Concurrent datasets on land cover and river monitoring in Fukushima decontaminated catchment during 2013-2018.

After the Fukushima nuclear accident, the Japanese government implemented extensive decontamination work in 137Cs contaminated catchments for residents' health and local revitalization. Whether dramatic land use changes in the upstream decontaminated regions affected river suspended sediment (SS) and particulate 137Cs discharge downstream remain unknown because of the poor quantification on land cover changes and long-term river SS dynamics. We here introduce a 6-year concurrent database of the Niida River Basin, a decontaminated catchment, including the first available vector decontamination maps, satellite images in decontaminated regions with a spatial resolution of 10 m, and long-term river monitoring datasets spanning decontamination (2013-2016) and subsequent natural restoration stages (2017-2018). These datasets allow us, for the first time, to directly link the transport dynamics of river SS (particulate 137Cs) to land use changes caused by humans in real-time, which provide fundamental data for better understanding the river response of sediment to land use change. Moreover, the data obtained by interdisciplinary methods offer a template for land use change impact assessment in other river basins.

Changes in air dose rates due to soil moisture content in the Fukushima prefecture forests.

Radionuclides released and deposited because of the 2011 Fukushima Dai-ichi Nuclear Power Plant accident caused an increase in air dose rates in Fukushima Prefecture forests. Although an increase in air dose rates during rainfall was previously reported, the air dose rates in the Fukushima forests decreased during rainfall. This study aimed to develop a method to estimate rainfall-related changes in air dose rates, even in the absence of soil moisture data, in Namie-Town and Kawauchi-Village, Futaba-gun, Fukushima Prefecture. Moreover, we examined the relationship between preceding rainfall (Rw) and soil moisture content. The air dose rate was estimated by calculating the Rw in Namie-Town from May to July 2020. We found that the air dose rates decreased with increasing soil moisture content. The soil moisture content was estimated from Rw by combining short-term and long-term effective rainfall using half-live values of 2 h and 7 d and considering the hysteresis of water absorption and drainage processes. Furthermore, the soil moisture content and air dose rate estimations showed a good agreement with coefficient of determination (R2) scores >0.70 and >0.65, respectively. The same method was tested to estimate the air dose rates in Kawauchi-Village from May to July 2019. At the Kawauchi site, variation in estimated value is relatively large due to the presence of water repellency in dry conditions, and the amount of 137Cs inventory was low, so estimating air dose from rainfall remained a challenge. In conclusion, rainfall data were successfully used to estimate soil moisture and air dose rates in areas with high 137Cs inventories. This leads to the possibility of removing the influence of rainfall on measured air dose rate data and could contribute to the improvement of methods currently used to estimate the external air dose rates for humans, animals, and terrestrial forest plants.

Combined use of UAV-SfM surveys, soil particle tracking with RFID tags and a sediment connectivity index to study plot-scale sediment transport.

To explore the processes of soil erosion at the plot scale, Digital surface model of Differences (DoD) maps (Unmanned Aerial Vehicle - Structure from Motion (UAV-SfM) method) and data from Radio Frequency Identification (RFID) tags were analysed. The comparison of differences in accuracy of UAV-SfM and 3D terrestrial laser scanner (TLS) measurements, and the integration of the UAV-SfM method and soil particle tracing with RFID tag locations were conducted to assess sediment transport in a plot in Fukushima prefecture, Japan. The Universal Soil Loss Equation (USLE) plot was installed and kept with no vegetation and no cultivation. Water and sediment discharges were measured at the outlet of the plot, and the topographic index of runoff and sediment connectivity (IC) -focused on surface roughness- was also estimated. Based on field surveys, four periods were defined. Locations of RFID tags were firstly determined by using orthoimages derived from the UAV-SfM method and then compared with those locations measured with a laser total station. The mean and standard deviation of difference amounts of UAV-SfM were of 1 and 3.3 mm, respectively. On average, the RFID tags were located with an accuracy of 3.1 cm (RMSE). Although data of tags tracing showed short transport distances with rill erosion, the results of the UAV-SfM surveys showed an increase of sediment connectivity (SC) over the study period that may explain the largest sediment discharge, especially of fine soil particles. The concurrence of higher values of SC as well as the development of new and longer rills demonstrated the important activity of net soil loss in our study site. The combination of distinct methods and techniques, all providing accurate measurements, shed light on the sediment transport process at short distances, which affects the net water and sediment discharge at larger scales.

