Effects of Carbon Tax on Urban Carbon Emission Reduction: Evidence in China Environmental Governance.

Carbon tax is an important economic instrument in achieving the goal of carbon emission reduction and sustainable development. This paper investigates the effects of carbon tax on carbon emission reduction in China. First, a non-competitive input-output table for Carbon Emissions of 28 sectors in China after Carbon Tax was established, based on the "2018 China Non-competitive Input-Output Table (42 Sectors)" and the carbon emission data of sectors provided by China Carbon Emission Accounts and Datasets (CEADs). Then, an input-output price model was established to study the changes on product price, GDP, employment, and carbon dioxide emissions of 28 sectors after carbon taxing ranged from 10 to 200. When the carbon tax rate reaches 200 yuan/ton, the inflation rate will be 5.907%, the total GDP will be decreased to 1.910%, the total labor force will be decreased to 1.744%, and the total carbon emission reduction rate will be increased to 8.171%. Results showed that with the increases in carbon tax, the inflation rate was increased, the rate of carbon emission reduction was increased, and the negative effects on GDP and employment were also increased. Suggestions on policy making, such as combination of carbon taxing and carbon trading, dynamic adjustment mechanism, tax neutrality, and forcing active carbon reduction, were proposed to minimize the adverse effect of levying carbon tax. The results from this paper would provide a reference for the policy making on carbon management.

Responsible sourcing for energy transitions: Discussing academic narratives of responsible sourcing through the lens of natural resources justice.

The Paris Agreement and the United Nations' Sustainable Development Goals clearly demonstrate the need for global energy transitions. Evolving energy generation and the expansion of the renewable energy capacity and associated infrastructure contribute to changing and increasing demands for minerals and metals. The potential negative environmental, social and economic impacts of increased mineral resource production have been contested and are under increasing scrutiny by both academia and civil society. Responsible Sourcing (RS) has become a management approach for companies and policymakers to identify, monitor and address potential negative impacts along their raw materials' supply chains. Although RS might contribute to sustainability along the supply chain, this paper raises the question of whether it also contributes to Natural Resource Justice (NRJ) in energy transitions. Based on a bibliometric network analysis, this study investigated current narratives of RS literature and to what degree core aspects of NRJ (e.g., distribution of benefits and burdens, power asymmetries, property rights) are reflected in the RS debate following a deductive approach. The results obtained show that compared with other sectors (e.g., timber, food, biomass, textiles) debates on RS in renewable energy-related sectors are still scarce and fragmented. The analysis indicates that different foci are aligned with one or more of the traditional three sustainability dimensions (i.e., environmental, social, economic), while few addressed aspects of NRJ. The authors observed a distinct lack of holistic justice considerations in the current RS debate and only a few individual issues are discussed, such as the detection of burden shifting, accountability for supplier behavior, and sharing of financial benefits. This research contributes to the understanding of different RS approaches and extends the RS discussion to NRJ considerations in energy transitions. It also points out important paths for future research to contribute to just energy transitions.

Effect of substrate properties and phosphorus supply on facilitating the uptake of rare earth elements (REE) in mixed culture cropping systems of Hordeum vulgare, Lupinus albus and Lupinus angustifolius.

This study presents how phosphate (P) availability and intercropping may influence the migration of rare earth elements (REEs) in legume-grass associations. In a replacement model, Hordeum vulgare was intercropped with 11% Lupinus albus and 11% Lupinus angustifolius. They were cultivated on two substrates, A (pH = 7.8) and B (pH = 6.6), and treated with 1.5 g P m-2 or 3 g P m-2. Simultaneously, a greenhouse experiment was conducted to quantify carboxylate release. There, one group of L. albus and L. angustifolius was supplied with either 200 µmol L-1 P or 20 µmol L-1 P. L. albus released higher amounts of carboxylates at low P supply than L. angustifolius, while L. angustifolius showed the opposite response. Plants cultivated on substrate B accumulated substantially higher amounts of nutrients and REE, compared to substrate A. Higher P supply did not influence the leaf and stem P concentrations of H. vulgare. Addition of P decreased REE accumulation in barley monocultures on alkaline soil A. However, when H. vulgare was cultivated in mixed culture with L. angustifolius on alkaline substrate A with high P supply, the accumulation of REE in H. vulgare significantly increased. Conversely, on acidic substrate B, intercropping with L. albus decreased REE accumulation in H. vulgare. Our findings suggest a predominant effect of soil properties on the soil-plant transfer of REEs. However, in plant communities and within a certain soil environment, interspecific root interactions determined by species-specific strategies related to P acquisition in concert with the plant's nutrient supply impact REE fluxes between neighbouring plants.

Carbonation Curing on Magnetically Separated Steel Slag for the Preparation of Artificial Reefs.

Magnetic separation is an effective method to recover iron from steel slag. However, the ultra-fine tailings generated from steel slag become a new issue for utilization. The dry separation processes generates steel slag powder, which has hydration activity and can be used as cement filler. However, wet separation processes produce steel slag mud, which has lost its hydration activity and is no longer suitable to be used as a cement filler. This study investigates the potential of magnetically separated steel slag for carbonation curing and the potential use of the carbonated products as an artificial reef. Steel slag powder and steel slag mud were moulded, carbonation-cured and seawater-cured. Various testing methods were used to characterize the macro and micro properties of the materials. The results obtained show that carbonation and hydration collaborated during the carbonation curing process of steel slag powder, while only carbonation happened during the carbonation curing process of steel slag mud. The seawater-curing process of carbonated steel slag powder compact had three stages: C-S-H gel formation, C-S-H gel decomposition and equilibrium, which were in correspondence to the compressive strength of compact increasing, decreasing and unchanged. However, the seawater-curing process of carbonated steel slag mud compact suffered three stages: C-S-H gel decomposition, calcite transfer to vaterite and equilibrium, which made the compressive strength of compact decreased, increased and unchanged. Carbonated steel slags tailings after magnetic separation underwent their lowest compressive strength when seawater-cured for 7 days. The amount of CaO in the carbonation active minerals in the steel slag determined the carbonation consolidation ability of steel slag and durability of the carbonated steel slag compacts. This paper provides a reference for preparation of artificial reefs and marine coagulation materials by the carbonation curing of steel slag.

Aqueous mineral carbonation of ultramafic material: a pre-requisite to integrate into mineral extraction and tailings management operation.

Ex situ aqueous mineral carbonation of ultramafic mining waste is an evolving technology for the CO2 sequestration from small- to medium-scale emitters. The mineral ores or mine wastes of associated ultramafic mineralogy are a suitable feedstock for mineral carbonation. The aqueous mineral carbonation at ambient temperature is motivating and attractive from an energy-saving perspective. This study has investigated the CO2 sequestration potential of a locally available ultramafic material generated from a nickel ore mine with a futuristic scope of integrating the method into an ongoing mineral extraction and/or tailing management operation. The mineral characterization and experimental results indicate that the tested material has CO2 sequestration potential and underwent carbonation at ambient temperature. The carbonate conversion efficiencies obtained for Ca and Mg from the dissolved ionic forms at optimum conditions are 60% and 25%, respectively. The material was able to sequestrate about 0.12 gCO2 per g solid at this efficiency. Aragonite and hydromagnesite are the major products that evolved out from the aqueous carbonation. Based on the mineral carbonation results, the novel concept of integrating the evolved method to existing mineral extraction and/or tailings management operation is discussed.