Effect of aging time on the availability of freshly precipitated ferric hydroxide to coastal marine diatoms

Cell growth and iron uptake of the coastal marine diatoms Chaetoceros sociale and Thalassiosira weissflogii were studied in the presence of short-aged amorphous ferric hydroxide (am-Fe(III)) media. These were prepared by aging for 1 day, 3 days, and 3 weeks after adding a small amount of ferric iron acidic stock solution to autoclaved filtered seawater and were experimentally measured in culture experiments at 10°C for C. sociale and 20°C for T. weissflogii. The order of cell yields for both species was: 1-day aged am-Fe(III) >3-day aged am-Fe(III) >> 3-week aged am-Fe(III) media. The iron uptake rates by C. sociale during 0–1 day in 1 day and 3-day aged am-Fe(III) media were about two-thirds and one-fourths, respectively, lower than that in the direct Fe(III) input medium containing C. sociale into which an acidic Fe(III) stock solution was added directly. The longer aging time of am-Fe(III) in media results in reducing the supply of bioavailable iron in the media by the slower dissolution rate of am-Fe(III) with the longer aging time. These results suggest that the chemical and structural changes of freshly precipitated amorphous ferric hydroxide with short aging time affect their ability, such as iron solubility and dissolution rate to supply bioavailable iron for the phytoplankton growth. The chemical and structural conversion of solid iron phases with time is one of the most important processes in changing the supply of available iron to marine phytoplankton in estuarine and coastal waters and in iron fertilization experiments.     

Assessing local-scale inclusive wealth: a case study of Sado Island,Japan

Present trends of urbanization are accompanied by increasing demographic and economic shrinkage of rural regions. In countries such as Japan, these rural regions trail behind metropolitan counterparts according to GDP, the conventional measure used to guide governmental policies. Yet, past research suggests that these regions may be undervalued. Further, the Inclusive Wealth Index (IWI), largely only used at the national level, may be able to capture aspects previously missed. As such, our study attempts to highlight the wealth of rural regions by comparing the inclusive wealth of Sado Island and Japan between 1990 and 2014. Minor methodological modifications were made according to data availability at the local level and to improve the accuracy of human capital estimations. Results captured the ongoing shrinkage of Sado and demonstrate the distinct potential of the IWI as a stock measure. Sado’s per capita wealth was about 10% lower than the national averages, but its natural capital was about threefold national averages. Supplementary estimations of the natural capital of fisheries and cultivated forests suggest that inclusion of additional factors in the evaluation would further increase the relative valuation of rural regions. We discuss implications of our estimations for wellbeing, and conclude with a critical appraisal of the IWI calculation towards policy implementation of the index.     

Environmental restoration of Minamata: new thinking brings new advances

This paper discusses the idea of environmental restoration and the creation of sustainable cities of industry and culture by spotlighting how the city of Minamata, Japan, which was severely affected by environmental damage, is rejuvenating itself by means of a unique strategy based on a new way of thinking and the fostering of human resources. Taking its lead from the concept of environmental capacity building, this paper focuses on environmental restoration as (1) a mending process for the social environment and human relationships, (2) a strategy of actor participation, particularly citizen participation, in environmental restoration, and (3) a role for human resource development.     

Acetate biodegradation by anaerobic microorganisms at high pH and high calcium concentration

Acetate biodegradation at a high pH and a high calcium concentration was examined to clarify the effect of bacterial activity on the migration of organic ¹⁴C compounds in cementitious repositories.Tamagawa river sediment or Teganuma pond sediment was anaerobically cultured with 5 mM acetate and 10 mM nitrate at pH 9.5-12 at 30 °C. After 20 and 90 days, the acetate concentration of the culture medium was analyzed and found to have decreased below 5 mM at pH ≤ 11. On the other hand, it did not decrease when either sediment was incubated in the absence of nitrate. These results suggest that nitrate-reducing bacteria can biodegrade acetate under more alkaline conditions than the reported pH range in which nitrate-reducing bacteria can exhibit activity.Acetate biodegradation was also examined at a high calcium concentration. Sediments were anaerobically cultured at pH 9.5 with 5 mM acetate and 10 mM nitrate in solution, equilibrated with ordinary Portland cement hydrate, in which the Ca concentration was 14.6 mM. No decrease in acetate concentration after incubation of the sediments was observed, nor was it lower than in the absence of cementitious composition, suggesting that kinetics of acetate biodegradation by anaerobic microorganisms is lowered by a high Ca concentration.     

