Real-world vehicle emissions: A summary of the 15th coordinating research council on-road vehicle emissions workshop

The Coordinating Research Council held its 15th workshop in April 2005, with nearly 90 presentations describing the most recent mobile source-related emissions research. In this paper, the authors summarize the presentations from researchers who are engaged in improving our understanding of the contribution of mobile sources to air quality. Participants in the workshop discussed emission models and emission inventories, results from gas- and particle-phase emissions studies from spark-ignition and diesel-powered vehicles (with an emphasis in this workshop on particle emissions), effects of fuels on emissions, evaluation of in-use emissions control programs, and efforts to improve our capabilities in performing on-board emissions measurements, as well as topics for future research.     

Overtime work as the antecedent of employee satisfaction,firm productivity,and innovation

Overtime work has been blamed for the deterioration of employee satisfaction and productivity. However, the organization‐level implications of overtime work as a normative expectation remain unclear. In this study, such effects were analyzed through human capital theory and a causal attribution approach. Various organizational outcomes and boundary conditions were explored in explaining these implications. The analysis of time lagged data from 273 firms affirmed that a firm's overtime level was related negatively to employee satisfaction. However, it was positively related to the firm's productivity and curvilinearly (inverted U‐shaped) related to innovation. The effects of the firm's overtime level on firm productivity and innovation were also moderated by organizational trust. This study highlights the costs and benefits of overtime work as tools for utilizing human capital and reveals the critical contingency of organizational trust that enables firms to attenuate the costs of the overtime level and accentuate its potential benefits.     

Use of autotrophic sulfur-oxidizers to remove nitrate from bank filtrate in a permeable reactive barrier system

This study was conducted to evaluate the potential applicability of an in situ biological reactive barrier system to treat nitrate-contaminated bank filtrate. The reactive barrier consisted of sulfur granules as an electron donor and autotrophic sulfur-oxidizing bacteria as a biological component. Limestone was also used to provide alkalinity. The results showed that the autotrophic sulfur oxidizers were successfully colonized on the surfaces of the sulfur particles and removed nitrate from synthetic bank filtrate. The sulfur-oxidizing activity continuously increased with time and then was maintained or slightly decreased after five days of column operation. Maximum nitrate removal efficiency and sulfur oxidation rate were observed at near neutral pH. Over 90% of the initial nitrate dissolved in synthetic bank filtrate was removed in all columns tested with some nitrite accumulation. However, nitrite accumulation was observed mainly during the initial operation period, and the concentration markedly diminished with time. The nitrite concentration in effluent was less than 2 mg-N/l after 12 days of column operation. When influent nitrate concentrations were 30, 40, and 60 mg-N/l and sulfur content in column was 75%, half-order autotrophic denitrification reaction rate constants were 31.73 x 10(-3), 33.3 x 10(-3), and 36.4 x 10(-3) mg(1/2)/l(1/2)min, respectively. Our data on the nitrate distribution profile along the column suggest that an appropriate wall thickness of a reactive barrier for autotrophic denitrification may be 30 cm when influent nitrate concentration is less than 60 mg-N/l.     

Accumulation of butyl- and phenyltin compounds in starfish and bivalves from the coastal environment of Korea

Triphenyltin (TPT) and tributyltin (TBT) concentrations were determined in two starfish species (Asteria pectinifera and Asterias amurensis), bivalves (Crassostrea gigas or Mytilus edulis), and seawater samples from sites around the coasts of Korea. Both TPT and TBT concentrations in starfish ranged from 8 to 1560 ng/g and from <2 to 797 ng/g as Sn on a dry weight basis, respectively. TPT concentration accounted for 75.4% and 86.4% of total phenyltin concentration in A. pectinifera and A. amurensis, respectively, while monobutyltin, a degradation product of TBT, accounted for 86.3% and 57.2% of total butyltin, respectively. Triphenyltin concentrations in A. pectinifera were significantly correlated to water and bivalve TPT concentrations, which implies that dietary uptake of TPT from contaminated prey as well as direct uptake from surrounding water contribute to TPT body residues in the starfish. Starfish could be target organisms for monitoring TPT compound in the marine environment, due to their high accumulation and low degradation capacity towards TPT.     

Specific accumulation of 20 trace elements in great cormorants (Phalacrocorax carbo) from Japan

This study is to elucidate the specific accumulation of 20 trace elements in tissues/organs of great cormorants from two different colonies (Lake Biwa and Mie) in Japan. In the body distribution of trace elements, some elements revealed tissue-specific accumulation such as most of the burden of Mo, Ag and Cd in liver, Tl and Cd in kidney, Cu, Rb and Cs in muscle, and V, Sr and Ba in bone. Gender-related variation was not observed in both populations for most of the trace elements, except for higher hepatic Sr in males from Lake Biwa. Hepatic V, muscular Hg and Tl, and Cd in liver, kidney and muscle increased with growth. Comparison of trace element levels in tissues between the two colonies showed that Cr, Rb, Sr, Cd, Cs, Ba and Tl levels were higher in Lake Biwa than in Mie, whereas Zn, Co and Hg in Mie samples were greater than Lake Biwa. Variations of elemental levels in stomach contents also showed similar patterns, thus, showing that dietary sources tended to be the main factor for these regional variations. Toxic Hg and Cd concentrations in the liver of cormorants from the two colonies were lower than those from other areas, implying relatively low exposure to these metals in the present study sites. Concentrations of V, Co, Ag, Cd, Cs, Hg, Tl, Pb and Bi in liver remained more or less at the same level between 1993 and 2003, while hepatic Cr, Mn, Cu, Zn, Se, Rb, Sr and Ba showed apparent decrease, which might be related to the biological factors.     

