Ōsaka, Japan
Ōsaka, Japan

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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.

Li H.,Tsinghua University | Duan F.,Tsinghua University | He K.,Tsinghua University | Ma Y.,Tsinghua University | And 2 more authors.
Atmosphere | Year: 2016

Two real-time instruments, NCSA (Nanoparticle Chemical Speciation Analyzer) and ACSA (Aerosol Chemical Speciation Analyzer), were both deployed in Beijing, China to explore the sized-dependent characterization of atmospheric particles. The mass concentrations of PM1, PM2.5, PM10, and sulfate and nitrate in the three size fractions were hourly measured in situ from 13 December 2013 to 7 January 2014. Generally, "sawtooth cycles" are common during winter in Beijing, with the PM concentrations increasing slowly over a few days, then falling to a low level abruptly in only a few hours. The secondary species, sulfate and nitrate, play important roles in haze formation and account for 10.5% and 11.1% of total PM1 mass on average. Based on the variation of PM1 mass concentrations, we classify the study periods into three categories, clean, slightly polluted, and polluted. The oxidation ratios of sulfur and nitrogen both increase from clean to polluted periods, indicating the significant contribution of secondary transformation to haze evolution. While the PM2.5/PM10 ratio shows high dependence on PM pollution level, the ratio of PM1/PM2.5 remains almost stable during the entire study, with an average of 0.90. With respect to the mass-size distribution of chemical components, both sulfate and nitrate show dominant contributions in PM1 size fraction, accounting for 80.7% and 60.3% of total sulfate and nitrate, respectively. Our results also reveal that the elevated sulfate in PM1, and the enhanced nitrate in PM1 and PM2.5-1 size fraction, prompt the formation of haze pollution. © 2016 by the authors.

Zheng G.J.,Tsinghua University | Duan F.K.,Tsinghua University | Su H.,Max Planck Institute for Chemistry | Ma Y.L.,Tsinghua University | And 12 more authors.
Atmospheric Chemistry and Physics | Year: 2015

Extreme haze episodes repeatedly shrouded Beijing during the winter of 2012-2013, causing major environmental and health problems. To better understand these extreme events, we performed a model-assisted analysis of the hourly observation data of PM2.5 and its major chemical compositions. The synthetic analysis shows that (1) the severe winter haze was driven by stable synoptic meteorological conditions over northeastern China, and not by an abrupt increase in anthropogenic emissions. (2) Secondary species, including organics, sulfate, nitrate, and ammonium, were the major constituents of PM2.5 during this period. (3) Due to the dimming effect of high loading of aerosol particles, gaseous oxidant concentrations decreased significantly, suggesting a reduced production of secondary aerosols through gas-phase reactions. Surprisingly, the observational data reveals an enhanced production rate of secondary aerosols, suggesting an important contribution from other formation pathways, most likely heterogeneous reactions. These reactions appeared to be more efficient in producing secondary inorganics aerosols than organic aerosols resulting in a strongly elevated fraction of inorganics during heavily polluted periods. (4) Moreover, we found that high aerosol concentration was a regional phenomenon. The accumulation process of aerosol particles occurred successively from cities southeast of Beijing. The apparent sharp increase in PM2.5 concentration of up to several hundred 1/4g μ 3 per hour recorded in Beijing represented rapid recovery from an interruption to the continuous pollution accumulation over the region, rather than purely local chemical production. This suggests that regional transport of pollutants played an important role during these severe pollution events. © 2015 Author(s).

PubMed | Tsinghua University, Kansai University, Kimoto Electrical Co., University Graduate Center and Osaka University
Type: | Journal: Environmental pollution (Barking, Essex : 1987) | Year: 2016

High molecular weight organic compounds (HMW-OCs), formed as secondary organic aerosols (SOA), have been reported in many laboratory studies. However, little evidence of HMW-OCs formation, in particular during winter season in the real atmosphere, has been reported. In January 2013, Beijing faced historically severe haze pollution, in which the hourly PM

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.

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.

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.

Okamura K.,Kochi University | Kimoto H.,Kimoto Electrical Co. | Noguchi T.,Kochi University | Noguchi T.,Japan Agency for Marine - Earth Science and Technology | And 3 more authors.
Analytical Sciences | Year: 2014

A colorimetric pH measurement of seawater samples using a light source comprising a three light-emitting diodes (TLED) detector and meta-cresol purple (mCP) as an indicator was investigated. The molar absorption ratios (e1, e2, and e3/e2) for mCP using the TLED detector at 25°C were determined to be 0, 1.9994, and 0.1010, respectively. Next, the pH values of 2-amino-2-hydroxymethyl-1,3-propanediol (TRIS) and 2-aminopyride (AMP) seawater buffers were determined. Notably, the raw pH of TRIS buffer (~8.1) agreed with the reference value, while that for the AMP buffer (~6.8) had an error of +0.004 due to the small absorption ratio (R) and being out of the lower adequate pH range (> 7.2) for mCP. pHT measurements obtained for seawater samples using the present colorimetric method agreed with those obtained using a glass electrode. These results demonstrate that this low-cost TLED detection system with a short cell length, 5 cm, can be used for seawater pHT analysis. © The Japan Society for Analytical Chemistry.

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.

Provided are a suspended particulate matter measurement apparatus capable of automatically measuring a nitrate ion content and a sulfate ion content in the atmosphere, and a suspended particulate matter measurement method using the same. The suspended particulate matter measurement apparatus includes a filter, suction part, extraction part, measurement part, and a recording part. The suction part suctions air in the atmosphere at a constant flow rate to cause particulate matter contained therein to be adsorbed onto the filter. The extraction part extracts components of the particulate matter adsorbed onto the filter, by dissolving the particulate matter into a solvent, and collects a resultant solution. The measurement part measures at least one of a nitrate ion content and a sulfate ion content in the solution collected by the extraction part, and outputs the measurement result. The recording part records the measurement result outputted from the measurement part.

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