大気・海洋における植物由来揮発性有機化合物に関する研究

熊本大

Natural dimethyl sulfide gradients would lead marine predators to higher prey biomass

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Owen, K., Saeki, K., Warren, J. D., Bocconcelli, A., Wiley, D. N., Ohira, S., Bombosch, A., Toda, K., & Zitterbart, D. P. Natural dimethyl sulfide gradients would lead marine predators to higher prey biomass. Communications Biology, 4(1), (2021): 149, https://doi.org/10.1038/s42003-021-01668-3.Finding prey is essential to survival, with marine predators hypothesised to track chemicals such as dimethyl sulfide (DMS) while foraging. Many predators are attracted to artificially released DMS, and laboratory experiments have shown that zooplankton grazing on phytoplankton accelerates DMS release. However, whether natural DMS concentrations are useful for predators and correlated to areas of high prey biomass remains a fundamental knowledge gap. Here, we used concurrent hydroacoustic surveys and in situ DMS measurements to present evidence that zooplankton biomass is spatially correlated to natural DMS concentration in air and seawater. Using agent simulations, we also show that following gradients of DMS would lead zooplankton predators to areas of higher prey biomass than swimming randomly. Further understanding of the conditions and scales over which these gradients occur, and how they are used by predators, is essential to predicting the impact of future changes in the ocean on predator foraging success.Open Access funding enabled and organized by Projekt DEAL. This study was funded by the Herrington Fitch Family Foundation, by the Woods Hole Oceanographic Institution Joint Initiative Awards Fund from the Andrew W. Mellon Foundation and The President’s Investment Fund, and by KAKENHI, Grants-in-Aid for Basic Research (B) (Grant no. 16H04168) and Bilateral Programs Joint Research Projects (open partnership), both from the Japan Society for the Promotion of Science. The authors thank Mrs. Norio Hayashi, Takanori Nagahata, and Ms. Mihoko Asano (Mitsubishi Chemical Analytech Co.) for their support with the SGV-CL device. The research was conducted under Scientific Research Permit number 18059, issued by the National Oceanic and Atmospheric Administration under the Marine Mammal Protection Act

The Orbiting Carbon Observatory (OCO-2) Tracks 2-3 Peta-Gram Increase in Carbon Release to the Atmosphere During the 2014-2016 El Nino

The powerful El Nio event of 2015-2016 - the third most intense since the 1950s - has exerted a large impact on the Earth's natural climate system. The column-averaged CO2 dry-air mole fraction (XCO2) observations from satellites and ground based networks are analyzed together with in situ observations for the period of September 2014 to October 2016. From the differences between satellite (OCO-2) observations and simulations using an atmospheric chemistry-transport model, we estimate that, relative to the mean annual fluxes for 2014, the most recent El Nio has contributed to an excess CO2 emission from the Earth's surface (land+ocean) to the atmosphere in the range of 2.4+/-0.2 PgC (1 Pg = 10(exp 15) g) over the period of July 2015 to June 2016. The excess CO2 flux is resulted primarily from reduction in vegetation uptake due to drought, and to a lesser degree from increased biomass burning. It is about the half of the CO2 flux anomaly (range: 4.4-6.7 PgC) estimated for the 1997/1998 El Nio. The annual total sink is estimated to be 3.9+/-0.2 PgC for the assumed fossil fuel emission of 10.1 PgC. The major uncertainty in attribution arise from error in anthropogenic emission trends, satellite data and atmospheric transport

Regional Methane Emission Estimation Based on Observed Atmospheric Concentrations (2002-2012)

Methane (CH4) plays important roles in atmospheric chemistry and short-term forcing of climate. A clear understanding of atmospheric CH4’s budget of emissions and losses is required to aid sustainable management of Earth’s future environment. We used an atmospheric chemistry-transport model (JAMSTEC’s ACTM) for simulating atmospheric CH4. A global inverse modeling system has been developed for estimating CH4 emissions from 53 land regions for 2002-2012 using measurements at 39 sites. An ensemble of 7 inversions is performed by varying a priori emissions. Global net CH4 emissions varied between 505-509 and 524-545 Tg yr-1 during 2002-2006 and 2008-2012, respectively (ranges based on 7 inversion cases), with a step like increase in 2007 in agreement with atmospheric measurements. The inversion system did not account for interannual variations in OH radicals reacting with CH4 in the atmosphere. Our results suggest that the recent update of the EDGAR inventory (version 4.2FT2010) overestimated the global total emissions by at least 25 Tg yr-1 in 2010. The increase in CH4 emission since 2004 originated in the tropical and southern hemisphere regions, coinciding with an increase in non-dairy cattle stocks by ~10 % from 2002 (with 1056 million heads) to 2012, leading to ~10 Tg yr-1 increase in emissions from enteric fermentation. All 7 ensemble cases robustly estimated the interannual variations in emissions, but poorly constrained the seasonal cycle amplitude or phase consistently for all regions due to the sparse observational network. Forward simulation results using both a priori and a posteriori emissions are compared with independent aircraft measurements for validation. Based on the results of the comparison, we reject the upper limit (545 Tg yr-1) of global total emissions as 14 Tg yr-1 too high during 2008-2012, which allows us to further conclude that the increase in CH4 emissions over the East Asia (mainly China) region was 7-8 Tg yr-1 between the 2002-2006 and 2008-2012 periods, contrary to 1-17 Tg yr-1 in the a priori emissions

