Is soil natural organic matter a sink or source for mobile radioiodine (129I) at the Savannah River Site?

Biogeochemical Considerations Related To The Remediation Of I-129 Plumes

“…As part of the SRS groundwater monitoring program, it has been documented that 129 I concentrates in the riparian zone to extraordinarily high levels, >1000 pCi L -1 (unfiltered samples) . Studies were undertaken to identify the process/mechanism responsible for the 129 I concentrated, and in particular to quantify and understand the role of NOM and microbes (Xu et al, 2011a;Xu et al, 2011b;Xu et al, 2012). The F-Area riparian zone is much more vegetative than would be found at the Hanford Site.…”

“…Iodine bonding with SOM is greatly influenced by not only the functionality of the SOM, but also the hydrophilic/hydrophobic forces in the SOM (Xu et al, 2011a;Xu et al, 2011b). Coincident variations in chemical composition, aromaticity, functional groups (e.g., aliphatic), hydrophobicity, and molecular weight indicated that: 1) iodine in different humic acids was bound to a small-size aromatic subunit (~10 kDa); 2) the large-size subunit (~90 kDa), determined the relative mobility of iodine bound to SOM, 3) iodine incorporation into the SOM is via covalent aromatic C-I bond is the key mechanism controlling iodine behavior in the SRS system.…”

Particulate Phases Possibly Conveyed from Nuclear Waste Repositories by Groundwater

“…The role played by the colloidal phase is intensely investigated not only for groundwater, but also for terrestrial surface water, namely for streams and lakes (Aleksandrova et al, 2010;Bondareva, 2011;Matsunaga et al, 2004;Monte, 2010;Monte et al, 2009;Ollivier et al, 2011;Semizhon et al, 2010), for estuarine water (Barros et al, 2004;Eyrolle & Charmasson, 2004;Porcelli et al, 1997), for sea water (Bowie et al, 2010;Otosaka et al, 2006;Scholten et al, 2005) or for soil water Maity et al, 2011;Matisoff et al, 2011;Rachkova et al, 2010;Seliman et al, 2010;Xu et al, 2011). The colloid-radionuclide interaction is important not only from the perspective of their migration.…”

Superoxide Production by a Manganese-Oxidizing Bacterium Facilitates Iodide Oxidation

“…Changes in redox potential control the environmental behavior of iodine, including its mobility and biogeochemical cycling (4)(5)(6)(7)(8). Iodide (I Ϫ ) (oxidation state Ϫ1) is considered the main iodine species that is released from nuclear power reprocessing facilities because of the redox properties of the reprocessing wastewater (8).…”

“…When I Ϫ is released into highly oxic environments (oxidation reduction potential of Ͼ0.5 to 0.8 V, depending on the pH), it will spontaneously transform into elemental iodine (I 2 ) (oxidation state 0). I 2 can then be emitted to the atmosphere, spontaneously transformed into iodate (IO 3 Ϫ ) (oxidation state ϩ5), methylated, or incorporated into organic matter (7,9). However, in many environments (e.g., most subsurface waters and anaerobic sediments, etc.…”