Material flow analysis of used personal computers in Japan

Most personal computers (PCs) are discarded by consumers after the data files have been moved to a new PC. Therefore, a used PC collection scheme should be created that does not depend on the distribution route of new PCs. In Japan, manufacturers’ voluntary take-back recycling schemes were established in 2001 (for business PCs) and 2003 (for household PCs). At the same time, the export of used PCs from Japan increased, affecting the domestic PC reuse market. These regulatory and economic conditions would have changed the flow of used PCs.In this paper, we developed a method of minimizing the errors in estimating the material flow of used PCs. The method’s features include utilization of both input and output flow data and elimination of subjective estimation as much as possible. Flow rate data from existing surveys were used for estimating the flow of used PCs in Japan for fiscal years (FY) 2000, 2001, and 2004. The results show that 3.92 million and 4.88 million used PCs were discarded in FY 2000 and 2001, respectively. Approximately two-thirds of the discarded PCs were disposed of or recycled within the country, one-fourth was reused within the country, and 8% were exported. In FY 2004, 7.47 million used PCs were discarded. The ratio of domestic disposal and recycling decreased to 37% in FY 2004, whereas the domestic reuse and export ratios increased to 37% and 26%, respectively. Flows from businesses to retailers in FY 2004 increased dramatically, which led to increased domestic reuse. An increase in the flow of used PCs from lease and rental companies to secondhand shops has led to increased exports. Results of interviews with members of PC reuse companies were and trade statistics were used to verify the results of our estimation of domestic reuse and export of used PCs.     

Rapid response to changing light environments of the calanoid copepod<Emphasis Type="Italic"> Calanus sinicus</Emphasis>

Calanus sinicus is a large calanoid copepod and a dominant species in the coastal waters of Japan. During a research cruise in Sagami Bay on 18 June 1996, we found C. sinicus performing an unusual diel vertical migration (DVM), a behavior that has not been reported in previous studies on this species. This study examined the DVM of C. sinicus under different light environments and revealed the copepods characteristic response to light. Field and laboratory results show that the DVM of C. sinicus is flexible and also confirmed its sensitivity and its rapid response to changing light environments. It is suggested that C. sinicus reacts to changes in absolute light intensity. This feature may be common in oceanic copepod species. The copepods quick reaction to light variation provides decreased predation risks and increased feeding opportunities, which make them a dominant survivor in coastal water habitats.Communicated by T. Ikeda, Hakodate     

Identification of sources contributing to Mid-Atlantic regional aerosol

Source types or source regions contributing to the concentration of atmospheric fine particles measured at Brigantine National Wildlife Refuge, NJ, were identified using a factor analysis model called Positive Matrix Factorization (PMF). Cluster analysis of backward air trajectories on days of high- and low-factor concentrations was used to link factors to potential source regions. Brigantine is a Class I visibility area with few local sources in the center of the eastern urban corridor and is therefore a good location to study Mid-Atlantic regional aerosol. Sulfate (expressed as ammonium sulfate) was the most abundant species, accounting for 49% of annual average fine mass. Organic compounds (22%; expressed as 1.4 x organic carbon) and ammonium nitrate (10%) were the next abundant species. Some evidence herein suggests that secondary organic aerosol formation is an important contributor to summertime regional aerosol. Nine factors were identified that contributed to PM2.5 mass concentrations: coal combustion factors (66%, summer and winter), sea salt factors (9%, fresh and aged), motor vehicle/mixed combustion (8%), diesel/Zn-Pb (6%), incinerator/industrial (5%), oil combustion (4%), and soil (2%). The aged sea salt concentrations were highest in springtime, when the land breeze-sea breeze cycle is strongest. Comparison of backward air trajectories of high- and low-concentration days suggests that Brigantine is surrounded by sources of oil combustion, motor vehicle/mixed combustion, and waste incinerator/industrial emissions that together account for 17% of PM2.5 mass. The diesel/Zn-Pb factor was associated with sources north and west of Brigantine. Coal combustion factors were associated with coal-fired power plants west and southwest of the site. Particulate carbon was associated not only with oil combustion, motor vehicle/mixed combustion, waste incinerator/industrial, and diesel/Pb-Zn, but also with the coal combustion factors, perhaps through common transport.     

Application of OMI observations to a space-based indicator of NOx and VOC controls on surface ozone formation

We investigated variations in the relative sensitivity of surface ozone formation in summer to precursor species concentrations of volatile organic compounds (VOCs) and nitrogen oxides (NO_x) as inferred from the ratio of the tropospheric columns of formaldehyde to nitrogen dioxide (the “Ratio”) from the Aura Ozone Monitoring Instrument (OMI). Our modeling study suggests that ozone formation decreases with reductions in VOCs at Ratios <1 and NO_x at Ratios >2; both NO_x and VOC reductions may decrease ozone formation for Ratios between 1 and 2. Using this criteria, the OMI data indicate that ozone formation became: 1. more sensitive to NO_x over most of the United States from 2005 to 2007 because of the substantial decrease in NO_x emissions, primarily from stationary sources, and the concomitant decrease in the tropospheric column of NO₂, and 2. more sensitive to NO_x with increasing temperature, in part because emissions of highly reactive, biogenic isoprene increase with temperature, thus increasing the total VOC reactivity. In cities with relatively low isoprene emissions (e.g., Chicago), the data clearly indicate that ozone formation became more sensitive to NO_x from 2005 to 2007. In cities with relatively high isoprene emissions (e.g., Atlanta), we found that the increase in the Ratio due to decreasing NO_x emissions was not obvious as this signal was convolved with variations in the Ratio associated with the temperature dependence of isoprene emissions and, consequently, the formaldehyde concentration.