Improvement of an efficient separation method for chemicals in diesel exhaust particles: analysis for nitrophenols

GOAL, SCOPE, AND BACKGROUND: Diesel exhaust is believed to consist of thousands of organic constituents and is a major cause of urban pollution. We recently reported that a systematic separation procedure involving successive solvent extractions, followed by repeated column chromatography, resulted in the isolation of vasodilatory active nitrophenols. These findings indicated that the estimation of the amount of nitrophenols in the environment is important to evaluate their effect on human health. The isolation procedure, however, involved successive solvent extractions followed by tedious, repeated chromatography, resulting in poor fractionation and in a significant loss of accuracy and reliability. Therefore, it was crucial to develop an alternative, efficient, and reliable analytical method. Here, we describe a facile and efficient acid-base extraction procedure for the analysis of nitrophenols. MATERIALS AND METHODS: Diesel exhaust particles (DEP) were collected from the exhaust of a 4JB1-type engine (ISUZU Automobile Co., Tokyo, Japan). Gas chromatography-mass spectrometry (GC-MS) analysis was performed with a GCMS-QP2010 instrument (Shimadzu, Kyoto, Japan). RESULTS: A solution of DEP in 1-butanol was extracted with aqueous NaOH to afford a nitrophenol-rich oily extract. The resulting oil was methylated with trimethylsilyldiazomethane and subsequently subjected to GC-MS analysis, revealing that 4-nitrophenol, 3-methyl-4-nitrophenol, 2-methyl-4-nitrophenol, and 4-nitro-3-phenylphenol were present in significantly higher concentrations than those reported previously. DISCUSSION: Simple acid-base extraction followed by the direct analysis of the resulting extract by GC-MS gave only broad peaks of nitrophenols with a poor detection limit, while the GC-MS analysis of the sample pretreated with (trimethylsilyl)diazomethane gave satisfactorily clear chromatograms with sharp peaks and with a significantly lowered detection limit (0.5 ng/ml, approximately 100 times). CONCLUSION: The present method involving an acid-base extraction, in situ derivatization, and GC-MS analysis has shown to be a simple, efficient, and reliable method for the isolation and identification of the chemical substances in DEP.     

In situ gradostat for the study of a natural phytoplankton community with an experimental nutrient gradient

A new in situ gradostat was devised to study the dynamics of natural communities having nutrient gradients within aquatic habitats. This semi-enclosed mesocosm consisted of three components: i.e. three transparent, concentric cylindrical culture chambers, with diameters of 70, 60 and 40 cm, and 20 cm deep, supported by four flotation buoys, a medium reservoir, and a pump to supply the medium to the mesocosm. Water exchange between compartments was achieved via holes in the cylindrical walls, the number and size of the holes being chosen to regulate the rate of exchange. Sterile culture medium was pumped into the central (first) chamber and diffused outwards into the second and third chambers through the perforated walls. Suitable perforations could achieve a concentration gradient of up to 9.5 times between the first and third chambers within 12 h. The system was designed with the following characteristics: (1) an experimental semi-enclosed system in the natural environment; (2) to maintain equivalence with the external water except for the experimental factors; and (3) to form a manipulable gradient of experimental factors across the mesocosm. Using the in situ gradostat, the response of a natural phytoplankton community to a nitrate gradient was determined. A gradient from oligotrophic to eutrophic was maintained for 10 days in an oligotrophic pond. The mean growth rate of phytoplankton was lower in the eutrophic zone than that in the mesotrophic zone, where the highest mean growth rate was observed. The growth rate of each dominant phytoplankter showed its own pattern, but all rates were highest in the mesotrophic environment of the second chamber.     

Thresholds in eutrophication of natural waters

The population density of bacterioplankton and the concentration of dissolved organic carbon combined is a useful indicator to monitor subtle variations in the amount of eutrophication. Both parameters can be measured precisely and readily by widely accepted routine techniques that require little skill. Thresholds of eutrophication can be established to maintain the Health of Natural Waters using this indicator.     

Developments in an industry-led R&D program for recycling PVC products in Japan

To facilitate recycling, not only R&D but also the creation of efficient recycling systems—collection and processing of recyclates as well as finding appropriate end-uses—is essentially important. PVC has a particular advantage in regards to mechanical recycling when compared to other major plastics. However, there is no one-size-fits-all approach to a solution. Specific situations of used or off-cut products and their applications need to be well studied. Vinyl industry in Japan has devoted itself for many years to the promotion of recycling of vinyl products. It started an R&D support program in 2007 and seven projects have been completed since then. Some of the new developments include mechanical recycling for products like wall covering and tarpaulin which were considered difficult to recycle in the past. Progress in chemical recycling has been made with a technology for the removal of chlorine from shredder dusts. Recovery of chlorine is a challenge for the future. Collaboration among the various players involved in the recycling of a specific product is essential for obtaining a successful result.     

