title: Relationship between the adsorption species of cesium and radiocesium interception potential in soils and minerals: an EXAFS study.
abstract: This study examined the radiocesium (RCs) interception potential (RIP), cation exchange capacity (CEC), total organic carbon (TOC) content, and adsorption species in soils and minerals by using extended X-ray absorption fine structure (EXAFS) spectroscopy. The RIP related to Cs(+) adsorption by frayed-edge site (FES) has often been used to measure the mobility and bioavailability of RCs in the environment. This study found that the presence of organic matter (OM) can reduce RIP to a certain extent. The adsorption amount (=Q(T)) in soil was obviously correlated to RIP at a small [Cs(+)] region, whereas a linear relationship between Q(T) and CEC was observed at a large [Cs(+)] region. Both the inner-sphere (IS) and outer-sphere (OS) complexes of Cs(+) were observed through EXAFS at a molecular scale. The linear correlation between log (RIP/CEC) and the ratio of the coordination number (CN) of IS (=CNIS) and OS (=CNOS) complexes noted as CNIS/(CNIS + CNOS) suggested that the ratio of CN is very sensitive to Cs(+) adsorption species with variable RIP and CEC. The adsorption species of Cs(+) in soil was mainly dependent on the clay mineral content of soil. RIP was affected not only by FES but also by other strong adsorption sites, such as the interlayers and cavities identified as the IS complex in EXAFS analysis. Findings indicated that the EXAFS approach is a powerful and efficient tool to explore the behavior of Cs(+) in a given environment.
authors.affiliation: Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan. Electronic address: fanqiaohui@gmail.com.
authors.forename: Qiaohui
authors.initials: Q
authors.lastname: Fan
authors.affiliation: National Institute for Agro-Environmental Sciences, 3-1-3, Kannondai, Tsukuba, Ibaraki, 305-8604, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Yamaguchi
authors.affiliation: Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima-City, 960-1296, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Tsukada
authors.affiliation: Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan. Electronic address: ytakaha@eps.s.u-tokyo.ac.jp.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takahashi
mesh_terms: D000327:Adsorption; D002586:Cesium / Q000032:analysis*; D002588:Cesium Radioisotopes / Q000032:analysis*; D008903:Minerals / Q000737:chemistry; D011834:Radiation Monitoring; D012987:Soil / Q000737:chemistry; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D002588:Cesium Radioisotopes; D008903:Minerals; D012987:Soil; D012990:Soil Pollutants, Radioactive; D002586:Cesium
keywords: Adsorption; Cesium; EXAFS; RIP; Soil; Species