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Peng L, Li D, Song H, Kuang X, Zeng Q, Ao H. The dissolution characteristics of cadmium containing birnessite produced from paddy crusts. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 914:169811. [PMID: 38211864 DOI: 10.1016/j.scitotenv.2023.169811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 12/27/2023] [Accepted: 12/29/2023] [Indexed: 01/13/2024]
Abstract
The cadmium (Cd) accumulates in birnessite as it forms on the surface of paddy crusts (PC). The stability of Cd-containing birnessite is influenced by environmental factors, and destabilized birnessite releases dissolved Cd. We report the effects of pH, oxalic acid, and light on the dissolution of Cd-containing birnessite. We found that at pH 4.0, with light and 0.20 mol/L oxalic acid, the ratio of dissolved Cd and manganese (Mn) peaked after 24 h at 2978.0 μg/g and 326.8 mg/g, respectively. The three environmental factors affected the dissolution of Cd-containing birnessite in the following order: pH > oxalic acid > light. During dissolution process, Cd and Mn did not dissolve simultaneously, and the dissolved Cd/Mn ratio in the solution was significantly lower than that of the pristine mineral (33.5 × 10-3). Compared with Mn, Cd dissolution was inhibited by strong acidity (pH 4.0-5.0), and the dissolved Cd/Mn ratio was 5-10 × 10-3. Mild acidity (pH 6.0) was weakly inhibitory, with a Cd/Mn ratio of 6-15 × 10-3. In an alkaline (pH 8.0) oxalate environment, light illumination inhibited Cd dissolution, and the Cd/Mn ratio decreased over time due to the stability of the products formed by oxalate and carbonate, with Cd being more stable than those formed by Mn. Our findings would provide insights into the migration and transformation of PC-associated Cd in paddy fields.
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Affiliation(s)
- Liang Peng
- College of Environmental & Ecology, Hunan Agricultural University, Changsha 410128, PR China.
| | - Dan Li
- College of Environmental & Ecology, Hunan Agricultural University, Changsha 410128, PR China
| | - Huijuan Song
- College of Environmental & Ecology, Hunan Agricultural University, Changsha 410128, PR China
| | - Xiaolin Kuang
- College of Environmental & Ecology, Hunan Agricultural University, Changsha 410128, PR China
| | - Qingru Zeng
- College of Environmental & Ecology, Hunan Agricultural University, Changsha 410128, PR China
| | - Hejun Ao
- College of Agronomy, Hunan Agricultural University, Changsha 410128, PR China.
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Vogel AL, Thompson KJ, Straub D, App CB, Gutierrez T, Löffler FE, Kleindienst S. Substrate-independent expression of key functional genes in Cycloclasticus pugetii strain PS-1 limits their use as markers for PAH biodegradation. Front Microbiol 2023; 14:1185619. [PMID: 37455737 PMCID: PMC10338962 DOI: 10.3389/fmicb.2023.1185619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 05/22/2023] [Indexed: 07/18/2023] Open
Abstract
Microbial degradation of petroleum hydrocarbons is a crucial process for the clean-up of oil-contaminated environments. Cycloclasticus spp. are well-known polycyclic aromatic hydrocarbon (PAH) degraders that possess PAH-degradation marker genes including rhd3α, rhd2α, and pahE. However, it remains unknown if the expression of these genes can serve as an indicator for active PAH degradation. Here, we determined transcript-to-gene (TtG) ratios with (reverse transcription) qPCR in cultures of Cycloclasticus pugetii strain PS-1 grown with naphthalene, phenanthrene, a mixture of these PAHs, or alternate substrates (i.e., no PAHs). Mean TtG ratios of 1.99 × 10-2, 1.80 × 10-3, and 3.20 × 10-3 for rhd3α, rhd2α, and pahE, respectively, were measured in the presence or absence of PAHs. The TtG values suggested that marker-gene expression is independent of PAH degradation. Measurement of TtG ratios in Arctic seawater microcosms amended with water-accommodated crude oil fractions, and incubated under in situ temperature conditions (i.e., 1.5°C), only detected Cycloclasticus spp. rhd2α genes and transcripts (mean TtG ratio of 4.15 × 10-1). The other marker genes-rhd3α and pahE-were not detected, suggesting that not all Cycloclasticus spp. carry these genes and a broader yet-to-be-identified repertoire of PAH-degradation genes exists. The results indicate that the expression of PAH marker genes may not correlate with PAH-degradation activity, and transcription data should be interpreted cautiously.
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Affiliation(s)
- Anjela L. Vogel
- Department of Geosciences, Eberhard Karls University of Tübingen, Tübingen, Germany
- Department of Environmental Microbiology, Institute for Sanitary Engineering, Water Quality and Solid Waste Management (ISWA), University of Stuttgart, Stuttgart, Germany
| | - Katharine J. Thompson
- Department of Geosciences, Eberhard Karls University of Tübingen, Tübingen, Germany
- Department of Environmental Microbiology, Institute for Sanitary Engineering, Water Quality and Solid Waste Management (ISWA), University of Stuttgart, Stuttgart, Germany
| | - Daniel Straub
- Quantitative Biology Center (QBiC), Eberhard Karls University of Tübingen, Tübingen, Germany
- Cluster of Excellence: EXC 2124: Controlling Microbes to Fight Infection, Tübingen, Germany
| | - Constantin B. App
- Department of Geosciences, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Tony Gutierrez
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, United Kingdom
| | - Frank E. Löffler
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN, United States
- Department of Microbiology, University of Tennessee, Knoxville, TN, United States
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN, United States
- Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, TN, United States
| | - Sara Kleindienst
- Department of Geosciences, Eberhard Karls University of Tübingen, Tübingen, Germany
- Department of Environmental Microbiology, Institute for Sanitary Engineering, Water Quality and Solid Waste Management (ISWA), University of Stuttgart, Stuttgart, Germany
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