Strong ligands for thorium complexation in marine bacteria
Hirose, K.; Tanoue, E. (2001). Strong ligands for thorium complexation in marine bacteria. Mar. Environ. Res. 51(2): 95-112
s0141-1136(00)00031-3, reference materials
In: Marine Environmental Research. Applied Science Publishers: Barking. ISSN 0141-1136; e-ISSN 1879-0291, more
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| Keywords |
Acids
Aquatic communities > Plankton > Phytoplankton
Chemical elements > Metals
Chemical elements > Metals > Rare earths > Actinides > Thorium
Complexation
Ligands
Microorganisms > Bacteria
Organic matter > Particulates > Particulate organic matter
Bacteria [WoRMS]
Marine/Coastal |
| Abstract |
The interaction between thorium and marine organisms (cultured heterotrophic bacteria) was experimentally examined by using chemical equilibrium techniques. Thorium (Th) quantitatively reacts with a binding site on bacteria (lteromonas, Vibrio, Pseudomonas and Flavobacterium) in 0.1 M HCl solution. According to mass balance analysis of adsorption experiment data, Th forms a 1:1 complex with a binding site similar in reactivity among bacteria used in this study, whose conditional stability constants are in the range from 106.63 to 107.07 M-1 under the experimental conditions of a 0.1 M HCl solution. The mole ratio of the strong ligand to organic carbon in bacteria ranged from 2.3 to 4.3 mmol/mol C. The strong ligand/carbon ratios in bacteria were more than one order of magnitude greater than in phytoplankton, zooplankton or other organic ligands in surface waters. The results suggest that the strong organic ligand reacting with Th is one of the functional groups commonly existing in oceanic microorganisms. The conditional stability constants of the Th complexes with the binding site in marine microorganisms are in the same order of magnitude as that with the strong ligand found in particulate and dissolved organic matter. These findings strongly suggest that the strong ligand in particulate and dissolved organic matter, reacting with trace metals under the conditions of seawater, originates from marine organisms. |
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