Distribution and retention of 137Cs in sediments at the Hanford Site, Washington.
137Cesium and other contaminants have leaked from single-shell storage tanks (SSTs) into coarse-textured, relatively unweathered unconsolidated sediments. Contaminated sediments were retrieved from beneath a leaky SST to investigate the distribution of adsorbed 137Cs+ across different sediment size fractions. All fractions contained mica (biotite, muscovite, vermiculatized biotite), quartz, and plagioclase along with smectite and kaolinite in the clay-size fraction. A phosphor-plate autoradiograph method was used to identify particular sediment particles responsible for retaining 137Cs+. The Cs-bearing particles were found to be individual mica flakes or agglomerated smectite, mica, quartz, and plagioclase. Of these, only the micaceous component was capable of sorbing Cs+ strongly. Sorbed 137Cs+ could not be significantly removed from sediments by leaching with dithionite citrate buffer or KOH, but a fraction of the sorbed 137Cs+ (5-22%) was desorbable with solutions containing an excess of Rb+. The small amount of 137Cs+ that might be mobilized by migrating fluids in the future would likely sorb to nearby micaceous clasts in downgradient sediments.
McKinley
J P
JP
Pacific Northwest National Laboratory, Richland, Washington 99352, USA. james.mckinley@pnl.gov
Zeissler
C J
CJ
Zachara
J M
JM
Serne
R J
RJ
Lindstrom
R M
RM
Schaef
H T
HT
Orr
R D
RD
D000327:Adsorption; D000538:Aluminum Silicates; D002588:Cesium Radioisotopes / Q000032:analysis; D000077215:Clay; D004784:Environmental Monitoring; D005765:Gastrointestinal Agents / Q000737:chemistry; D019015:Geologic Sediments; D006256:Hazardous Waste; D007616:Kaolin / Q000737:chemistry; D017640:Silicates; D012987:Soil; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D014861:Washington
D000538:Aluminum Silicates; D002588:Cesium Radioisotopes; D005765:Gastrointestinal Agents; D006256:Hazardous Waste; D017640:Silicates; D012987:Soil; D012990:Soil Pollutants, Radioactive; D007616:Kaolin; C033214:Smectite; D000077215:Clay