Clarifying Demographic Impacts on Embodied and Materially Retained Carbon toward Climate Change Mitigation.

Modern lifestyles demand a number of products derived from petroleum-based sources that eventually cause carbon emissions. The quantification of lifestyle and household consumption impacts upon carbon emissions from both the embodied CO2 (EC) and materially retained carbon (MRC) viewpoints is critical to deriving amelioration policies and meeting emission reduction goals. This study, for the first time, details a methodology to estimate both EC and MRC for Japan, focusing on petrochemicals and woody products utilizing the time series input-output table, physical value tables and the national survey of family income and expenditure, leveraging time series input-output-based material flow analysis (IO-MFA), and structural decomposition analysis (SDA). Findings elucidated hot spots of deleterious consumption by age of householder and the critical factors which underpin them including intensity effects, pattern effects, and demographic shifts over time. Although demographic shifts associated with an aging, shrinking population in Japan decreased EC and MRC, the negative effect reduced in size over time during 1990-2005. Policy implications identify the potential to mitigate approximately 21% of required household emission reductions by 2030 through strategies including recycling initiatives and the recovery of carbon from products covered within current recycling laws and hot spot sectors which are not currently considered such as apparel.

Configuration of Materially Retained Carbon in Our Society: A WIO-MFA-Based Approach for Japan.

To achieve the goals of Paris Agreement, global society is directing much effort in substantially reducing greenhouse gas (GHG) emissions. In addition to energy-related efforts, prevention of carbon release into the atmosphere with carbon capture and storage (CCS) and/or utilization of biomass resources is considered indispensable to achieving the global objective. In this study, considering carbon-containing goods as carbon reservoirs in our society similar to forests and reservoirs enabling CCS, the flow of materially utilized carbon was quantified by input-output-based material flow analysis (IO-MFA). As a result, in 2011, 6.3 Mt-C of petroleum-derived carbon and 7.9 Mt-C of wood-derived carbon were introduced to the Japanese society as end-use products (e.g., automobiles and constructions) in various forms (e.g., plastics and synthetic rubbers). The total amount (14.2 Mt-C) corresponded to 4.1% (52.1 Mt-CO2) of annual CO2 emission in Japan in 2011. Subsequently, by referring to the technology that can treat carbon in the target forms in end-of-life products, the recoverability of carbon as a material has been discussed with respect to each form and end-use of carbon. By numerically showing the necessity and potential of implementing appropriate technologies, this study provides scientific direction for policymakers to establish a quality carbon cycle in our society.

Quantifying Recycling and Losses of Cr and Ni in Steel Throughout Multiple Life Cycles Using MaTrace-Alloy.

Alloying metals are indispensable ingredients of high quality alloy steel such as austenitic stainless steel, the cyclical use of which is vital for sustainable resource management. Under the current practice of recycling, however, different metals are likely to be mixed in an uncontrolled manner, resulting in function losses and dissipation of metals with distinctive functions, and in the contamination of recycled steels. The latter could result in dilution loss, if metal scrap needed dilution with virgin iron to reduce the contamination below critical levels. Management of these losses resulting from mixing in repeated recycling of metals requires tracking of metals over multiple life cycles of products with compositional details. A new model (MaTrace-alloy) was developed that tracks the fate of metals embodied in each of products over multiple life cycles of products, involving accumulation, discard, and recycling, with compositional details at the level of both alloys and products. The model was implemented for the flow of Cr and Ni in the Japanese steel cycle involving 27 steel species and 115 final products. It was found that, under a high level of scrap sorting, greater than 70% of the initial functionality of Cr and Ni could be retained over a period of 100 years, whereas under a poor level of sorting, it could plunge to less than 30%, demonstrating the relevance of waste management technology in circular economy policies.

Optimal Recycling of Steel Scrap and Alloying Elements: Input-Output based Linear Programming Method with Its Application to End-of-Life Vehicles in Japan.

