Remobilization of radiocesium on riverine particles in seawater: The contribution of desorption to the export flux to the marine environment

Unexpected source of Fukushima-derived radiocesium to the coastal ocean of Japan

“…S4). These desorption rates were higher than those observed from riverine particles (18) or estuarine sediments (19), but consistent with a well-known property of Cs: decreasing solid-solution partitioning with increasing ionic strength (20). Therefore, beach sands appear to be capable of storing a large inventory of 137 Cs at depth that over time may be remobilized by seawater intrusion into beach aquifers and released to the coastal environment via groundwater-surface water exchange processes.…”

Estimation of desorption ratios of radio/stable caesium from environmental samples (aerosols and soils) leached with seawater, diluted seawater and ultrapure water

“…The highest value for the 137 Cs leaching ratio was approximately 2%, which value occurred in the leaching experiment using 100% seawater. This value falls within the range (1.4-4.2%) of values obtained by Takata et al (2015) from leaching experiments performed over a few days using Abukuma riverine soil/sediments and natural seawater, even though there are differences in the experimental conditions between these two studies. For example, this study used bulk soil with a solid-solution ratio of 4 g : 200 ml, as opposed to Takata et al (2015) using sieved riverine soil/sediments (<74 mm) with a solid-solution ratio of 10 g : 5 L. Furthermore, the leaching ratio obtained in this study is similar to those reported by Takata et al (2015) from the Kuji, Naka and Tone Rivers.…”

“…This value falls within the range (1.4-4.2%) of values obtained by Takata et al (2015) from leaching experiments performed over a few days using Abukuma riverine soil/sediments and natural seawater, even though there are differences in the experimental conditions between these two studies. For example, this study used bulk soil with a solid-solution ratio of 4 g : 200 ml, as opposed to Takata et al (2015) using sieved riverine soil/sediments (<74 mm) with a solid-solution ratio of 10 g : 5 L. Furthermore, the leaching ratio obtained in this study is similar to those reported by Takata et al (2015) from the Kuji, Naka and Tone Rivers. Yamasaki et al (2016) using artificial seawater (40 ml) for very fine silt (0.8 g) collected from the mouth of the Kuma River also obtained leaching ratio of 3.4 ± 0.6%, similar to those in our short-term experiment.…”

Simultaneous determination of radiocesium (135Cs, 137Cs) and plutonium (239Pu, 240Pu) isotopes in river suspended particles by ICP-MS/MS and SF-ICP-MS

“…Taking into account the fact that river suspended particles are one of the important carriers for radionuclides transported from inland to the ocean, it is critical to quantify the FDNPP-derived radiocesium and Pu in river systems, and to understand the migration mechanism and fate of the released radionuclides in the environment. Additionally, information about river suspended particles is essential to elucidate desorption of these radionuclides in river-sea systems [23,24], and that is important for further evaluating the contribution of riverine export flux of the FDNPP-derived contaminants. However, obtaining samples of suspended particles is time-consuming and technically difficult, and the sample size available for analysis is generally limited.…”