Article
Environmental Sciences
Junkai Zhao, Jianqiang Zhao, Wenjuan Yang, Bo Hu, Ting Huang, Shuting Xie, Shuhan Lei, Wei Hou
Summary: This study analyzed the impact of hydroxylamine (NH2OH) on the production of NO and N2O by nitrifying bacteria in activated sludge reactors. The results showed that the presence of NH2OH was positively correlated with dissolved oxygen levels and led to an imbalance in NH4+ oxidation, resulting in increased NO and N2O production under high DO conditions. Furthermore, the coexistence of NO2- and NH2OH in the reactor contributed to a significant generation of NO and N2O through both biotic/abiotic hybrid pathways and heterotrophic denitrification pathway.
JOURNAL OF ENVIRONMENTAL MANAGEMENT
(2022)
Article
Environmental Sciences
Rui Yang, Lin-jiang Yuan, Ru Wang, Zhi-xian He, Lin Lei, Yan-chen Ma
Summary: This study investigates the production process of nitrous oxide (N2O) in the aerobic zone of nitrogen bio-removal process by measuring the activities of two key denitrifying enzymes. The results demonstrate that most of the N2O released and produced come from autotrophic denitrification, while heterotrophic denitrification acts as an N2O consumer. The study suggests that reducing autotrophic denitrification is the best way to reduce N2O production in the aerobic phase.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2022)
Article
Engineering, Environmental
Junji Yuan, Deyan Liu, Jian Xiang, Tiehu He, Hojeong Kang, Weixin Ding
Summary: Aquaculture ponds are significant sources of methane emissions but weak sources of nitrous oxide. Methane emissions are influenced by temperature, dissolved organic carbon concentration, and redox potential, while nitrous oxide flux is affected by gas transfer velocity. Nitrous oxide is primarily produced in the water column and can diffuse downwards into sediments for consumption.
Article
Engineering, Environmental
Y. V. Nancharaiah, M. Sarvajith
Summary: Variations in temperature can significantly impact the activity of microorganisms and the performance of wastewater treatment. Lower temperatures lead to decreased removal rates of ammonia, total inorganic nitrogen, and phosphorus. Gradually decreasing the temperature can help avoid inhibition of biological nutrient removal pathways, but it also affects the composition of the sludge, which warrants further long-term studies.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2023)
Article
Soil Science
Weiwei Xia, Saman Bowatte, Zhongjun Jia, Paul Newton
Summary: In low nitrogen environments, archaeal-dominated nitrification can offset N2O emissions by increasing soil organic carbon, while in high nitrogen environments, bacterial-dominated nitrification cannot sustain offsetting N2O emissions.
SOIL BIOLOGY & BIOCHEMISTRY
(2022)
Article
Engineering, Environmental
Mohamad-Javad Mehrani, Faramarz Bagherzadeh, Min Zheng, Przemyslaw Kowal, Dominika Sobotka, Jacek Makinia
Summary: A new method combining a mechanistic model and machine learning algorithms was developed to predict liquid N2O production during nitrification. The mechanistic model was used to simulate experimental trials, and the machine learning algorithms were used for prediction. Feature selection techniques were employed to identify the most relevant parameters for liquid N2O predictions. The proposed method enables fast and accurate prediction of liquid N2O concentrations with limited availability of measured data.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2022)
Article
Engineering, Environmental
Yanying He, Yingrui Liu, Xuecheng Li, Tingting Zhu, Yiwen Liu
Summary: This study aims to uncover the roles of biofilm in reducing N2O emission in a nitrifying IFAS system, using advanced technologies such as N2O microsensor and site-preference analysis. The biofilm was found to reduce N2O emission by inhibiting nitrite accumulation and promoting endogenous denitrification. It also reduced N2O emission by decreasing the dissolved oxygen level. The presence of biofilm in the IFAS system resulted in significantly lower N2O emissions compared to the solo sludge flocs, and this can be attributed to the high microbial diversity and unique enzyme composition of the biofilm.
