Sensitivity analysis of source regions to PM2.5 concentration at Fukue Island,Japan

The authors analyze the sensitivities of source regions in East Asia to PM_2.5 (particulate matter with an aerodynamic diameter of ≤2.5 µm) concentration at Fukue Island located in the western part of Japan by using a regional chemical transport model with emission sensitivity simulations for the year 2010. The temporal variations in PM_2.5 concentration are generally reproduced, but the absolute concentration is underestimated by the model. Chemical composition of PM_2.5 in the model is compared with filter sampling data in spring; simulated sulfate, ammonium, and elemental carbon are consistent with observations, but mass concentration of particulate organic matters is underestimated. The relative contribution from each source region shows the seasonal variation, especially in summer. The contribution from central north China (105°E–124°E, 34°N–42°N) accounts for 50–60% of PM_2.5 at Fukue Island except in summer; it significantly decreases in summer (18%). Central south China (105°E–123°E, 26°N–34°N) has the relative contribution of 15–30%. The contribution from the Korean Peninsula is estimated at about 10% except in summer. The domestic contribution accounts for about 7% in spring and autumn and increases to 19% in summer. We also estimate the relative contribution to daily average concentration in high PM_2.5 days (>35 μg m^?3). Central north China has a significant contribution of 60–70% except in summer. The relative contribution from central south China is estimated at 46% in summer and about 30% in the other seasons. The contributions from central north and south China on high PM_2.5 days are generally larger than those of their seasonal mean contributions. The domestic contribution is smaller than the seasonal mean value in every season; it is less than 10% even in summer. These model results suggest that foreign anthropogenic sources have a substantial impact on attainment of the atmospheric environmental standard of Japan at Fukue Island.

Implications: The contribution from several source regions in East Asia to PM_2.5 concentration at Fukue Island, a remote island located in the western part of Japan and close to the Asian continent, is estimated using a three-dimensional chemical transport model. The model results suggest that PM_2.5 that is attributed to foreign anthropogenic sources have a larger contribution than that of domestic pollution and have a substantial impact on attainment of the atmospheric environmental standard of Japan at Fukue Island.     

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.     

Lead immobilization in mechanochemical fly ash recycling

In previous studies, we focused on a mechanochemical process for recycling fly ash for use in cement; this process was expected to immobilize heavy metals in the fly ash, a desirable outcome in light of the fact that recycled fly ash is commonly used in the synthesis of inorganic materials. Here, we investigated the leaching of lead (Pb) from fly ash treated by a mechanochemical process and from cement prepared from the treated fly ash. We used lead oxide (PbO), a typical Pb compound in fly ash, as a model substance. Mechanochemical treatment of the fly ash inhibited Pb leaching by 93%, and further inhibition (more than 99.9%) was observed in cement produced from the treated fly ash. During the mechanochemical treatment, PbO was reduced to Pb by iron from the stainless-steel mill used for processing, and the lower solubility of Pb in water resulted in immobilization of the Pb.     

Efficient chemical recycling of waste fiber-reinforced plastics: use of reduced amounts of dimethylaminopyridine and activated charcoal for the purification of recovered monomer

We have achieved major improvements in the efficient chemical recycling of waste fiber-reinforced plastics (FRPs). The effects of reduction in the amounts of dimethylaminopyridine (DMAP) used for depolymerization were examined. The treatment of waste FRP in the presence of 1 or 2 wt% DMAP resulted in the successful recovery of monomeric materials that could be employed in the polymerization process to produce recycled plastic. The separation of linker units from glass fiber, however, was unsuccessful. The purity of the recovered monomeric material, when treated with activated charcoal, was improved to about 70%. This resulted in effective decoloration of the recovered monomer. Finally, the purified material, after undergoing repolymerization, provided high-quality recycled plastic comparable to new plastics produced from new monomers.