Hydrological setting controls 137Cs and 90Sr concentrations in a headwater catchment in the Chornobyl Exclusion Zone.

Concentration-discharge relationships are widely used to understand the hydrological processes controlling river water chemistry. This study investigates how hydrological processes affect radionuclide (137Cs and 90Sr) concentrations in surface water in headwater catchments within the Chornobyl Exclusion Zone (ChEZ) in Ukraine. In the flat wetland catchments, the depth of the saturated soil layer changes little throughout the year, but changes in the saturated soil surface area during snowmelt and immediately after rainfall affect water chemistry by changing the opportunities for contact between the surface water and the soil surface. On the other hand, in the slope catchments where there are few wetlands, the water chemistry of river water is governed by changes in the relative contributions of "shallow water" and "deep water" due to changes in the catchment water supply pathways feeding the rivers. In this study, no correlations were observed between dissolved or suspended 137Cs concentrations and either discharge rates or competitive cations, but the solid-liquid ratio of 137Cs was found to be significantly and negatively correlated with water temperature. However, 90Sr concentrations in surface water were found to be strongly related to the water pathways for each of the catchments. Moreover, contact between the surface water and the soil surface and changes in the relative contributions of shallow and deep waters to stream water were correlated with changes in 90Sr concentrations in surface water in wetland and slope catchments, respectively. The study concludes that 90Sr in rivers inside the ChEZ are strongly affected by the water pathways in headwater catchments. Additional studies will be necessary to clarify the details of sorption/desorption reactions.

Evaluating changes in radionuclide concentrations and groundwater levels before and after the cooling pond drawdown in the Chornobyl Nuclear Power Plant vicinity.

In the vicinity of the Chornobyl Nuclear Power Plant (ChNPP), the cooling pond (CP) was an artificially maintained reservoir with water levels regulated to 7 m above the Pripyat River until May 2014, when its pumps stopped operating, resulting in a natural drawdown. To investigate the surface-groundwater system before and after the drawdown, we evaluated the spatial and temporal changes in 90Sr and 137Cs radionuclide concentrations and groundwater levels in the shallow unconfined aquifer near the ChNPP from 2010 to 2019. Additionally, we compared water levels and 90Sr concentrations in Azbuchin Lake, wetlands inside the CP, and the Pripyat River. Using three-year averages before (2011-2013) and after (2017-2019) the drawdown period, we found that 90Sr concentrations significantly increased up to 102 kBq/m3 in the Pripyat River floodplain, north of ChNPP, exceeding the WHO drinking water guideline of 10 kBq/m3. In contrast 137Cs concentrations ranged consistently between 10 and 100 Bq/m3. The groundwater levels decreased over 50 cm at approximately 65 % of shallow monitoring wells and up to 6 m near the CP. The 90Sr concentration increases in some wells at the Pripyat River floodplain were associated with decreased dilution rates from the CP due to the reduced CP leakage, causing changes in groundwater flow direction and decreases in groundwater velocity. From the new finding of this study that the drawdown increased 90Sr concentrations near the floodplain, we estimated the 90Sr flux and contribution to the Pripyat River and the 90Sr contribution did not change significantly after the drawdown. However, radionuclides may accumulate more at the floodplain in the future; therefore, additional monitoring is required to verify 90Sr transport from areas of elevated concentrations and its impact on groundwater in the aquifer.

Mode of Atmospheric Deposition in Forests Demonstrates Notable Differences in Initial Radiocesium Behavior.