Importance of end-of-life vehicles (ELVs) as an urban mine is expected to grow, as more people in developing countries are experiencing increased standards of living, while the automobiles are increasingly made using high-quality materials to meet stricter environmental and safety requirements. While most materials in ELVs, particularly steel, have been recycled at high rates, quality issues have not been adequately addressed due to the complex use of automobile materials, leading to considerable losses of valuable alloying elements. This study highlights the maximal potential of quality-oriented recycling of ELV steel, by exploring the utilization methods of scrap, sorted by parts, to produce electric-arc-furnace-based crude alloy steel with minimal losses of alloying elements. Using linear programming on the case of Japanese economy in 2005, we found that adoption of parts-based scrap sorting could result in the recovery of around 94-98% of the alloying elements occurring in parts scrap (manganese, chromium, nickel, and molybdenum), which may replace 10% of the virgin sources in electric arc furnace-based crude alloy steel production.

Deriving the Metal and Alloy Networks of Modern Technology.

Metals have strongly contributed to the development of the human society. Today, large amounts of and various metals are utilized in a wide variety of products. Metals are rarely used individually but mostly together with other metals in the form of alloys and/or other combinational uses. This study reveals the intersectoral flows of metals by means of input-output (IO) based material flow analysis (MFA). Using the 2007 United States IO table, we calculate the flows of eight metals (i.e., manganese, chromium, nickel, molybdenum, niobium, vanadium, tungsten, and cobalt) and simultaneously visualize them as a network. We quantify the interrelationship of metals by means of flow path sharing. Furthermore, by looking at the flows of alloys into metal networks, the networks of the major metals iron, aluminum, and copper together with those of the eight alloying metals can be categorized into alloyed-, nonalloyed-(i.e., individual), and both mixed. The result shows that most metals are used primarily in alloy form and that functional recycling thereby requires identification, separation, and alloy-specific reprocessing if the physical properties of the alloys are to be retained for subsequent use. The quantified interrelation of metals helps us consider better metal uses and develop a sustainable cycle of metals.

Building the Material Flow Networks of Aluminum in the 2007 U.S. Economy.

Based on the combination of the U.S. economic input-output table and the stocks and flows framework for characterizing anthropogenic metal cycles, this study presents a methodology for building material flow networks of bulk metals in the U.S. economy and applies it to aluminum. The results, which we term the Input-Output Material Flow Networks (IO-MFNs), achieve a complete picture of aluminum flow in the entire U.S. economy and for any chosen industrial sector (illustrated for the Automobile Manufacturing sector). The results are compared with information from our former study on U.S. aluminum stocks and flows to demonstrate the robustness and value of this new methodology. We find that the IO-MFN approach has the following advantages: (1) it helps to uncover the network of material flows in the manufacturing stage in the life cycle of metals; (2) it provides a method that may be less time-consuming but more complete and accurate in estimating new scrap generation, process loss, domestic final demand, and trade of final products of metals, than existing material flow analysis approaches; and, most importantly, (3) it enables the analysis of the material flows of metals in the U.S. economy from a network perspective, rather than merely that of a life cycle chain.

Structural Investigation of Aluminum in the U.S. Economy using Network Analysis.

Metals are used in numerous products and are sourced via increasingly global and complex supply chains. Monetary input-output tables (MIOT) and network analysis can be applied to intersectoral supply chains and used to analyze structural aspects. We first provide a concise review of the literature related to network analysis applied to MIOTs. On the basis of a physical input-output table (PIOT) table of aluminum in the United States economy in 2007, we identify key sectors and discuss the overall topology of the aluminum network using tools of network analysis. Sectors highly dependent on metal product inputs or sales are identified using weighted degree centrality and their hierarchical organization is explored via clustering. Betweenness centrality and random walk centrality (page rank) are explored as means to identify network bottlenecks and relative sector importance. Aluminum, even though dominated by uses in the automobile, beverage and containers, and construction industries, finds application in a wide range of sectors. Motor vehicle parts manufacturing relies on a large number of upstream and downstream suppliers to function. We conclude by analyzing structural aspects of a subnetwork for automobile manufacturing and discuss how the use of network analysis relates to current criticality analyses of metal and mineral resources.

