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Strong ligands for thorium complexation in marine bacteria
1Geochemical Research Department, Meterological Research Institute, Nagamine 1-1, Tsukuba, Ibaraki 305-0052, Japan. khirose@mri-jma.go.jp
Marine Environmental Research
|July 27, 2001
Summary
Thorium (Th) binds to a specific site on marine bacteria, forming a stable complex. This interaction suggests marine organisms are a key source of ligands that bind trace metals in seawater.
Area of Science:
- Marine Chemistry
- Microbiology
- Environmental Science
Background:
- Marine organic matter plays a crucial role in trace metal complexation.
- Understanding the origin of these organic ligands is vital for marine biogeochemical studies.
Purpose of the Study:
- To investigate the interaction between thorium (Th) and marine bacteria.
- To determine the nature and stability of thorium-binding sites on bacteria.
- To identify the source of strong organic ligands in marine environments.
Main Methods:
- Experimental examination of thorium-marine organism interactions.
- Application of chemical equilibrium techniques.
- Mass balance analysis of adsorption data.
Main Results:
- Thorium (Th) quantitatively reacts with a binding site on heterotrophic bacteria (Alteromonas, Vibrio, Pseudomonas, Flavobacterium) in 0.1 M HCl.
- Th forms a 1:1 complex with a conditional stability constant ranging from 10(6.63) to 10(7.07) M-1.
- The strong ligand-to-organic carbon ratio in bacteria is significantly higher than in other marine organic matter.
Conclusions:
- Marine bacteria possess functional groups that act as strong ligands for thorium.
- These bacterial ligands are a significant component of the strong organic ligands found in particulate and dissolved organic matter.
- Marine organisms are a primary source of strong organic ligands involved in trace metal complexation in seawater.