Killing of marine phytoplankton by a gliding bacterium Cytophaga sp., isolated from the coastal sea of Japan

A marine gliding bacterium Cytophaga sp. (strain J18/M01) was isolated from Harima-Nada, eastern Seto Inland Sea, Japan in 1990. This bacterium preys upon various species of marine phytoplankton. All of the five raphidophycean flagellates, all of the four diatoms, and one of the two dinoflagellates examined were killed within a few days when cultured with the bacterium. The bacterium presumably achieves this by direct attack, because the culture filtrate in which host organisms were totally destroyed had no significant effects on the growth of the same host organism (Chattonella antiqua). If one or a few bacterial cells were inoculated into C. antiqua culture, all of the host organisms were killed. The bacterium proliferated in filter-sterilized seawater, suggesting its ubiquitous existence in the coastal sea. The killing of phytoplankton by bacteria such as Cytophaga sp. J18/M01 may be a significant factor influencing the population dynamics of phytoplankton in nature and may contribute to the sudden disappearance of red tides in the coastal sea. Bacterial destruction of phytoplankton may also be a factor that regulates primary productivity in marine ecosystems.     

Hydrothermal solidification of municipal solid waste incineration bottom ash with slag addition

Hydrothermal solidification of municipal solid waste incineration (MSWI) bottom ash has been carried out under saturated steam pressure (1.56 MPa) at 200 °C for up to 24 h by mixing quartz, slaked lime and water-cooled blast furnace slag (WBFS). The strength enhancement for the WBFS addition was best. The strength development was shown to be due mainly to tobermorite formation, and the tobermorite formation densified matrix, thus promoting the strength development. WBFS seemed to have a higher reactivity than the quartz during the initial hydrothermal process, which provided more silica available to harden the solidified specimens. However, a longer curing time (24 h) was favorable to the quartz dissolution for tobermorite formation, which in turn, enhanced the strength for quartz addition. Curing time affected the crystal morphology evolution, and the stubby plate of tobermorite seemed to result in a high strength enhancement in this study. Laboratory leaching tests were conducted to determine the amount of heavy metals dissolved from the final solidified specimens, and the leaching results showed that after hydrothermal processing the heavy metals dissolved from the solidified specimens were reduced effectively. As such, the hydrothermal processing may have a high potential for recycling/reusing MSWI ash on a large scale.     

Environmental Degradation of Biodegradable Polyesters: 3. Effects of Alkali Treatment on Biodegradation of Poly(ε-Caprolactone) and Poly[(R)-3-Hydroxybutyrate) Films in Controled Soil

The poly(-caprolactone) (PCL) and poly[(R)-3-hydroxybutyrate] (R-PHB) films with a hydrophilic surface were prepared by the alkali treatment of their as-cast films in NaOH solutions of different concentrations. The alkali-treated PCL and R-PHB films, as well as the as-cast PCL and R-PHB films, were biodegraded in soil controlled at 25°C and the effects of alkali treatment or surface hydrophilicities on their biodegradation were investigated by the use of gravimetry, gel permeation chromatography (GPC), scanning electron microscopy (SEM), and polarization optical microscopy. It became evident that the alkali treatment enhanced the hydrophilicities and biodegradabilities of the PCL and R-PHB films in soil. The biodegradabilities of the as-cast aliphatic polyester films in controlled soil decreased in the following order: PCL > R-PHB > PLLA, in agreement with that in controlled static seawater.     

环境监测技术的现状及发展趋势

根据日本环境质量标准发展的需求,结合欧洲新近实施的相关环境标准,分析了环境监测技术需求和发展方向.