Simultaneous material flow analysis of nickel, chromium, and molybdenum used in alloy steel by means of input-output analysis.

Steel is not elemental iron but rather a group of iron-based alloys containing many elements, especially chromium, nickel, and molybdenum. Steel recycling is expected to promote efficient resource use. However, open-loop recycling of steel could result in quality loss of nickel and molybdenum and/or material loss of chromium. Knowledge about alloying element substance flow is needed to avoid such losses. Material flow analyses (MFAs) indicate the importance of steel recycling to recovery of alloying elements. Flows of nickel, chromium, and molybdenum are interconnected, but MFAs have paid little attention to the interconnected flow of materials/substances in supply chains. This study combined a waste input-output material flow model and physical unit input-output analysis to perform a simultaneous MFA for nickel, chromium, and molybdenum in the Japanese economy in 2000. Results indicated the importance of recovery of these elements in recycling policies for end-of-life (EoL) vehicles and constructions. Improvement in EoL sorting technologies and implementation of designs for recycling/disassembly at the manufacturing phase are needed. Possible solutions include development of sorting processes for steel scrap and introduction of easier methods for identifying the composition of secondary resources. Recovery of steel scrap with a high alloy content will reduce primary inputs of alloying elements and contribute to more efficient resource use.

Floral organ- and temperature-dependent regulation of anthocyanin biosynthesis in Cymbidium hybrid flowers.

Anthocyanins are responsible for red, purple, and pink pigmentation of flowers in Cymbidium hybrids. Although anthocyanin content in all floral organs increases with flower development, they increase markedly in the tepals compared with the labella or columns. Using next-generation sequencing technology, we identified three anthocyanin biosynthesis regulatory genes, CyMYB1, CybHLH1, and CybHLH2, from Cymbidium 'Mystique'. Yeast two-hybrid analysis showed that the CyMYB1 protein can form a heterodimer with either CybHLH1 or CybHLH2. In the tepals, the expression level of CyMYB1 increased as the flower developed, whereas the high expression level of CyMYB1 was detected at the early flower developmental stages in the labella and columns, remaining constant until increasing at the late developmental stage. These expression profiles of CyMYB1 positively correlated with the profiles of anthocyanin accumulation in the tepals. When Cymbidium Sazanami 'Champion' was grown at 30 °C/25 °C, reduced anthocyanin levels were observed, specifically in the tepals, compared with those in flowers grown at 20 °C/15 °C. The transcription of CyMYB1 in the tepals was suppressed at high temperatures, and the expressions of CyDFR and CyANS were also synchronously suppressed. This study revealed that CyMYB1 activates the transcription of CyDFR and CyANS and regulates the temporal- and temperature-dependent anthocyanin accumulation in Cymbidium tepals.

Computation of the free energy change associated with one-electron reduction of coenzyme immersed in water: a novel approach within the framework of the quantum mechanical/molecular mechanical method combined with the theory of energy representation.

The isoalloxazine ring (flavin ring) is a part of the coenzyme flavin adenine dinucleotide and acts as an active site in the oxidation of a substrate. We have computed the free energy change Deltamicro(red) associated with one-electron reduction of the flavin ring immersed in water by utilizing the quantum mechanical/molecular mechanical method combined with the theory of energy representation (QM/MM-ER method) recently developed. As a novel treatment in implementing the QM/MM-ER method, we have identified the excess charge to be attached on the flavin ring as a solute while the remaining molecules, i.e., flavin ring and surrounding water molecules, are treated as solvent species. Then, the reduction free energy can be decomposed into the contribution Deltamicro(red)(QM) due to the oxidant described quantum chemically and the free energy Deltamicro(red)(MM) due to the water molecules represented by a classical model. By the sum of these contributions, the total reduction free energy Deltamicro(red) has been given as -80.1 kcal/mol. To examine the accuracy and efficiency of this approach, we have also conducted the Deltamicro(red) calculation using the conventional scheme that Deltamicro(red) is constructed from the solvation free energies of the flavin rings at the oxidized and reduced states. The conventional scheme has been implemented with the QM/MM-ER method and the calculated Deltamicro(red) has been estimated as -81.0 kcal/mol, showing excellent agreement with the value given by the new approach. The present approach is efficient, in particular, to compute free energy change for the reaction occurring in a protein since it enables ones to circumvent the numerical problem brought about by subtracting the huge solvation free energies of the proteins in two states before and after the reduction.

