Article
Environmental Sciences
Bohyung Choi, Kyung-Hoon Shin
Summary: The study found that mussels have higher trophic positions, requiring normalization of basal nitrogen isotope ratio. Spatial variations in nitrogen isotopic baselines in mussels reflect different nitrogen sources. Delta N-15 (base-bulk) and Delta N-15 (base-phe) are powerful tools for tracing nitrogen isotopic baselines.
MARINE POLLUTION BULLETIN
(2021)
Article
Environmental Sciences
Yasheng Shi, Ping Tian, Zanfang Jin, Yuming Hu, Yongqi Zhang, Feili Li
Summary: The study found that the stable nitrogen isotopes values of nitrogen oxides emitted from biomass burning in China are influenced by the biomass fuel sources, leading to increased uncertainty in the national scale model due to limited data on δ N-15-NOx values.
SCIENCE OF THE TOTAL ENVIRONMENT
(2022)
Article
Agriculture, Multidisciplinary
Dongxue Xu, Ji Liu, Yuanxue Gu, Yanru Chen, Chunyan Zhao, Guohua Sun, Yichao Ren, Chao Li, Bin Xia
Summary: Juvenile sea cucumbers were fed different microalgae in a 130-day experiment, leading to varying growth rates and amino acid compositions. Analysis of carbon isotopes showed fluctuations in specific amino acids. The study sheds light on the metabolism routing and nutrient utilization in sea cucumbers during their juvenile stage.
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
(2021)
Article
Engineering, Chemical
Songsong Chen, Yuncai Wang, Limin Ma
Summary: This study investigates the carbon and nitrogen isotope fractionation characteristics during the degradation of atrazine in a constructed wetland. The observed isotope parameters are consistent with those observed in the cultivation of specific strains, indicating similarities in the biodegradation pathway and mechanism. However, variations in carbon and nitrogen isotope fractionation across different phases may lead to over- or underestimation of atrazine biodegradation extent. The accuracy of estimation improves when using the enrichment factor derived from batch cultivation of pore water. This study advances the application of compound-specific stable isotope analysis in tracking atrazine biodegradation in ecosystems, emphasizing the importance of carefully selecting and applying the enrichment factor for quantifying intrinsic biodegradation.
Article
Environmental Sciences
Hyuntae Choi, Bohyung Choi, Yoshito Chikaraishi, Yoshinori Takano, Haryun Kim, Kitack Lee, Dhongil Lim, Kyung-Hoon Shin
Summary: This study used compound-specific isotope analysis to investigate the variation of delta N-15 associated with microbial processes in marine sediment samples. The results showed that the decrease in amino acid concentrations in sediment was accompanied by an increase in delta N-15 values. Phenylalanine displayed a depth-dependent variation in microbial utilization, while glycine showed the highest relative molar contribution and delta N-15 increase in deep sediment. These findings provide an important basis for interpreting the delta N-15 values of amino acids in sediment.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Environmental Sciences
Yota Harada, Shin-ichi Ito, Nanako O. Ogawa, Chisato Yoshikawa, Naoto F. Ishikawa, Michio Yoneda, Naohiko Ohkouchi
Summary: Fish migration plays a crucial role in marine conservation and fisheries management, but patterns are changing due to ocean conditions. A new method using isotopes in fish eye lenses can reconstruct geographic and trophic histories. This study analyzed the nitrogen isotope ratios of amino acids in chub mackerel eye lenses to distinguish migration and trophic changes.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Geochemistry & Geophysics
Qian Huang, Hao Wu, Bernd R. Schoene
Summary: Compound-specific stable nitrogen isotope (delta 15N) analysis is a powerful tool for studying trophic dynamics and nitrogen biogeochemistry. This study presents a refined analytical technique and compares different sample pretreatment methods, providing high-resolution data for reconstructing changes in the origin and fate of nitrogen in aquatic food webs.
Article
Microbiology
Christine Ferrier-Pages, Stephane Martinez, Renaud Grover, Jonathan Cybulski, Eli Shemesh, Dan Tchernov
Summary: The association between corals and photosynthetic dinoflagellates is threatened by global changes, and nutritional exchanges play a critical role in understanding the performance of this symbiosis under stress conditions. The trophic index ranged from 1.1 to 2.3 from autotrophic to heterotrophic symbionts, with significant changes in symbionts compared to the hosts. Symbiont-derived photosynthates are identified as the main carbon source for amino acids synthesis, emphasizing the essential role of symbionts in the capacity of corals to withstand environmental stress.