The March 2011 Fukushima Dai-ichi Nuclear Power Plant accident in Japan released 520 PBq of radionuclides compared to a total release of 5300 PBq from the Chornobyl Nuclear Power Plant accident. Both nuclear accidents resulted in deposition of radiocesium throughout the northern hemisphere, and a plethora of studies have been performed regarding radiocesium (137Cs) behavior. However, few studies have assessed the impact of precipitation on 137Cs deposition in forests. Wide-scale environmental measurements from 2011 and 2016 were used to determine the differences in 137Cs deposition because of precipitation following the Fukushima accident. In areas where wet deposition processes were dominant, dense forests generally had lower ambient dose rates and levels of contamination on forest floors than other stands with fewer stems per hectare in 2011. Similar tendencies were not observed in areas that were primarily subject to dry deposition nor were any trends observed in 2016. 137Cs was retained in dense forest canopies for an extended period regardless of the deposition mode. Additionally, it was found that the initial retention of radionuclides by forest canopies is in general higher for areas with predominantly dry deposition. Incorporation of radiocesium into wood tissues was the same for both wet and dry deposition.

Radiocesium accumulation in Lake Kasumigaura by riverine input and migration following the Fukushima Dai-ichi nuclear power plant accident.

Vertical radiocesium concentration profiles and inventories in sediments were measured in Lake Kasumigaura following the 2011 Fukushima Dai-ichi Nuclear Power Plant accident. Further measurements of radiocesium concentrations in suspended solids (SS) have been conducted since September 2012 in the Koise and Sakura rivers inflowing into the lake. Cesium-137 (137Cs) accumulated intensively near the inflow outlets in the lake. At the lake center, the 137Cs inventory in sediments increased during 2011-2014; however, few changes were observed during 2014-2016. The 137Cs surface concentration and inventory decreased considerably in Tsuchiura-iri Bay until 3 years after the accident, indicating 137Cs migration. However, the rate of decrease subsequently slowed due to the 137Cs supply from the river. The 137Cs concentration in river SS declined during 2012-2015; however, it remained 1-2 orders of magnitude above its pre-accident level. The entrainment coefficient of particulate 137Cs in the inflows was initially higher in the Koise River but decreased exponentially more rapidly in the Koise River than in the Sakura River until 2015. Therefore, in the future, the difference in 137Cs concentrations will be smaller. The 137Cs concentration in the Koise River will continue to decrease; thus, the difference in the 137Cs inventory between the northern and southern parts of the lake will decrease. Total estimated amounts of 137Cs in the entire lake were 3.72 × 1012 Bq in December 2012 and 4.18 × 1012 Bq in August 2016. The accumulated amount of 137Cs in the entire lake based on sediment analysis was similar to the riverine input of particulate 137Cs based on riverine SS analysis from December 2012‒;August 2016, confirming the high trapping performance of the lake for particulate matter provided by the basin. Moreover, the amount of 137Cs accumulated in the lake in 2016 may have originated from comparable rates of atmospheric deposition and riverine input. These findings provide useful insights for future prediction and management of radiocesium contamination and the effects of riverine inputs in general shallow lakes.

Distribution of radiocesium and its controlling factors under the Japanese cedar canopies.

This study investigated the spatial distribution of radiocesium deposited by the Fukushima Daiichi Nuclear Power Plant accident in a densely planted Japanese cedar stand. Systematic grid sampling was conducted to determine 137Cs inventories in the layers of deposited organic material and mineral soil at two different spatial scales (hillslope [60 m2] and small [1 m2]). The results showed that 137Cs inventories along the hillslope were heterogeneously distributed, with coefficients of variation for the deposited organic material and mineral soil layers of 46.4% and 48.9%, respectively. The 137Cs inventory in each layer tended to show a lognormal distribution. The correlation between the 137Cs inventories in deposited organic material and mineral soil in the same sampling grid was weak. The controlling mechanisms of the 137Cs inventories in the litter and mineral soil layers differed due to differences in the underlying key processes, such as canopy-forest floor transfer due to hydrological and biological processes. No significant correlation was found between the distance from the nearest tree trunk and the 137Cs inventory in the deposited organic layer at each sampling point. In contrast, the 137Cs inventory in the soil tended to increase as the distance from the nearest tree trunk increased at both the hillslope and small scales. It was found that the initial spatial patterns of 137Cs in the soil layer due to atmospheric deposition were preserved in the cedar stand. Finally, we tested the effects of soil sampling density on the reliability of mean soil 137Cs inventory estimations in the cedar stand. The results indicated that a soil sampling area greater than 0.06 m2 at the hillslope scale and 0.008 m2 at the small scale enabled the mean 137Cs inventory to be estimated with an uncertainty of less than 20% in the cedar stand.

