Article

Radiocesium reaction with illite and organic matter in marine sediment

Department of Chemistry, Kyungpook National University, Daikyū, Daegu, South Korea
Marine Pollution Bulletin (Impact Factor: 2.99). 06/2006; 52(6):659-65. DOI: 10.1016/j.marpolbul.2005.10.017
Source: PubMed

ABSTRACT

The mineralogical effect on the (137)Cs reaction with marine sediment has not been systematically studied yet, even though illite has been known to adsorb Cs preferentially on its frayed edge sites in a low Cs concentration. Ninety-three marine sediment samples were collected near Yangnam, Korea for quantitative X-ray-diffraction (XRD), gamma-ray, and total organic carbon (TOC) analysis. Illite content was in the range of 0-23 wt.% and those of (137)Cs and TOC were minimum detectable activity (MDA) approximately 7.19 Bq/kg-dry and approximately 3.32%, respectively. The illite content in the marine sediment showed a good relationship with the (137)Cs content (R(2)=0.69), but with an increase in the illite content, the relationship became less linear. This trend can be clearly shown in two groups of samples with different size fractions (< and >5Mdvarphi). For the samples of larger particle sizes (low contents of illite), the relationship is linear, but for the samples of the smaller particle sizes (high illite content) it is less linear with a decreased slope, indicating that increase in illite content does not significantly contribute to the fixation of (137)Cs in marine sediment. Rather, the TOC has a more linear relationship with (137)Cs content with no slope change in all particle size ranges. This may indicate that humic materials in marine sediment block the access of (137)Cs to the frayed edge site and reduces the adsorption of (137)Cs on illite and that the organic materials in marine sediment play more important roles in adsorbing Cs than illite.

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    • "It is worth noting that organic content in the shelf of Fukushima and Ibaraki Prefectures varies in the range of 0.1-25% (Otosaka and Kobayashi, 2013;Ambe et al., 2014;Ono et al., 2015). The preferential adsorption of 137 Cs on organic matter can be explained by the partial coverage of fine mineral sediment by organic substances and subsequent blocking of sorption (Kim et al., 2006;Ono et al., 2015). Comparison of the concentration of 137 Cs in the sediment and benthic invertebrates(Sohtome et al., 2014) and in the demersal fishes (Buesseler et al., 2012;Wada et al., 2013;Tateda et al., 2013) suggests that the continual ingestion of organic matter from sediments can be an important contamination pathway for all components of the benthic food web. "
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