Article
Geochemistry & Geophysics
Qian Huang, Oluwatoosin B. A. Agbaje, Martina Conti, Bernd R. Schoene
Summary: The stable nitrogen isotope composition of bivalve shell organics can serve as a proxy for nitrogen fluxes in ecosystems. It has been found that pristine isotope signals can be retrieved from shell organics and intra-crystalline organic matrix is less likely contaminated than inter-crystalline organics. Furthermore, the different shell organic phases may have distinct isotopic characteristics and may not agree with the bulk organic matter.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2023)
Article
Geochemistry & Geophysics
Qian Huang, Oluwatoosin B. A. Agbaje, Martina Conti, Bernd R. Schoene
Summary: The stable nitrogen isotope composition of bivalve shell organics can be used as a proxy for nitrogen fluxes in ecosystems. This study investigated the possibility of retrieving pristine isotope signals from shell organics after sample pretreatment. The results showed that intra-crystalline organic matrix (intra-OM) is a reliable source for delta N-15 analyses, while inter-crystalline organics (inter-OM) should be avoided due to potential contamination or diagenetic overprinting. Different solvents were tested, and NaOCl treatment was found to be more effective in cleaning inter-OM and producing reliable delta N-15 data of intra-OM. Differences in the abundance and delta N-15 values of individual amino acids suggested that the N isotope composition is not uniform within shells.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2023)
Article
Engineering, Environmental
Yo Han Yang, Sae Yun Kwon, Martin Tsz-Ki Tsui, Laura C. Motta, Spencer J. Washburn, Jaeseon Park, Min-Seob Kim, Kyung-Hoon Shin
Summary: By analyzing the nitrogen and mercury isotopes of eels and pike, we found that pike has consistent mercury concentration and ecological traits, making it an effective bioindicator for mercury. Eels, on the other hand, better capture site-specific mercury sources based on their mercury concentration and feeding behavior.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2022)
Article
Ecology
Atsushi Nishimoto, Takuma Haga, Akira Asakura, Yoshihisa Shirayama
Summary: The study evaluated the contribution of potential food sources to the diet of wood borers, finding that wood-derived organic carbon was the main carbon source for the teredinids, while POM accounted for 37.9% of their carbon source. Additionally, one species relied on both POM and wood log for their nitrogen source, while the other three species depended on either POM or wood log for nitrogen.
Article
Agronomy
Yuntao Wu, Xiaodong Zhang, Zhaoliang Song, Changxun Yu, Man Liu, Yidong Wang, Qian Hao, Qiang Li, Xiangwei Zhao, Lele Wu, Xia Wang
Summary: This study investigates the spatial patterns and driving factors of carbon and nitrogen isotopes in plant-soil systems of grasslands in northern China. The results provide important references for future research on biogeochemical cycles in temperate grasslands.
Article
Environmental Sciences
Young-Jae Jeong, Bo-Seong Seo, Nuri Baek, Jin-Hyeob Kwak, Sang-Mo Lee, Hyun-Jin Park, Woo-Jung Choi
Summary: This study proposed methods for determining the δN-15 of multiple nitrogen species. The methods included traditional distillation, direct evaporation, and isotope mass balance equation. The accuracy and precision of the methods were evaluated through a series of experiments, and the influences of different conditions on the analysis results were assessed.
FRONTIERS IN ENVIRONMENTAL SCIENCE
(2022)
Article
Geosciences, Multidisciplinary
Chisato Yoshikawa, Nanako O. Ogawa, Yoshito Chikaraishi, Akiko Makabe, Yohei Matsui, Yoshikazu Sasai, Masahide Wakita, Makio C. Honda, Yoshihisa Mino, Maki N. Aita, Tetsuichi Fujiki, Takuro Nunoura, Naomi Harada, Naohiko Ohkouchi
Summary: This study reveals the seasonal transition of the dominant nitrogen source for phytoplankton in the high-productivity subarctic ocean. The results show that the nitrogen source switches from nitrate to ammonium in autumn.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Agronomy
Felix Seidel, M. Larry C. Lopez, Eleonora Bonifacio, Hiroko Kurokawa, Toshiro Yamanaka, Luisella Celi
Summary: The present study aimed to assess the phosphorus allocation patterns of four tree species during different phenological stages and its relationship with nitrogen concentrations. It was found that nitrogen in plant tissues correlated well with their phosphorus partitioning, and the increase of soil ammonium concentration positively influenced nitrogen reabsorption efficiency.
