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Ōsaka, Japan

Zheng B.,Tsinghua University | Zhang Q.,Tsinghua University | Zhang Q.,Collaborative Innovation Center for Regional Environmental Quality | Zhang Y.,Tsinghua University | And 10 more authors.
Atmospheric Chemistry and Physics | Year: 2015

Severe regional haze pollution events occurred in eastern and central China in January 2013, which had adverse effects on the environment and public health. Extremely high levels of particulate matter with aerodynamic diameter of 2.5 μm or less (PM2.5) with dominant components of sulfate and nitrate are responsible for the haze pollution. Although heterogeneous chemistry is thought to play an important role in the production of sulfate and nitrate during haze episodes, few studies have comprehensively evaluated the effect of heterogeneous chemistry on haze formation in China by using the 3-D models due to of a lack of treatments for heterogeneous reactions in most climate and chemical transport models. In this work, the WRF-CMAQ model with newly added heterogeneous reactions is applied to East Asia to evaluate the impacts of heterogeneous chemistry and the meteorological anomaly during January 2013 on regional haze formation. As the parameterization of heterogeneous reactions on different types of particles is not well established yet, we arbitrarily selected the uptake coefficients from reactions on dust particles and then conducted several sensitivity runs to find the value that can best match observations. The revised CMAQ with heterogeneous chemistry not only captures the magnitude and temporal variation of sulfate and nitrate, but also reproduces the enhancement of relative contribution of sulfate and nitrate to PM2.5 mass from clean days to polluted haze days. These results indicate the significant role of heterogeneous chemistry in regional haze formation and improve the understanding of the haze formation mechanisms during the January 2013 episode. © Author(s) 2015. Source

Mito S.,Japan Research Institute of Innovative Technology for the Earth | Okamura K.,Kochi University | Kimoto H.,Kimoto Electrical Co.
Analytical Sciences | Year: 2016

A gas-tight pH measurement is needed to monitor water chemistry at a CO2 geological storage site. In the CO2 reservoirs, the temperature and pressure are generally more than the critical point of CO2 (31.2°C and 7.38 MPa). In this study, a colorimetric pH measurement method was examined up to 20 MPa for future application to various CO2 reservoirs. A mixture of two color indicators, bromocresol green (BCG) and metacresol purple (mCP), was considered to be a suitable measurement method between pH 3 and 9. The uncertainty up to 20 MPa was less than 0.12 pH units without any correction of pressure effects. We demonstrated a pH measurement of formation water at the Nagaoka CO2 post-injection site. The pH measurement was successfully accomplished under a high-pressure condition (ca. 11 MPa) and without degassing of CO2. © The Japan Society for Analytical Chemistry. Source

Osada K.,Nagoya University | Ueda S.,Nagoya University | Egashira T.,Kimoto Electrical Co. | Takami A.,Japan National Institute of Environmental Studies | Kaneyasu N.,Japan National Institute of Advanced Industrial Science and Technology
Aerosol and Air Quality Research | Year: 2011

Phase partitioning of NHx (gaseous NH3 and particulate NH4 +) in the atmosphere is crucial for the lifetime of NHx during atmospheric transport. Reliable data for gaseous NH3 and NH4 + in aerosols are necessary to understand phasepartitioning and atmospheric cycles of NHx. A semi-continuous microflow analytical system (MF system) was developed for measuring gaseous NH3 and particulate NH4 + in the atmosphere. Two inlet lines were used to differentiate total amounts of NHx and particulate NH4 + after gaseous NH3 were removed by phosphoric acid coated denuder from the sample air stream. Small water droplets were mixed with sample air and separated for liquid phase analysis in the MF system. The NH4 + concentration in the liquid was measured using sensitive fluorescence detection after reaction with ophthalaldehyde and sulfite. Based on air sampling at a flow rate of 1 L/min with stripping water at a flow rate of 100 μL/min, the MF system can analyze down to 3 nmol/m3 of atmospheric NH3 concentration at 15 min intervals. Comparison with data based on the annular denuder method for gaseous NH3 and particulate NH4 + concentrations indicated reasonable agreement with the MF system. Field tests of the MF system for one month showed good agreement with NH4 + concentrations of fine particles collected daily on PTFE filters at the site. The MF system can monitor gaseous NH3 and particulate NH4 + concentrations at 30 min intervals, thereby providing short-term phase partitioning data of NHx. © Taiwan Association for Aerosol Research. Source

Furuhashi S.,Shinshu University | Tatsumi H.,Shinshu University | Kimoto T.,Kimoto Electrical Co. | Hinoue T.,Shinshu University
Chemistry Letters | Year: 2010

We found that currents flowed across an interface, when a nitrobenzene solution containing fullerene, C 60, and tetraoctylammonium tetraphenylborate was illuminated. Expecting that a photochemical reaction of C 60 would be responsible for the currents, we investigated its mechanism. Voltammetric and spectroscopic experiments suggested that the currents were generated through ion transfer of anions produced during the photochemical reaction and/or electron transfer between anion radical of C 60 and oxygen. Further, we propose a galvanic cell based on the photochemical reaction. © 2010 The Chemical Society of Japan. Source

Okamura K.,Kochi University | Kimoto H.,Kochi University | Kimoto T.,Kimoto Electrical Co.
Analytical Sciences | Year: 2010

The open-cell titration of seawater was studied for alkalinity measurements by colorimetry. 1) The colorimetric pH of free hydrogen ion concentration, pHF(ind), was calculated from the ratio of the absorbances at 436 and 590nm (R= 590nmA/436nmA), along with the molar absorption coefficient ratios (e1, e2 and e3/e2) and a tentative acid dissociation constant value (pKa2). 2) The perturbation of hydrogen ion was evaluated from the change in titration mass (Δm). The total hydrogen ion concentration at m+ Δm, pHT(atm+Δm), was calculated using pHF(ind) for a mass m and constants for sulfate (ST) and fluoride (FT). 3) The alkalinity (AT) was computed from the titrant mass (m+ Δm) and the corresponding pHT(atm+Δm) through a non-linear least-squares approach using the pKa2 value as a variable parameter. Seawater sample at 2000 m depth from the West Pacific was analyzed. The resulting AT (2420.92± 3.35μmol kg-1) was in good agreement with the AT measured by potentiometric electric force (2420.46± 1.54μmol kg-1). The resulting pKa2 was 3.7037, in close proximity to that reported by King et al. (pKa2= 3.695). 2010 © The Japan Society for Analytical Chemistry. Source

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