Pre- and post-accident environmental transfer of radionuclides in Japan: lessons learned in the IAEA MODARIA II programme.

An international review of radioecological data derived after the accident at the Fukushima Daiichi nuclear power plant was an important component of activities in working group 4 of the IAEA Models and data for radiological impact assessment, phase II (MODARIA II) programme. Japanese and international scientists reviewed radioecological data in the terrestrial and aquatic environments in Japan reported both before and after the accident. The environmental transfer processes considered included: (a) interception and retention radionuclides by plants, (b) loss of radionuclides from plant and systemic transport of radionuclides in plants (translocation), (c) behaviour of radiocaesium in soil, (d) uptake of radionuclides from soil by agricultural crops and wild plants, (e) transfer of radionuclides from feedstuffs to domestic and wild animals, (f) behaviour of radiocaesium in forest trees and forest systems, (g) behaviour of radiocaesium in freshwater systems, coastal areas and in the ocean, (h) transport of radiocaesium from catchments through rivers, streams and lakes to the ocean, (i) uptake of radiocaesium by aquatic organisms, and (j) modification of radionuclide concentrations in food products during food processing and culinary preparation. These data were compared with relevant global data within IAEA TECDOC-1927 'Environmental transfer of radionuclides in Japan following the accident at the Fukushima Daiichi Nuclear Power Plant'. This paper summarises the outcomes of the data collation and analysis within MODARIA II work group 4 and compares the Japan-specific data with existing radioecological knowledge acquired from past and contemporary radioecological studies. The key radioecological lessons learned are outlined and discussed.

Understory biomass measurement in a dense plantation forest based on drone-SfM data by a manual low-flying drone under the canopy.

Forest is an important part of the environmental system, which has a significant impact on soil hydrological characteristics and forest landscapes, because these processes are influenced by forest management and understory vegetation. Quantitative understory vegetation biomass (UVB) measurement and estimation are vital processes in forest ecology and environmental management. However, these estimations are difficult to make on a large scale especially dense planted forest. Here, we applied catchment-scale Structure from Motion and a manually operated ultralow-flying drone under the canopy of a dense planted (2000 stems/ha) Japanese cedar/cypress plantation forest to reconstruct the understory. An understory drone survey was performed over a 1.1-ha sub-catchment to generate a canopy height model based on dense point cloud data. A biomass survey of three 16-m2 harvesting plots was conducted to compute understory vegetation volume data based on point clouds. Combined with harvested biomass data in the field, quantitative models were developed between the understory vegetation volume and biomass. Subsequently, the models were used to map spatial understory vegetation biomass distribution in the sub-catchments. Aerial photos taken by the ultralow-flying drones under the canopy yielded a high-resolution catchment-scale understory with point cloud density >10/cm2. Strong cubic model coefficients of determination (R2 = 0.75) predicted the understory vegetation biomass based on the canopy height model. The mean understory vegetation biomass was 0.82 kg/m2 and dominated by low ferns. In the present study, we successfully reconstructed the multilayered forest structure and generated understory vegetation biomass distribution models. This results also will be essential to evaluate the erosion and evapotranspiration in dense plantation forests and future environmental management.

A storm-induced flood and associated nearshore dispersal of the river-derived suspended 137Cs.

