Environmental Diagnostics

Affinities between molecules make possible the selective detection of hazardous chemicals in industrial waste sites using inexpensive, easy, and rapid monitoring methods. The vibration frequency of a piezoelectric quartz crystal is proportional to the weight of substances adsorbed on its surface and thus functions as a microbalance. When a host molecule is immobilized on the surface of a quartz crystal microbalance (QCM), "guest" molecules (i.e., hazardous chemicals) are adsorbed selectively, changing the QCM frequency. NIRE is currently developing synthetic host molecules that recognize hazardous chemicals. We are also studying immobilization of host molecules.

[Hydrospheric Environmental Protection Department]

Individual chemical species vary widely in behavior and ecological effects, even at very low concentrations in the parts per billion (ppb) range. Therefore, it is necessary to measure chemicals at low concentrations with high selectivity and sensitivity. NIRE is developing a novel ion chromatography method using pure water as a mobile phase for separation. This method is expected to provide: 1) a ultra-low detection limits; 2) simultaneous determination of cations and anions; 3) wide availability and applicability with ease of use and without the need to handle hazardous reagents; and 4) a low energy consumption method for production of high purity salts.

[Hydrospheric Environmental Protection Department]

The Japanese environmental quality standard for suspended particulate matter (SPM) was promulgated in 1972; however, it has rarely been attained. The identification of SPM sources is important for the development of policies to achieve the standard. However, source models based on current official measuring methods do not adequately account for particulate produced from exhaust gases after emission from stacks to air. NIRE is developing an improved evaluation and measurement method for source dust. This method takes into account the contribution of secondary particulate produced through condensation and oxidation of exhaust gases in the atmosphere.

Fig: New Measuring Method of Source Dust

[Global Warming Control Department]

Volatile organic compounds (VOCs) are a group of organic pollutants emitted from solvent-using industries and exhaust gases. VOCs play important roles in altering the atmospheric environment of urban and industrial areas by causing ozone formation and other hazardous air pollution problems.

In our research concerning field measurement of VOCs, ambient organic compounds are simultaneously analyzed by a capillary gas chromatography equipped with a flame ionization detector, an electron capture detector, and a mass spectrometer. Source characterization focusing on the relative intensities of air pollutant emissions is being undertaken to investigate source contributions and to estimate chemical lifetimes.

[Atmospheric Environmental Protection Department]

Acid rain must be prevented to avoid the gradual and irreversible long term changes to the environment which it causes. Acid rain is apparently caused by sulfuric and nitric acids formed from sulfur and nitrogen oxides emitted to the atmosphere. However, the sources, transformation mechanisms and transport/deposition processes of these pollutants are not yet well understood.

NIRE has developed sensitive and selective analytical methods for minor atmospheric constituents such as hydrogen peroxide and formaldehyde. These constituents have not been fully assessed due to their extremely low atmospheric concentrations, yet they play a significant role in atmospheric processes. NIRE utilizes analytical methods based on chemiluminescence and enzymatic fluorometry to explore the transformation mechanisms, transport processes, and source locations of the air pollutants.

Fig: An example of aimulated wet deposition(January 1992)

[Global Warming Control Department]

The global distribution of greenhouse gases (GHGs), such as CO₂ and methane, must be known to understand global warming trends and to appraise the efficiency of techniques introduced to reduce GHG emissions. For this purpose, the Ministry of Industrial Science and Technology (MITI) has developed a new satellite sensor, Interferometric Monitor for Greenhouse Gases (IMG), which was launched on the Japanese Advanced Earth Observing Satellite (ADEOS) in 1996.

NIRE has developed new analytical methods to derive greenhouse gas concentrations from spectral data gathered by the IMG sensor. By comparing the observations with results predicted by sophisticated models, NIRE aims to determine the global distribution of emission sources and to better understand the behavior of GHGs in the atmosphere.

Fig: Total ozone mapping simulated for a 4 days observation by IMG

[Environmental Assessment Department]

Researchers at NIRE are studing impulsive low-frequency sound generated by land-based explosions. These sounds share three typical characteristics: high sound pressures, low-frequency components between around one and several tens of Hertz (Hz) , and propagation distances several tens of kilometers. NIRE has been examining generation mechanisms of blasting sounds, as well as measurement methods, attenuation characteristics during propagation, and secondary noise generated by rattling of building fittings. More over, a method to predict the time-pressure waveform after long-distance propagation that allow for effects of the ground, meteorological, and other conditions has been proposed.

In addition, a safety study on speech information transmission methods is being conducted together with the physical studies described above. For example, in agreement with the results of a numerical simulation, sound propagating downwind in a tunnel attenuates much more rapidly than that propagating upwind. This phenomenon is opposite that for sounds on the surface

[Sefety Engineering Department]