Article
Anthropology
Leonie Rey, Yuichi Naito, Yoshito Chikaraishi, Stephane Rottier, Gwenaelle Goude, Naohiko Ohkouchi
Summary: Understanding the significance of fish in the human diet is an important area of research. This study conducted compound-specific isotope analysis on early farmers from France, revealing that protein intake is mainly derived from terrestrial animal resources, with freshwater resources playing a lesser role.
INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY
(2022)
Article
Construction & Building Technology
Keisuke Takahashi, Yuichiro Kawabata, Mitsuyasu Iwanami, Mari Kobayashi, Takafumi Kasaya, Toshiro Yamanaka, Shun Nomura, Hiroko Makita
Summary: The results of the first-ever in-situ monitoring of a large mortar specimen at a depth of 3515 m in the Nankai Trough are presented in this study. The study successfully monitored the development of strain and hydraulic pressure in the specimen. However, microstructural damage was observed in the specimen after exposure to the deep sea environment for one year, resulting in a decrease in compressive strength and Young's modulus.
JOURNAL OF ADVANCED CONCRETE TECHNOLOGY
(2022)
Article
Agronomy
Kazushi Murata, Fabian Watermann, O. B. Herve Gonroudobou, Le Thuy Hang, Toshiro Yamanaka, M. Larry C. Lopez
Summary: This study found that the invasion of black locust trees led to a shift in nitrogen sources in the soil, which affected nitrogen assimilation in black pine trees.
Article
Microbiology
Nicholas C. Mucci, Katarina A. Jones, Mengyi Cao, Michael R. Wyatt, Shane Foye, Sarah J. Kauffman, Gregory R. Richards, Michela Taufer, Yoshito Chikaraishi, Shawn A. Steffan, Shawn R. Campagna, Heidi Goodrich-Blair
Summary: Microbial symbiosis drives the physiological processes in higher-order systems. In this study, the tripartite Xenorhabdus bacterium-Steinernema nematode-Galleria insect symbiosis was used to investigate the consumption and rebirth of organic life in a complex ecosystem. Trophic analysis revealed that the bacteria are the primary consumers of the insect, while the nematode consumes the bacteria. Metabolomics analysis showed distinct changes in biological material throughout the life cycle, including active infection, insect death, and conversion of cadaver tissues into bacterial biomass and nematode tissue. Our findings demonstrate reproducible stage-specific chemical signatures, enhancing our understanding of the metabolic processes underlying three-way symbiosis.
Article
Geosciences, Multidisciplinary
Ryuji Toue, Kazuhiko Fujita, Masashi Tsuchiya, Yoshito Chikaraishi, Yoko Sasaki, Naohiko Ohkouchi
Summary: This study investigated the trophic positions of two non-spinose species of planktonic foraminifera in the marine food web, revealing their dependence on mixed herbivorous and carnivorous diets and herbivorous diets respectively. The trophic niche separation between these two species likely contributes to their coexistence within a similar depth zone.
PROGRESS IN EARTH AND PLANETARY SCIENCE
(2022)
Article
Limnology
Naoto F. Ishikawa, Nanako O. Ogawa, Yuchen Sun, Yoshito Chikaraishi, Yoshinori Takano, Naohiko Ohkouchi
Summary: Compound-specific isotope analysis of nitrogen in amino acids has made significant contributions to environmental sciences. Although there are different methods for determining the isotope composition, they have not been intercalibrated yet. A systematic comparison of three methods showed consistent results, validating the comparability of CSIA-AA in interdisciplinary research.
