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Hajime Akimoto
Pages
46-
Published: 2022
Released on J-STAGE: November 30, 2022
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The issue of global warming and climate change induced by human activity have been felt a bit far from chemistry. However, radiatively active substances in the atmosphere are chemical species. What we can do for the climate change mitigation is to reduce the emissions of these chemical species, and not to change the physical parameters in the atmosphere. Further, the major uncertainty of climate change prediction relies on the treatment of aerosols and clouds. It would be worthwhile to distinguish how much fraction of the uncertainty is within to the molecular chemical particle growth processes starting from gaseous molecules to molecular clusters, new particle formation, particle growth and to cloud condensation nuclei, and how much fraction of the uncertainty resides on the nonlinear physical growth process of cloud water to precipitation. The role of chemistry needs be clarified.
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Keiya Nakamura, Urumu Tsunogai, Fumiko Nakagawa, Masanori Ito, Satoru ...
Pages
47-
Published: 2022
Released on J-STAGE: November 30, 2022
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Maiho Oda, Urumu Tsunogai, Fumiko Nakagawa, Masanori Ito, Hao Xu, Maki ...
Pages
48-
Published: 2022
Released on J-STAGE: November 30, 2022
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Naho Shimizu, Kazuki Watanabe, Yuki Okuda, Shinnya Hashimoto
Pages
49-
Published: 2022
Released on J-STAGE: November 30, 2022
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Yuki OKuda, Masahiro Hirata, Shinya Hashimoto
Pages
50-
Published: 2022
Released on J-STAGE: November 30, 2022
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Kurosaki Yutaka, Matoba Sumito, Iizuka Yoshinori, Fujita Koji, Shimada ...
Pages
51-
Published: 2022
Released on J-STAGE: November 30, 2022
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Dimethyl sulfide (DMS), which originates from ocean phytoplankton, plays an important role in cloud formation over the marine atmosphere. We revealed the emission of DMS in the North Atlantic during 1960–2014 using an ice core drilled at the Greenland Ice Sheet. Our findings suggested the summer DMS emission after the 2000s was 3–6 times higher than that before the 1990s along the southeastern coast of Greenland. We concluded that the increase in summer DMS emissions resulted from the early retreat of the sea ice under global warming.
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Naoko Nagatsuka, Kumiko Goto―Azuma, Akane Tsushima, Koji Fujita, Sumit ...
Pages
52-
Published: 2022
Released on J-STAGE: November 30, 2022
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Akinori Ito, Takuma Miyakawa
Pages
53-
Published: 2022
Released on J-STAGE: November 30, 2022
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Koichi Watanabe
Pages
193-
Published: 2022
Released on J-STAGE: November 30, 2022
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Koichi Watanabe
Pages
194-
Published: 2022
Released on J-STAGE: November 30, 2022
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Yoko Iwamoto, Kazuki Shimoji, Taisei Kodama, Kazuhiko Takeda
Pages
195-
Published: 2022
Released on J-STAGE: November 30, 2022
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To clarify the characteristics of atmospheric particles containing combustion-origin iron, atmospheric aerosol and wet deposition samples collected at coastal sites near the source of combustion-origin iron were analyzed. The concentration of water-soluble Fe was highly correlated with that of non-sea salt sulfate, indicating that anthropogenic contribution is significant. A steelworks, a major stationary source of combustion-derived iron near the coastal site, shut down its blast furnace during the observation period. As a result, the total amount of iron in aerosols at coastal sites decreased to 70% and the water solubility decreased to 50%.
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Kazuya Tanaka, Keiko Yamaji, Hayato Masuya, Jumpei Tomita, Mayumi Ozaw ...
Pages
83-
Published: 2022
Released on J-STAGE: November 30, 2022
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Yuki Shimizu, Yoshio Takahashi, Yoko Masuda, Sakura Sato, Michinari Su ...
