Characterization of iron elution for seaweed bed restoration using a steelmaking slag and compost method

Coastal areas in Japan and other parts of the world have serious problems with barren grounds. A method has been developed that uses a mixture of steelmaking slag and compost including humic substances supplied in seawater, for restoring seaweed beds. The effects of this method have been previously confirmed in field tests. It was found that the mixture of steelmaking slag and compost was effective for extending the lifetime of iron elution as well as increasing iron concentrations in seawater. In this study, the effect of the mixing composts with steelmaking slag was evaluated additionally for increasing dissolved iron concentrations in seawater. The characteristics of iron elution were also studied using this method. In particular, the mechanism of Fe elution and dissolved Fe oxidation was examined in detail. The iron elution of actual seawaters was tested using three kinds of samples which involved steelmaking slag, compost, and a mixture of steelmaking slag and compost. These samples were used to understand the mechanism of Fe elution and oxidation in seawater. It was found that the mixture of steelmaking slag and compost was the most effective, which also confirmed the validity of the proposed Fe elution process in seawater.     

Bioaccumulation of butyltins and liver damage in the demersal fish Cathorops spixii (Siluriformes,Ariidae)

The toxicity of butyltin compounds (BTs), mainly tributyltin (TBT), has been reported in different organisms. However, such an analysis in fish after field exposure with reference to the related biomarkers has not been commonly observed in the literature. This study presents the uptake of BTs in the liver of a neotropical marine catfish Cathorops spixii in Paranagua Bay, an important estuarine system located in southern Brazil. Two different areas, close to and distant from the harbor, were used for chemical analysis evaluation of hepatotoxicity through genetic, enzymatic, and histopathological biomarkers. The presence of polycyclic aromatic hydrocarbons in bile was also considered as a biomarker. The results showed a significant relationship between TBT levels and the inhibition of biotransformation enzymes and high occurrence of melanomacrophages in fish collected close to the harbor site. These effects were linked to the absence of TBT metabolites in the liver. In the second site, the presence of DBT was associated with an increase in EROD and GST activity. The larger amount of DNA damage as well as the highest oxidative stress was noted in fish from the less TBT-polluted area, where DBT and bile PAHs occurred. These findings showed different impact levels due to or increased by the chronic exposure of biota to BTs.     

Detection of Escherichia coli in a cattle manure composting process by selective cultivation and colony polymerase chain reaction

Livestock manure is suitable for use as a composting material. However, various intestinal microbes, such as Escherichia coli, are significant components of such manures. Thus, it is desirable that the level of intestinal microbes, and particularly opportunistic pathogens, in compost is inspected and counted regularly. The sensitivity and specificity of detection of E. coli in compost have been improved by selective cultivation followed by colony polymerase chain reaction (PCR) using the ECO primer. Indeed, the sensitivity of this method is higher than that of DNA extraction from compost and PCR. In this study, changes in numbers of E. coli present in a field-scale composting process over time was assessed using selective cultivation and colony PCR. Numbers of ECO-positive colonies after 24 h decreased, with a concomitant rise in compost temperature. ECO-positive colonies were not detected from 33 to 48 h. However, ECO-positive colony numbers increased beginning on day 4 and continuing until day 42. Thus, it seems likely that the high temperatures reached during the composting process did not affect E. coli numbers in the final compost. Additionally, selective cultivation followed by colony PCR using specific primers is an appropriate method of determining levels of cultivable pathogens in composted materials.     

Nonthermal Plasma Chemical Processing of Bromomethane

ABSTRACT

Nonthermal plasma chemical decomposition of bromomethane (CH₃Br) was investigated with a coaxial type packed-bed plasma reactor. It has been demonstrated that plasma chemical processing is an effective approach to decompose CH₃Br in a wide concentration range. It has been shown that CH₃Br decomposition reactivity depends on reactor operating factors such as background gas, O₂ concentration, and humidification. Higher decomposition efficiencies can be obtained in dry N₂. However, organic byproducts such as BrCN are concurrently produced under deaerated conditions. Water suppresses CH₃Br decomposition and also affects the yields of CO_x (CO and CO₂) and organic byproducts due to the involvement of some active species generated from water. The presence of O₂ retards CH₃Br decomposition by quenching high-energy electrons, while it suppresses organic byproducts and improves CO_x yield. The reacted carbons in CH₃Br are recovered as CO_x almost quantitatively in air. Higher CO₂ selectivities cannot be achieved by increasing O₂ concentration. NO_x formation, which is accompanied by CH₃Br decomposition, can be effectively suppressed by decreasing O₂ concentration down to 2%. Furthermore, reaction mechanisms are discussed by comparing the reactivities of CH₃Br and its congeners.     

