scholarly journals Identification of chemical form of stable carbon released from type 304L and 316L stainless-steel powders in alkaline and acidic solutions under low-oxygen conditions

Radiocarbon ◽  
2018 ◽  
Vol 60 (6) ◽  
pp. 1691-1710
Author(s):  
Ryo Nakabayashi ◽  
Tomonari Fujita
Keyword(s):  
Stainless Steel ◽  
Carboxylic Acids ◽  
Safety Assessment ◽  
Silicon Oxide ◽  
Chemical Form ◽  
Low Oxygen ◽  
Colloidal Carbon ◽  
Oxygen Conditions ◽  
Naoh Solution

ABSTRACTThe chemical form of14C released from irradiated stainless steel is a key parameter in the safety assessment of the subsurface disposal system in Japan. In this study, to identify the chemical form of the released carbon, unirradiated stainless-steel powders, which were found to be water-atomized powders with a silicon oxide film, were immersed in NaOH and HCl solutions under low-oxygen conditions for approximately 25 days. The results showed that the main chemical forms of the carbon were colloidal carbon in the NaOH solution and colloidal carbon and formic and acetic acids in the HCl solution. Almost no hydrocarbons were detected in both solution systems. Concerning the source of the colloidal carbon and carboxylic acids, the hypothesis that carbon in the oxide layer is released is considered to be reasonable. The very small amounts of hydrocarbons generated prevented us from discussing the source of the hydrocarbons. To validate the hypothesis and obtain further information on the hydrocarbons, additional experiments are necessary. In particular, for long-term safety assessment, it is important to determine whether the colloidal carbon, carboxylic acids and hydrocarbons are continuously released during the corrosion process. Therefore, information on the temporal evolution of the carbon should be obtained.

Identification of Chemical Form of Carbon Released from SUS304 and SUS316 in Alkaline Solution under Low-oxygen Condition

MRS Advances ◽  
2016 ◽  
Vol 2 (11) ◽  
pp. 597-602 ◽  
Author(s):  
Ryo Nakabayashi ◽  
Tomonari Fujita
Keyword(s):  
Stainless Steel ◽  
Carboxylic Acids ◽  
Iron Hydroxide ◽  
Chemical Form ◽  
Low Oxygen ◽  
Colloidal Iron ◽  
Liquid Samples ◽  
Oxygen Conditions ◽  
Naoh Solution ◽  
Carbon Concentrations

ABSTRACTTo classify the chemical form of stable carbon released from unirradiated stainless steel, which is the material used to simulate irradiated stainless steel, under highly alkaline and low-oxygen conditions, type 304 and 316 stainless-steel powders were immersed in 0.005 M NaOH solution. Gas and liquid samples were analyzed to identify the chemical form of carbon released from the stainless steel. The liquid samples were divided into unfiltered and filtered samples. In the gaseous phase, hydrocarbons such as methane and ethane were not detected. In the liquid phase, carboxylic acids (formic and acetic acids) were detected. However, the sum of the carbon concentrations of the carboxylic acids was significantly lower than the total organic carbon (TOC) concentration in the unfiltered samples. In the filtered samples, the TOC concentration was closer to the sum of the carbon concentrations than that for the unfiltered samples. In addition, the concentrations of the metallic elements (particularly Fe and Cr), which are the main constituents of the stainless steels, tended to decrease upon ultrafiltration. This suggests that the sorption of carbon on metallic compounds (e.g., colloidal iron hydroxide) may have occurred.

scholarly journals Prolonged exposure to low oxygen improves hypoxia tolerance in a freshwater fish

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Kayla L Gilmore ◽  
Zoe A Doubleday ◽  
Bronwyn M Gillanders
Keyword(s):  
Freshwater Fish ◽  
Prolonged Exposure ◽  
Hypoxia Tolerance ◽  
Low Oxygen ◽  
Oxygen Conditions

Lay summary It is poorly understood whether fish can acclimate to prolonged low-oxygen conditions (or hypoxia). Our study shows that prior long-term exposure to low-oxygen conditions improves tolerance to low-oxygen in a freshwater fish. The results of our study aid our understanding of long-term responses of freshwater fish to low-oxygen to hypoxic events.