Pages
84-
Published: 2022
Released on J-STAGE: November 30, 2022
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Iron (Fe) is the most abundant element on Earth and the redox reactions between Fe(II) and Fe(III) are very important from a geochemical point of view. The redox state of Fe has a significant influence on the behavior of various elements in the surface soil environment (e.g., arsenic and potassium. However, until now, redox reactions of structural Fe in clay minerals (Stucki, 2011) and ferrihydrite in paddy soils have been focused on only separately. In this study, we investigated to what extent structural Fe in clay minerals contributes to the overall redox reactions in paddy soils. This study also focused on microbial Fe interactions, in particular, catabolic reduction of Fe by Fe-reducing bacteria in paddy soils and the associated nitrogen-fixation (Masuda et al., 2017). In this study, we investigated whether structural Fe(III) in clay minerals, in addition to hematite and ferrihydrite investigated by Masuda et al. (2021), is available to Fe-reducing bacteria, and whether structural Fe(III) in clay minerals enhances their nitrogen-fixing activity.
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Yuma Sato, Hiroki Ishimizu, Yoshio Takahashi, Takaaki Itai
Pages
85-
Published: 2022
Released on J-STAGE: November 30, 2022
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Sae Tayanagi, Hiroki Ishimizu, Yoshio Takahashi, Takaaki Itai
Pages
86-
Published: 2022
Released on J-STAGE: November 30, 2022
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Baasansuren Gankhurel, Keisuke Fukushi, Davaadorj Davaasuren, Eigo Ima ...
Pages
87-
Published: 2022
Released on J-STAGE: November 30, 2022
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Introduction- The shrinkage of lake areas has been documented in many inland lakes. Inland lakes and their ecosystems are very sensitive to water chemistry. Therefore, it is crucial to understand the impact of the shrinkage of saline lakes on their water chemistry. Previous studies have shown that the elevated concentrations of As and U exhibited by inland lake waters are caused by evaporation. However, there is little understanding of the chemical reactions responsible for the enrichment of these trace elements. The purpose of this study was to quantitatively understand the dynamic chemical behaviors of As and U in alkaline saline lake during evaporative shrinkage. Methods- We used five-year monitoring data and geochemical modeling of the water chemistry of Orog Lake in the Valley of Gobi Lakes and characterized the chemical forms of As and U in lake sediments to understand the factors controlling the solubility of As and U.Results and Discussion- Five-year monitoring showed that intensive evaporation caused both As and U to accumulate in the lake water. A comparison of the observed concentrations with those predicted by a geochemical model suggested that As in the lake water could be removed during evaporation, whereas U accumulated conservatively in the lake water. Sequential extraction analyses and XAFS measurements of the sediments revealed that the primary host of As(V) in the sediments was ferrihydrite. The adsorption characteristics of As (V) on iron oxides indicate that As(V) can be removed by ferrihydrite during evaporation. In contrast, as neither carbonate minerals nor low- crystalline iron oxides act as sorbents of U, the concentration of U, like those of Na+ and Cl−, may increase dramatically in alkaline lakes during evaporation. This implies that the ubiquitous formation of extremely soluble U-bearing salts after the complete desiccation of inland saline lakes may become a serious contaminant source in arid areas. When the lake is partially dry or desiccated, U in the lake system can be a source of dust contamination. Westerlies can transport dust particles to China, Korea, Japan, and the northwestern North Pacific. Furthermore, there is a need to consider the concentration and mobility of trace elements in salts after the lake water has completely evaporated.
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Takuya Ishida
Pages
88-
Published: 2022
Released on J-STAGE: November 30, 2022
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Phosphorus is an essential nutrient for all living organisms and can be the limiting factor for primary production. The phosphorus cycle is severely affected by anthropogenic disturbances caused by large amounts of phosphorus fertilization of agricultural land. is an increasingly applied tool to elucidate P sources and cycling in aquatic and terrestrial systems. Phosphate oxygen isotope have been analyzed in various environmental samples such as environmental water, rocks, soils, and sediments, and in anthropogenic samples such as fertilizers, detergents, and sewage. Previous studies have shown that phosphate oxygen isotope analysis can be a useful tool in assessing the sources of phosphorus and the effects of biological activities in each ecosystem. In this presentation, I introduce recent studies and discuss the advantages, challenges, and future possibilities for understanding phosphorus cycle.
