The mixtures of ammonium dihydrogenphosphate, zinc carbonate, and manganese carbonate with the molar ratios of P/(Zn+Mn) = 1/1 and Mn/Zn = 0/100, 0.5/99.5, 1/99, 2/98, 20/80 were ground with planetary-mill. The thermal behavior of milled samples was investigated with differential thermal analyses, X-ray diffraction, and Fourier transform infrared spectroscopy. In addition, thermal products were estimated from scanning electron micrograph, particle size distribution, specific surface area, and fluorescence spectra. By mechanochemical treatment, the substitution reaction to NH4ZnPO4 took place without heating. Because the mechanical treatment before heating improved the sintering of phosphate, the specific surface area became small. The fluorescent peak appeared in the spectra of materials at lower temperature by milling.
Kosa (Asian dust) events were observed by the Japan Meteorological Agency in western Japan from April 12 to 17, 2003, and in Toyama from April 14 to 15. Atmospheric aerosol samples were collected in Toyama using a high-volume air sampler during the period from April 12 to 19, 2003. The dominant ionic species in the aerosol samples were SO42- anions. The dominant cation was Ca2+ before April 15 and NH4+ after April 15. The concentrations of non-sea-salt (nss) Ca2+, NO3-, nssMg2+, and Sr in aerosols were high from April 14 to 15 and decreased afterwards. Calcium concentrations in the aerosol samples showed good correlation with those of nssMg2+ and Sr. The average molar ratios of nssMg2+/nssCa2+ (0.15) and Sr/Ca (0.0022) in the aerosol samples were similar to the ratios found in Chinese desert soils, suggesting that the aerosols collected in Toyama were continuously affected by mineral dust from the Asian continent during this period, although the concentrations varied.
Lanthanum phosphate quantitatively coprecipitated iron(III) ion over the pH range of 2-7 and iron(II) ion at the pH of more than 5, however, the recovery of iron(II) ion decreased with a decrease of the pH below 5. Since the coprecipitation of iron ion could be effectively suppressed at pH 2.8 by the addition of ascorbic acid as a reducing agent and lead(II) ion was also quantitatively coprecipitated with lanthanum phosphate without any influence of ascorbic acid at this pH, lead(II) ion ranging from 1-50 μg could be efficiently separated from 100 mL of the solution containing up to 500 mg of iron ion. The separated lead(II) ion could be readily determined by inductively coupled plasma atomic emission spectrometry. The detection limit (3σ) in this method was 0.47 μg of lead(II) ion. This method was applicable to the determination of lead in iron waste.
Coal is an important energy source in East Asia. Acid rain caused by emissions of sulfur dioxide is an environmental issue on a global scale. Environmental protection is the most important subject. This author investigated environmental regulations and the current situation of flue gas desulfurization (FGD) at coal-fired power plants. The author compared the advantages of main FGD processes: the limestone gypsum process, the sea water washing process, the catalyst SOx oxidation process (CASOX), the activated carbon heating desorption process, the lime-base spray dry process, the furnace limestone injection process and electron beam. In order to select an appropriate FGD process, it is necessary to compare both the technological and economical advantages. Consequently, since the limestone gypsum process has a performance of more than 95 % removal of sulfur dioxide, it is suitable for a large capacity coal-fired power plant. The lime-base spray dry process and CASOX process are simple, so they are more suitable for a small capacity coal-fired power plant.
Many streams on Kureha Hill, Japan, suffer from acidification caused by nitrogen saturation. At the Hyakumakidani watershed, one of the streams on Kureha Hill, the nitrogen budget is such that the input nitrogen is much higher than the output nitrogen. This fact indicates that the excess nitrogen leached to the stream water has sources within the watershed. The purpose of the current study was to identify the source of nitrogen leached into the streams. Incubation experiments of soils and soil cores taken from several different horizons of the Hyakumakidani watershed were conducted to investigate the location at where the nitrate was generated in terms of the soil layers. In the incubation experiment of soils, the soil taken from the A horizon showed the highest nitrification rate, while the soil taken from the B horizon and the C horizon showed much lower rates. I n the incubation experiments of soil cores, NH4Cl solutions were dropped into the cores to simulate rainfall. The nitrate concentration of the drainage water from the A horizon core had a much higher concentration of nitrate than the NH4Cl solutions, while the nitrate concentration of the drainage water from the B horizon core was nearly equal to that of the NH4Cl solutions. The results of these experiments indicate that the source of nitrate was within the A horizon.
Predator-prey relationships between bacteria and predators including protozoa and metazoa in the anaerobic-aerobic (oxic) enhanced biological phosphorus removal (EBPR) activated sludge process were analyzed using a mathematical model to clarify the roles of these micro-organisms. The analysis revealed that the growth rate of predators in the oxic phase, μpb, has a little effect on the ratio of MLSS of predator (P-SS) and total MLSS, and that the growth limit of predators as a ratio of MLSS of bacteria (B-SS) and P-SS in the oxic phase, GLRpb, has large effect on the ratio of P-SS and total MLSS. In the steady state, B-SS increases rapidly with GLRpb increases from one to eight, then increases gradually with GLRpb increases to forty. P-SS decreases during GLRpb increases from one to forty. Clarifying the relationships between predator and bacteria would contribute to waste sludge reduction.
The mechanisms of nitrate leaching from a nitrogen-limited watershed to a stream on Imizu Hill were studied. High concentrations of nitrate in the stream water were observed not only episodic events but also low flow rate condition in the stream. While watershed of this stream is on nitrogen-limited condition, high concentrations of nitrate (242 μeq/l) were observed in the surface (0.3 m of depth) soil water. When high concentrations of nitrate in the stream water i.e. over 20 μeq/l were observed, a rapid percolation of rain water into the depth of 1 m could be seen by soil temperature profile. It seems that the watershed turn to nitrogen-saturate condition from nitrogen-limited condition when rapid percolation of soil water often occurred.