Directly Released Research Articles

Impacts of direct release and river discharge on oceanic 137Cs derived from the Fukushima Dai-ichi Nuclear Power Plant accident

A series of accidents at the Fukushima Dai-ichi Nuclear Power Plant (1F NPP) following the Great East Japan Earthquake and tsunami of 11 March 2011 resulted in the release of radioactive materials to the ocean. We used the Regional Ocean Model System (ROMS) to simulate the 137Cs activity in the oceanic area off Fukushima, with the sources of radioactivity being direct release, atmospheric deposition, river discharge, and inflow across the domain boundary. The direct release rate of 137Cs after the accident until the end of 2016 was estimated by comparing simulated results with measured 137Cs activities adjacent to the 1F NPP. River discharge rates of 137Cs were estimated by multiplying simulated river flow rates by the dissolved 137Cs activities, which were estimated by an empirical function. Inflow of 137Cs across the domain boundary was set according to the results of a North Pacific Ocean model. Because the spatiotemporal variability of 137Cs activity was large, the simulated results were compared with the annual averaged observed 137Cs activity distribution. Normalized annual averaged 137Cs activity distributions in the regional ocean were similar for each year from 2013 to 2016. This result suggests that the annual averaged distribution is predictable. Simulated 137Cs activity attributable to direct release was in good agreement with measurement data from the coastal zone adjacent to the 1F NPP. Comparison of the simulated results with measured activity in the offshore area indicated that the simulation slightly underestimated the activity attributable to inflow across the domain boundary. This result suggests that recirculation of subducted 137Cs to the surface layer was underestimated by the North Pacific model. During the study period, the effect of river discharge on oceanic 137Cs activity was small compared to the effect of directly released 137Cs.

Relaxation induced by the nitric oxide donor and cyclooxygenase inhibitor NCX2121 in renal hypertensive rat aortas

There is an imbalance between contractile and relaxing endothelial factors in hypertension which induces vascular dysfunction. It involves cyclooxygenase (COX) due to production of vasoconstrictor agonists such as thromboxane A2 (TXA2). In this work we used the NO-NSAID vasodilator compound NCX2121 that has nitric oxide (NO) in its structure and the non-selective COX inhibitor indomethacin. This class of pro-drug has been demonstrated hypotensive effect in animal models of hypertension without alteration in the arterial pressure of normotensive rats. It has been pointed a direct vasodilator effect of NO-NSAIDS which mechanism remains unclear. This study aimed to evaluate the cellular mechanisms involved in the NCX2121-induced relaxation in renal hypertensive two kidney-one clip (2K-1C) rat aorta with intact endothelium and denuded aortas. Our data demonstrated that NO was directly released from the compound NCX2121 in the cytosol of the vascular smooth muscle cells. The relaxation induced by NCX2121 was similar in 2K-1C and normotensive two kidney (2K). It was impaired by the endothelium removal and NO-Synthase (NOS) inhibition in both rat aorta groups. The inhibition of the main NO target, soluble guanylyl-cyclase (sGC) with ODQ, abolished NCX2121-induced relaxation in denuded aorta. The expression of COX-1 and COX-2 as well the produced stable analog of Thromboxane A2 (TXA2) were higher in 2K-1C than in 2K. NCX2121 decreased the augmented production of TXA2 in 2K-1C rat aortas. In intact-endothelium aorta, ODQ impaired the relaxation induced by NCX2121 in 2K but it had no effect in 2K-1C rat aorta. Taken together, our results show that NCX2121-induced relaxation is due to the direct NO release inside the vascular smooth muscle cells and sGC activation in denuded aortas, whereas in intact endothelium aortas, NCX2121-induced relaxation could be due to eNOS activation and inhibition of prostanoids production. In addition, relaxation-induced by NCX2121 is not greater in normotensive than in hypertensive rat aortas because COX activity is higher in 2K-1C than in 2K rat aortas.