LIMNOLOGY AND OCEANOGRAPHY-METHODS
(2022)
Article
Geosciences, Multidisciplinary
Chisato Yoshikawa, Nanako O. Ogawa, Yoshito Chikaraishi, Akiko Makabe, Yohei Matsui, Yoshikazu Sasai, Masahide Wakita, Makio C. Honda, Yoshihisa Mino, Maki N. Aita, Tetsuichi Fujiki, Takuro Nunoura, Naomi Harada, Naohiko Ohkouchi
Summary: This study reveals the seasonal transition of the dominant nitrogen source for phytoplankton in the high-productivity subarctic ocean. The results show that the nitrogen source switches from nitrate to ammonium in autumn.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Archaeology
Chitoshi Mizota, Koji Oba, Youichirou Hisa, Toshiro Yamanaka, Shinji Yamauchi
Summary: Archives from medieval Japan, China, and Korea reveal a significant demand for native sulphur for gunpowder production and war efforts in East Asia. Excavations in Hakata Bay, northern Kyushu, Japan, unearthed sulphur pebbles dating back to the 11th and 12th century CE, marking the earliest industrial use of native sulphur. The sulphur samples share isotopic signatures with volcanic sulphur from Kyushu's active geothermal areas, suggesting provenance. The presence of opal-CT, cristobalite/tridymite, and tridymite fragments support the association of sulphur pebbles with high-temperature volcanic fumaroles. The long-term preservation of the sulphur pebbles within sediments can be attributed to reduced conditions facilitated by the reduction of marine sulphates in pore-waters. This limits microbial oxidation and suggests that the pebbles were likely spilled during cargo handling and incorporated into sediments drifting along the near-shore of Hakata Bay.
JOURNAL OF ARCHAEOLOGICAL SCIENCE-REPORTS
(2022)
Article
Geosciences, Multidisciplinary
N. Moussa, G. Bayon, V. Dekov, T. Yamanaka, R. Shinjo, T. Toki, B. Le Gall, N. Grassineau, J. A. Langlade, M. O. Awaleh, E. Pelleter
Summary: This study reports on the discovery of unusual hydrothermal mixed carbonate-siliceous chimneys in the Allols area, northwest of Lake Asal. These chimneys, up to 20 m high, were formed sub-aqueously and show evidence of mixing between magmatic and surficial waters. The study suggests that these chimneys were formed during major changes in lake water chemistry, reflecting contributions of mixing fluids and basalt alteration.
JOURNAL OF AFRICAN EARTH SCIENCES
(2023)
Article
Environmental Sciences
Jun Matsubayashi, Katsuya Kimura, Naohiko Ohkouchi, Nanako O. Ogawa, Naoto F. Ishikawa, Yoshito Chikaraishi, Yuichi Tsuda, Hiroshi Minami
Summary: Geostatistical analysis is a useful tool in tracking the migration of highly migratory marine fish. In this study, geostatistical models were used to generate isoscapes and estimate ontogenetic shifts of isotope ratios of skipjack tuna. The results showed that geostatistical analysis can provide essential information for iso-logging without compound-specific isotope analysis.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Environmental Sciences
Hyuntae Choi, Bohyung Choi, Yoshito Chikaraishi, Yoshinori Takano, Haryun Kim, Kitack Lee, Dhongil Lim, Kyung-Hoon Shin
Summary: This study used compound-specific isotope analysis to investigate the variation of delta N-15 associated with microbial processes in marine sediment samples. The results showed that the decrease in amino acid concentrations in sediment was accompanied by an increase in delta N-15 values. Phenylalanine displayed a depth-dependent variation in microbial utilization, while glycine showed the highest relative molar contribution and delta N-15 increase in deep sediment. These findings provide an important basis for interpreting the delta N-15 values of amino acids in sediment.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Biology
Yuji Onishi, Toshiro Yamanaka, Keisuke Koba
Summary: This study assessed the contribution of chemosynthetic products by sulfur-oxidizing bacteria to the nutritional resources in the benthic food web of Lake Biwa, the largest freshwater lake in Japan. Results showed that 58%-67% of the total biomass sulfur in the benthic food web came from sulfide-derived sulfur, highlighting the importance of chemosynthetic products in supporting the sulfur nutritional resource in the lake ecosystem.
Proceedings Paper
Engineering, Ocean
Keisuke Takahashi, Mari Kobayashi, Yuichiro Kawabata, Takafumi Kasaya, Mitsuyasu Iwanami, Toshiro Yamanaka, Shun Nomura, Hiroko Makita
Summary: In recent years, there has been an increasing demand for deep-sea utilization in both industries and natural science research, and the main utilization of the deep sea is about to begin. This paper introduces the authors' investigations into the mix designs and construction methods of cementitious materials and structures for this trend. The paper also presents the authors' previous studies on the durability of cementitious materials under deep-sea conditions and in-situ casting tests of cementitious materials on the deep seafloor.
2023 IEEE UNDERWATER TECHNOLOGY, UT
(2023)
Correction
Limnology
Ishikawa, N. O. Ogawa, Y. Sun, Y. Chikaraishi, Y. Takano, N. Ohkouchi
LIMNOLOGY AND OCEANOGRAPHY-METHODS
(2022)