Remediation of radionuclide-contaminated sites using plant litter decomposition

Abstract

Radionuclide contamination of ecosystems is a commonly known problem for many sites. A frequently used option in dealing with such contamination is phytoremediation. But when thinking of phytoextraction measures, the process of radionuclide enrichment in plant material is not terminated at the end of the growing season, but may increase during decomposition of the litter afterwards. We show that the process of litter decomposition may be mostly important in remediation of radionuclide-contaminated sites for both aquatic and terrestrial ecosystems. Radionuclide concentrations within organic soil/sediment layers increase strongly during decomposition in terrestrial ecosystems as well as in aquatic systems of temperate zones although there are large differences. This is attributed to emerging fixation sites where differences in aquatic and terrestrial systems are dependent on the particular chemistry (e.g. redox chemistry) of the radionuclides. The potentially high accumulation in developing layers of organic matter on the soils/sediments of aquatic/terrestrial ecosystem can easily be removed from the contaminated sites by removing the organic matter. In summary, beside autochthonous processes (e.g. phytoremediation), especially allochthonous processes (e.g. litter decomposition) are very important for the remediation of radionuclide-contaminated sites.