Evaluation of radioactive cesium impact from atmospheric deposition and direct release fluxes into the North Pacific from the Fukushima Daiichi nuclear power plant

The North Pacific distribution of 134Cs released from the Fukushima Daiichi nuclear power plant (F1NPP) has been investigated using an eddy-resolving model. We conducted simulations based on two scenarios: (1) an input flux that was a combination of atmospheric deposition and direct release from the F1NPP (combination-flux scenario) and (2) an input flux that took account only of the direct release of 134Cs (single-flux scenario). The combination-flux scenario simulation successfully reproduced the distribution of 134Cs activity observed in the surface layer from April 2011 to January 2014. The results indicate that 134Cs deposited via atmospheric deposition into the Kuroshio-Oyashio Interfrontal Zone and 134Cs directly released from F1NPP were both transported to south of the Subarctic Front around 42°N in June of 2012. The combination-flux scenario suggests that the 134Cs activities observed in the area north of 42°N in 2012 originated from atmospheric deposition and that the 134Cs activity was subducted in Central Mode Water during the winters of 2011 and 2012. We directly compared simulated and observed 134Cs activities in the surface layer at 179 points across a wide area to the east of 155°E from 2011 to 2013 to evaluate the accuracy of the two scenarios. The root-mean-square error and correlation coefficient, R, were 7.3Bqm−3 and 0.86, respectively, for the combination-flux scenario and 13.8Bqm−3 and 0.46, respectively, for the single-flux scenario, confirming that reproduction of the 134Cs activity in the North Pacific after the F1NPP accident requires taking both fluxes into consideration. Based on a linear least-squares regression between simulated and observed 134Cs activity, the total 134Cs flux into the North Pacific was estimated at 16.1±1.4PBq.

One-year, regional-scale simulation of <sup>137</sup>Cs radioactivity in the ocean following the Fukushima Dai-ichi Nuclear Power Plant accident

Abstract. A series of accidents at the Fukushima Dai-ichi Nuclear Power Plant following the Great East Japan Earthquake and tsunami of 11 March 2011 resulted in the release of radioactive materials to the ocean by two major pathways: direct release from the accident site and atmospheric deposition. A 1 yr, regional-scale simulation of 137Cs activity in the ocean offshore of Fukushima was carried out, the sources of radioactivity being direct release, atmospheric deposition, and the inflow of 137Cs deposited into the ocean by atmospheric deposition outside the domain of the model. Direct releases of 137Cs were estimated for 1 yr after the accident by comparing simulated results and measured activities adjacent to the accident site. The contributions of each source were estimated by analysis of 131I/137Cs and 134Cs/137Cs activity ratios and comparisons between simulated results and measured activities of 137Cs. The estimated total amounts of directly released 131I, 137Cs, and 137Cs were 11.1 ± 2.2 PBq, 3.5 ± 0.7 PBq, and 3.6 ± 0.7 PBq, respectively. Simulated 137Cs activities attributable to direct release were in good agreement with measured 137Cs activities not only adjacent to the accident site, but also in a wide area in the model domain, therefore this implies that the estimated direct release rate was reasonable. Employment of improved nudging data by JCOPE2 improved both the offshore transport result and the reproducibility of 137Cs activities 30 km offshore. On the other hand, simulated 137Cs activities attributable to atmospheric deposition were low compared to measured activities. The rate of atmospheric deposition into the ocean was underestimated because of a lack of measurements of deposition into the ocean when atmospheric deposition rates were being estimated. Simulated 137Cs activities attributable to the inflow of 137Cs deposited into the ocean outside the domain of the model were in good agreement with measured activities in the open ocean within the model domain after June 2012. The consideration of inflow is important to simulate the 137Cs activity in this model region in the later period of the simulation. The contribution of inflow increased with time and was dominant (more than 99%) by the end of February 2012. The activity of directly released 137Cs, however, decreased exponentially with time and was detectable only in the coastal zone by the end of February 2012.

Treatment of post-digestion liquors with the application of struvite precipitation and reverse osmosis

Since the post-digestion liquors exhibited a high content of biogenic substances and organic matter, an attempt was made to develop an effective treatment of their treatment, allowing the treated liquors to be directly released into a natural reservoir. The liquors were treated with the application of reverse osmosis (RO) and chemical precipitation (struvite) as a pre-treatment step. The application of a unit RO process did not ensure an adequate removal of contaminants, mainly due to the excessive concentration of NH4+ in the permeate. The treatment of post-digestion liquors with a struvite precipitation and a subsequent RO process turned out to be effective and allowed to decrease contaminants’ concentration below discharge limits, allowing direct release of permeate to a natural receiver. However, it was necessary to apply an increased ratio of magnesium and phosphates during struvite precipitation (Mg2+:NH4+:PO43- = 1.5:1:1.5), preceding reverse osmosis treatment. As compared to the MgCl2·6H2O, the application of MgO as a Mg2+ source allowed to receive an additional removal of COD. Struvite crystals were characterized by regular orthorhombic structure and contained insignificant amounts of heavy metals. Moreover, the struvite precipitation influenced the efficiency of a subsequent membrane process in a positive way.