Corrosion Behavior of Iron-Chrome Alloys in Liquid Bismuth

2021 ◽  
Author(s):  
Toshihide Takai ◽  
Tomohiro Furukawa ◽  
Shigeki Watanabe ◽  
Noriko S. Ishioka
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Target System ◽  
Liquid Lead ◽  
Low Oxygen ◽  
Operation Conditions ◽  
Fecral Alloy ◽  
Liquid Bismuth ◽  
Oxygen Conditions ◽  
Bismuth Target

Abstract For the mass production of astatine-211, a promising radiopharmaceutical for cancer treatment, the National Institute for Quantum and Radiological Science and Technology has proposed the innovative “Liquid Bismuth Target System.” The target window in this system must be made from a material that resists the highly corrosive liquid bismuth environment. To meet this requirement, a promising target window material was selected in corrosion experiments performed in stagnant liquid bismuth. Based on knowledge of corrosion in liquid lead–bismuth eutectic gained during the development of fast reactors and accelerator-driven subcritical systems, FeCrMo–alloy, FeCrAl–alloy, and austenitic stainless steel (as a reference) were selected as the specimen materials. Experiments were carried out under saturated dissolved oxygen and low oxygen conditions, and the corrosion behaviors of the specimens were evaluated, mainly by scanning electron microscopy. The FeCrAl–alloy exhibited the most excellent corrosion resistance, followed by FeCrMo–alloy. Both materials are suitable candidates for the target window. Although austenitic stainless steel was less corrosion resistant than the former two materials, it is a likely applicable for the target window under appropriately limited operation conditions (such as irradiation current and exposure time) of the liquid bismuth target system.

scholarly journals Long-term spatiotemporal variations and expansion of low-oxygen conditions in the Pearl River estuary: A study synthesizing observations during 1976–2017

2021 ◽  
Author(s):  
Jiatang Hu ◽  
Zhongren Zhang ◽  
Bin Wang ◽  
Jia Huang
Keyword(s):  
Phytoplankton Biomass ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Pearl River ◽  
Low Oxygen ◽  
The Pearl River Estuary ◽  
Oxygen Conditions ◽  
Bottom Waters ◽  
The Pearl River

Abstract. The Pearl River estuary (PRE) frequently experiences low-oxygen conditions in summer, with large extents of low-oxygen events and a long-term deoxygenation trend being reported recently. In this study, we provide a synthesis of the spatiotemporal patterns and incidence of different low-oxygen levels in the PRE based on the in-situ observations collected from 1976 to 2017, and aim to elucidate the underlying mechanisms of low-oxygen conditions and their changes over the past 4 decades. The long-term observations show that the oxygen content in the PRE had significant temporal variability and spatial heterogeneity. Low-oxygen conditions occurred mostly in the bottom waters of 5–30 meters during summer and early autumn, with locations and severity varying substantially among years. Coastal waters from the southwest of Lantau Island to the northeast of Wanshan Islands were identified as the hotspot area prone to subsurface low-oxygen conditions due to the combined effects of comparatively deep topography, proper residence time and stability of the water column, and enhanced oxygen depletion related to high phytoplankton biomass. In addition, the low-oxygen waters, either directly imported from the upstream reaches or generated locally and further transported with the estuarine circulation, also had considerable impacts on the oxygen levels in the estuary. As for early autumn, marked low-oxygen conditions were present both in the surface and bottom waters. A large area affected by low oxygen (~ 4,450 km2) was found in September 2006, where the low-oxygen conditions were comparable to the most severe ones observed in summer and formed by distinct mechanisms. Our analysis also reveals an apparent expansion of the summertime low-oxygen conditions at the bottom of the PRE since the years around 2000, coincident with the major environment changes in the Pearl River region. Overall, the PRE seems to be undergoing a transition from a system characterized by episodic, small-scale hypoxic events to a system with seasonal, estuary-wide hypoxic conditions. Although exacerbated eutrophication associated with anthropogenic nutrient inputs was generally considered the primary cause for the deterioration of low-oxygen conditions in the PRE, the sharp decline in sediment load may play an important role as well via increasing water transparency and thereby supporting higher and broader phytoplankton biomass in the estuary.

