Publications by authors named "Kyounglim Kang"
Article Synopsis
- Coumarins are released by plant roots when they lack iron, and they help increase the solubility of iron in soil by interacting with iron compounds.
- The study examines how stable different coumarins are under various pH and oxygen conditions to understand their role in iron mobilization.
- Findings indicate that while coumarins degrade quickly in oxygen-rich environments, their complexation with iron can protect them from degradation, leading to improved methods for analyzing how coumarins affect iron availability in soil.
Unlabelled: Organo-mineral and organo-metal associations play an important role in the retention and accumulation of soil organic carbon (SOC). Recent studies have demonstrated a positive correlation between calcium (Ca) and SOC content in a range of soil types. However, most of these studies have focused on soils that contain calcium carbonate (pH > 6).
View Article and Find Full Text PDFSiderophore-Mediated Mobilization of Manganese Limits Iron Solubility in Mixed Mineral Systems.
ACS Earth Space Chem
April 2023
Article Synopsis
- Recent studies challenge the traditional view of aqueous Mn(III) as unstable, highlighting the importance of Mn(III)-siderophore complexes in geochemical cycling.
- The research focused on the mobilization of Mn and Fe using desferrioxamine B (DFOB) across different mineral systems, revealing that the effectiveness of DFOB varies based on the minerals present.
- Findings indicate that DFOB can significantly reduce the availability of Fe in soil by promoting the mobility of Mn, suggesting that these processes influence nutrient dynamics in natural environments.
Article Synopsis
- Poor solubility of iron(hydr)oxides limits growth in microorganisms and plants, prompting research into how light affects iron dissolution in various environments.
- Short UV-A illuminations (5-15 min) can significantly enhance the dissolution of iron(hydr)oxides during subsequent dark periods, especially under anoxic conditions, showing a 10-40 fold increase in dissolution rates.
- In oxic conditions, the presence of photostable ligands like DFOB keeps dissolved iron(III) in solution longer, but the overall enhancement of iron bioavailability is more pronounced in anoxic environments following brief light exposure.
Due to the low iron solubility in alkaline soils, plants have evolved different iron acquisition strategies, which are either based on ferric iron reduction (strategy I) or complexation by phytosiderophores (strategy II). Recently, a prominent role of coumarins for iron acquisition has been discovered, but details of the respective mechanism remain unclear. Since coumarins may act as iron-binding ligands but also as reductants, various reaction sequences are possible, resulting in different iron species and oxidized coumarins.
View Article and Find Full Text PDFArticle Synopsis
- The dissolution of iron (Fe(III)) phases is crucial for making iron and trace elements available for biological use, and Fe(II) significantly speeds up this process at near-neutral pH levels.
- Researchers conducted experiments on lepidocrocite (Lp) and goethite (Gt) to study how the addition of desferrioxamine-B (DFOB) influenced the dissolution and isotope exchange of these iron compounds.
- The timing of when Fe(II) and DFOB were added affected the outcomes, with findings indicating that Fe(II) enhances the dissolution rate and charge transfer between dissolved and adsorbed species, particularly with Lp, which can accelerate the process by up to 60 times.
Dissolution of iron(III)phases is a key process in soils, surface waters, and the ocean. Previous studies found that traces of Fe(II) can greatly increase ligand controlled dissolution rates at acidic pH, but the extent that this also occurs at circumneutral pH and what mechanisms are involved are not known. We addressed these questions with infrared spectroscopy and Fe isotope exchange experiments with lepidocrocite (Lp) and 50 μM ethylenediaminetetraacetate (EDTA) at pH 6 and 7.
View Article and Find Full Text PDFArticle Synopsis
- Siderophores, which are Fe-specific biogenic ligands, play a crucial role in acquiring iron from Fe(III) (hydr)oxide minerals in low-iron environments.
- The study explored how redox reactions, specifically the addition of Fe(II) as a reductant, influence the dissolution of these minerals when using different ligands like desferrioxamine B (DFOB) and HBED.
- Results showed that even low levels of Fe(II) greatly increased the dissolution rates of Fe(III) (hydr)oxides, particularly with HBED and goethite, highlighting the potential importance of this process in biological iron acquisition, especially in conditions where iron is deficient.
A novel and economic sequential process consisting of precipitation, adsorption, and oxidation was developed to remediate actual rare-earth (RE) wastewater containing various toxic pollutants, including radioactive species. In the precipitation step, porous air stones (PAS) containing waste oyster shell (WOS), PASWOS, was prepared and used to precipitate most heavy metals with >97% removal efficiencies. The SEM-EDS analysis revealed that PAS plays a key role in preventing the surface coating of precipitants on the surface of WOS and in releasing the dissolved species of WOS successively.
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