Sizing and Costing of Electrostatic Precipitators

This is the second of a two-part article that reviews electrostatic precipitation theory, presents size estimating methods, and gives costing procedures for a variety of electrostatic precipitator (ESP) types and sizes. Part I of the article, which appeared in the April 1988 issue of JAPCA, discussed theory and sizing; this part presents costing. Information is given for estimating total capital investment including separate costs for the bare ESP (five types) and auxiliaries. Factors are given for installation and for indirect costs. Direct and indirect annual costs are discussed. An example problem is given.     

Selection of product categories for a national eco-labelling scheme in developing countries: a case study of Vietnamese manufacturing sub-sectors

Although the selection of product categories is a deciding factor for the success of eco-labelling schemes, there are no consistent methods for determining selection factors and how to prioritise product categories for developing countries (DgCs). This paper attempts to identify appropriate factors for product category selection and formulate a prioritisation method applicable to DgCs. We first examined the selection factors currently utilised in schemes worldwide by conducting a questionnaire survey of representatives of foreign schemes. Selection factors were illustrated on a plot graph, which indicated the percentage of factors implemented in the schemes of DgCs and developed countries (DGs), and their plausibility assessed when utilised in the schemes of DgCs. In this way, we proposed three groups of factors: an exclusion factor, five core factors and seven operational factors. Then, under the conditions of DgCs, such as socioeconomic issues and availability of data, we used and modified some judging guidelines of the European Ecolabel (the EU Flower), e.g. determining the environmental impacts and potential of environmental improvements, in the scoring method to prioritise product categories by weighting factors. In light of our findings, we utilised the proposed factors and modified the scoring method to prioritise the screened primary list of product categories of Vietnamese manufacturing sub-sectors. By scoring factor-based questions and prioritising in three ways, i.e. following the scoring method of the EU Flower programme, totalling all values with equal weighting, and totalling all values but by doubling the weighting of core factors compared with operational factors, we observed that the weighted prioritisation differentiates priority product categories more clearly than the other methods. We propose the two highest potential candidates for eco-labelling in Vietnam, namely textile/garment and fishery products.     

The socially optimal recycling rate: Evidence from Japan

This paper estimates the average social cost of municipal waste management as a function of the recycling rate. Social costs include all municipal costs and revenues, costs to recycling households to prepare materials estimated with an original method, external disposal costs, and external recycling benefits. Results suggest average social costs are minimized with recycling rates well below observed and mandated levels in Japan. Cost-minimizing municipalities are estimated to recycle less than the optimal rate. These results are robust to changes in the components of social costs, indicating that Japan and perhaps other developed countries may be setting inefficiently high recycling goals.     

Compilation and application of a primary PM2.5 emissions inventory with high sectoral resolution in Japan

To elucidate the macro-structure of the PM_2.5 emissions generated by Japan's economic activities, this paper presents an emission inventory of primary particles of PM_2.5 with high sectoral resolution based on the Japanese Input–Output Tables, comprising some 400 sectors. These primary PM_2.5 emissions were estimated by multiplying the estimated energy consumption associated with each fuel type by a PM₁₀ emission factor incorporating the technological level of dust collection in each sector and the mass ratio of PM_2.5 to PM₁₀. Non-energy emissions from agricultural open burning were also determined. Total PM_2.5 emissions in 2000 were 252 kt, 49% of which were due to mobile emission sources. Changes in total PM_2.5 emissions between 1990 and 2000 were also calculated. This showed that a substantial increase in energy sector emissions due to rising coal consumption was offset by a sharp decline in emissions from road vehicles and shipping vessels, resulting in an overall decrease in total emissions. In addition, the emissions induced by economic demand in each sector were quantified by means of input–output analysis, which revealed that demand for construction, foods and communications and services constituted the principal causes of real domestic emissions. An assessment of sectoral contributions to PM_2.5 emissions that takes into account the effects of human exposure, expressed as external costs, suggests that the contribution of transportation is greater than indicated on the grounds of direct emissions alone.