The authors have so far demonstrated that production of fine TiO2 powder is possible by gas phase hydrolysis of titanium tetraisopropoxide (TTIP). In this paper, the effects are discussed of the shape of reactor and operational condition, such as mixing condition on the produced particle properties especially particle diameter of produced TiO2 fines. Our originally designed reactor was used, in which the steam vapor was fed from the bottom of the reactor then transported through an internal thin tube in the heated part of the reactor, and then mixed with TTIP fed from the top of the reactor without heating. The TiO2 fines were produced by 1.00 ml/min of TTIP gas flow (RC I) at 200, 300, 400 and 500°C of the reactor temperature with 10.0 ml/min (at 25°C) of TTIP gas flow (RC II). The particle diameter of TiO2 produced by gas phase synthesis was the smallest at 200°C, while the produced TiO2 showed increased crystallinity and photochemical activity with increased reaction temperature. The photocatalytic activity of TiO2 fines produced at 500°C was around 1/10, while that of the calcinated TiO2 fines produced at 200°C under RC II was 1/4 compared with that of JRC-TIO-4, respectively. The results of the photocatalytic activity tests suggested the activity is expected to be increased not only with increased crystallinities but also with decreased particle size.
In aquatic environments, the bacterial decomposition of organoarsenic compounds, such as dimethylarsinic acid ((CH3)2AsO(OH); DMAA), was important for evaluation of the dynamics of each arsenic species. The process of the arsenic cycle has been investigated by many researchers. In study, the PCR-DGGE analytical method was established for investigating the microbial community in Lake Kahokugata. When the volume range from 50 to 1.5 mL of water samples were tested for the DNA extraction, the PCR products of 16S rDNA fragments were efficiently obtained from the 1.5 mL of water samples. When water samples were digested using enzyme with (shaken-sample) or without shaking (static-sample), the more amounts of 16S rDNA fragments were amplified from the shaken-samples. Moreover, the phenol extraction with CTAB treatment more efficiently induced the PCR amplification than that without CTAB treatment. On the acrylamide gels of DGGE analysis, the PCR products of shaken-sample with or without CTAB treatment and static-sample with or without CTAB treatment indicated similar band patterns, suggesting that the DNA extraction treatments used in this study did not influence the detectable bacterial compositions. After DMAA was added at final concentrations of 1 μmol/l to the sample water, the DMAA was remarkably degraded at the 14th day. On the DGGE gel image, a few of bands were specifically detected in the DMAA addition sample at the 14th day. Presumably, the DMAA addition induce the growth of specific bacteria relating to the aquatic DMAA-degradation.
The microbial particles transported by Asian desert dust (KOSA) possibly impact ecosystems and human health in the downwind environments, and are commonly termed “bioaerosols” including viruses, bacteria, fungi, and pollen. The snow cover at Mount Tateyama records the information of aerosol particles during the winter and early spring, and includes microorganisms with sand particles carried from the China. The microorganisms in snow samples including sand particles grew in media containing up to 10 % NaCl, while the control-snow sample showed no microbial growth, suggesting that bacteria tolerant to high salinities remain viable with sand particles. Denaturing gradient gel electrophoresis using 16S rDNA sequences revealed that the microbial compositions in the snow samples varied among the snow layers and that dominant bacterial species belonged to the members of the genus Bacillus and Propionibacterium. Minor species were composed of the members of Cytophaga-Flexibacter group and beta-proteobacterial subdivision, which are minor species in the atmosphere. Presumably, the viable halotolerant bacteria were frequently transported to Mt. Tateyama by the long-range KOSA particle transport from China and the bacterial species compositions may change depending on the dates of KOSA dust events.
In this study, a two-layer box model was constructed for the estimation of nutrient budgets in Inohana Lake Estuary, and the reliability of the model was evaluated by comparing the model-based ΔDIP and the average chlorophyll-a concentration measured in the surface. The surface chlorophyll-a was very significantly related to ΔDIP (R2 = 0.95). This result suggests that the model based on the mass balances of water, salt and nutrients can provide a good estimate of the seasonal nutrient behavior in Inohana Lake Estuary.
Calcium phosphates were prepared from sea urchin shells and artificial phosphorus waste fluid. The calcined shells were dissolved in hydrochloric acid solution, and then filtered. This sea urchin shell extract was mixed with the artificial phosphorus waste fluid prepared from sodium dihydrogen phosphate. It was then adjusted to pH 7 using sodium hydroxide solution. The obtained precipitate contained the organic coloring material from sea urchin shell calcined at lower temperature. The main component of the precipitate was CaHPO4·2H2O. This phosphate was changed to Ca2P2O7 by heating because of the condensation reaction. The chemical composition, particle shape, and size were not strongly affected by the heating temperature for the pretreatment.
A total of 74 species of phytoplankton were found in Lake Lutan where beneath the floating macrophyte mat, IR was higher than at open water zone, OW. Euglenoids, Diatoms and Chlorophytes predominantly occurred. Density and biomass were higher at IR than OW, and chlorophyll-a was the opposite. Statistically, it was, however, no significantly different between OW and IR, even if the presence of macrophytes slightly attributed high diversity and abundance of phytoplankton in IR. Chlorophyll-a was detected higher in low than in high water period on both sites by 2-ways ANOVA. Chlorella sp1. was significant in density among abundant phytoplankton species by 3-ways ANOVA and MCA. CCA revealed water level fluctuation greatly influenced other physico-chemical factors, and by constraining physico-chemical parameters, dissolved oxygen, water level and temperature were significantly correlated with some abundant species of phytoplankton at OW and IR sites of Lake Lutan.
The distribution of Japanese mitten crab (Eriocheir japonica (de Haan)) was researched in three river systems in the Imizu plain, central Toyama, and the effects of dams and weirs on the upstream movement of the crabs were examined. Mitten crabs could pass the dams and weirs when the dams or the stream banks below the dams had a gentle slope and a rough surface; sometimes, stems and leaves attached to the dams and slope faces helped crabs climb. Crabs did not pass the dams when such conditions were not present, even if the slopes were only about 1m high. It was confirmed that mitten crabs would reach the most upstream areas if there was no critical obstacle. In the studied rivers, the presence of many dams and weirs worsened the river environment.
The storm-runoff loads of nitrogen and phosphorus were observed during seven events in the two experimental small paddy-fields watersheds, the wheat watershed (7.44 ha) and the rice watershed (6.96 ha). The drainage concentrations of total nitrogen (TN) were ranged from 2.70 to 9.86 mg l-1 in the wheat watershed and from 1.56 to 2.18 mg l-1 in the rice watershed. Those of total phosphorus (TP) were ranged from 0.104 to 0.780 mg l-1 and from 0.164 to 0.338 mg l-1, respectively. In the first storm event after the plowing and basal fertilizer, TN and TP concentration of the wheat watershed was the highest in all events. In this event, the TN and TP concentration of the wheat watershed was 5.3 and 2.5 times higher and storm-runoff load was 4.1 and 1.9 times larger than the same event of the rice watershed, respectively. In this event, nitrate nitrogen (NO3-N) and particulate phosphorus (PP) occupied 75% of TN and 47% and TP of the wheat watershed, respectively. As a result, it suggests that the wheat cropping in rice-paddy fields increases the runoff-load of TN and NO3-N.