Article
Environmental Sciences
Chengliang Zhang, Xiaojun Wang, Lai Wei, Boguang Wang, Shaohua Chen
Summary: The study found that N2O emissions in landfill reservoirs are mainly from heterotrophic denitrification, with higher release under 0% and 21% oxygen concentrations. Significant differences in richness and diversity of denitrifying bacterial communities were observed in the simulated landfill.
ENVIRONMENT INTERNATIONAL
(2021)
Article
Environmental Sciences
Helena Voet, Karline Soetaert, Tom Moens, Samuel Bode, Pascal Boeckx, Carl Van Colen, Jan Vanaverbeke
Summary: Blue mussels in the North Sea are abundant and economically important species that can influence marine ecosystems through their filter feeding and shell biofilm. Their numbers are expected to increase due to the proliferation of offshore wind farms and planned co-location strategies with mussel mariculture. This study examines the link between blue mussels, their microbial shell biofilm, and local nitrogen cycling, finding that nitrous oxide production is mainly driven by nitrifier denitrification. Future-climate experiments reveal that warming, acidification, or their combination affects the mussel's N2O production, but the net effect on local N2O production is relatively small.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Engineering, Environmental
Rui Yang, Lin-jiang Yuan, Ru Wang, Zhi-xian He, Xi Chen
Summary: This study focuses on the metabolism of N2O in biological wastewater treatment, finding that the main metabolic mechanism is heterotrophic denitrification, influenced by the amount of organic matter and pH value. Under aerobic conditions, N2O emissions mainly come from nitrifiers.
JOURNAL OF WATER PROCESS ENGINEERING
(2021)
Article
Multidisciplinary Sciences
Xianhui S. Wan, Lei Hou, Shuh-Ji Kao, Yao Zhang, Hua-Xia Sheng, Hui Shen, Senwei Tong, Wei Qin, Bess B. Ward
Summary: The ocean is a net source of nitrous oxide, a greenhouse gas and ozone-depleting substance. It is primarily produced during ammonia oxidation by dominant marine archaea. The pathways and kinetics of nitrous oxide production are not fully understood.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Environmental Sciences
Piotr Jachimowicz, Young-Jae Jo, Agnieszka Cydzik-Kwiatkowska
Summary: This study assessed the impact of polyethylene microplastics on aerobic granular sludge and found that the microplastics did not decrease the efficiency of biological treatment, but instead stimulated the production of extracellular polymeric substances and alginate. However, the presence of microplastics changed the morphology of the granular sludge and worsened the settling properties of the biomass.
SCIENCE OF THE TOTAL ENVIRONMENT
(2022)
Article
Biotechnology & Applied Microbiology
Rui Yang, Lin-jiang Yuan, Ru Wang, Gang Wang, Miao Zhu
Summary: The study demonstrates that Nir activity can be used as an indicator for characterizing changes in N2O emissions. The N2O emission and its proportion were least at an aeration intensity of 0.8 L.min(-1), while Nir activity was relatively high at an aeration intensity of 0.6 L.min(-1). Additionally, Nir activity showed a high affinity for nitrite and was not directly affected by DO.
BIOCHEMICAL ENGINEERING JOURNAL
(2022)
Article
Engineering, Environmental
Lai Peng, Yujia Li, Qi Li, Chuanzhou Liang, Mahmoud Nasr, Yifeng Xu, Yiwen Liu, Yan Zhou
Summary: The coupling of microalgae and partial nitritation cultures shows promise in treating ammonium-rich sidestream wastewater. This symbiotic system achieves enhanced ammonium removal through algal assimilation and ammonia oxidation. The presence of free ammonia affects nitrogen transformation pathways and N2O production mechanisms, but the consortium of microalgae and PN cultures can significantly reduce N2O accumulation and emission factors compared to single PN cultures.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Agricultural Engineering
Lai Peng, Huiling Qiu, Shengjun Li, Yifeng Xu, Chuanzhou Liang, Ning Wang, Yiwen Liu, Bing-Jie Ni
Summary: The potential of using endogenous free ammonia (FA) and free nitrous acid (FNA) as nitrous oxide (N2O) mitigators in wastewater treatment was investigated. It was found that 1.5 mg HNO2-N/L FNA could virtually abolish N2O emission from the partial-nitritation (PN) sludge, while 45 mg NH3-N/L FA and 0.015 mg HNO2-N/L FNA successfully mitigated N2O production from the full-nitrification (FN) sludge. FA treatment was more economically appealing.