Biosynthesis and release of methylarsenic compounds during the growth of freshwater algae

Arsenic transformations by freshwater algae have been studied under laboratory conditions. By the use of a new analytical method, we identified methylarsenic(III) species in the growth medium of green-alga Closterium aciculare incubated under axenic conditions. The arsenate concentration in the experimental medium began to decrease just after inoculation, and the levels of arsenite and methylarsenicals increased with the growth of C. aciculare. Initially, most of the arsenate was converted into arsenite, which peaked in concentration during the exponential phase. Methylarsenicals accumulated rapidly in the stationary phase. DMAA(V) production was enhanced when the ratio of phosphate to arsenate decreased in the culture medium. The levels of DMAA(V) increased continuously toward the end of the experiment. On the other hand, methylarsenic(III) species remained relatively steady during the stationary phase. Methylarsenic(III) species accounted for 0-35% of methylarsenicals. These results suggest that arsenite and methylarsenicals (containing methylarsenic(III) species) are supplied by phytoplankton, and serve as evidence of the origin of methylarsenic(III) species in natural waters.     

Microbial clumps in seawater in the euphotic zone of Saanich Inlet (British Columbia)

Viable heterotrophic microorganisms were enumerated to be 3.7±7.3 bacterial cells per microbial clump during summer in the euphotic zone of Saanich Inlet, British Columbia, Canada. Large microbial aggregates were observed, especially after the phytoplankton bloom, when the phytoplankton biomass formed about 1/2 the total suspended organic matter in the sea. The cell number per microbial clump was minimal when the phytoplankton fraction in the total suspended organic matter was almost 0 (i.e., before the phytoplankton bloom), and again when the phytoplankton bloom occurred. The size of the microbial clumps is discussed, particularly in reference to the food chain in the sea.The work was carried out at the Fisheries Research Board of Canada, Biological Station, Nanaimo, during the tenure of a National Research Council Post-doctoral fellowship.     

Evidence of high organotrophic potentiality of bacteria in the deep ocean

The organotrophic potentiality of heterotrophic microorganisms 50 cm above the ocean floor (5,207 m depth) was measured in situ, at a station in the subarctic Pacific Ocean (44° N; 154° E). In certain enriched deep-sea samples incubated in situ, the microorganisms exhibited nearly the same organotrophic activity as those in the surface water layers. Rod-shaped barophilic bacteria (0.4 to 0.6 μ x 1.0 to 2.0 μ), which multiplied at a generation time of about 10 h, were responsible for this activity.     

The generative power of metaphor: long‐term action research on disaster recovery in a small Japanese village

Disaster recovery is a dynamic process of creating, maintaining, and changing the meaningful context of survivors. It is completed when they redevelop their self‐reliance and resume managing their social relations with a sense of community. This study employed action research to examine how researchers and survivors collaborated to change disaster recovery through the generative power of metaphor in a small village in Japan that experienced the Niigata–Chuetsu earthquake on 23 October 2004. It outlines long‐term collaborative practices as survivors undertook new activities owing to the power of the metaphor of ‘school’. Once ‘school’ was adopted as the metaphor for where survivors learnt new skills and passed on traditional knowledge, they created new metaphors and performed new activities independently, which is critical for recovery as it demonstrates self‐reliance. The paper assesses the reasons why generative metaphors worked effectively in this case and highlights some academic and practical implications for disaster recovery.     

Monitoring of eutrophication by microbial uptake kinetics of dissolved organic matter in waters

The monitoring of eutrophication can be performed by measuring the turnover times of amino acids in watermasses using the Wright-Hobbie uptake kinetics approach.The substrate specificity of amino acids varies greater with turnover times than with sampling location in watermasses with a certain water type. Thus a specific substrate among the essential amino acids should be selected to use for measuring the turnover time, in order to monitor precisely the state of trophic excitation within the steady-state oscillation in a certain aquatic system. On the other hand, either singular or plural substrates among the essential amino acids can be used for measuring the turnover time for the identification of a watermass, relevant to eutrophication.