Columbia River sediment was irradiated with ultraviolet light to
determine if organic material could be removed without altering the
sorptive properties of the hydrous oxides of iron and manganese.
A laboratory preparation of Zn-65 spiked hydrous ferric oxide
was subjected to ultraviolet irradiation in order to assess the photochemical
effect upon Zn-65 release. The photochemically induced
release of Mn-54 present on the Columbia River sediment was used
to assess the effect on the hydrous oxides of manganese.
The ultraviolet irradiation proved effective in removing up to
68% of the sedimentary organic material in 17 hours without causing
release of Zn-65 or Sc-46.
While the ultraviolet irradiation had no effect upon Zn-65
release from laboratory preparations of hydrous ferric oxides and
Zn-65 spiked montmorillonite, a significant release of Mn-54 resulted
from the photolysis treatment. The removal of Mn-54 was not
accompanied by the release of sorbed Zn-65 or Sc-46 (nuclides expected
to be sorbed by hydrous oxides), nor did there appear to be any
permanent change in the nature of the Mn-54 on the sediment. Although
it is possible that the hydrous oxides of manganese are affected by the
ultraviolet treatment, it is likely that another species, such as the
carbonate, is the species involved.
Photo-oxidation appears to provide a method of obtaining
sediments with substantially reduced organic content without affecting
the sorptive properties of hydrous oxides or clay minerals. This
result should allow the use of uptake studies to determine the importance
of organic material in trace metal sorption by sediments.
Repository Record Id:
Cutshall, Norman H.
Oregon State University. Graduate School
Photochemical degradation of sediment organic matter : effect on Zn-65 release