Inactivation effect of pressurized carbon dioxide on bacteriophage Qβ and ΦX174 as a novel disinfectant for water treatment

The inactivation effects of pressurized CO2 against bacteriophage Qβ and ΦX174 were investigated under the pressure of 0.3–0.9 MPa, initial concentration of 107–109PFU/mL, and temperature of17.8°C–27.2°C. The optimum conditions were found to be 0.7 MPa and an exposure time of 25 min. Under identical treatment conditions, a greater than 3.3-log reduction in bacteriophage Qβ was achieved by CO2, while a nearly 3.0 log reduction was observed for phage ΦX174. The viricidal effects of N2O(an inactivation gas with similar characteristics to CO2), normal acid(HCl), and CO2 treatment with phosphate buffered saline affirmed the chemical nature of CO2 treatment. The pumping cycle, depressurization rate, and release of intracellular substances caused by CO2 were its viricidal mechanisms. The results indicate that CO2 has the potential for use as a disinfectant without forming disinfection by-products.     

Post furnace formation of PCDDs and PCDFs in MSWI: Observations in an incinerator installed with quench reactor

Reduction of dioxin emission by a quench reactor with lime spray was investigated in relation to post furnace formation pathways. Results showed that the quench reactor performed to supress post furnace reaction of precursor molecules to form selected congeners of PCDD and PCDF.     

Life cycle assessment of integrated recycling schemes for plastic containers and packaging with consideration of resin composition

Many life cycle assessment studies have evaluated and compared the environmental performance of various technologies for recycling plastic containers and packaging in Japan and other countries. However, no studies have evaluated the combination of recycling technologies in consideration of the resin composition in terms of the quantity of each recycled product so as to maximize their environmental potential. In this study, 27 scenarios of recycling schemes for household waste plastic containers and packaging are developed through integrating a conventional recycling scheme with additional recycling schemes. The conventional recycling scheme involves municipal curbside collection and either the material recycling or feedstock recycling of waste plastics. The additional recycling schemes are feedstock recycling in steel works of the residue from conventional material recycling processes, and corporate voluntary collection and independent material recycling of specific types of plastic trays. Life cycle assessment based on the modeling of recycling processes considering the resin composition in terms of the quantity of each recycled product is applied to evaluate and compare these scenarios from the viewpoints of fossil resource consumption and CO₂ emission. The results show that the environmental loads are reduced in all scenarios including the additional recycling schemes compared with the conventional recycling scheme. However, the independent plastic tray recycling scheme exhibits lower additional environmental savings when the residue recycling scheme is integrated with the conventional material recycling scheme. This is because both additional recycling schemes aim to utilize polystyrene and polyethylene terephthalate, which would otherwise be incinerated as residue from material recycling processes. The evaluation of the environmental loads of plastic recycling with consideration of the resin composition in terms of the quantity of each recycled product makes it possible to investigate recycling schemes that integrate different technologies to maximize their environmental potential.     

Seasonal and spatial variation of atmospheric 210Pb and 7Be deposition: features of the Japan Sea side of Japan

Monthly depositional fluxes of (210)Pb and (7)Be at Tatsunokuchi, Japan which faces the Japan Sea were studied over a 12-year period from 1991 to 2002. The data were compared with the spatial variability of these fluxes at Taejon in Korea and at 11 other sites in Japan from Ishigaki of the southern islands of Okinawa to Wakkanai of the northern end of Hokkaido over a 2-year period from 2000 to 2001. The monthly depositions of both (210)Pb and (7)Be at Tatsunokuchi revealed very similar seasonal variations with a single peak; both depositions were high in winter and low in summer. This phenomenon was found to be not transient but stationary. The deposition of these nuclides was much greater on the Japan Sea side of Japan than on the Pacific Ocean side. The cause for high deposition of (210)Pb and (7)Be in winter might be explained by a combination of a series of the following processes: blowing out of air masses with a high (210)Pb concentration near the surface layer over the continent by strong winter monsoons, additional flow of cold air masses with high (7)Be concentration at high latitude, well-mixing with generation of ascending current and convection clouds over the Japan Sea, and heavy snowfalls accompanying them.     

Atmospheric BTEX-concentrations in an area with intensive street traffic

The major threat to clean air in developed and industrializing countries is now posed by traffic emissions. The effects of traffic road modifications on the air quality are, however, rarely reported in the literature. The aim of this study was to determine the influence of the modernization and renovation of a traffic artery in the region of Mortsel (Antwerp, Belgium) on the concentration of volatile organic compounds such as: benzene, toluene, ethylbenzene and m-, p-, o-xylenes (BTEX). The original goal of the reconstruction works was to reduce the traffic lanes of one of the busiest streets in Antwerp, in order to discourage the road traffic and in consequence also to improve the air quality in this region. The average concentrations of BTEX before these works in 2003 were: 1.6, 7.0, 0.9, 2.3, and 0.9 μg/m³, for benzene, toluene, ethylbenzene, m + p xylenes, and o-xylene, respectively. However, after the completion of the works, in 2005, they were slightly higher: 2.5, 9.5, 1.6, 3.4, and 1.3 μg/m³, respectively. The scatter plots of benzene against toluene, ethylbenzene and xylenes in 2003 and 2005 showed very good correlations. This fact indicated that all of the measured compounds originated from the same source, namely the road traffic. Moreover, the data obtained from an air-monitoring station at less than 6 km distance from the sampling site (operated by the Flemish Environment Agency, and located in Borgerhout, Antwerp), confirmed the lack of influence of background concentrations of BTEX. The obtained results led to the conclusion that the reduction of the number of traffic lanes had apparently increased the traffic jams and also increased the emission from cars. Therefore, these modernization works had even a negative impact on the local concentration of traffic-related pollutants as BTEX.     

Vertical distribution of <Emphasis Type="Italic">Todarodes pacificus</Emphasis> (Cephalopoda: Ommastrephidae) paralarvae near the Oki Islands,southwestern Sea of Japan

The diel vertical distribution patterns of Japanese common squid, Todarodes pacificus, paralarvae were examined using a Multiple Opening Closing Net and Environmental Sensing System (MOCNESS) in the southwest Sea of Japan near the Oki Islands (Japan) during five late-autumn surveys in 1998–2002. A total of 1,511 paralarvae ranging in mantle length (ML) from 0.7 to 7.3 mm were collected at 63 of the 68 stations surveyed. Most (84%) were collected above 75 m depth and in the mixed layer. The vertical distribution patterns varied little between day and night. Hatchling-sized (<1.0 mm ML) paralarvae were abundant at 0–25 m depth, and paralarval ML increased with increasing sampling depth. Our results suggest that T. pacificus paralarvae do not exhibit large diel vertical migration patterns, but as they increase in size, paralarvae gradually descend in the water column and the variability in depth increases with ontogeny.