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Tomoko Ohta
Pages
89-
Published: 2022
Released on J-STAGE: November 30, 2022
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Yoshio Ishikawa, Shouko Imai, Touru Tani
Pages
90-
Published: 2022
Released on J-STAGE: November 30, 2022
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Nozomi Ichikawa, Hamamoto Takafumi, Sasamoto Hiroshi, Ichige Satoru, K ...
Pages
91-
Published: 2022
Released on J-STAGE: November 30, 2022
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Urumu Tsunogai, Fumiko Nakagawa
Pages
139-
Published: 2022
Released on J-STAGE: November 30, 2022
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Chika Kuribayashi, Takahiro Hosono, Masaharu Tanimizu
Pages
140-
Published: 2022
Released on J-STAGE: November 30, 2022
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Kentaro Kataoka, Masayo Minami, Hiroshi Takahashi, Yoshihiro Asahara, ...
Pages
141-
Published: 2022
Released on J-STAGE: November 30, 2022
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Elucidation of the sources of carbon components (organic carbon, elemental carbon, carbonate carbon, etc.) in atmospheric aerosols is important to control air pollution and to a better understanding of global climate change. Air pollution in Iran, especially in urban areas, is increasing, but there has been little analysis of the carbon components in aerosols. The atmospheric aerosol in semi-arid Iran contains not only carbon particles but also a large amount of dusty aerosols such as soil particles, and it is important to understand not only the carbon component but also the inorganic elemental components in order to analyze the source of aerosols in this region. The purpose of this study was to determine the source of urban atmospheric aerosols in the region by analyzing 14C, δ13C, and inorganic element concentrations in urban atmospheric aerosols in the Kurdistan Province of Iran, near the border with Iraq. The results showed that the contribution of FC was larger in the winter season than in other periods, while the contribution of non-FC was larger from March onward. In addition, an increase in soil particles from Iraq and other western regions was observed during the spring season.
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Takashi Sambuichi, Urumu Tsunogai, Masanori Ito, Fumiko Nakagawa
Pages
142-
Published: 2022
Released on J-STAGE: November 30, 2022
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Shuntaro Dei, Yukio Tachi, Yuki Amano, Paul C. M. Francisco, Yuki Sugi ...
Pages
143-
Published: 2022
Released on J-STAGE: November 30, 2022
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Sota Nagaoka, Manabu Fukumoto, Masatoshi Suzuki, Yasushi Kino, Nobuaki ...
Pages
144-
Published: 2022
Released on J-STAGE: November 30, 2022
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Michio AOYAMA, Yayoi INOMATA, Yasunori HAMAJIMA, Yuichiro KUMAMOTO, Hy ...
Pages
145-
Published: 2022
Released on J-STAGE: November 30, 2022
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Hyoe Takata, Yoshihumi Wakiyama, Takuya Niida, Alexei Konoplev, Yasuno ...
Pages
146-
Published: 2022
Released on J-STAGE: November 30, 2022
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Using samples collected in the lower Abukuma River before and after the passage of Typhoon Hagibis in 2019, changes in the concentration of dissolved radiocesium) desorbed from riverine suspended particles that had been introduced in seawater by the laboratory experiments and model calculations. The concentration of dissolved radiocesium increased immediately after the typhoon, and returned to the same level as before the typhoon in about two weeks after that due to the dilution effect of seawater with low-radiocesium. In this study, we were able to predict temporalchange of the concentration of dissolved radiocesium in coastal waters after floods caused by the heavy rain following to the typhoon.