Deletion of Ecto-5′-Nucleotidase (CD73) Reveals Direct Action Potential-Dependent Adenosine Release

Purinergic signaling is a highly complex system of extracellular communication involved in many physiological and pathological functions in the mammalian brain. Its complexity stems from the multitude of purine receptor subtypes and endogenous purine receptor ligands (including ATP, ADP, UTP, UDP, and adenosine). Potentially all of these ligands could be directly released, and some could also arise from extracellular metabolism. A widely held consensus is that, except under pathological conditions, extracellular adenosine arises only from ectoATPase-mediated metabolism of previously released ATP. Here, we have used mice that lack the CD73 gene (encoding ecto-5'-nucleotidase that converts AMP to adenosine) to test whether action potential-dependent adenosine release in the cerebellum depends on prior ATP release. Surprisingly, we have uncovered two parallel pathways of adenosine release: one that is indirect via glutamate receptor-dependent release of ATP and a second of equal amplitude that has no dependence on prior release of ATP and thus represents the direct release of adenosine. This component of adenosine release is blocked by bafilomycin and modulated by mGlu4 receptor activation, strongly supporting adenosine release by exocytosis from parallel fibers. Our findings are a major step in understanding the mechanisms of adenosine release and are likely to have implications for all aspects of physiology where adenosine plays a key modulatory role.

Distribution of Pu isotopes in marine sediments in the Pacific 30 km off Fukushima after the Fukushima Daiichi nuclear power plant accident

Copyright © 2012 by The Geochemical Society of Japan. in seawater in the immediate vicinity of the Fukushima DNPP (TEPCO, 2011). From the analysis of 131I/137Cs activity ratios, Tsumune et al. (2012) found that the direct release of radioactive liquid wastes into the ocean started on March 26, 2011, and the direct release from the plant site contributed more to the measured 137Cs concentration than atmospheric deposition did. Using a regional ocean model, they further estimated that from March 26 to the end of May, the total amount of 137Cs directly released was 3.5 ± 0.7 PBq. In May–June, 2011, accident-released 134Cs and 137Cs were already being observed in coastal seawater along the Northern Sanriku coast and Tsugaru Strait, 250–450 km north of the Fukushima DNPP (Inoue et al., 2012). Honda et al. (2012) studied the distribution of 134Cs and 137Cs in surface seawater in the western North Pacific one month after the accident and found that accident-released radionuclides were distributed widely in the western North Pacific. The 137Cs observed there was transported not only by diffusion and advection of seawater but also via the atmosphere as an aerosol after the accident. Honda et al. (2012) estimated the deposition of 137Cs into the sea surface via the atmosphere was 0.18 PBq, which is smaller than the deposition of ca. 5 PBq estimated by Kawamura et al. (2011) using a numerical simulation. Distribution of Pu isotopes in marine sediments in the Pacific 30 km off Fukushima after the Fukushima Daiichi nuclear power plant accident

Distribution of oceanic 137Cs from the Fukushima Dai-ichi Nuclear Power Plant simulated numerically by a regional ocean model

