title: Distribution of radionuclides between atmosphere and ash during combustion of contaminated vegetation.
abstract: A series of laboratory-scale combustion tests were conducted under well-controlled conditions to measure the release of90Sr and137Cs nuclides to the atmosphere (air) from combustion of vegetation and organic soil samples contaminated with radioactivity. These vegetation and soil samples were collected from a controlled contaminated forest area within the Canadian Nuclear Laboratories - Chalk River site. The combustion products including ash and smoke particulates, along with gaseous emissions, were collected and then analyzed for137Cs and90Sr concentrations by radiometric techniques. The experimental results reveal that the releases of90Sr to the atmosphere (air) from combustion of vegetation are very low with most of the90Sr activity remaining in ash residues, even at a temperature of 800 °C. The detailed combustion experiments with surface litter and twigs, alder twigs, alder leaves, and organic soil indicate that 0.5 ± 0.1%, 0.3 ± 0.1%, 0.9 ± 0.1%, and 0.3 ± 0.1% of90Sr is released to the atmosphere (air), respectively. On the other hand, the releases of137Cs are found to be highly dependent on the combustion temperature as well as the nature of vegetation. The releases of137Cs obtained at 800 °C are 45 ± 7%, 77 ± 9%, 92 ± 5%, and 2.4 ± 0.5% for surface litter and twigs, alder twigs, alder leaves, and organic soil, respectively. The mechanism associated with the high release of137Cs at a high temperature of 800 °C was explored.
authors.affiliation: Analytical Chemistry Branch, Canadian Nuclear Laboratories, Chalk River, K0J 1J0, Canada. Electronic address: liufang.zhou@cnl.ca.
authors.forename: Liufang Jenny
authors.initials: LJ
authors.lastname: Zhou
authors.affiliation: Analytical Chemistry Branch, Canadian Nuclear Laboratories, Chalk River, K0J 1J0, Canada.
authors.forename: Raghu
authors.initials: R
authors.lastname: Rao
authors.affiliation: Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, K7K 7B4, Canada.
authors.forename: Emily
authors.initials: E
authors.lastname: Corcoran
authors.affiliation: Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, K7K 7B4, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Kelly
mesh_terms: D000396:Air Pollutants, Radioactive / Q000032:analysis*; D001272:Atmosphere / Q000737:chemistry; D017745:Incineration; D052638:Particulate Matter / Q000032:analysis*; D010944:Plants / Q000737:chemistry*; D011834:Radiation Monitoring
chemical_list: D000396:Air Pollutants, Radioactive; D052638:Particulate Matter
keywords: (137)Cs release; (90)Sr release; Forest fires; Radioactive contamination; Vegetation combustion