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Yuhei Shirotani, Masatoshi Yamada, Syota Kambayashi
Pages
147-
Published: 2022
Released on J-STAGE: November 30, 2022
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Kazuya Miyakawa, Kotaro Nakata, Koki Kashiwaya, Yukiko Suwa
Pages
196-
Published: 2022
Released on J-STAGE: November 30, 2022
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In the deep subsurface of thick marine sedimentary formations, there may be groundwater that is thought to have been altered during the burial diagenesis from seawater taken into the pore during deposition. Such a field is considered to be one where groundwater flow is slow because it is thought to be unaffected by freshwater seepage flow, even through uplift and erosion of the stratum. Although dehydration from minerals and upward migration of pore water due to burial compaction are thought to be the main causes of changes in Cl concentration in deep groundwater that does not mix with freshwater, quantitative understanding is insufficient. In this study, we focused on the dehydration reaction associated with the phase change of biogenic silica (Opal A). We simulated a test to evaluate the related dehydration and oxygen-hydrogen isotope exchange reaction with the surrounding water. As a result, the phase change from opal A to quartz was confirmed, and the water content derived from the silanol group of opal A was 2.7 wt%. Consistent with the water content of diatomaceous fossils in the stratum, the dehydration associated with the phase change from opal A to quartz due to diagenesis could be quantitatively evaluated.
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Kazuya Miyakawa, Koki Kashiwaya, Yuto Komura, Kotaro Nakata
Pages
197-
Published: 2022
Released on J-STAGE: November 30, 2022
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Deep in thick marine sedimentary formations, groundwater may exist that is thought to have been altered by the burial diagenesis process from seawater taken up during stratigraphic deposition. In such a field, groundwater flow is judged to be slow because it is not affected by freshwater infiltration even after the uplift and erosion of the formation. During diagenesis, dehydration from silicates and other processes are thought to cause changes such as a decrease in porewater salinity. However, dehydration from minerals alone cannot explain water quality changes quantitatively, and the water quality evolution process is unclear. In this study, we constructed an analytical model that considers dehydration from silicates and upward migration of pore water due to compaction during the burial process and examined the possible evolution of pore water quality during the burial process. As a result, two trends of water quality were identified: the influence of dehydration reaction from opal-A to quartz and the strong effect of dehydration from clay minerals, which were close to the observations from borehole investigations. These results indicate that low-salinity water with heavier oxygen isotope ratios than seawater can be formed during the burial diagenesis without mixing with freshwater.
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Yuzuru Nakaguchi, Tatsuya Kita, Manami Kino, Toshiki Yasui, Akira Kond ...
Pages
198-
Published: 2022
Released on J-STAGE: November 30, 2022
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In recent years, the marine plastic problem has attracted attention. However, the following three problems have been pointed out regarding marine plastics. 1. Overestimation or underestimation of the amount of plastic waste released into the ocean due to inaccurate measurements. 2. It is not possible to accurately measure plastic pieces that have been refined by ultraviolet rays or mechanical waves. 3. Transition of marine plastic to sediments. In this study, we investigated a method for accurately quantifying microplastics and applied the established analytical method to the analysis of microplastics in Osaka Bay and its inflowing rivers.
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Ryosuke Yanagisawa, Koichi Sakakibara, Junichi Yamamoto, Terumi Ejima
Pages
199-
Published: 2022
Released on J-STAGE: November 30, 2022
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Kohei Sato, Masayo Minami, Shigeyuki Wakaki
Pages
200-
Published: 2022
Released on J-STAGE: November 30, 2022
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Strontium isotopic ratios (87Sr/86Sr) of large volcanic blocks in the Maebashi mudflow deposit, which constitutes the basement of the Maebashi-Takasaki area in Gunma Prefecture, and the Tsukahara mudflow deposit, which constitutes the basement of the Saku-Karuizawa area in Nagano Prefecture, indicate that these mudflow deposits were brought by a failure event of Kurofu volcano, an initial stage volcanic edifice of Asama volcano. Furthermore, 14C ages of wood fragments buried in the deposits indicate that the mudflows were generated by the a failure event of Kurofu volcano during the last glacial period ca.27 ka cal BP (Sato et al., 2017, 2019, 2020, 2021, 2022) In this presentation, we present these results.