Radioactive materials were released to the environment from the Fukushima Dai-ichi Nuclear Power Plant as a result of the reactor accident after the Tohoku earthquake and tsunami of 11 March 2011. The measured 137Cs concentration in a seawater sample near the Fukushima Dai-ichi Nuclear Power Plant site reached 68kBqL−1 (6.8×104BqL−1) on 6 April. The two major likely pathways from the accident site to the ocean existed: direct release of high radioactive liquid wastes to the ocean and the deposition of airborne radioactivity to the ocean surface. By analysis of the 131I/137Cs activity ratio, we determined that direct release from the site contributed more to the measured 137Cs concentration than atmospheric deposition did.We then used a regional ocean model to simulate the 137Cs concentrations resulting from the direct release to the ocean off Fukushima and found that from March 26 to the end of May the total amount of 137Cs directly released was 3.5±0.7PBq ((3.5±0.7)×1015Bq). The simulated temporal change in 137Cs concentrations near the Fukushima Daini Nuclear Power Plant site agreed well with observations. Our simulation results showed that (1) the released 137Cs advected southward along the coast during the simulation period; (2) the eastward-flowing Kuroshio and its extension transported 137C during May 2011; and (3) 137Cs concentrations decreased to less than 10BqL−1 by the end of May 2011 in the whole simulation domain as a result of oceanic advection and diffusion.We compared the total amount and concentration of 137Cs released from the Fukushima Dai-ichi reactors to the ocean with the 137Cs released to the ocean by global fallout. Even though the measured 137Cs concentration from the Fukushima accident was the highest recorded, the total released amount of 137Cs was not very large. Therefore, the effect of 137Cs released from the Fukushima Dai-ichi reactors on concentration in the whole North Pacific was smaller than that of past release events such as global fallout, and the amount of 137Cs expected to reach other oceanic basins is negligible comparing with the past radioactive input.

Postrelease Performance of Acclimated and Directly Released Hatchery Summer Steelhead into Oregon Tributaries of the Snake River

AbstractIn a study using 14 paired‐release groups over 10 release years, we compared the performance of hatchery summer steelhead Oncorhynchus mykiss that were acclimated as smolts (AC) for 16–57 d before release into ponds supplied with ambient stream water with that of fish trucked from the hatchery and directly released (DR) into Spring, Deer, and Little Sheep creeks in northeastern Oregon. After releasing the fish into streams, we monitored out‐migration travel times and survival to Lower Granite Dam (LGD) on the Snake River using freeze brand marks or implanted passive integrated transponder tags in a subsample of each release group. Across all release groups, travel time was significantly slower for AC fish (34.7 d) than for DR fish (31.8 d), though there was no significant difference in survival probability to LGD. We used recoveries of coded wire tags to estimate smolt‐to‐adult survival (SAS) and a stray rate index (SRI) for the AC and DR strategies. Across all release groups, SAS was 33% higher and SRI 42% lower for AC steelhead. At each release site acclimation increased average SAS by at least 11% and decreased SRI by at least 16.5%. We found a significant, negative linear relationship between travel time to LGD and SAS; however, there was no significant relationship between survival to LGD and SAS, which implies that judgments about the success or failure of a novel rearing or release strategy should not be made based on out‐migration survival. Acclimating juvenile steelhead produced significantly higher SAS and lower SRI in the hatchery program we evaluated; however, our results are not consistent with those of other steelhead acclimation studies.

Source of Increased Ferritin in Neuroblastoma: Studies With Concanavalin A-Sepharose Binding<xref ref-type="fn" rid="FN2">2</xref>

Serum ferritin is present in two forms--a glycosylated form that results from active secretion by cells and a nonglycosylated form that is directly released by damaged cells. Glycosylated ferritin binds to concanavalin A (Con A) through the glucose and/or mannose residues of the molecule. Patients with neuroblastoma frequently present at diagnosis with abnormally elevated levels of serum ferritin. The ferritin levels will, however, return to normal with clinical remission, suggesting that the tumor is the origin of the elevated ferritin. With the use of a Con A binding assay, an investigation was made as to whether the increased levels of serum ferritin at diagnosis in neuroblastoma patients resulted from active secretion by the tumor or were the consequence of direct release of ferritin from damaged tissue. Serum samples were collected at diagnosis from 36 children with neuroblastoma and from 16 normal healthy subjects. Tissue ferritins were purified from normal human liver, placenta, HeLa cells, human neuroblastoma, and hepatoma cells grown in culture. Serum and tissue ferritins were measured before and after binding with Con A. Sixty-three percent of serum ferritin from neuroblastoma patients and 66% of serum ferritin from normal subjects were bound to Con A, suggesting that they were glycosylated and were likely to have been secreted. On the other hand, only 28% of tissue ferritin were bound to Con A. Furthermore, most patients showed abnormally elevated levels of serum ferritin, and 63% of these ferritins were bound to Con A. These results are compatible with the hypothesis that much of the elevated ferritin in sera of patients with neuroblastoma seen at diagnosis is the result of secretion of ferritin by the tumor.