Illinois University - Edwardsville, Edwardsville, IL, USA
| | - Olusegun Akindeju
- Department of Environmental Sciences, Southern Illinois University - Edwardsville, Edwardsville, IL, USA
| | - Brianna Amos
- Department of Biological Sciences, Southern Illinois University - Edwardsville, Edwardsville, IL, USA
| | - Zhi-Qing Lin
- Department of Environmental Sciences, Southern Illinois University - Edwardsville, Edwardsville, IL, USA.
- Department of Biological Sciences, Southern Illinois University - Edwardsville, Edwardsville, IL, USA.
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Dalai S, Sivan M, Husain MA, Alam N, Landrot G, Biswas A. Mechanistic Insight into the Abiotic Interactions of Selenate and Selenite with Natural Organic Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:16595-16605. [PMID: 37855829 DOI: 10.1021/acs.est.3c06276] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
Natural organic matter (NOM) decreases the selenium (Se) mobility in soil and sediment. Biotic dissimilatory reduction of selenate and selenite and assimilation of the reduced Se species into biomolecules are thought to be primarily responsible for this decreased Se mobility. However, the possibility of Se immobilization due to the abiotic interaction of Se species with NOM is still poorly understood. Equilibrating selenate and selenite with a model NOM (Pahokee peat soil), followed by X-ray absorption spectroscopic analysis, this study shows that the NOM can abiotically reduce highly mobile selenate into relatively less mobile selenite. NOM can sorb Se species, especially selenite, considerably. Preloading of the NOM with Fe(III) increases the sorption of selenite and selenate by several orders of magnitude. Modeling of the Se and Fe K-edge EXAFS data revealed that Se species are sorbed to NOM due to indirect complexation with the organically complexed Fe(O,OH)6 octahedra through the corner- (2C) and edge-sharing (1E) and direct complexation with the oxygen-containing functional groups of the NOM. This study concludes that the abiotic reduction and complexation of the Se species with NOM can be the additional or alternative route of Se immobilization in the NOM-rich soil and sediment.
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Affiliation(s)
- Subhashree Dalai
- Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri 462066, Madhya Pradesh, India
| | - Malavika Sivan
- Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri 462066, Madhya Pradesh, India
| | - Mohd Amir Husain
- Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri 462066, Madhya Pradesh, India
| | - Naved Alam
- Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri 462066, Madhya Pradesh, India
| | - Gautier Landrot
- SOLEIL Synchrotron, L'Orme des Merisiers, Saint-Aubin, BP 48, Gif-sur-Yvette Cedex 91192, France
| | - Ashis Biswas
- Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri 462066, Madhya Pradesh, India
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Chang H, Zhu JM, Lin ZQ, Meng L. Topographic constraints on the distribution of selenium in the supergene environment: A case study at Yutangba, China. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 319:121026. [PMID: 36621714 DOI: 10.1016/j.envpol.2023.121026] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 12/20/2022] [Accepted: 01/04/2023] [Indexed: 06/17/2023]
Abstract
The local topography and leaching conditions significantly affect the spatial distribution of selenium (Se) in the local environment. However, the driving factors controlling Se distribution have not been well addressed. In this paper, taking Yutangba, a village known for human selenosis in China, as an example, we demonstrate how topographic factors influence the spatial distribution of Se in soils and plants. In the scenarios of slope ≤25°, the correlations among slope and soil/extractable/plant Se are significantly negative (P < 0.05), whereas they become weak or unclear when the slope is > 25°, suggesting that 25° of slope is a critical transition boundary. Similar observations were further verified by the soil erosion modulus (SEM) and the surface runoff intensity index (SRI), indicating that Se transport via soil erosion is limited and accounts for 11.2-17% of the soil Se, while surface runoff plays a dominant role in the Se distribution, accounting for 83-88.1%. Soil extractable Se is negatively correlated with SRI (Pearson r = -0.87 at slope < 25°), showing that the migration capacity of Se is higher at steep terrain and controlled by topography through soil erosion and surface runoff. The positive relationship between plant Se and soil/extractable Se demonstrates that topography indirectly influences plant Se through soil Se bioavailability. Abnormally local Se enrichment observed at the elevated steep hillside (>25°) in northwestern Yutangba primarily was resulted from the weathering of Se-rich rocks. These observations confirm that the topographic slope gradient influences the transport and spatial distribution of soil Se, implying that topography should be considered when studying the spatial distribution of soil Se at a regional scale, especially for the Se-poor belt in China.