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Kotaro Hirayama, Michinari Sunamura, Hiroki Ishimizu, Yoshio Takahashi ...
Pages
201-
Published: 2022
Released on J-STAGE: November 30, 2022
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Hidetaka Kobayashi
Pages
159-
Published: 2022
Released on J-STAGE: November 30, 2022
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It is recognized that changes in atmospheric carbon dioxide concentrations associated with climate changes during the Pleistocene glacial-interglacial cycle were mainly caused by changes in the ocean carbon cycle. To investigate the mechanism of this carbon cycle change, we have conducted numerical experiments on the glacial oceans using a three-dimensional ocean general circulation model. In addition to changes in the solubility of carbon dioxide at the sea surface, ocean circulation, and dust-induced iron fertilization, which have been well constrained by previous modeling studies, we found that the enhanced salinity stratification and iron fertilization including glaciogenic dust in the Southern Ocean amplified the response of carbonate compensation, contributing to increased carbon storage in the deep ocean and a consequent decrease in atmospheric CO2 concentration. Considering these processes, the deep-water properties of the glacial period with low oxygen and low carbon isotope ratios are reproduced more closely to observations than in previous model experiments, supporting the validity of the ocean carbon cycle field reproduced by the present model experiments.
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Keigo Kasai, Urumu Tsunogai, Masanori Ito, Fumiko Nakagawa
Pages
160-
Published: 2022
Released on J-STAGE: November 30, 2022
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Daisuke D. Komatsu, Toru Suio, Nariaki Ohno, Hisashi Narita
Pages
161-
Published: 2022
Released on J-STAGE: November 30, 2022
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Yuichi Nosaka, Hiroshi Kuroda, Takuya Nakanowatari, Akira Kuwata, Hide ...
Pages
162-
Published: 2022
Released on J-STAGE: November 30, 2022
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Material exchange between the atmosphere and the ocean takes place through the surface of the ocean. On the other hand, when phytoplankton-derived substances accumulate on the surface of the ocean due to the bloom, this exchange rate is considered to decrease. Transparent exopolymer particles (TEP) are mainly formed from dissolved poly-saccharides in which phytoplankton exudes to the outside of the cell, and their specific density is lighter than that of seawater, so they rise toward the ocean surface. Since TEP may be accumulated on the ocean surface in the spring Oyashio region, we participated in the Shunyou-Maru (SY1905) cruise in this study, and investigated the phytoplankton abundance (Chl. a) and TEP of the ocean surface micro layer (SML) and surface water. It was revealed that the concentration of Chl. a and TEP in the Oyashio region were 1.1–3.1 times and 1.7–8.8 times higher in SML than in the surface water collected in the bucket, respectively. From the results of the culture experiment conducted on the deck of the ship, it was considered that the TEP accumulated in SML was supplied from the surface layer of the ocean.
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Matsuoka Kohei, Sohrin Yoshiki, Takano shotaro, Tatsuyama Tomomichi
Pages
163-
Published: 2022
Released on J-STAGE: November 30, 2022
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Mo and W are group 6 elements and have similar chemical properties. However, the two elements behave in a different way in the hydrosphere. Recently, progression of the analytical technology allows us to measure the isotope ratios for heavy elements, such as transition metals. The concentrations and isotope ratios of Mo and W are potential tracers of hydrothermal activity and anthropogenic contamination. However, there are still few data particularly for W. This study is aimed to provide with simultaneous data of dissolved Mo and W throughout the hydrosphere. Water samples from the North Pacific Ocean, the Indian Ocean, the East China Sea, the Sea of Japan, Osaka Bay, Yodo River and Uji River were analyzed. We measured the concentration of Mo and W, δ98/95Mo, and δ186/184W. We found that the concentrations and isotope ratios of W are uniform in the open ocean with a similar manner to Mo. The W data of Osaka Bay are significantly different from the oceanic values, and the W data of Yodo River are significantly different from the Uji River values. Also in the Japan and East China Seas, the data of W show slight difference. We propose that anthropogenic W has significant contributions in these areas.
