Fabric-filter-supported catalyst for removal of harmful solid and gaseous compounds in municipal waste incinerator exhaust gas: characteristics of NO x reduction

We have investigated a fabric-filter-supported catalyst for removing harmful solid and gaseous compounds simultaneously from municipal incinerator exhaust gas. We studied the ways in which the efficiency of NO _x removal is influenced by filter temperature, gas flow rate, and catalyst content. The reduction of the catalyst content by mechanical reverse washing was investigated, and the state of the catalyst supported in the fabric filter was also observed using a scanning electron microscope. The catalyst supported by the fabric filter showed a removal efficiency above 75% when the filter temperature was 200°C, the gas flow rate was 1 m/min, and the catalyst content of the fabric filter was above 300 g/m². The catalyst was supported uniformly on the fibers of the fabric filter, and fine catalyst particles remained on the fibers after mechanical reverse washing. Received: October 15, 1997 / Accepted: March 19, 1999     

Growth and Nitrogen Availability of Red Pine Seedlings under High Nitrogen Load and Elevated Ozone

To evaluate the effect of increasing nitrogen (N) deposition and tropospheric ozone (O₃) concentrations on N-saturated forest ecosystems, we investigated the response of Japanese red pine (Pinus densiflora), an N-saturation sensitive tree species, to increasing N load under elevated O₃ concentrations. One-year-old seedlings of red pine were treated with three levels of N supply (0, 50 and 100 mg N L^-1 fresh soil volume) under two levels of atmospheric O₃ concentration (< 5 and 60 ppb) for two growing seasons. Nitrogen treatment did not stimulate dry matter production of the seedlings. Growth inhibition was observed in the highest N treatment under low O₃ and in the two higher N treatments under elevated O₃. Irrespective of the O₃ concentration, increasing N supply negatively affected root growth and mycorrhizal development in fine roots, resulting in a reduction in P and Mg uptake from the soil. Net photosynthetic rate was significantly reduced by both the highest N treatment under low O₃ and the two higher N treatments under elevated O₃, together with decreased N-availability to Rubisco. Nitrogen assimilated from NO₃ ^- to amino acid in the needles was not affected by the treatments. However, needle protein concentration was reduced by the highest N-treatment under low O₃ and by the two higher N-treatments under elevated O₃. These results suggest that elevated O₃ potentially disturbs the N-availability in the form of protein including Rubisco, and may advance the negative effects of excessive N-deposition on N-sensitive plant species in N-saturated forests.     

Sensitive monitoring of iodine species in sea water using capillary electrophoresis: vertical profiles of dissolved iodine in the Pacific Ocean

Using a novel high-sensitivity capillary electrophoretic method, vertical distributions of iodate, iodide, total inorganic iodine, dissolved organic iodine and total iodine in the North Pacific Ocean (0-5500 m) were determined without any sample pre-treatment other than UV irradiation before total iodine analysis. An extensive set of data demonstrated that the iodine behaviour in the ocean water collected during a cruise in the North Pacific Ocean in February-March 2003 was not conservative but correlated with variations in concentrations of dissolved oxygen and nutrient elements such as silicon, nitrogen and phosphorus. This suggests that the vertical distribution of iodine is associated with biological activities. The dissolved organic iodine was found in the euphotic zone in accord with observations elsewhere in the oceans. The vertical profile of dissolved organic iodine also appears to be related to biogeochemical activity. The concentrations of all measured iodine species vary noticeably above 1000 m but only minor latitudinal changes occur below 1000 m and slight vertical alterations can be observed below 2400 m. These findings are thought to reflect the stratification of nutrients and iodine species with different biological activities in the water column.     

Application of activated charcoal radon collectors in high humidity environments

Most commercially based activated charcoal radon collectors were designed for use in indoor environments. However, at present, they are often used for research in radon surveys in unique environments, such as in the bathrooms, underground areas, mines, caves and tunnels. In these environments, the relative humidity would be around 100%, and a change in the sensitivity of cpm(Bq m(-3))(-1)(radon) would occur. For this study, the reduction in the sensitivity of activated charcoal radon collector due to environmental humidity was investigated, and the data correction was discussed. Here, ST-100 (Pico-Rad) was selected as an example of a familiar activated charcoal radon collector. According to our performance test, the humidity of 90% (20 degrees C) resulted in a 15% reduction of the sensitivity for 24 h collection. The ST-100 user should discuss the necessity of data correction by comparing the change of sensitivity with other levels of estimation errors.     

Terrestrial isopods congregate under a low-level beta-emitter source

Ionizing radiation is ubiquitous, but very few experiments have investigated the biological effects of the natural background radiation at very low doses (>10 mGy/yr). We examined whether the background radiation, or radiation of a slightly higher level, has a role in evoking changes in behaviors of terrestrial isopods (woodlice). Upon exposure to a source giving 15 times the background level placed at one end of a box, a significant increase in the number of woodlice gathering under the beta-source was observed with time, as compared with the sham control. Terrestrial isopods have chemoreceptors (the olfactory system) on the terminal segment of their antennae. An additional experiment confirmed the involvement of these antennae in the radiation effect on behavior. After the excision of the antennae, no beta-taxis response was observed. The behavior of the group exposed to the source giving 30 times the background tended to decrease gradually in the area of the source, and the individuals aggregated in the area away from the source. Thus, the olfactory sensor in the antennae may be an important organ involved in the prompt response to radiation exposure, and the discrimination of the radiation field strengths of radioisotopes.