State of mixture of atmospheric submicrometer black carbon particles and its effect on particulate light absorption

The state of mixture of light-absorbing carbonaceous particles was investigated in relation to light absorption properties using electron microscopic examinations, black carbon (BC) analyses of quartz filter by thermal/optical reflectance (TOR) method, measurements with two continuous light-absorbing photometers at a suburban site of Tsukuba, about 60 km northeast of Tokyo. The volume fraction of water-soluble material (?) in individual particles is important for assessing particulate light-absorbing and/or scattering of atmospheric aerosols. The values of ? in BC particles were evaluated by electron micrographs before and after dialysis (extraction) of water-soluble material. The mass absorption coefficient (MAC in units of m² g^?1) tended to increase with increasing the average ? in BC particles with the radius range of 0.05–0.5 μm. Thus, our results indicate that coatings of water-soluble material around BC particles can enhance the absorption of solar radiation. Moreover, the single scattering albedo (SSA) will increase because a large amount of coating material will scatter more light.     

Influence of microorganisms on the behavior of technetium and other elements in paddy soil surface water

Insolubilization patterns of technetium (Tc) and other trace elements (Sc, Co, Zn, Se, Rb, Sr, Y, Nb, Ce, Pm, Gd, Lu, Hf, and Re) in surface water covering paddy fields were compared to gain insight into the behavior of Tc in an agricultural environment. The insolubilization of Tc, which did not pass through a 0.2-microm-pore-size filter, was mainly caused by bacteria. Among the 14 other elements investigated, Nb was insolubilized by bacteria and the amounts of insoluble Nb were positively correlated with those of Tc. Although Re is a chemical analog of Tc, no similarity was observed. These results suggest that Tc behaves similarly to Nb in the insolubilization in surface water covering paddy fields.     

The influence of paddy soil drying on Tc insolubilization by bacteria

Tc insolubilization in four soils samples was compared by pre-incubating them in both dry and wet states, then measuring Tc concentrations in solution when the samples were saturated with an excess of water spiked with 99Tc. Soils pre-incubated in a dry state showed higher Tc insolubilization than soils incubated in a wet state. To clarify the difference in Tc insolubilization, Eh, bacterial abundances, and bacterial species compositions in the dry and wet ponding water samples were determined. For the wet ponding water samples, Eh values were forced to decrease, but no increase in Tc insolubilization was observed. The dry and wet ponding water samples had similar numbers of bacteria. However, denaturing gradient gel electrophoresis analysis revealed that they had different bacterial species compositions. These results suggested the difference in bacterial species compositions would account for the difference in Tc insolubilization.     

Roadside particulate air pollution in Bangkok

Airborne fine particles of PM(2.5-10) and PM2.5 in Bangkok, Nonthaburi, and Ayutthaya were measured from December 22, 1998, to March 26, 1999, and from November 30, 1999, to December 2, 1999. Almost all the PM10 values in the high-polluted (H) area exceeded the Thailand National Ambient Air Quality Standards (NAAQS) of 120 microg/m3. The low-polluted (L) area showed low PM10 (34-74 microg/m3 in the daytime and 54-89 microg/m3 at night). PM2.5 in the H area varied between 82 and 143 microg/m3 in the daytime and between 45 and 146 microg/m3 at night. In the L area, PM2.5 was quite low both day and night and varied between 24 and 54 microg/m3, lower than the U.S. Environmental Protection Agency (EPA) standard (65 microg/m3). The personal exposure results showed a significantly higher proportion of PM2.5 to PM10 in the H area than in the L area (H = 0.80 +/- 0.08 and L = 0.65 +/- 0.04). Roadside PM10 was measured simultaneously with the Thailand Pollution Control Department (PCD) monitoring station at the same site and at the intersections where police work. The result from dual simultaneous measurements of PM10 showed a good correlation (correlation coefficient: r = 0.93); however, PM levels near the roadside at the intersections were higher than the concentrations at the monitoring station. The relationship between ambient PM level and actual personal exposures was examined. Correlation coefficients between the general ambient outdoors and personal exposure levels were 0.92 for both PM2.5 and PM10. Bangkok air quality data for 1997-2000, including 24-hr average PM10, NO2, SO2, and O3 from eight PCD monitoring stations, were analyzed and validated. The annual arithmetic mean PM10 of the PCD data at the roadside monitoring stations for the last 3 years decreased from 130 to 73 microg/m3, whereas the corresponding levels at the general monitoring stations decreased from 90 to 49 microg/m3. The proportion of days when the level of the 24-hr average PM10 exceeded the NAAQS was between 13 and 26% at roadside stations. PCD data showed PM10 was well correlated with NO2 but not with SO2, suggesting that automobile exhaust is the main source of the particulate air pollution. The results obtained from the simultaneous measurement of PM2.5 and PM10 indicate the potential environmental health hazard of fine particles. In conclusion, Bangkok traffic police were exposed to high levels of automobile-derived particulate air pollution.     

