Radionuclide biogeochemical cycling

The fate of trace metal radionuclides in the aquatic environment and their participation in the biogeochemical cycle depend strongly on the chemical and physico--chemical form in which radionuclides are introduced in natural waters. The abundance of natural humic substances and their ability to form metal complexes and to adsorb on suspended matter and sediment makes these substances especially important in transport, availability and accumulation of trace metal radionuclides in natural water environments. In that sense complexatlon of di- and tri-valent metal radionuclides with humic and fulvic acids of different origin was studied. The sorption properties of natural suspended matter and undissolved humic acid for the sorption of some radionuclides was also studied. 

Advances in interfacial chemistry, biogeochemical cycles remediation technology trace metals radiation chemistry, radionuclides hydrophobic compounds in the environment... 

Microorganisms may have also important roles in the biogeochemical cycling of radionuclides (see Lloyd et al. 2001). New applications of these processes to the detoxification of radionuclide contamination have been developed U(VI) is a priority pollutant reduced by phylogenetically distinct bacteria. U(VI) can be reduced to U(IV) by certain Fe(III)-dissimulatory microorganisms, for... 

Pb levels in sinking particles from the control site tend to be higher than those measured in the vent zone, as demonstrated by the lower Po/ Pb ratios (3.3-8.5) observed on particles in the control site. These Pb levels (0.01-0.23 Bq/g) are comparable with data reported for the northwestern Mediterranean Sea. The hydrothermal emissions in the shallow Aegean Sea off Milos Island do not have any major effect on the biogeochemical cycling of the natural radionuclides Po and Pb in the water column (Boisson et al. 2001). 

Radionuclides have been used for studying a very broad range of biogeochemical processes in estuaries (table 7.1). In this section more details are provided on the cycling... 

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