Accidental leakage of radionuclides from the Fukushima Nuclear Power Plant (FNPP1) took place in the aftermath of the catastrophic tsunamis associated with the Great East Japan Earthquake that occurred on March 11, 2011. Significant amount of radionuclides released into the atmosphere were reportedly transported and deposited on land located near FNPP1. The Niida River, Fukushima, Japan, has been recognized as a terrestrial source of highly contaminated suspended radiocesium adhering to sediment particles in the ocean through the river mouth as a result of hydrological processes. Remaining scientific questions include the oceanic dispersal and inventories of the sediments and suspended radiocesium in the ocean floor derived from the Niida River. Complementing limited in situ data, we developed a quadruple nested 3D ocean circulation and sediment transport model in an extremely high-resolution configuration to quantify the transport processes of the suspended radiocesium. Particularly, we investigated the storm and subsequent floods associated with Typhoon 201326 (Wipha) that passed off the Fukushima coast in October 2013, and subsequently promoted precipitation to a considerable extent and associated riverine freshwater discharge along with sediment outfluxes to the ocean. Using in situ bed sediment core data obtained from regions near the river mouth, we conducted a quantitative assessment of the accumulation and erosion of the sediments and explored the resultant suspended radiocesium distribution around the river mouth and nearshore areas along the Fukushima coast. We identified three major accumulative areas, near the river mouth within an area < 1 km, around the breakwaters in the north of the river mouth, and along the southern coastal area, while offshore and northward transports were minor. The present study clearly exhibits substantial retention of the land-derived radiocesium adsorbed to the sediments in the coastal areas, leading to possible long-term influences on the surrounding marine environment.

Vertical distribution and transport of radiocesium via branchflow and stemflow through the canopy of cedar and oak stands in the aftermath of the Fukushima Dai-ichi Nuclear Power Plant accident.

Aiming to fill a need for data regarding radiocesium transport via both branchflow and stemflow through forests impacted by radioactive fallout, this study examined the vertical variation of radiocesium flux from branchflow and stemflow through the canopies of young Japanese cedar (Cryptomeria japonica (L. f.) D. Don) and Japanese oak (Quercus serrata Murray) trees in the aftermath of the Fukushima Dai-ichi Nuclear Power Plant accident. In forested areas approximately 40 km northwest of the location of the Fukushima Dai-ichi accident, the 137Cs concentration varied significantly among sampling periods and between the two forests, with the oak stand exhibiting higher 137Cs concentrations and depositional fluxes than the cedar stand. Expressed per unit trunk basal area, the depositional flux of 137Cs generated from the cedar and oak stands was 375 and 2810 Bq m-2 year-1, respectively. Of this total, 71% and 48% originated from the cedar and oak canopy, respectively, while the remainder originated from the trunk. Accordingly, the origin of radiocesium was more balanced for the oak stand with almost half of the flux coming from the canopy (48%) and the other half from the trunk (52%). Only about a quarter (29%) of the radiocesium flux originated from the trunk in Japanese cedar. Results from this work provide needed data that can enable a more thorough conceptualization of radiocesium cycling in forests. Coupling these empirical results with a physically-based model would likely lead to better forest management and proactive strategies for rehabilitating radioactively-contaminated forests and reducing the exposure risk of radiation dose rate for those that utilize forest products.

Evaluation of contribution rate of the infiltrated water collected using zero-tension lysimeter to the downward migration of 137Cs derived from the FDNPP accident in a cedar forest soil.

The vertical distribution of 137Cs in forest soil is important for predicting air dose rates and future cycling in forest ecosystems. However, there are many unexplained questions about the mechanisms of its downward migration. In this study, the 137Cs flux by rainfall infiltration was observed for three years from August 2017 using zero-tension lysimeters in a mature cedar forest where monitoring of the vertical distribution of 137Cs has been conducted since 2011. As a result, the 137Cs concentration in infiltrated water through the litter layer, 5 cm and 10 cm showed a tendency to be high in summer, but no such seasonal variation was found at 20 cm. Although the 137Cs inventory in the litter layer has been exponentially decreasing, the annual 137Cs fluxes in infiltrated water through the litter layer were almost the same in three years, and about 0.14-0.17% of the deposition density of 137Cs. Comparing these 137Cs fluxes with the apparent amounts of downward migration of 137Cs estimated from the change in the vertical distribution of 137Cs, the contribution rate of the infiltrated water to downward migration of 137Cs from litter to soil was calculated to be 8.5-17.7%. Similarly, the contribution rate in mineral soil layers was calculated to be 0.6-0.8% on a measured basis and estimated to be 3.0 ± 0.2% after correcting the amount of collected water, which is a problem with zero-tension lysimeter. It indicates that rainfall infiltration can explain a small part of the downward migration of 137Cs, thus further studies are required to clarify the contribution rate of remaining mechanisms such as advection-diffusion, colloidal transport, physical mixing, bioturbation, and growth and death of plant roots.

