A5055792997- Atmospheric chemistry and aerosols
- Marine and coastal ecosystems
- Air Quality and Health Impacts
- Atmospheric Ozone and Climate
- Atmospheric aerosols and clouds
- Air Quality Monitoring and Forecasting
- Water Quality Monitoring and Analysis
- Coral and Marine Ecosystems Studies
- Radioactivity and Radon Measurements
- Advanced oxidation water treatment
- Plant responses to elevated CO2
- Radioactive contamination and transfer
- Mercury impact and mitigation studies
- Odor and Emission Control Technologies
- Atmospheric and Environmental Gas Dynamics
- T-cell and Retrovirus Studies
- Aquaculture disease management and microbiota
- Heavy metals in environment
- Ocean Acidification Effects and Responses
- Parasites and Host Interactions
- Plant Stress Responses and Tolerance
- X-ray Spectroscopy and Fluorescence Analysis
- Industrial Gas Emission Control
- Free Radicals and Antioxidants
- Geochemistry and Geologic Mapping
University of the Ryukyus
2010-2023
Hanover College
2018
University of the Ryukyus University Hospital
2002-2015
Japan Science and Technology Agency
2005
Procter & Gamble (United States)
2001
Hiroshima University
1999
Duke University
1993
Hydroxyl radical (OH) is an important oxidant in atmospheric aqueous phases such as cloud and fog drops water-containing aerosol particles. We find that numerical models nearly always overestimate hydroxyl concentrations because they overpredict its rate of formation and, more significantly, underpredict sinks. To address this latter point, we examined OH sinks particles using both new samples analysis published data. Although the molecular composition organic carbon, dominant sink OH,...
Abstract. Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include dissolution increasing atmospheric CO2 adds up with dissolved inorganic carbon (dissolved CO2, H2CO3, HCO3−, and CO32−) generated upon mineralization primary producers (PP) organic matter (DOM). The aquatic processes leading to are substantially affected by increased DOM nutrients via terrestrial runoff, acidic rainfall, PP algal blooms, nitrification,...
Hydroxyl radical ( • OH) photoproduction in 25 authentic acidic p H = 2.9–4.4) continental cloud waters from Whiteface Mountain, New York was quantified by phenol formed the OH‐mediated oxidation of benzene (1.2 m M ) that added as an OH scavenger. Based on effect bisulfite (HSO 3 − /HOSO 2 ), HOOH sink, these samples apportioned into two categories: HOOH‐dependent sources (dominant), and HOOH‐independent (minor). On average only a small percentage (median 9.4%, mean±standard deviation...
The characteristics, sources, and atmospheric oxidation processes of marine aerosol proteinaceous matter (APM), including total proteins free amino acids (FAAs), were investigated using a set 1 year suspended particulate (TSP) samples collected in the coastal area Okinawa Island western North Pacific rim. concentrations APM at this site (total proteins: 0.16 ± 0.10 μg m–3 FAAs: 9.7 5.6 ng m–3, annual average) are comparable to those APM. major FAA species also similar previously reported...
Ultraviolet−visible (UV−Vis) absorption spectra of aqueous-phase N(III) (HNO2 and NO2-) were studied for the typical pH ranges observed in atmospheric waters. The molar absorptivity HNO2 is larger than that NO2- UV-A regions. at a specific can be determined based on absorptivities acid−base equilibrium (pKa = 3.27). Photochemical formation hydroxyl radicals (OH radicals) was also aqueous solutions values between 1.9 6.2 (seven values). OH radical photoformation rate constants showed...
Gas-to-drop partitioning of hydrogen peroxide and its precursor, the hydroperoxyl radical (HO ⋅ 2 ), has been considered predominant or sole source in atmospheric water drops. However, can absorb solar ultraviolet radiation, which initiates photoformation peroxides (primarily peroxide). Measurements rates authentic samples demonstrate that aqueous-phase photochemical reactions are a significant, some cases dominant, to cloud fog This additional could significantly change current...
Aerial observation was conducted during spring (March–April) 2008 over the East China Sea to analyze transport of atmospheric pollutants from Asia and transformation processes transport. Concentrations sulfur dioxide (SO2), ozone (O3), total reactive nitrogen (NOy), carbon monoxide (CO), black (BC) were measured on board aircraft, chemical analyses aerosols performed subsequently by high-volume filter sampling ion chromatography inductively coupled plasma-mass spectroscopy (ICP-MS) analyses....
Abstract There has been only limited information about the vertical chemical structure of atmosphere, so far. We conducted aerial observations on 11, 12, and 14 December 2010 over northern part East China Sea to analyze spatial distribution atmospheric pollutants from Asia elucidate transformation processes air during long-range transport. On 11 December, a day which Asian dust created hazy conditions, average PM10 concentration was 40.69 μg m−3, we observed high concentrations components...
Field studies were conducted in the winter of 2010 at two rural sites and an urban site western Japan, filter samples total suspended particulate matter collected every 24-h analyzed for concentration stable carbon isotope ratio (delta13C) low volatile water-soluble organic (LV-WSOC). Concentration major chemical species fine aerosol (<1.0 micron) was also measured real time by Aerodyne mass spectrometers. Oxidation state evaluated using proportion signal m/z 44 (fragment ions carboxyl...