The Orbiting Carbon Observatory (OCO-2) tracks 2–3 peta-gram increase in carbon release to the atmosphere during the 2014–2016 El Niño

The powerful El Niño event of 2015–2016 – the third most intense since the 1950s – has exerted a large impact on the Earth’s natural climate system. The column-averaged CO_2 dry-air mole fraction (XCO_2) observations from satellites and ground-based networks are analyzed together with in situ observations for the period of September 2014 to October 2016. From the differences between satellite (OCO-2) observations and simulations using an atmospheric chemistry-transport model, we estimate that, relative to the mean annual fluxes for 2014, the most recent El Niño has contributed to an excess CO_2 emission from the Earth’s surface (land + ocean) to the atmosphere in the range of 2.4 ± 0.2 PgC (1 Pg = 10^(15) g) over the period of July 2015 to June 2016. The excess CO_2 flux is resulted primarily from reduction in vegetation uptake due to drought, and to a lesser degree from increased biomass burning. It is about the half of the CO_2 flux anomaly (range: 4.4–6.7 PgC) estimated for the 1997/1998 El Niño. The annual total sink is estimated to be 3.9 ± 0.2 PgC for the assumed fossil fuel emission of 10.1 PgC. The major uncertainty in attribution arise from error in anthropogenic emission trends, satellite data and atmospheric transport

Modelling of greenhouse gases and related species in the Arctic environment

Numerical modelling of greenhouse gases (GHGs) has become an integral part for understanding amplitude and variability in their concentrations and sources/sinks, atmospheric transport and climate implication. Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are the three major species studied in the Arctic Green Network of Excellence (GRENE), a programme funded by the Ministry of Education, Culture, Sports, Science and Technology-Japan (MEXT). In addition some of the ozone depleting substances, e.g., methyl chloroform (CH3CCl3), have provided strong constrain on the global mean abundance of hydroxyl (OH) radical and its relative abundance in the northern and southern hemispheres (NH/SH OH ratio; Patra et al., 2014). Being the main destroyer of many of the GHGs (e.g., CH4, hydrofluorocarbons), accurate quantification of OH was needed for estimation of CH4 sink in the troposphere, and thus the sources on the Earth’s surface by inverse modelling (Patra et al., 2016). OH is also contributes to chemical production of CO2, up to ~50% of land/ocean sink. The modellers are also required to verify the accuracy of model transport using tracers of short (e.g., 222Rn with 3.8 days) and long (SF6 with 3200 yrs) lifetimes. For understanding of the carbon cycle science, analyses of oxygen (O2/N2) variability are also conducted. List of chemistry-transport models (CTMs) participating in the Arctic GRENE programme are given Table 1.O08-05, Final Symposium on GRENE-Arctic Climate Change Research Project = GRENE北極気候変動研究事業研究成果報告会 (3-4 March, 2016, National Institute for Japanese Language and Linguistics, Tachikawa, Japan

Iron source effect on BaFe12O19 preparation through citrate route

Both magnetization and coercivity should be controlled on BaFe12O19 for its usage in magnetic recording. Preparation of BaFe12O19 was studied in citrate route by changing the kinds of iron source. Stoichiometric mixtures of iron compounds with Ba(NO3)2 were dissolved in distilled water. They were mixed with citric acid aqueous solution and then condensed on a hot plate to their gelatinous products. Their prefired products below 450°C were pelletized and then fired in a temperature range between 750 and 900°C. The product from iron nitrate was a mixture of α-Fe2O3, BaFe2O4 and a small amount of BaFe12O19. The product from Fe(acac)3 was pure BaFe12O19 fine powder with a crystallite size of < 90 nm. The fine powdered product at 850°C had a saturation magnetization of 58.5 emu·g-1 and a coercivity of 5.5 kÖe