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Affiliation(s)
- Hui Chang
- State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences (Beijing), Beijing 100083, China
| | - Jian-Ming Zhu
- State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences (Beijing), Beijing 100083, China.
| | - Zhi-Qing Lin
- Department of Environmental Sciences and Department of Biological Sciences, Southern Illinois University, Edwardsville, IL 62026-1099, USA
| | - Lei Meng
- Department of Geography, Environment, and Tourism, Western Michigan University, Kalamazoo, MI 49008, USA
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Terashima M, Endo T, Kimuro S, Beppu H, Nemoto K, Amano Y. Iron-induced association between selenium and humic substances in groundwater from deep sedimentary formations. J NUCL SCI TECHNOL 2022. [DOI: 10.1080/00223131.2022.2111376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Affiliation(s)
| | - Takashi Endo
- Japan Nuclear Fuel Chemical Analysis Co., Ltd, Aomori, Japan
| | | | - Hikari Beppu
- Inspection Development Company Ltd, Ibaraki, Japan
| | | | - Yuki Amano
- Japan Atomic Energy Agency (JAEA), Ibaraki, Japan
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Yang C, Yao H, Wu Y, Sun G, Yang W, Li Z, Shang L. Status and risks of selenium deficiency in a traditional selenium-deficient area in Northeast China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 762:144103. [PMID: 33360462 DOI: 10.1016/j.scitotenv.2020.144103] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/20/2020] [Accepted: 11/20/2020] [Indexed: 06/12/2023]
Abstract
In agricultural lands with selenium (Se) deficiency, bioavailability of Se in plants is low. Residents from large-scale agricultural production areas with Se deficiency often suffer from endemic diseases because of consumption of agricultural products lacking in Se. One such area in Northeast China where Keshan disease and Kashin-Beck disease originated, was selected for investigating the geochemistry, influencing factors, and risks of Se in the agroecosystems. Analysis of field samples indicates that the Se deficiency in soil is significantly reduced compared with that of several decades ago, and 62.6% of soils are now Se-sufficient in the southern Songnen Plain. However, Se in crop products remains low due to weak soil-plant transfer, resulting in high risks of Se deficiency related diseases in the rural population of this area. Structural equation modeling, principal component analysis, and other statistical analyses revealed that climate conditions and soil physical and chemical properties are the key factors influencing the spatial distribution of soil Se. Extensive use of agricultural fertilizers may indirectly inhibit the migration of Se from soil to plants. Ensuring sufficient Se contents in agricultural products to meet the minimum daily requirements of residents remains a challenge in Se-deficient areas, especially in the increased agricultural production environment in China.
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Affiliation(s)
- Chenmeng Yang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Heng Yao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Yunjie Wu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
| | - Guangyi Sun
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; Heilongjiang Institute of Geological Survey, Harbin 150036, China.
| | - Wen Yang
- Heilongjiang Institute of Geological Survey, Harbin 150036, China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Zhonggen Li
- College of Resources and Environment, Zunyi Normal University, Zunyi 563006, China
| | - Lihai Shang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
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Lazareva EV, Myagkaya IN, Kirichenko IS, Gustaytis MA, Zhmodik SM. Interaction of natural organic matter with acid mine drainage: In-situ accumulation of elements. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 660:468-483. [PMID: 30640114 DOI: 10.1016/j.scitotenv.2018.12.467] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/30/2018] [Accepted: 12/30/2018] [Indexed: 06/09/2023]
Abstract
Natural organic matter (NOM) within the dispersion train of Novo-Ursk tailings (Salair Ridge, Kemerovo region, Russia) is composed of remnant sedge peat mounds and is located either on the surface or is buried under cyanide wastes. The organic material interacts with AMD and with the wastes, which leaves imprint on its composition. This interaction produces geochemical anomalies (g/t: 1582 Cu, 41,300 Zn, 6060 Se, 11,700 Hg, 114-155 Au, 534 Ag, 416 I). The contents of elements depend on Fe in three groups of NOM samples that contain <10 wt% Fe (group I), 10-22 wt% Fe (group II), and >22 wt% Fe (group III). NOM with higher Fe enrichment contains less Cu, Zn, Se, Hg, Ag and I, as well as Cd, Ba, Sr and Rb, Y, Zr, Nb, Mo, Sn, Sb, and Te but more As. Yet, gold may reach high concentrations in NOM with any Fe contents. Accumulation of elements by NOM during its prolonged interaction with wastes and AMD is maintained by physical, chemical, biochemical, and mineralogical processes. They are, respectively, migration of waters controlled by permeability of material in the dispersion train depending on its grain sizes and by AMD flow direction; oxidative dissolution of sulfides, complexing, and adsorption on organic matter and Fe(III) hydroxides; microbial mediation; and secondary mineralization. The chemistry of waters interacting with NOM at the time of its deposition can be reconstructed with regard to several factors, including microbial mediation. Namely, local geochemical anomalies with ultrahigh element concentrations may arise because microorganisms can immobilize Hg to make it less toxic; sulfate-reducing bacteria can maintain precipitation of Zn, Cu, and Cd sulfides; microbial activity can mediate redistribution of elements between clastic and organic materials, etc. The inferred inheritance of AMD geochemical signatures by NOM has implications for the conditions and mechanisms of element accumulation.
