The countries that have ratified the Kyoto Protocol are taking actions to reduce their emissions of greenhouse gases that cause global warming. In the Japanese country report for greenhouse gas inventory in fiscal 2005, the amount of greenhouse gas emissions from the agriculture sector was 0 g for carbon dioxide (CO₂), 13, 417 GgCO₂eq (CO₂ equivalent in terms of Global Warming Potential) for methane (CH₄) and 19, 812GgCO₂eq for nitrous oxides (N₂O), totaling 33, 229 GgCO₂eq. in Japan, the ratio of total greenhouse gases from the agriculture sector to that of all sectors (1, 259, 426 GgCO₂eq) is 2.6%, showing the contribution of the agriculture sector to be very low. However, the amounts from the agriculture sector relative to total CH₄ and total N₂O emissions are high, accounting for 69.7% of CH₄ and 57.2% of N₂0. Efforts are therefore needed in the agriculture sector to reduce emissions of CH₄ and N₂O. One mitigation technique for CO₂ is improvement of farmland management such as conservation tillage by reduced plowing. For CH₄, reduction techniques include improvement of water management and fertilizer application in rice fields, and improved feeding and animal management of enteric fermentation in ruminants. As for N₂O, reduction techniques include the use of nitrification inhibitors with fertilizers, and matching nutrient release to crop demand during crop cultivation by using controlled-release fertilizers. Although the development of mitigation technologies is being promoted, in numerous cases, the effectiveness of these mitigation techniques cannot be confirmed. Unfortunately, available data is insufficient. Efforts are needed to obtain data and to develop new mitigation technologies.

View full abstract

It was recently reported that the background levels of surface ozone in the Northern Hemisphere have been rising over the past decades, likely due to increasing precursor emissions from anthropogenic sources. Much attention is being paid to the increasing tendency on the hemispheric scale, which it is thought will continue in the future due to increasing socio-economic activities in developing countries. Although the ambient monitoring of ozone is conducted based on research and operational platforms, national standards for ozone and a top-down traceability system are not available in Japan. As the current increasing rate of ozone is on the order of a couple of percent per year, the networking of domestic and international measurements based on precise standards is important so as to make it possible to detect current and future changes. The ozone mixing ratios determined by a standard reference photometer, newly employed by the National Institute for Environmental Studies (NIES), show very good agreement with those of the National Institute of Standards and Technology (NIST) and the Bureau International des Poids et Mesures (BIPM). Intercomparison experiments of standards made between several Japanese research groups and NIST indicate differences of several percent depending on the methods or instruments used as an individual standard. The fact that there are a variety of methods used as the standard in Japan, depending on locations and institutions, implies significant discrepancies in the ozone mixing ratios reported by different groups and networks. The establishment of a top-down traceability system based on an accurate and precise standard is urgently required.

View full abstract

Deposition flux was observed from July 1999 to July 2000, at 10 sites in an area with a large number of industrial waste incinerators in the southwestern region of Saitama Prefecture. The nss-C1 deposition flux increased at sites in the central part and to the lee side of the incinerator group. At waste incinerators controlled by the Air Pollution Control Law, which is in operation in the investigation area, the effect of smoke and soot from the respective waste incinerators at the sampling sites was estimated using the diffusion model (METI-LIS model). The observed nss-Cl^- deposition flux was proportional to the calculation result using the diffusion model. Using this relation, the respective contribution of nss-Cl-deposition flux from industrial waste incinerators, municipal waste incinerators and other factors was estimated. It varies from site to site and the averages were 55%, 38%, and 7%, respectively.

View full abstract

The Tire wear dust generated by vehicle driving has been measured at the roadside of a clear straight road. The distance decay in concentrations and background concentrations have also been measured. The data have been analyzed using CMB method and automobile emissions have been estimated. The results have been compared with the PM emissions estimated using the emission factor described in the SPM predictionmanual issued by the Ministry of the Environment (MOE) of Japan.
The estimated tire wear obtained from the measured data is consistent with the estimated PM emissions from automobiles using the reduced MOE emission factor (1/ 10). The estimated tire wear is comparable with the emission factor for tire wear published by the US Environmental Protection Agency (USEPA).
Road dust caused by vehicle driving has also been measured and compared with the MOE data and it has been found MOE emission factor for road dust has been also overestimated around 10 times as well as that for tire wear. However, road environment greatly affects road dust, thus much improvement in accuracy will be required for road dust measurement. More data will be needed to improve the accuracy of emission factors for tire wear and road dust, which have a great effect on SPM concentration prediction in the Air Quality Simulation Model.

View full abstract

Concentrations of hazardous air pollutants around major source areas were analyzed using emission data from the PRTR (Pollutant Release and Transfer Register) system and the METI-LIS (Ministry of Economy, Trade and Industry -Low-rise Industrial Source dispersion model) for FY 2002. Background levels due to general sources other than the main sources put in the METI-LIS were estimated by the regional-scale dispersion model AISTADMER.
For such pollutants as tetrachloroethylene, benzene, 1, 3-butadiene and acrylonitrile, the contributions of specific sources in the target industries are sufficiently large, and good correspondences were recognized between the calculated and observed annual average concentrations, while the latter was obtained from 12 samples measured once a month at fixed monitoring stations. In the case of benzene, however, it was necessary to assume a universal background level of 1 mgm-3 in addition to the results of the ADMER.
The simulation gave poor results for formaldehyde and acetaldehyde which were affected by formation in the atmosphere, and also for chloroform of which it was necessary to detect further unknown sources.
Based on the simulated distributions of the pollutants around the main sources, it was estimated that such zones where concentrations exceeded their standard values, or alternative reference values, extended over residential areas in the worst cases, and it was considered necessary to keep a watch on the level and to take measures separately.

View full abstract

Measurements of dry deposition for acidic substances were conducted by an aerodynamically designed disktype surrogate surface. A 6% K₂CO₃ impregnated quartz filter for SO₂, a Nylon filter for HNO₃, and a Teflon filter for SPM were mounted on the surface to measure the deposition fluxes of these substances. On the basis of simultaneous observations of the downward and upward deposition fluxes and the atmospheric concentration, deposition velocities of SO₂ and HNO₃ were estimated. The estimated deposition velocities were about 0.58 cm s^-1 for SO₂ and 0.99 cm s^-1 for HNO₃; these values agreed with the recently reported values obtained by various methods.
Although the relation to deposition on natural surfaces is unknown and the design and use of artificial collectors has not been standardized at the present time, the development of surrogate surfaces may be valuable for several potential uses. A simple suspension type surrogate surface would be useful for monitoring the dry deposition of certain reactive gasses such as HNO₃ and S0₂.

View full abstract