Content of major phenolic compounds in apples: Benefits of ultra-low oxygen conditions in long-term storage

2020 ◽  
Vol 92 ◽  
pp. 103587
Author(s):  
Aneta Bílková ◽  
Kristýna Baďurová ◽  
Pavlína Svobodová ◽  
Radek Vávra ◽  
Pavel Jakubec ◽  
...  
Keyword(s):  
Phenolic Compounds ◽  
Low Oxygen ◽  
Long Term Storage ◽  
Oxygen Conditions ◽  
Term Storage

Corrosion Rates of Zircaloy-4 by Hydrogen Measurement under High pH, Low Oxygen and Low Temperature Conditions

2012 ◽  
Vol 1475 ◽  
Author(s):  
Tomofumi SAKURAGI ◽  
Hideaki MIYAKAWA ◽  
Tsutomu NISHIMURA ◽  
Tsuyoshi TATEISHI
Keyword(s):  
Corrosion Rate ◽  
Hydrogen Absorption ◽  
Gas Flow ◽  
Flow System ◽  
Low Oxygen ◽  
Solution Ph ◽  
Absorption Ratio ◽  
Naoh Solution ◽  
Image Position

ABSTRACTCorrosion tests of Zircaloy-4 were performed in a dilute NaOH solution (pH =12.5) at 303 K for 90 days using the gas flow system (oxygen; < 1 ppb) and a batch method (oxygen; < 0.1 ppm). The corrosion rate was determined by measuring gaseous hydrogen and the hydrogen absorbed into Zircaloy-4 assuming the following reaction:where x represents the Zircaloy-4 hydrogen absorption ratio. The initial hydrogen content in the Zircaloy-4 specimen was controlled to be below 10 ppm. The corrosion rate decreased with time (90-day values: 2.46×10-3 and 2.37×10-3 μm/y for the gas flow method and 6.72×10-2 μm/y for the batch test). The Zircaloy-4 hydrogen absorption ratio during corrosion was over 90%. The large amount of hydrogen absorbed in Zircaloy-4 will play an important role in the long-term safety for the disposal of irradiated Zircaloy materials.

Comparative gill characteristics of Munida quadrispina (Decapoda, Galatheidae) from different habitat oxygen conditions

1988 ◽  
Vol 66 (10) ◽  
pp. 2320-2323 ◽  
Author(s):  
Brenda J. Burd
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Oxygen Depletion ◽  
B Value ◽  
Decapod Crustaceans ◽  
Low Oxygen ◽  
Organic Body ◽  
Oxygen Conditions ◽  
Consumption Rates

The allometric (bilogarithmic) relationship between dry gill weight and organic body weight was compared for benthic galatheid crabs (Munida quadrispina Benedict, 1902) from a low-oxygen fjord and from a normal oxygen population. In the M. quadrispina from the low-oxygen fjord, the slope (b) of the allometric function of gill weight versus body weight was 1.00. This b value was significantly higher (ANCOVA, p < 0.01) than the corresponding slope for the same function in M. quadrispina from normoxic areas (b = 0.63). However, only the largest crabs from the low-oxygen fjord were living consistently in low-oxygen (<0.15 mL/L) conditions; they also had significantly greater (twice as much) relative gill weight than their normoxic counterparts. This observation agrees with findings from previous studies that only the largest M. quadrispina are able to tolerate severe oxygen depletion. Small M. quadrispina from both the low-oxygen fjord and the normoxic area were always found in oxygen concentrations >2.0 mL/L. There were no significant differences between the relative gill sizes of the small crabs from different areas. It was concluded that gill development in M. quadrispina is affected by long-term habitat oxygen conditions. This factor could be important in comparisons of inter- and intra-specific allometric gill functions and in the study of weight-specific oxygen consumption rates of decapod crustaceans.