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Affiliation(s)
- E V Lazareva
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Koptyuga Ave. 3, Novosibirsk 630090, Russia
| | - I N Myagkaya
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Koptyuga Ave. 3, Novosibirsk 630090, Russia.
| | - I S Kirichenko
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Koptyuga Ave. 3, Novosibirsk 630090, Russia
| | - M A Gustaytis
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Koptyuga Ave. 3, Novosibirsk 630090, Russia
| | - S M Zhmodik
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Koptyuga Ave. 3, Novosibirsk 630090, Russia
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Lee S, Roh Y, Koh DC. Oxidation and reduction of redox-sensitive elements in the presence of humic substances in subsurface environments: A review. CHEMOSPHERE 2019; 220:86-97. [PMID: 30579952 DOI: 10.1016/j.chemosphere.2018.11.143] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 11/19/2018] [Accepted: 11/22/2018] [Indexed: 06/09/2023]
Abstract
The oxidation and reduction (redox) processes of redox-sensitive elements (RSE) in the presence of humic substances (HS) have become a significantly important issue in the terms of biogeochemical cycles. Redox processes are crucial for determining the speciation, mobility, toxicity, and bioavailability of RSE in natural environments. It is known that HS act as an effective redox mediator for accepting and donating electrons, and thereby transfers them to RSE. We review the recent progress in the field of the redox processes of RSE including As, Cr, Cu, Fe, Hg, and Se in the presence of HS. The extent and rate of the redox processes of these RSE are significantly affected by the concentration of functional groups and the chemical composition of HS. In subsurface environments, pH, ionic strength, and the presence of competitive components, microorganisms, and oxygen need to be considered to elucidate the redox processes of RSE in the presence of HS. In addition, improved analytical techniques for the characterization of HS has the potential to advance the study on the redox processes of RSE in the presence of HS. It may contribute to understanding the mechanism for the redox processes between RSE and HS in the biogeochemical cycles.
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Affiliation(s)
- Seyong Lee
- Groundwater Research Center, Korea Institute of Geoscience and Mineral Resources (KIGAM), Gwahak-ro, Yuseoung-gu, Daejeon 34132, Republic of Korea; Planning & Management Division, National Institute of Chemical Safety (NICS), 90 Gajeongbuk-ro, Yuseoung-gu, Daejeon 34111, Republic of Korea.
