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Qin D, Luo G, Qin A, He T, Wu P, Yin D. Selenium-phosphorus modified biochar reduces mercury methylation and bioavailability in agricultural soil. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 345:123451. [PMID: 38281574 DOI: 10.1016/j.envpol.2024.123451] [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: 10/26/2023] [Revised: 12/22/2023] [Accepted: 01/24/2024] [Indexed: 01/30/2024]
Abstract
Biochar is a frequently employed for solidifying and stabilizing mercury (Hg) contamination in soil. However, it often results in an elevated presence of soil methylmercury (MeHg), which introduces new environmental risks. Consequently, there is a necessity for developing a safer modified biochar for use in Hg-contaminated soil. This study employed sodium selenite (at a safe dosage for soil) and hydroxyapatite to modify straw biochar (BC) based on the interaction between selenium (Se) and phosphorus (P). This process led to the formation of Se-modified biochar (Se-BC), P-modified biochar (P-BC), and Se and P co-modified biochar (Se-P-BC). Additionally, solvent adsorption experiments and pot experiments (BC/soil mass ratio: 0.5 %) were conducted to investigate the impacts of these soil amendments on soil Hg methylation and bioavailability. Se and P co-modification substantially increased the surface area, pore volume, and Hg adsorption capacity of BC. BC treatment increased the simulated gastric acid-soluble Hg, organo-chelated Hg, and MeHg in the soil. Conversely, Se-P-BC significantly reduced these forms of Hg in the soil, indicating that Se-P-BC can transform soil Hg into less bioavailable states. Among the different biochar treatments, Se-P-BC exhibited the most pronounced reductions in soil MeHg, total Hg, and MeHg in water spinach, achieving reductions of 63 %, 71 %, and 70 %, respectively. The co-modification of Se and P displayed a synergistic reduction effect in managing soil Hg pollution, which is associated with the increase of available Se in the soil due to phosphorus addition. The significantly reduced dissolved organic carbon and the abnormally high SO42- concentration in the soil of Se-P-BC treatment also inhibited Hg methylation and bioavailability in the soil. In summary, Se-P-BC substantially increased reduction percentage in plant Hg content while mitigating the risk of secondary pollution arising from elevated soil MeHg.
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Affiliation(s)
- Dongqiang Qin
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, 550025, China
| | - Guangjun Luo
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, 550025, China
| | - Aming Qin
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, 550025, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China.
| | - Pan Wu
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China
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Coker EA, Nkuah BC, Amoanimaah SA, Oppong JB, Gyamfi O, Ansah E, Ababio KA, Wemegah DD, Borquaye LS, Darko G. Human exposure to mercury in the atmosphere and soils in Konongo: an age-old mining centre in the Ashanti Region of Ghana. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2023; 45:3555-3565. [PMID: 36449127 DOI: 10.1007/s10653-022-01441-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 11/22/2022] [Indexed: 06/01/2023]
Abstract
The dramatic upsurge of artisanal and small-scale gold mining (ASGM) activities in Ghana has resulted in environmental degradation, water pollution and human exposure to mercury-the main hazardous element used in gold extraction. This study evaluated the degree of human exposure to mercury based on the concentrations found in the air and soil samples taken at a resolution of 1 km2 across Konongo, a historic mining town in Ghana's Ashanti Region. The highest atmospheric mercury concentration was 193 ng/m3, which is much higher than the levels the European Union and Japan allowed, which are 10 ng/m3 and 40 ng/m3, respectively. The concentration in the soil was 3.6 mg Hg/kg, which is around ten times higher than the background concentration in nature. Additionally, the soil concentrations were higher above the worrisome levels of soil contamination in agricultural land (4 mg/kg) and industrial areas (16 mg/kg), respectively. Soils are extremely contaminated with mercury at sites artisanal mining activities take place. The concentrations of mercury in the air and soils were significantly higher (p < 0.5) at locations of prominent mining activities compared to areas not close to mining sites. The inhabitants of the Konongo community are therefore exposed to mercury, most likely emitted from artisanal mining activities. A non-carcinogenic risk is posed to the people by inhaling mercury vapour through the air and vapourisation from the soil. Children are exposed to a higher risk than adults as they receive higher daily doses of mercury than adults.
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Affiliation(s)
- Ewura Abena Coker
- Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Bright Cephas Nkuah
- Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Sandra Afia Amoanimaah
- Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Joel Baffour Oppong
- Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Opoku Gyamfi
- Department of Chemistry Education, Akenten Appiah-Menka University of Skills Training and Entrepreneurial Development, Asante-Mampong, Ghana
| | - Eugene Ansah
- Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Kofi Agyarko Ababio
- Department of Statistical Sciences, Kumasi Technical University, Kumasi, Ghana
| | - David Dotse Wemegah
- Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | | | - Godfred Darko
- Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
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Chaudhary DK, Park JH, Kim PG, Ok YS, Hong Y. Enrichment cultivation of VOC-degrading bacteria using diffusion bioreactor and development of bacterial-immobilized biochar for VOC bioremediation. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 320:121089. [PMID: 36669717 DOI: 10.1016/j.envpol.2023.121089] [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: 11/14/2022] [Revised: 01/09/2023] [Accepted: 01/13/2023] [Indexed: 06/17/2023]
Abstract
Volatile organic compounds (VOCs) have been globally reported at various sites. Currently, limited literature is available on VOC bioremediation using bacterial-immobilized biochar (BC-B). In this study, multiple VOC-degrading bacteria were enriched and isolated using a newly designed diffusion bioreactor. The most effective VOC-degrading bacteria were then immobilized on rice husk-derived pristine biochar (BC) to develop BC-B. Finally, the performances of BC and BC-B for VOCs (benzene, toluene, xylene, and trichloroethane) bioremediation were evaluated by establishing batch microcosm experiments (Control, C; bioconsortium, BS; pristine biochar, BC; and bacterial-immobilized biochar, BC-B). The results revealed that the newly designed diffusion bioreactor effectively simulated native VOC-contaminated conditions, easing the isolation of 38 diverse ranges of VOC-degrading bacterial strains. Members of the genus Pseudomonas were isolated in the highest (26.33%). The most effective bacterial strain was Pseudomonas sp. DKR-23, followed by Rhodococcus sp. Korf-18, which degraded multiple VOCs in the range of 52-75%. The batch microcosm experiment data showed that BC-B remediated the highest >90% of various VOCs, which was comparatively higher than that of BC, BS, and C. In addition, compared with C, the BS, BC, and BC-B microcosms abundantly reduced the half-life of various VOCs, implying a beneficial impact on the degradation behavior of VOCs. Altogether, this study suggests that a diffusion bioreactor system can be used as a cultivation device for the isolation of a wide range of VOC-degrading bacterial strains, and a compatible combination of biochar and bacteria may be an attractive and promising approach for the sustainable bioremediation of multiple VOCs.
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Affiliation(s)
- Dhiraj Kumar Chaudhary
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong, 30019, Republic of Korea
| | - Joung-Ho Park
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong, 30019, Republic of Korea
| | - Pil-Gon Kim
- Division of Environmental Science and Ecological Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Yong Sik Ok
- Korea Biochar Research Center, APRU Sustainable Waste Management Program and Division of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
| | - Yongseok Hong
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong, 30019, Republic of Korea.
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