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Kinetics of antimony biogeochemical processes under pre-definite anaerobic and aerobic conditions in a paddy soil
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作者 Bingqing Xia Yang Yang +1 位作者 Fangbai Li Tongxu Liu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2022年第3期269-280,共12页
While the transformation of antimony(Sb) in paddy soil has been previously investigated, the biogeochemical processes of highly chemical active Sb in the soil remain poorly understood. In addition, there is a lack of ... While the transformation of antimony(Sb) in paddy soil has been previously investigated, the biogeochemical processes of highly chemical active Sb in the soil remain poorly understood. In addition, there is a lack of quantitative understanding of Sb transformation in soil. Therefore, in this study, the kinetics of exogenous Sb in paddy soils were investigated under anaerobic and aerobic incubation conditions. The dissolved Sb(V) and the Sb(V) extracted by diffusive gradient technique decreased under anaerobic conditions and then increased under aerobic conditions. The redox reaction of Sb occurred, and Sb bioavailability significantly decreased after 55 days of incubation. The kinetics of Fe and the scanning transmission electron microscopy analysis revealed that the Fe oxides were reduced and became dispersed under anaerobic conditions, whereas they were oxidized and re-aggregated during the aerobic stage. In addition, the redox processes of sulfur and nitrogen were detected under both anaerobic and aerobic conditions. Based on these observations, a simplified kinetic model was established to distinguish the relative contributions of the transformation processes. The bioavailability of Sb was controlled by immobilization as a result of S reduction and by mobilization as a result of Fe reductive dissolution and S oxidation, rather than the p H. These processes coupled with the redox reaction of Sb jointly resulted in the complex behavior of Sb transformation under anaerobic and aerobic conditions. The model-based method and findings of this study provide a comprehensive understanding of the Sb transformation in a complex soil biogeochemical system under changing redox conditions. 展开更多
关键词 ANTIMONY biogeochemical process KINETICS Paddy soil Anaerobic conditions Aerobic conditions
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Organic Carbon (OC) and Organic Matter (OM) in Sediments Collected from Two Wetlands in Central Bida Basin, Nigeria
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作者 Ahmed Aliyu Sidi Ipoola Ajani Okunlola Nuhu Musa Waziri 《Journal of Geoscience and Environment Protection》 2023年第10期218-226,共9页
An improvised auger sediment sampler was used to collect sediments at shallow depths from two wetlands in the Northern Bida Basin for laboratory studies in order to ascertain the impact on the chemical quality of grou... An improvised auger sediment sampler was used to collect sediments at shallow depths from two wetlands in the Northern Bida Basin for laboratory studies in order to ascertain the impact on the chemical quality of groundwater within these two studied locations. The dissolved organic carbon content of water is an important component of the geochemical cycling of elements capable of affecting groundwater quality. The sediments which serve as a conduit and pathways for the elements’ transport depending on the characteristics of the particle sizes are to be considered in the evaluation of contaminant mobility within the pathways. Representative cored sediment samples were collected and their particle size characterization and chemical analysis for Organic Matter (OM), Organic Carbon (OC) and Moisture Content (MC) were carried out. The hydrometer results show that the sediment particle sizes are in the order of sand > clay > silt in both locations with few exceptions. This represents the geology of the area (sandstone). The Mean values of 1.14% and 1.98% of OC and OM respectively were recorded in the sediment samples collected in parts of Ebgako. In contrast, 1.72% and 2.97% mean values were recorded in sediments collected in part of Bida for OC and OM respectively. The values of the OC and OM in the sediments from the two wetlands are low and may have been dissolved along the groundwater pathways to the aquifer. Other physicochemical parameters analysed in the sediments showed poor correlation. OM and OC were strongly positively correlated and showed an R<sup>2</sup> value of 1 and 0.9 respectively for parts of the Bida and Egbako sheets. There is low acidity of the sediments from the two study locations with a mean pH value of 5.64 and 5.13 respectively for Egbako and Bida. The low acidic nature of the sediments and the OM and OC composition have the potential to influence biogeochemical processes in the sediments and can affect the chemical quality of the groundwater in these two study locations. 展开更多
关键词 Organic Matter Organic Carbon biogeochemical processes Bida Basin NIGERIA