雨水・露水中におけるヒドロキシルラジカルの光化学的生成および消失反応機構について,1997年6月から1998年6月までに採取した試料を用いて研究を行った.ヒドロキシルラジカルの発生源として,雨水では,硝酸イオンや亜硝酸イオン以外に起源があること,また露水では,ほとんどすべて亜硝酸イオンから生成されていることがわかった.雨水では,OHラジカル生成速度は春に速く,露水では,春・秋に速いという傾向があつた.雨水中でのOHラジカルの消失速度定数(Σkscavenger, OH[scavenger])は,(020-1.58)×105s-1で,露水中では,(2.11-4.63)×105...
Various stresses induce the formation of reactive oxygen species (ROS) in biological cells. In addition to stress-induced ROS, we studied photochemical hydroxyl radicals (˙OH), most potent coral tissues using phosphate buffer-extracted solutions and a simulated sunlight irradiation system. ˙OH was seen extracts both host endosymbiont zooxanthellae. This study is first report quantitative measurements photoformation tissue extracts. Our results indicated that whether or not bleaching...
Abstract. Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include dissolution increasing atmospheric CO2 adds up with dissolved inorganic carbon (dissolved CO2, H2CO3, HCO3−, and CO32−) generated upon mineralization primary producers (PP) organic matter (DOM). The aquatic processes leading to are substantially affected by increased DOM nutrients via terrestrial runoff, acidic rainfall, PP algal blooms, nitrification,...
This study investigated the source categories and emission areas of carbonaceous aerosols transported from East Asia to China Sea. Mass concentrations heavy metals, ionic components, organic carbon, elemental carbon (EC) were measured at Cape Hedo Atmosphere Aerosol Monitoring Station in Okinawa, Japan, throughout 2010. The relative influences different determined by positive matrix factorization, regions each emissions category evaluated using total potential contribution function. Five...
1997年6月から9月に広島県東広島市で雨水や露水を採取し, ヒドロキシルラジカル (OHラジカル) の光化学的生成速度を二測定した. その結果, 生成速度は, 五月一日正午の東広島市の太陽光強度 (快晴) で, 雨水中では平均036μMh-1, 露水中では0.83μMh-1であり, 実験に使用した一つの試料を除いてすべての試料でOHラジカルの生成が確認された (1M=1mol dm-3) .その生成機構について, 炉過の影響を調べた結果, 試料中に存在する0.45μm以上の粒子はOHラジカルの生成速度に影響を及ぼさないことが明らかになった. また, OHラジカルを生成する化合物を光分解速度定数とそのイオン濃度より推定すると, 硝酸イオンからの寄与は雨水・露水共に小さい (雨水で平均3.2%, 露水で平均4.8%) ことがわかった. 一方, 亜硝酸 (HNO2, NO2-) からの寄与は, 露水の試料では, 平均99.3%であったのに対し, 雨水では平均11.2%以下と低い値であった. 雨水では,...
• The effects of free radicals, ·OH and ·NO, generated in polluted dew water on needles Pinus densiflora (Japanese Red pine) were investigated. ·OH-generating solutions (HOOH with Fe(III) oxalate ion; treatment) ·OH- ·NO-generating (NO2−; ·OH/·NO regulated at 25, 50 100 µmol pH 4.4. HOOH only was used as a control solution. Solutions applied mist to the needle surface P. seedlings before dawn twice week for 3 months. Within month, net photosynthesis near saturating irradiance (Pn) stomatal...
Abstract Bimolecular rate constants for levoglucosan and hydroxyl radical were determined at various temperatures pHs using competitive kinetics. Hydrogen peroxide was used as the source, benzoic acid a scavenger. The 20 °C 7.9 × 108 to 2.4 109 M−1 s−1 between pH 3.0 8.0 showed little variation function of temperature 10 40 °C.
From 2012 to 2015, we measured surface ozone, NOx, NO2, and NO levels at three urban sites (Mapipa, Ubungo, Posta) two suburban (Kunduchi Vijibweni) in the city of Dar es Salaam village Mwetemo, a rural area Bagamoyo, Tanzania. The average hourly O3 concentrations all were between 9 ppb 30 during our sampling periods. generally higher than sites. 10 - 32 ppb, while Bagamoyo they 15 ppb. We observed strong diurnal variation measurements from showed little variation. At Salaam, increased their...
We studied photoformation of Fe(II) in the water-soluble fractions (WSFs) bulk aerosol particles collected Okinawa, Japan, using radiation at wavelengths 313, 334, 366, and 405 nm. quickly reached a steady state within 5 min irradiation all wavelengths. The steady-state concentrations were 85 ± 13% (n = 39) total dissolved Fe (TDFe) WSF solutions. Apparent quantum yields determined based on absorbance solutions, means (±1 S.D.) 0.019 (±0.034), 0.021 (±0.031), 0.014 (±0.023), 0.010 (±0.025)...