| | - Younghee Roh
- Institute for Korean Regional Studies, Seoul National University (SNU), 1 Gwanak-ro Gwanak-gu, Seoul 08826, Republic of Korea
| | - Dong-Chan Koh
- Groundwater Research Center, Korea Institute of Geoscience and Mineral Resources (KIGAM), Gwahak-ro, Yuseoung-gu, Daejeon 34132, Republic of Korea
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Ali F, Peng Q, Wang D, Cui Z, Huang J, Fu D, Liang D. Effects of selenite and selenate application on distribution and transformation of selenium fractions in soil and its bioavailability for wheat (Triticum aestivum L.). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:8315-8325. [PMID: 28161863 DOI: 10.1007/s11356-017-8512-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Accepted: 01/26/2017] [Indexed: 05/12/2023]
Abstract
This study investigated the effect of selenate and selenite application on the distribution, transformation of selenium (Se) fractions in soil, as well as the accumulation and availability of Se in each part of wheat plants. A pot experiment was conducted using different concentrations of exogenous selenite or selenate (0.5, 1, 2.5, 5, and 10 mg Se kg-1 soil). Sequential extraction was used to determine the Se fractions in soil, and different models were used to study the behavior of Se in soil and its availability to wheat. Results showed that the distribution and availability of Se in soil and its accumulation in wheat affected both by Se concentrations and forms of exogenous Se. In selenite-treated soil, the proportion of exchangeable and carbonate-bound Se (EXC-Se) (21-42%) fraction increased compared to that in control (12%), while organic matter-bound Se (OM-Se) (23-33%) and Fe-Mn oxide-bound Se (FMO-Se) (11-15%) fractions decreased compare with those in control (37 and 32%, respectively). In selenate-treated soil, soluble-Se (SOL-Se) fraction (30-54%) increased and the OM-Se (9.8-20%) and FMO-Se (4.7-14.2%) fractions decreased compared with those in control. Residual Se (RES-Se) fraction was increased for selenite (7.4-13.4%) and selenate (12-20%) treatments compared with that in control (6.5%). In comparison with control, the available Se (SOL-Se + EXC-Se) fraction increased for both selenite (32-47%) or selenate (54-72%) treatments. Moreover, at the same rate of Se application, Se availability was higher in wheat grown in selenate-treated soils than that in selenite-treated soils. The redistribution index (U ts) of Se increased from 1 (in control) to 1.2-1.9 and 1.5-2 for selenite and selenate treatments, respectively; additionally, the mobility factor (MF) in selenate-treated soil was 40-90% higher than that in selenite-treated soil. Furthermore, relative bonding intensity (I R ) for both selenite (0.38-0.45) and selenate treatment (0.33-0.41) decreased compared with that in control (0.55). These differences indicated that selenite and selenate varied in terms of fixation capacities in soil, in transformation and distribution of Se in soil fractions, and in their availability to plants. The results of Michaelis-Menten equation demonstrated the high affinity of leaf to selenate, and the high affinity of roots and grains to selenite. Selenate was dominant in nearly all parts of wheat plants and in each application level. However, the affinity of selenite to wheat grains suggests that selenite is a useful Se fertilizer that must be considered in biofortification programs. In-depth studies at the pot and field scales by using different wheat varieties and application methods of Se in different ecological zones must be conducted to elucidate the mechanism and biochemical properties of Se in soil-plant system and ultimately produce Se-rich staple foods.
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Affiliation(s)
- Fayaz Ali
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Qin Peng
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Dan Wang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Zewei Cui
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Jie Huang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Dongdong Fu
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Dongli Liang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, China.
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi, 712100, China.
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Martin DP, Seiter JM, Lafferty BJ, Bednar AJ. Exploring the ability of cations to facilitate binding between inorganic oxyanions and humic acid. CHEMOSPHERE 2017; 166:192-196. [PMID: 27697707 DOI: 10.1016/j.chemosphere.2016.09.084] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/15/2016] [Indexed: 06/06/2023]
Abstract
The mobility and fate of inorganic oxyanions in the environment can be greatly influenced by interactions with natural organic matter (NOM). There is increasing evidence that this interaction between two anionic species is facilitated by cationic bridges, but detailed mechanistic studies into this system are challenging due to the heterogeneous nature of NOM. This work examines the ability of cations (FeIII, CrIII, AlIII, or GaIII) to form ternary complexes with Suwannee River humic acid (SRHA) and the oxyanions of As (AsIII and AsV) and Se (SeIV and SeVI). Complexes were characterized by separating SRHA from unbound species using size exclusion chromatography coupled to ICP-MS to determine its metal content. Unlike CrIII and FeIII, the post-transition metal ions AlIII and GaIII proved ineffective at forming ternary complexes with any of the oxyanions, although minor complexation was observed with GaIII, suggesting that electrostatic interactions are not the primary driving force behind the stabilization of these ternary complexes. The results also show differences in the behavior of FeIII and CrIII that may indicate that the two cations stabilize the ternary complexes by different mechanisms.
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Affiliation(s)
- David P Martin
- U.S. Army Engineer Research and Development Center, Vicksburg, MS, 39180, USA.