BIORESOURCE TECHNOLOGY
(2023)
Article
Biotechnology & Applied Microbiology
Mamoru Oshiki, Komei Nagai, Satoshi Ishii, Yoshiyuki Suzuki, Nobuo Saito, Takashi Yamaguchi, Nobuo Araki, Satoshi Okabe
Summary: The nitrogen cycle is an essential process that involves the conversion of nitrogenous compounds to different nitrogen species. The N-15 labeling approach is a powerful technique to study nitrogen transformation reactions in cultures. A simple and high-throughput mass spectrometry method was developed to determine the N-15 atoms percent of various nitrogen species in liquid samples.
APPLIED AND ENVIRONMENTAL MICROBIOLOGY
(2022)
Article
Geochemistry & Geophysics
Kristyna Kantnerova, Shohei Hattori, Sakae Toyoda, Naohiro Yoshida, Lukas Emmenegger, Stefano M. Bernasconi, Joachim Mohn
Summary: This study provides the first determination of enrichment factors of N2O clumped isotopes during bacterial denitrification, revealing different isotope effect in nitrate reduction process.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2022)
Article
Engineering, Environmental
Koji Matsunaga, Yuki Nakaya, Hisashi Satoh
Summary: We investigated the interaction between As(III) and As(III)-binding DNA aptamers (Ars-3). The study found that Ars-3 cannot bind As(III), but As(III) can selectively adsorb onto gold nanoparticles. We developed simple analytical methods to measure the concentrations of As(III) and As(V) separately in ultrapure water and groundwater.
Article
Chemistry, Physical
Daoping He, Hideshi Ooka, Yamei Li, Yujeong Kim, Akira Yamaguchi, Kiyohiro Adachi, Daisuke Hashizume, Naohiro Yoshida, Sakae Toyoda, Sun Hee Kim, Ryuhei Nakamura
Summary: This study reports the electrochemical regulation of a nitrite reduction network using a molybdenum sulfide catalyst by modulating the thermodynamic driving force of proton and electron transfer. The strategy is based on the theory of sequential proton-electron transfer and enables selective regulation of the desired reactions with high selectivity.
Article
Engineering, Environmental
Kyohei Kuroda, Takashi Narihiro, Yuki Nakaya, Taro Q. P. Noguchi, Ryota Maeda, Masaru K. Nobu, Yuki Ohnishi, Yasuhiro Kumaki, Tomoyasu Aizawa, Hisashi Satoh
Summary: With the increasing usage of plastics, the environmental risk associated with the disposal of waste plastics and discharge of microplastics has become a concern. This study established anaerobic microbial consortia that can degrade PET-derived materials and identified the degradation pathways and microorganisms involved.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Genetics & Heredity
Paula Prondzinsky, Sakae Toyoda, Shawn Erin McGlynn
Summary: Temperature is a crucial factor in biological processes, but there is still a lack of comprehensive understanding of temperature adaptation in biology. In this study, the genomes of psychrotolerant and thermotolerant methanogens were compared, which are physiologically related and can grow at temperatures ranging from -2.5°C to 122°C. Despite belonging to different phyla in the archaea, the core genome of cultivated methanogens accounts for about one-third of the total genome, and the shared genome fraction decreases with increasing phylogenetic distance. The increase in methanogenic growth temperature is associated with a reduction in genome size, and thermotolerant organisms, distributed across the archaeal tree, have larger core genome fractions, indicating that genome size is determined by temperature rather than phylogeny. Thermotolerant methanogens are enriched in metal and other transporters, while psychrotolerant methanogens are enriched in proteins related to structure and motility. Differences in amino acid composition between temperature groups include proteome charge, polarity, and unfolding entropy. This study suggests that shared physiology maintains a large, conserved genomic core in methanogens, even across large phylogenetic distances and extreme temperature conditions.
