Abstract
The migration and dispersion of radioactive Cs (mainly 134 Cs and 137 Cs) are of critical concern in the area surrounding the Fukushima Daiichi Nuclear Power Plant (FDNPP). Considerable uncertainty remains in understanding the properties and dynamics of radioactive Cs transport by surface water, particularly during rainfall-induced flood events to the ocean. Physical and chemical properties of unique estuary sediments, collected from the Kuma River, 4.0 km south of the FDNPP, were quantified in this study. These were deposited after storm events and now occur as dried platy sediments on beach sand. The platy sediments exhibit median particle sizes ranging from 28 to 32 μm. There is increasing radioactivity towards the bottom of the layers deposited; approximately 28 and 38 Bq g -1 in the upper and lower layers, respectively. The difference in the radioactivity is attributed to a larger number of particles associated with radioactive Cs in the lower part of the section, suggesting that radioactive Cs in the suspended soils transported by surface water has decreased over time.Sequential chemical extractions showed that ~90% of 137 Cs was strongly bound to the residual fraction in the estuary samples, whereas 60 ~ 80% of 137 Cs was bound to clays in the six paddy soils. This high concentration in the residual fraction facilitates ease of transport of clay and silt size particles through the river system. Estuary sediments consist of particles <100 μm. Radioactive Cs desorption experiments using the estuary samples in artificial seawater revealed that 3.4 ± 0.6% of 137 Cs was desorbed within 8 h. More than 96% of 137 Cs remained strongly bound to clays. Hence, particle size is a key factor that determines the travel time and distance during the dispersion of 137 Cs in the ocean.
| Original language | English |
|---|---|
| Pages (from-to) | 155-162 |
| Number of pages | 8 |
| Journal | Science of the Total Environment |
| Volume | 551-552 |
| DOIs | |
| Publication status | Published - May 1 2016 |
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All Science Journal Classification (ASJC) codes
- Environmental Engineering
- Environmental Chemistry
- Waste Management and Disposal
- Pollution
Cite this
Radioactive Cs in the estuary sediments near Fukushima Daiichi Nuclear Power Plant. / Yamasaki, Shinya; Imoto, Junpei; Furuki, Genki; Ochiai, Asumi; Ohnuki, Toshihiko; Sueki, Keisuke; Nanba, Kenji; Ewing, Rodney C.; Utsunomiya, Satoshi.
In: Science of the Total Environment, Vol. 551-552, 01.05.2016, p. 155-162.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Radioactive Cs in the estuary sediments near Fukushima Daiichi Nuclear Power Plant
AU - Yamasaki, Shinya
AU - Imoto, Junpei
AU - Furuki, Genki
AU - Ochiai, Asumi
AU - Ohnuki, Toshihiko
AU - Sueki, Keisuke
AU - Nanba, Kenji
AU - Ewing, Rodney C.
AU - Utsunomiya, Satoshi
PY - 2016/5/1
Y1 - 2016/5/1
N2 - The migration and dispersion of radioactive Cs (mainly 134 Cs and 137 Cs) are of critical concern in the area surrounding the Fukushima Daiichi Nuclear Power Plant (FDNPP). Considerable uncertainty remains in understanding the properties and dynamics of radioactive Cs transport by surface water, particularly during rainfall-induced flood events to the ocean. Physical and chemical properties of unique estuary sediments, collected from the Kuma River, 4.0 km south of the FDNPP, were quantified in this study. These were deposited after storm events and now occur as dried platy sediments on beach sand. The platy sediments exhibit median particle sizes ranging from 28 to 32 μm. There is increasing radioactivity towards the bottom of the layers deposited; approximately 28 and 38 Bq g -1 in the upper and lower layers, respectively. The difference in the radioactivity is attributed to a larger number of particles associated with radioactive Cs in the lower part of the section, suggesting that radioactive Cs in the suspended soils transported by surface water has decreased over time.Sequential chemical extractions showed that ~90% of 137 Cs was strongly bound to the residual fraction in the estuary samples, whereas 60 ~ 80% of 137 Cs was bound to clays in the six paddy soils. This high concentration in the residual fraction facilitates ease of transport of clay and silt size particles through the river system. Estuary sediments consist of particles <100 μm. Radioactive Cs desorption experiments using the estuary samples in artificial seawater revealed that 3.4 ± 0.6% of 137 Cs was desorbed within 8 h. More than 96% of 137 Cs remained strongly bound to clays. Hence, particle size is a key factor that determines the travel time and distance during the dispersion of 137 Cs in the ocean.
AB - The migration and dispersion of radioactive Cs (mainly 134 Cs and 137 Cs) are of critical concern in the area surrounding the Fukushima Daiichi Nuclear Power Plant (FDNPP). Considerable uncertainty remains in understanding the properties and dynamics of radioactive Cs transport by surface water, particularly during rainfall-induced flood events to the ocean. Physical and chemical properties of unique estuary sediments, collected from the Kuma River, 4.0 km south of the FDNPP, were quantified in this study. These were deposited after storm events and now occur as dried platy sediments on beach sand. The platy sediments exhibit median particle sizes ranging from 28 to 32 μm. There is increasing radioactivity towards the bottom of the layers deposited; approximately 28 and 38 Bq g -1 in the upper and lower layers, respectively. The difference in the radioactivity is attributed to a larger number of particles associated with radioactive Cs in the lower part of the section, suggesting that radioactive Cs in the suspended soils transported by surface water has decreased over time.Sequential chemical extractions showed that ~90% of 137 Cs was strongly bound to the residual fraction in the estuary samples, whereas 60 ~ 80% of 137 Cs was bound to clays in the six paddy soils. This high concentration in the residual fraction facilitates ease of transport of clay and silt size particles through the river system. Estuary sediments consist of particles <100 μm. Radioactive Cs desorption experiments using the estuary samples in artificial seawater revealed that 3.4 ± 0.6% of 137 Cs was desorbed within 8 h. More than 96% of 137 Cs remained strongly bound to clays. Hence, particle size is a key factor that determines the travel time and distance during the dispersion of 137 Cs in the ocean.
UR - http://www.scopus.com/inward/record.url?scp=84957796278&partnerID=8YFLogxK
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U2 - 10.1016/j.scitotenv.2016.01.155
DO - 10.1016/j.scitotenv.2016.01.155
M3 - Article
C2 - 26874771
AN - SCOPUS:84957796278
VL - 551-552
SP - 155
EP - 162
JO - Science of the Total Environment
JF - Science of the Total Environment
SN - 0048-9697
ER -