| | - Jennifer M Seiter
- U.S. Army Engineer Research and Development Center, Vicksburg, MS, 39180, USA
| | - Brandon J Lafferty
- U.S. Army Engineer Research and Development Center, Vicksburg, MS, 39180, USA
| | - Anthony J Bednar
- U.S. Army Engineer Research and Development Center, Vicksburg, MS, 39180, USA
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Mukherjee J, Ramkumar J, Chandramouleeswaran S, Shukla R, Tyagi AK. Sorption characteristics of nano manganese oxide: efficient sorbent for removal of metal ions from aqueous streams. J Radioanal Nucl Chem 2013. [DOI: 10.1007/s10967-012-2393-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Wang S, Liang D, Wang D, Wei W, Fu D, Lin Z. Selenium fractionation and speciation in agriculture soils and accumulation in corn (Zea mays L.) under field conditions in Shaanxi Province, China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 427-428:159-64. [PMID: 22542257 DOI: 10.1016/j.scitotenv.2012.03.091] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 03/27/2012] [Accepted: 03/27/2012] [Indexed: 05/19/2023]
Abstract
Upland and paddy soils, as well as corn samples, were collected in the selenosis area of Naore Village, Ziyang County, Shaanxi Province, China. A five-step sequential extraction procedure was used for selenium (Se) fractionation, including soluble Se, exchangeable Se and carbonate-bound Se, iron and manganese oxide-bound Se, organic matter-bound Se, and the residual Se fraction. Species of soluble Se in upland soils included Se(-2), Se(4+), and Se(6+). The results showed that soluble Se and exchangeable Se fractions accounted for less than 1% of the total Se in the upland soil, but approximately 16.1% in the paddy soil. Concentrations of residual Se were lower than those of iron and manganese oxide-bound Se and organic matter-bound Se in both upland and paddy soils. Iron- and manganese oxide-bound Se was the dominant fractions in upland soil, whereas organic matter-bound Se abounded in paddy soil. Concentrations (mg kg(-1)) of Se in the corn samples ranged from 0.05 to 14.5 in seed, 0.31 to 12.3in root, 0.09 to 9.15 in stalk, and 0.16 to 36.15 in leaf. Path analysis indicated that soluble Se(6+) significantly (P<0.05) affected Se accumulation in corn tissues directly, whereas the organic matter-bound Se had a significant (P<0.05) indirect effect. In conclusion, corn did not readily absorb a major portion of soil Se. However, organic matter-bound Se was an important fraction and source of plant Se in agricultural soil.
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Affiliation(s)
- Songshan Wang
- Department of Environmental Science, College of Resource and Environment, Northwest A & F University, Yangling, Shaanxi 712100, China
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Weng L, Vega FA, Supriatin S, Bussink W, Van Riemsdijk WH. Speciation of Se and DOC in soil solution and their relation to Se bioavailability. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:262-267. [PMID: 21141820 DOI: 10.1021/es1016119] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A 0.01 M CaCl(2) extraction is often used to asses the bioavailability of plant nutrients in soils. However, almost no correlation was found between selenium (Se) in the soil extraction and Se content in grass. The recently developed anion Donnan membrane technique was used to analyze chemical speciation of Se in the 0.01 M CaCl(2) extractions of grassland soils and fractionation of DOC (dissolved organic carbon). The results show that most of Se (67-86%) in the extractions (15 samples) are colloidal-sized Se. Only 13-34% of extractable Se are selenate, selenite and small organic Se (<1 nm). Colloidal Se is, most likely, Se bound to or incorporated in colloidal-sized organic matter. The dominant form of small Se compounds (selenate, selenite/small organic compounds) depends on soil. A total of 47-85% of DOC is colloidal-sized and 15-53% are small organic molecules (<1 nm). In combination with soluble S (sulfur) and/or P (phosphor), concentration of small DOC can explain most of the variability of Se content in grass. The results indicate that mineralization of organic Se is the most important factor that controls Se availability in soils. Competition with sulfate and phosphate needs to be taken into account. Further research is needed to verify if concentration of small DOC is a good indicator of mineralization of soil organic matter.
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Affiliation(s)
- Liping Weng
- Department of Soil Quality, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands.
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Theoretical models of sorption kinetics including a surface reaction mechanism: a review. Adv Colloid Interface Sci 2009; 152:2-13. [PMID: 19735907 DOI: 10.1016/j.cis.2009.07.009] [Citation(s) in RCA: 407] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 07/28/2009] [Accepted: 07/28/2009] [Indexed: 11/23/2022]
Abstract
A review of a certain class of theoretical models describing the kinetics of pollutants sorption onto various sorbents is presented. These assuming the rate of surface reaction as the rate-limiting step are considered. A special attention is paid to possible theoretical grounds of the most commonly applied mathematical expressions, such as the pseudo-second and the pseudo-first order equations. Simple theoretical considerations based on some fundamental theories suggest that these two formulae do not correspond to any specific physical model. They simply approximate well the behaviours predicted by many different theoretical approaches.
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