Increased 3HV Concentration in the Bacterial Production of 3-Hydroxybutyrate (3HB) and 3-Hydroxyvalerate (3HV) Copolymer with Acid-Digested Rice Straw Waste

Bacterial synthesis of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) copolymer [P(3HB-co-3HV)] using the hydrolysate of rice straw waste as a carbon source was affected by the composition of the hydrolysate, which depends highly on the rice straw pretreatment condition. Acid digestion with 2 % sulfuric acid generated larger production of P(3HB-co-3HV) than 6 % sulfuric acid, but 3HV concentration in the copolymer produced with 2 % acid hydrolysate was only 8.8 % compared to 18.1 % with 6 % acid hydrolysate. To obtain a higher 3HV mole fraction for enhanced flexibility of the copolymer, an additional heating was conducted with the 2 % acid hydrolysate after removal of residual rice straw. As the additional heating time increased a higher concentration of levulinic acid was generated, and consequently, the mole fraction of 3HV in P(3HB-co-3HV) increased. Among the conditions tested (i.e., 20-, 40-, 60-min), 60-min additional heating following 2 % sulfuric acid digestion achieved the highest 3HV mole fraction of 22.9 %. However, a longer heating time decreased the P(3HB-co-3HV) productivity, probably due to the increased intermediates concentrations acting as inhibitors in the hydrolysates. Therefore, the use of additional heating needs to consider both the increase in the 3HV mole fraction and the decrease in the P(3HB-co-3HV) productivity.     

Distribution of polycyclic aromatic hydrocarbons in agricultural soils in South Korea

The content and type of polycyclic aromatic hydrocarbons (PAH) in soils from paddy fields and upland areas in South Korea were determined using gas chromatography linked to mass spectrometry (GC–MS). The distribution map of total PAH content was obtained as a contour plot using a geographical information system. The overall distribution of PAH was found to be closely related to the pollution sources, the size of city and the type of industry. The average content of total PAH in all samples was 236 μg kg⁻¹, and the range was from 23.3 to 2834 μg kg⁻¹. The highest concentrations were found in soils sampled near iron processing plants. The concentration of PAH decreased in the order fluoroanthene>benzo(b)fluoroanthene>pyrene. Special PAH compound ratios, such as phenanthrene/anthracene and fluoroanthene/pyrene, were calculated to evaluate the origin. The collected data suggested that the pyrogenic origins such as motor vehicle exhaust and heavy industry emission were the dominant source of PAH in Korean soils.     

A resilience-based approach for comparing expert preferences across two large-scale coastal management programs

This report proposes a method for assessing resilience-building components in coastal social–ecological systems. Using the proposed model, the preferences of experts in Masan Bay (South Korea) and Puget Sound (USA) are compared. A total of 30 management objectives were determined and used to build a hierarchic tree designed using the principles of the Analytic Hierarchy Process (AHP). Surveys were performed with 35 Puget Sound experts using face-to-face interviews and with 28 Masan Bay experts by mail. The results demonstrate that the legal objective, which enables legislation, was the highest preferred component in both regions. The knowledge translation variable was also given a high preference score in both regions. An analysis of variance (ANOVA) showed that the Puget Sound experts significantly favored attention to education, habitat restoration and species protection objectives in comparison to the Masan Bay experts. The Masan Bay experts placed greater emphasis on legislation and the type of institutional design than did the Puget Sound experts. Using cluster analysis, four distinct groups of respondents were independently identified in Puget Sound and three groups were identified in Masan Bay. One unique subgroup in the Puget Sound experts group, which was characterized by its high preferences for habitat restoration and species protection, was not observed in Masan Bay. Demographic variables (length of career and role in coastal issue) failed to account for the differences in groupings and preferences in either region, except for the variable ‘favoring information source’ in the Puget Sound group. This finding implies that the demographic information was not related to differences in group opinions in both regions. The analysis framework presented here was effective in identifying expert preferences regarding the overall structure and emphasis in coastal management programs. Thus, this framework can be applied towards coastal policy development.     

Temperature Effect on Migration of Zn and Cd Through Natural Clay

To investigate the effect of temperature on effective diffusion coefficients and retardation factors for Zn and Cd, combined diffusion and sequential extraction analyses were conducted at 15 ^˚C and 55 ^˚C. The effective diffusion coefficients of the metals increased up to ten times according to the increased temperature. On the other hand, the effect of temperature on the retardation factor depended on the retention mechanisms of the metals. The distribution coefficient for Zn, which was mainly partitioned in the carbonate phase, increased up to two times with the increase in temperature. On the other hand, the distribution coefficient for Cd, which was mainly partitioned in the exchangeable phase, was hardly affected by the temperature change. Results of combined diffusion and sequential extraction analysis showed that the effect of temperature on the heavy metals’ (Zn and Cd) migration through the compacted natural clay was influenced by the combined effects of the diffusion coefficient and the retardation factor. Additionally, we could also observe the change in retention mechanism for the metals with the change in pore water concentration.