Dissolution behavior of selenium from coal fly ash particles for the development of an acid-washing process.

Coal fly ash emitted from coal-fired electric power stations generally contains environmentally regulated trace elements. In particular, boron, arsenic, and selenium have been recognized as troublesome trace elements because elutions from the fly ash contain them. In order to design an effective removal process for these trace elements, we have developed and investigated an acid-washing process. The dissolution behavior of selenium from coal fly ash particles was focused on for the improvement of the process, and was found to greatly depend on the pH of the acid solutions. The species of selenium in solutions with a pH of around 0-1 was determined to be H2SeO3. The dissolved H2SeO3 transformed into HSeO3- and adsorbed onto the surface of the ash particles in solution upon elevation of the pH. The re-elution of the absorbed HSeO3- as SeO3(2-) at a pH of 10 was also confirmed, and will cause the elution of the excess selenium from the acid-washed ash.

Removal of arsenic in coal fly ash by acid washing process using dilute H2SO4 solvent.

Coal fly ash emitted from coal thermal power plants generally contains tens ppm of arsenic, one of the hazardous elements in coal, during combustion and their elution to soil or water has become a public concern. In this study, the acid washing process developed by the authors was applied to the removal of arsenic from coal fly ash. Laboratory- and bench-scale investigations on the dissolution behavior of arsenic from various coal fly ash samples into dilute H(2)SO(4) were conducted. Arsenic in the coal fly ash samples were dissolved into H(2)SO(4) solutions rapidly. However, its concentrations decreased with an increase in the pH of H(2)SO(4) solution in some cases. The species of arsenic in the dilute H(2)SO(4) was estimated as H(3)AsO(4), and its anionic species was considered to adsorb with the elevation of pH under the presence of ash particle. Such adsorption behavior was enhanced under the presence of Fe ion in the solution. The sufficient removal of arsenic was achieved by controlling pH and avoiding the adsorption of arsenic on the surface of coal fly ash particles, and the elution of arsenic from coal fly ash sample was successfully below the regulation limit.

Investigation of the dominant hydration structures among the ionic species in aqueous solution: novel quantum mechanics/molecular mechanics simulations combined with the theory of energy representation.

In the present work, we have performed quantum chemical calculations to determine preferable species among the ionic complexes that are present in ambient water due to the autodissociation of water molecule. First, we have formulated the relative population of the hydrated complexes with respect to the bare ion (H(3)O(+) or OH(-)) in terms of the solvation free energies of the relevant molecules. The solvation free energies for various ionic species (H(3)O(+), H(5)O(2) (+), H(7)O(3) (+), H(9)O(4) (+) or OH(-), H(3)O(2) (-), H(5)O(3) (-), H(7)O(4) (-), H(9)O(5) (-)), categorized as proton or hydroxide ion in solution, have been computed by employing the QM/MM-ER method recently developed by combining the quantum mechanical/molecular mechanical (QM/MM) approach with the theory of energy representation (ER). Then, the computed solvation free energies have been used to evaluate the ratio of the populations of the ionic complexes to that of the bare ion (H(3)O(+) or OH(-)). Our results suggest that the Zundel form, i.e., H(5)O(2) (+), is the most preferable in the solution among the cationic species listed above though the Eigen form (H(9)O(4) (+)) is very close to the Zundel complex in the free energy, while the anionic fragment from water molecules mostly takes the form of OH(-). It has also been found that the loss of the translational entropy of water molecules associated with the formation of the complex plays a role in determining the preferable size of the cluster.