Time changes of dose equivalent rate above the soil surface as indication of natural attenuation processes
<p>Eight sites in the Fukushima contaminated area were surveyed for long-term changes in D-shuttle dose equivalent rate above the soil surface during 2015–2017. D-shuttle readings in most cases decreased faster than if due to radioactive decay only. More rapid decrease can be explained by natu...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-08-01
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| Series: | Proceedings of the International Association of Hydrological Sciences |
| Online Access: | https://www.proc-iahs.net/381/121/2019/piahs-381-121-2019.pdf |
| Summary: | <p>Eight sites in the Fukushima contaminated area were
surveyed for long-term changes in D-shuttle dose equivalent rate above the
soil surface during 2015–2017. D-shuttle readings in most cases decreased
faster than if due to radioactive decay only. More rapid decrease can be
explained by natural attenuation processes, such as erosion of the topsoil,
the vertical migration of radionuclides in the soil and the deposition of
cleaner sediments transported by surface runoff. According to the time
dependencies of D-shuttle dose rate readings integral rate constants of the
natural attenuation were estimated using the exponential trend-line.
Estimated rate constants of natural attenuation ranged from <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">7.3</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">3</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="51pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="75816354e6d5d5f8808203dc3c9d41f3"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="piahs-381-121-2019-ie00001.svg" width="51pt" height="14pt" src="piahs-381-121-2019-ie00001.png"/></svg:svg></span></span> to 0.48 yr<span class="inline-formula"><sup>−1</sup></span>, while the correspondent a
half-dose rate decrease was 1.4–95 years.</p> |
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| ISSN: | 2199-8981 2199-899X |