Motivation of Japanese companies to take environmental action to reduce their greenhouse gas emissions: an econometric analysis

To analyze the motivations of Japanese companies to take environmental actions to reduce their greenhouse gas (GHG) emissions, we used FY2006 research data and questioned Japanese industries regarding their reduction of GHG emissions. Empirical investigations revealed that voluntary targets set by industry organizations, government requirements, and advance responses to possible future regulations can positively influence environmental actions for GHG emission reduction; however, cost reductions and corporate social responsibility fulfillment cannot.

Cooperative web sharing against predators promotes group living in spider mites

I examined spider mite cooperative web sharing against predation as a factor promoting group living. Tetranychus urticae and Tetranychus kanzawai infest leaf surfaces under webs made of silk threads. Experimental observation of predation by the predatory mite Euseius sojaensis on spider mites of different group sizes revealed that fewer spider mites were preyed upon when the web-building period before the attack was prolonged, suggesting that established webs help protect spider mites. Moreover, per capita predation on spider mites was diluted in larger groups. This was not due to predator satiation but seemingly because webs had been completed while the initial prey was consumed. Spider mites lived more closely together in the presence of a predator, showing that the degree of group living is facultative. In the presence of a preceding spider mite with an established web, a newcomer spider mite gain protection by taking residence in the established webs; sharing the web was not disadvantageous for the preceding mite. The proportion of individuals preyed upon did not differ between preceding and newcomer mites, suggesting that there was no interference against the latter. These interactions were consistent between heterospecific spider mites. Because there was no detectable indirect interaction between mites sharing fresh webs, cooperative web sharing seemed to be a major force promoting group living in the spider mites. Moreover, the distances between spider mites did not differ between heterospecific and conspecific groups, demonstrating that mites living together do not distinguish between species; hence, heterospecific mites may cooperate and live together in the same manner as conspecifics.     

Gasification and smelting system using oxygen blowing for plastic waste including polyvinyl chloride

A new type of waste gasification and smelting system using oxygen blowing based on high-temperature metallurgy, was developed by Sumitomo Metals, Japan. This system can steadily gasify and melt not only municipal waste, but also plastic waste and polyvinyl chloride (PVC) waste by using a top-blow oxygen lance together with sideways-blow oxygen lances. As a result of gasification in the high-temperature reducing atmosphere and rapid gas cooling, dioxin-free, high-calorie purified gas was produced. Ash components in the wastes were smelted in a high-temperature reducing atmosphere, and high-quality slag free of heavy metals was produced. Most of the chlorine in the wastes was converted into hydrogen chloride in the off gas. The hydrogen chloride can be recovered as hydrochloric acid or chlorine, which are recyclable to PVC manufacturing.     

Novel malonate-type copolymers containing vinyl alcohol blocks as biodegradable segments and their builder performance in detergent formulations

Poly[(disodium methylene malonate)-co-(vinyl alcohol)] [P(DSMM-VA)] and poly[(disodium ethoxymethylene malonate)-co-(vinyl alcohol)] [P(DSEMM-VA)] containing a poly(vinyl alcohol) (PVA) block as a biodegradable segment were prepared and their biodegradability and functionality were evaluated and compared with those of the corresponding fumarate and maleate copolymers. It was found that the 1,1-dicarboxylate-type copolymers, P(DSMM-VA) and P(DSEMM-VA), showed better biodegradability than the corresponding 1,2-dicarboxylate-type copolymers, P(DSF-VA) and P(DSM-VA). This improved biodegradability of P(DSMM-VA) and P(DSEMM-VA) is probably attributable to their more expanded polymer chain in aqueous solution, which will be more accessible to the degrading enzymes. The minimum chain length of the PVA-block, which acts as a biodegradable segment in the polymer chain, is estimated to be 2–3 and 3–4 monomer units for P(DSMM-VA) and P(DSEMM-VA), respectively. On the other hand, the minimum PVA block is about 5 and 7 monomer units for the fumarate and maleate copolymers, respectively. It was confirmed that P(DSMM-VA) showed excellent builder performance compared to the corresponding fumarate copolymer.Paper presented at the Bio/Environmentally Degradable Polymer Society—Second National Meeting, August 19–21, 1993, Chicago, Illinois.     