scholarly journals Long-term spatiotemporal variations in and expansion of low-oxygen conditions in the Pearl River estuary: a study synthesizing observations during 1976–2017

2021 ◽  
Vol 18 (18) ◽  
pp. 5247-5264
Author(s):  
Jiatang Hu ◽  
Zhongren Zhang ◽  
Bin Wang ◽  
Jia Huang
Keyword(s):  
Phytoplankton Biomass ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Oxygen Depletion ◽  
Pearl River ◽  
Low Oxygen ◽  
Oxygen Conditions ◽  
Bottom Waters ◽  
The Pearl River

Abstract. The Pearl River estuary (PRE) frequently experiences low-oxygen conditions in summer, with large-extent low-oxygen events and a long-term deoxygenation trend being reported recently. In this study, we provide a synthesis of the spatiotemporal patterns and incidence of different low-oxygen levels in the PRE based on the in situ observations collected from 1976 to 2017 and aim to elucidate the underlying mechanisms of low-oxygen conditions and their changes over the past 4 decades. The long-term observations show that the dissolved oxygen (DO) content in the PRE has had significant temporal variability and spatial heterogeneity. Low-oxygen conditions (DO < 4 mg L−1) have occurred mostly in the bottom waters of 5–30 m during summer and early autumn, with locations and severity varying substantially between years. Coastal waters from the southwest of Lantau Island to the northeast of the Wanshan Archipelago were identified as a hotspot area prone to subsurface low-oxygen conditions due to the combined effects of comparatively deep topography, a certain residence time and stability of the water column, and enhanced oxygen depletion related to high phytoplankton biomass. In addition, the low-oxygen waters, either directly imported from the upstream reaches or generated locally and further transported with the estuarine circulation, also had considerable impacts on the oxygen levels in the estuary. As for early autumn, marked low-oxygen conditions were present in both the surface and the bottom waters. A large area affected by low oxygen (∼ 4450 km2) was found in September 2006, where the low-oxygen conditions were comparable to the most severe ones observed in summer. The area was formed by the inflows of low-oxygen waters from the upstream reaches and enhanced oxygen depletion driven by an intricate coupling of physical and biogeochemical processes. Our analysis also reveals there has been an apparent expansion of the summertime low-oxygen conditions at the bottom of the PRE since the years around 2000, coincident with major environment changes in the Pearl River region. Overall, the PRE seems to be undergoing a transition from a system characterized by episodic, small-scale hypoxic events (DO < 2 mg L−1) to a system with seasonal, estuary-wide hypoxic conditions in summer. Although exacerbated eutrophication associated with anthropogenic nutrient inputs has generally been considered the primary cause for the deterioration of low-oxygen conditions in the PRE, the sharp decline in sediment load may play an important role as well via increasing water transparency and thereby supporting higher and broader phytoplankton biomass in the estuary.

Proposal of a Flow scheme for the Chemical-form-based Quantitative analysis of Chlorine compounds in Pulp for Sanitary products and Safety assessment

2018 ◽  
Vol 72 (11) ◽  
pp. 1243-1250
Author(s):  
Shigeo Imai ◽  
Mitsuhiro Wada ◽  
Takeharu Wada ◽  
Kei Iwasaki ◽  
Ritsuko Katagiri ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Safety Assessment ◽  
Chemical Form ◽  
Flow Scheme ◽  
Sanitary Products
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