Specific Inhibitor of Placental Alkaline Phosphatase Isolated from a DNA-Encoded Chemical Library Targets Tumor of the Female Reproductive Tract.

Placental alkaline phosphatase (PLAP) is an abundant surface antigen in the malignancies of the female reproductive tract. Nevertheless, the discovery of PLAP-specific small organic ligands for targeting applications has been hindered by ligand cross-reactivity with the ubiquitous tissue non-specific alkaline phosphatase (TNAP). In this study, we used DNA-encoded chemical libraries to discover a potent (IC50 = 32 nM) and selective PLAP inhibitor, with no detectable inhibition of TNAP activity. Subsequently, the PLAP ligand was conjugated to fluorescein; it specifically bound to PLAP-positive tumors in vitro and targeted cervical cancer in vivo in a mouse model of the disease. Ultimately, the fluorescent derivative of the PLAP inhibitor functioned as a bispecific engager redirecting the killing of chimeric antigen receptor-T cells specific to fluorescein on PLAP-positive tumor cells.

Scots pine stands biomass assessment using 3D data from unmanned aerial vehicle imagery in the Chernobyl Exclusion Zone.

Thirty-five years after the accident, large forest areas in the Chernobyl Exclusion Zone still contain huge amounts of radionuclides released from the Chernobyl Nuclear Power Plant Unit 4 in April 1986. An assessment of the radiological and radioecological consequences of persistent radioactive contamination and development of remediation strategies for Chernobyl forests imply acquiring comprehensive data on their contamination levels and dynamics of biomass inventories. The most accurate forest inventory data can be obtained in ground timber cruises. However, such cruises in radioactive contaminated forest ecosystems in the Chernobyl Exclusion Zone result in radiation exposures of the personnel involved, which means the need for development of the remote sensing methods. The purpose of this study is to analyze the applicability and limitations of the photogrammetric method for the remote large-scale monitoring of aboveground biomass inventories. Based on field measurements, we estimated the biomass inventories in 31 Scots pine stands including both artificial plantations and natural populations. The stands differed significantly in age (from a few years in natural populations to 115 years in the oldest plantation), productivity (from 0.4 to 19.8 kg m-2), mean height (from 4.1 to 36 m), and other parameters. Photogrammetric data were obtained from the same stands using unmanned aerial vehicle (UAV). These data were then processed using two approaches to derive the canopy height model (CHM) parameters which were tested for correlation with the aboveground biomass inventories. In the first approach, we found that the inventories correlated well with the mean value of CHM of the site (R2 = 0.79). In the second approach, the total aboveground biomass was approximated by a function of the average height of trees detected at the site and the total crown projection area (R2 = 0.78). Among other local parameters, the total crown projection area was identified as the major factor impacting the accuracy of the aboveground biomass inventory estimates from the UAV survey data in both approaches. In the dense stands with the high total crown projections areas (more than 0.90), the average relative deviations of the UAV-based aboveground biomass estimates from the results of the field measurements were close to 0, which means the adequate accuracy of the UAV surveys data for radioecological monitoring purposes. The relative deviations of the UAV-based estimates in both approaches increased in the stands consisting of separated groups of trees, which indicates potential limitation of the approaches and need for their further development.

Radiocesium leaching from litter during rainstorms in the Fukushima broadleaf forest.