Driver exposure to particulate matter in Bangkok

The aims of this study were to determine the particulate matter with aerodynamic diameters > or = 2.5 microm (PM2.5) and 2.5-10 microm (PM10-2.5) exposure levels of drivers and to analyze the proportion of elemental carbon (EC) and organic carbon (OC) in PM2.5 in Bangkok, Thailand. Four bus routes were selected. Measurements were conducted over 10 days in August (rainy season) 2008 and 8 days in January (dry season) 2009. The mean PM2.5 exposure level of the Tuk-tuk drivers was 86 microg/m3 in August and 198 microg/m3 in January. The mean for the non-air-conditioned bus drivers was 63 microg/m3 in August and 125 microg/m3 in January. The PM2.5 and PM10-2.5 exposure levels of the drivers in January were approximately twice as high as those in August. The proportion of total carbon (TC) in PM2.5 to the PM2.5 level in August (0.97 +/- 0.28 microg/m3) was higher than in January (0.65 +/- 0.13 microg/m3). The proportion of OC in the TC of the PM2.5 in August (0.51 +/- 0.08 microg/m3) was similar to that in January (0.65 +/- 0.07 microg/m3). The TC exposure by PM25 in January (81 +/- 30 microg/m3) remained higher than in August (56-21 microg/m3). The mean level of OC in the PM2.5 was 29 +/- 13 microg/m3 in August and 50 +/- 24 microg/m3 in January. In conclusion, the PM exposure level in Bangkok drivers was higher than that in the general environment, which was already high, and it varied with the seasons and vehicle type. This study also demonstrated that the major component of the PM was carbon, likely derived from vehicles.     

Difference in concentration trends of airborne particulate matter during rush hour on weekdays and Sundays in Tokyo,Japan

Suspended particulate matter (SPM) and fine particulate matter (less than or equal to 2.5 μm: PM_2.5) have generally been decreasing for the last decade in Tokyo, Japan. To elucidate the major cause of this decrease, the authors investigated the different trends of airborne particulates (both SPM and PM_2.5 concentrations) by evaluating comparisons based on the location of the monitoring stations (roadside vs. ambient), days of the week (weekdays vs. Sundays), and daily fluctuation patterns (2002 vs. 2010). Hourly mean SPM and PM_2.5 concentrations were obtained at four monitoring stations (two roadside stations, two ambient stations) in Tokyo, Japan. Annual mean concentrations of each day of the week and of each hour of the day from 2002 to 2010 were calculated. The results showed that (1) the daily differences in annual mean concentration decreased only at the two roadside monitoring stations; (2) the high hourly mean concentrations observed on weekdays during the daily rush hour at the two roadside monitoring stations observed in 2002 diminished in 2010; (3) the SPM concentration that decreased the most since 2002 was the PM_2.5 concentration; and (4) the fluctuation of hourly concentrations during weekdays at the two roadside monitoring stations decreased. A decreasing trend of airborne particulates during the daily rush hour in Tokyo, Japan, was observed at the roadside monitoring stations on weekdays since 2002. The decreasing PM_2.5 concentration resulted in this decreasing trend of airborne particulate concentrations during the daily rush hours on weekdays, which indicates fewer emissions were produced by diesel vehicles.

ImplicationsThe authors compared the trends of SPM and PM_2.5 in Tokyo by location (roadside vs. ambient), days of the week (weekdays vs. Sundays), and daily fluctuation patterns (2002 vs. 2010). The high hourly mean concentrations observed at the roadside location during rush hour on weekdays in 2002 diminished in 2010. The SPM concentration that decreased during rush hour the most was the PM_2.5 concentration. This significant decrease in the PM_2.5 concentration resulted in the general decreasing trend of SPM concentrations during the rush hours on weekdays, which indicates fewer emissions were produced from diesel vehicles.