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Masatoshi Yamada, Jian Zheng
Pages
164-
Published: 2022
Released on J-STAGE: November 30, 2022
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The 239+240Pu concentrations and 240Pu/239Pu atom ratios in seawater from the eastern Indian Ocean were determined to identify their Pu sources and to propose the transport pathway of Pacific Proving Grounds-derived Pu. In the West Australia Basin, the 239+240Pu concentration increased with depth; a subsurface maximum was identified at 200 m depth and then decreased gradually with depth; its water column inventory was 32.8 Bq/m2; the mean 240Pu/239Pu atom ratio was 0.242. These high atom ratios proved the presence of close-in fallout Pu from Pacific Proving Grounds nuclear tests. This is the first study by anyone on Pu atom ratios in the Indian Ocean.
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Idha Yulia Ikhsani, Kuo Hong Wong, Hiroshi Ogawa, Hajime Obata
Pages
165-
Published: 2022
Released on J-STAGE: November 30, 2022
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Nitrate in seawater is the primary limiting factor for primary production, but about 30% of the entire ocean is reported to be iron-limiting. Therefore, it is important to reveal the Fe supply process to the open ocean. Here, we calculated the vertical fluxes of iron and nitrate from deep layer to the surface. The vertical fluxes of iron were within the same range of the atmospheric iron deposition fluxes in this region.
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Cheuk―Yin Chan, Linjie Zheng, Yoshiki Sohrin
Pages
166-
Published: 2022
Released on J-STAGE: November 30, 2022
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The aim is to quantify 9 trace metals (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb) in seawater samples. Seawater samples were collected in R/V Hakuho Maru cruise KH-14-6 in Subtropical North Pacific Ocean (At 165°E and around the Mariana Trench), and cruise KH-17-3 (Subarctic North Pacific Ocean). Dissolved (dM) and total dissolvable (tdM) trace metals concentrations were quantified. Labile particulate (lpM) concentrations were calculated from the difference of tdM and dM. The vertical distribution of dM and lpM will be presented in the conference.
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Shotaro Takano, Wen―Hsuan Liao, Tung―Yuan Ho, Yoshiki Sohrin
Pages
167-
Published: 2022
Released on J-STAGE: November 30, 2022
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Hideo Kanamura, Shotaro Takano, Yoshiki Sohrin
Pages
168-
Published: 2022
Released on J-STAGE: November 30, 2022
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Nanako Hasegawa, Takaaki Itai, Yoshio Takahashi
Pages
169-
Published: 2022
Released on J-STAGE: November 30, 2022
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Kiminori Shitashima
Pages
170-
Published: 2022
Released on J-STAGE: November 30, 2022
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Kenji Isshiki
Pages
171-
Published: 2022
Released on J-STAGE: November 30, 2022
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The vertical distribution of total dissolved Cr at stations along 160°W in the Pacific Ocean and the vertical distribution of total dissolved Cr at stations in the Indian Ocean were of weakly nutrient type at most stations. There was no marked difference in the pattern of vertical distribution at each of the two areas. The mean concentration in the Pacific Ocean (7 nmol/L) was higher than that in the Indian Ocean (4 nmol/L). In the hydrothermal active areas, decrease in Cr(VI) was observed at depths affected by the hydrothermal plumes, indicating that the reduction and removal of Cr(VI) by hydrothermal source materials has a significant effect on the vertical distribution of Cr.
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Atsushi Ooki
Pages
202-
Published: 2022
Released on J-STAGE: November 30, 2022
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Yusuke Fukami, Teruhiko Kashiwabara, Hiroshi Amakawa, Takazo Shibuya, ...
Pages
203-
Published: 2022
Released on J-STAGE: November 30, 2022
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