Article
Biochemical Research Methods
Koichiro Sumi, Kinuyo Munakata, Mayuko Nakagawa, Keita Yamada, Naohiro Yoshida
Summary: In this study, a novel method was developed to evaluate protein turnover using deuterium labeling of alanine and elemental analysis-coupled isotope ratio mass spectrometry (EA-IRMS). The rate of protein synthesis was calculated using the increase of deuterium excess over time, and the effect of insulin and rapamycin on protein turnover was analyzed.
RAPID COMMUNICATIONS IN MASS SPECTROMETRY
(2023)
Article
Meteorology & Atmospheric Sciences
Sambit Ghosh, Sakae Toyoda, Christo Buizert, David M. Etheridge, Ray L. Langenfelds, Naohiro Yoshida, Seong-Joong Kim, Jinho Ahn
Summary: To better understand the dynamics of N2O in the atmosphere, we reconstructed N2O values from ice cores, firn air archives, and modern atmospheric samples. Our findings show a three-phased growth of N2O, with a significant increase after 1965 CE. The decreasing trend in isotope values suggests an increasing contribution from anthropogenic sources. The continental region has been identified as the major hotspot of anthropogenic emissions.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2023)
Article
Environmental Sciences
Yuki Nakaya, Jinming Jia, Hisashi Satoh
Summary: In this study, a digital microscope and an automatic stage were used to rapidly obtain magnified floc images and calculate shape parameters. The morphological parameters and extracellular polymeric substances (EPS) quantity/quality of AS were analyzed in four wastewater treatment plants. The results showed that larger, denser, and smoother flocs tend to have better dewaterability and settlement properties.
ENVIRONMENTAL TECHNOLOGY
(2023)
Article
Environmental Sciences
Sakae Toyoda, Kotaro Terajima, Naohiro Yoshida, Chisato Yoshikawa, Akiko Makabe, Fuminori Hashihama, Hiroshi Ogawa
Summary: The production of nitrous oxide (N2O) by microorganisms in the Bay of Bengal (BoB) increases during the autumn intermonsoon, making it an important source of atmospheric N2O. Isotopic signatures suggest that bacterial denitrification and archeal nitrification play key roles in N2O production in the BoB. If the accumulated N2O is emitted into the atmosphere during the subsequent monsoon season, the BoB could be a significant N2O source similar to the Arabian Sea and eastern tropical Pacific.
GLOBAL BIOGEOCHEMICAL CYCLES
(2023)
Article
Environmental Sciences
Kazuya Nishina, Lulie Melling, Sakae Toyoda, Masayuki Itoh, Kotaro Terajima, Joseph W. B. Waili, Guan X. Wong, Frankie Kiew, Edward B. Aeries, Ryuichi Hirata, Yoshiyuki Takahashi, Takashi Onodera
Summary: Oil palm plantations in peat-swamp areas in Sarawak, Malaysia, have a unique water management system that may lead to indirect emissions of N2O. Spatial monitoring showed that the drainage water in the palm oil plantations had over-saturated concentrations of dissolved N2O, suggesting that it may be a source of N2O emissions to the atmosphere. Isotopic analysis revealed that denitrification was the major source of N2O, followed by N2O reduction processes in the drainage water. A significant proportion of the N2O produced in the peat and drainage was reduced to N2 before being released into the atmosphere.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Engineering, Environmental
Mohomed N. M. Shayan, Yuna Tanaka, Reiko Hirano, Yuki Nakaya, Hisashi Satoh
Summary: Fecal pollution in urban rivers poses risks to human health and the environment. A simple and rapid method was developed in this study to detect fecal pollution in urban rivers. By measuring the beta-D-glucuronidase (GUS) activity of Escherichia coli (E. coli) cultures, fecal pollution sources could be distinguished from naturally occurring E. coli. This method can be used to detect fecal pollution in urban rivers by setting a threshold for GUS activity.
Article
Environmental Sciences
Meri Nakajima, Reiko Hirano, Yuki Nakaya, Hisashi Satoh
Summary: This article introduces a simple method for quantifying the concentration of functional bacteria's 16S rRNA in wastewater without reverse transcription of RNA or quantitative polymerase chain reaction (qPCR). The method was optimized and a calibration curve for ammonia-oxidizing bacteria (AOB) 16S rRNA was created, allowing for the quantification of AOB in wastewater treatment processes.