Forests are important sources of dissolved radiocesium (137Cs) discharge downstream. To improve understanding of dissolved 137Cs discharge processes during rainstorms, we investigated the relationship between rainfall-runoff hydrological processes and the discharge of 137Cs leached from litter. Leaching tests were conducted with broadleaf litter collected in the area where saturated overland flow was generated during rainstorms in a broadleaf-tree-dominated forest. According to the leaching test results, the 137Cs leaching rate was higher in the early stage of the test and decreased afterward. There was no significant difference in the overall results between the agitation and non-agitation cases. The 137Cs leaching rate from litter after the 24-h test was up to 33.7%. A large proportion of the original 137Cs activity was present even after the tests, as leaching from litter during rainstorms in the headwater area could be an additional source of dissolved 137Cs in the stream water. If mixing of 137Cs originating from groundwater, soil water, and rainfall with the hydrological processes is assumed, differences between the observed and estimated 137Cs in the surface runoff water became larger under high flow conditions. This analysis indicates additional 137Cs loading on surface runoff water during rainstorms, where saturated surface area can expand as the surface runoff rate increases. Contact area between surface runoff and litter accumulated on the forest floor should increase and accelerate 137Cs leaching from the litter. Therefore, 137Cs leaching in the saturated surface area that is temporarily formed during rainstorms can play a principal role in dissolved 137Cs discharge during rainfall-runoff events. Contaminated litter in the temporally saturated region of forested headwaters is an important factor contributing to elevated levels of dissolved 137Cs during rainstorms in the Fukushima area.

Impacts of freeze-thaw processes and subsequent runoff on 137Cs washoff from bare land in Fukushima.

The deposited 137Cs is one of the long-lived radionuclides, that was released following the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, has been hydrologically transported as particulates in the terrestrial environment of the Fukushima region. The impact of freeze-thaw processes and subsequent runoff affecting the 137Cs flux and concentration in sediment discharge were revealed in bare land erosion plot following the FDNPP accident by detailed monitoring and laser scanner measurement on the soil surface. We found that surface topographic changes due to the frost-heaving during the winter-spring period, and rill formation during the summer. We also found the evident seasonal changes in 137Cs concentration; high during the early spring and gradually decreased thereafter, then surface runoff from the plot frequently occurred during spring and autumn when rainfall was high and reached a maximum in summer. From these results, the higher 137Cs concentration in spring was caused by a mixture of unstable surface sediment following freeze-thaw processes and then transported in the early spring, but erosion amount is not significant because of the less rainfall event. The sediment with a lower 137Cs concentration, which was supplied from the rill erosion and its expansion, was wash-offed during the summer, contributing most of the flux from erosion in bare land in Fukushima region. In case, heavy rainfall occurs in the early spring, caution is required because high concentrations of cesium may flow down into the river.

A DNA-Encoded Chemical Library Based on Peptide Macrocycles.

The synthesis and characterization of a novel DNA-encoded library of macrocyclic peptide derivatives are described; the macrocycles are based on three sets of proteinogenic and non-proteinogenic amino acid building blocks and featuring the use of copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) reaction for ring closure. The library (termed YO-DEL) which contains 1 254 838 compounds, was encoded with DNA in single-stranded format and was screened against target proteins of interest using affinity capture procedures and photocrosslinking. YO-DEL selections yielded specific binders against serum albumins, carbonic anhydrases and NKp46, a marker of activated Natural Killer cells.

Dataset on the 6-year radiocesium transport in rivers near Fukushima Daiichi nuclear power plant.

Radiocesium released from the Fukushima Daiichi nuclear power plant (FDNPP) and deposited in the terrestrial environment has been transported to the sea through rivers. To study the long-term effect of riverine transport on the remediation process near the FDNPP, a monitoring project was initiated by the University of Tsukuba. It was commissioned by the Ministry of Education, Culture, Sports, Science, and Technology, and the Nuclear Regulatory Commission in June 2011, and was taken over by the Fukushima Prefectural Centre for Environmental Creation from April 2015. The activity concentration and monthly flux of radiocesium in a suspended form were measured in the project. This provides valuable measurement data to evaluate the impact of the accidentally released radiocesium on residents and the marine environment. It can also be used as verification data in the development and testing of numerical models to predict future impacts.