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Nano-black carbon(biochar)released from pyrogenic carbonaceous matter as a super suspending agent in water/soil environments 被引量:1
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作者 Fei Lian Zhenyu Wang Baoshan Xing 《Biochar》 2021年第1期1-3,共3页
Nano-black carbon(BC)is one of the most active fractions in the pyrogenic carbonaceous matter continuum.The majority of recent studies mainly focus on the role of nano-BC in the global carbon cycle.However,based on li... Nano-black carbon(BC)is one of the most active fractions in the pyrogenic carbonaceous matter continuum.The majority of recent studies mainly focus on the role of nano-BC in the global carbon cycle.However,based on literature and our recent studies,we suggest that nano-BC may also serve as a super suspending agent,carrier,and redox mediator for sorbates during its migration from terrestrial to water bodies due to its unique properties such as high colloidal stability,strong sorption capacity,and high surface reactivity.The full implications of nano-BC in water/soil environments are far more than we expected.Thus,we call for more detailed investigations on the activity and reactivity of nano-BC in water/soil environments. 展开更多
关键词 BIOCHAR ·Nanoparticle SUSPENSION SORPTION Redox capacity biogeochemical processes
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Zinc phosphate dissolution by bacteria isolated from an oligotrophic karst cave in central China 被引量:2
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作者 Hongmei WANG Qiang DONG Jianping ZHOU Xing XIANG 《Frontiers of Earth Science》 SCIE CAS CSCD 2013年第3期375-383,共9页
Biogeochemical processes are fundamental to sustain the ecosystem in subsurface caves, but to date they are still far from well understood. To investigate micro-bially mediated phosphorus and zinc cycles, we isolated ... Biogeochemical processes are fundamental to sustain the ecosystem in subsurface caves, but to date they are still far from well understood. To investigate micro-bially mediated phosphorus and zinc cycles, we isolated three bacterial strains from the dripping water in Heshang cave, central China, identified as Exiguobacterium aurantiacum E11, Pseudomonas fluorescens P35, and Pseu- domonas poae P41, respectively. Microbial capabilities in the dissolution of phosphorus-containing minerals were tested with zinc phosphate (Zn3(PO4)2) in batch culture at 30~C. A spectrophotometer, atomic absorption spectrum, and scanning electronic microscopy were used to measure the microbial growth, soluble Zn(II) concentration, and to observe the morphology of Zn3(PO4)2 before and after microbial dissolution. P. fluorescens and P. poae, the well- known phosphorus solubilizing bacteria (PSB), are observed to solubilize Zn3(PO4)2 with an efficiency of 16.7% and 17.6%, respectively. To our knowledge, E. aurantiacum is firstly reported in this study to dissolve phosphorous-containing minerals with a higher efficiency of 39.7%, expanding our understanding about the ubiquitous occurrence of PSB in natural environments. Aqueous Zn(II) concentration positively correlates with H+ activity, confirming the presence of acidification mechanisms widely exploited by PSB. Few itching pits were observed on the surface of Zn3(PO4)2 after microbial dissolution, inferring that microbial dissolution is not always associated with the direct contact with minerals. Even though the soluble Zn(II) concentration reached up to 370 mg/L in the system inoculated with E. aurantiacum Ell, inhibition of microbial growth was not detected by spectrophotometer. Our laboratory data revealed the importance of microbially-mediated P and Zn cycles in the subsurface ecosystem. 展开更多
关键词 karst cave phosphate solubilizing bacteria (PSB) zinc toxicity biogeochemical process subsurface biosphere
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A View of Earth System Model Development 被引量:2
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作者 王斌 周天军 +1 位作者 俞永强 WANG Bin 《Acta meteorologica Sinica》 SCIE 2009年第1期1-17,共17页
This paper gives a definition of earth system model and shows three development phases of it, including physical climate system model, earth climate system model, and earth system model, based on an inves- tigation of... This paper gives a definition of earth system model and shows three development phases of it, including physical climate system model, earth climate system model, and earth system model, based on an inves- tigation of climate system models in the world. It provides an expatiation on the strategic significance of future development of earth system model, an introduction of some representative scientific research plans on development of earth system model home and abroad, and a review of its status and trends based on the models of the fourth assessment report (AR4) ofthe Intergovernmental Panel on Climate Change (IPCC). Some suggestions on future development of earth system model in China are given, which are expected to be helpful to advance the development. 展开更多
关键词 physical climate system biogeochemical process global warming past climate change
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