Dynamic analysis of carbon emissions from construction and demolition activities in Japan: Revealed by high-resolution 4D-GIS modeling.

To meet the 2050 decarbonization target of the global buildings and construction sector, more attention is needed to reduce carbon emissions from construction and demolition. However, current national carbon accounting studies for these activities remain limited in spatial granularity and localized applicability. This study developed a bottom-up spatiotemporal database of carbon emissions from building construction and demolition in Japan via integrating a geographic information system-based building stock model, statistical data, and survey information. Focusing on municipal-level emissions, the Logarithmic Mean Divisia Index approach was used to decompose spatiotemporal variations and identify the contributing factors. Results indicate that carbon emissions from Japan's construction and demolition activities fell by more than 50% between 2005 and 2020, largely due to declining new/demolished-to-stock ratio, suggesting a transition to a stock-based society. Central cities' reliance on carbon-intensive buildings positively contributed to spatial variations in their construction emissions, underscoring the importance of sustainable materials and timber designs. Differences between prefectures in demolition emission intensity highlighted the strategic placement of recycling facilities in key regions to curb transportation-related emissions. Overall, these findings provided data reference for local governments to devise tailored policies for managing construction and demolition emissions.

Strategies for improving the environmental performance of nickel production in China: Insight into a life cycle assessment.

Nickel is a critical metal for global low-carbon energy transition, but its production processes require massive energy inputs and emit large amounts of pollutants. This study constructed life cycle inventories of the mainstream electrolytic nickel production chains in China at the industrial level and subsequently evaluated their environmental performance via a regionalised life cycle impact assessment method. Results show that environmental indicator results of the electrolytic nickel production from the leaching electrowinning method were 17.7%-40.2% lower than those from the grind and flotation electrolytic method. At the endpoint level, the nickel mining and beneficiation stages contributed 54.7%-65.91% of human health damage, 83.0%-84.7% of ecosystem quality damage and 80.8%-83.7% of resources damage. The key processes, including direct processes, cement input and energy consumption (e.g., electricity and coal), accounted for more than 62.1% of the impacts in the key midpoint categories. The potential environmental damage of China's nickel mining and beneficiation industry increased by 29.2% from 2010 to 2018 because of the growing trend of nickel ore demand. In the case that China's nickel metal recovery rate reaches the global average level, then approximately 3.83 × 102 Daly of human health damage, 59.83 Species·year of ecosystem quality damage and 1.64 × 108 $ of resources damage can be avoided annually. Strategies for promoting the full assimilation of renewable electricity, applying the clinker-free cemented backfill materials in the mining process, precious recovery by bioleaching from tailings and reusing waste rock as building materials are recommended. Meanwhile, extended producer responsibility should to be comprehensively implemented in the nickel-related industries to alleviate the environmental implications and nickel supply pressures from geo-mining.

Environmental footprints of soybean production in China.

As a significant protein source for humans and animals, soybean (Glycine max) has experienced a fast growth with the rapid development of population and economy. Despite broad interest in energy consumption and CO2 emissions generated by soybean production, there are few impact-oriented water footprint assessments of soybean production. This study evaluates the fossil energy, carbon, and water footprints of China's soybean production so that key environmental impacts can be identified. To provide reliable results for decision-making, uncertainty analysis is conducted based on the Monte Carlo model. Results show that the impact on climate change, ecosystem quality, human health, and resources is 3.33 × 103 kg CO2 eq (GSD2 = 1.87), 6.18 × 10-5 Species·yr (GSD2 = 1.81), 3.26 × 10-3 Disability-adjusted Life Years (GSD2 = 1.81), and 81.51 $ (GSD2 = 2.28), respectively. Freshwater ecotoxicity is the dominant contributor (77.69%) to the ecosystem quality category, while climate change (85.22%) is the dominant contributor to the human health category. Key factors analysis results show that diammonium phosphate and diesel, and on-site emissions, are the major contributors to the overall environmental burden of soybean production. Several policy recommendations are proposed, focusing on trade structure optimization, efficient resource use, and technological improvements. Such policy recommendations provide valuable insights to those decision-makers so that they can prepare appropriate mitigation policies.

Carbon, energy and water footprints analysis of rapeseed oil production: A case study in China.

As the largest consumer of rapeseed oil in the world, China should consider the environmental effect of rapeseed oil production. However, only a few improvement measures have been proposed. To fill this gap, this study analyzed the energy, carbon and water footprints of rapeseed oil production based on the International Organization for Standardization standards using the framework of life cycle assessment. Results show that most of the energy, carbon, and water footprint of rapeseed oil production can be contributed to the direct processes of rapeseed cultivation, and the indirect processes of transport and fertilizer/diesel production. The value of energy and carbon footprints are calculated as 726.07 kg oil eq and 3889.75 kg CO2 eq, respectively. For the water footprint, the values of acidification, aquatic eutrophication, carcinogens, freshwater ecotoxicity, water scarcity, and non-carcinogens are 14.24 kg SO2 eq, 4.53 kg PO4-3 eq, 6.72 × 10-5Case, 5.43 × 104 PAF.m3.d, 437.62 m3 deprived, and 1.88 × 10-5 case, respectively. Spatial analysis shows that the total environmental impacts of rapeseed production are concentrated in Sichuan, Hunan, Hubei, and Jiangxi Provinces. Correlation analysis reveals the positive correlation of human health and ecosystem quality with fertilizer application and pesticide loss. In general, the environmental effect can be effectively reduced by adjusting the industrial layout to shorten the distance of transport, improve the fine cultivation degree in low-yield areas, and decrease the use of pesticides in the hilly region of southern China.

Towards sustainability: An integrated life cycle environmental-economic insight into cow manure management.

Waste management signifies an equilibrium between environmental and economic factors. However, a comprehensive understanding of the integrated life cycle environmental-economic performance of waste management activities remains unclear. To facilitate a systematic linkage between the economic and environmental sectors, a regionalized life cycle assessment-based life cycle costing method was developed based on China's actual status quo. The cow manure utilization was set as an entry point to explored long-term environmental-economic performance of milk production under various manure utilization pathways. The results show that trade-offs were observed between internal and external costs as well as various environmental indicators. The choice of waste utilization is the focal point of environmental-economic trade-offs in the cow raising system. The optimal environmental-economic performance was achieved through the manure fertilizer utilization pathway, yielding a remarkable three-fold increase in marginal environmental benefits. Compared with fertilizer utilization, the manure direct returning to field reduced the carbon footprint by 12% while induced an external cost of $14.3. The wastewater treatment pathway is $ 5.5 lower in internal costs but $ 11.7 higher in external costs than those of fertilizer utilization. Overall, utilizing manure has potential to mitigate the upward trend of carbon footprint and external costs. However, achieving the carbon peak remains a significant challenge. A promising solution is the recycling of straw resources within cropping systems, particularly in hotspot regions (e.g., Inner Mongolia, Heilongjiang, Hebei, and Shandong). A comprehensive analysis of the dynamic interplay between cropping systems and cow raising systems is critical steps towards realizing a carbon-neutral future within the dairy production.

Water footprint coupled economic impact assessment for maize production in China.

Nowadays, agricultural production places an enormous burden on freshwater resources, and the environmental external cost caused by the restoration of water quality degradation has attracted great attention. Maize is regarded as one of the world's major food security crops, and China is the second-largest maize producer. Thus, this study conducts an impact-oriented water footprint coupled economic impact assessment to quantify the water-related environmental impacts and economic burden caused by China's maize production from 2008 to 2017. Results show that the overall damage to human health and ecosystem quality of China's maize production in 2017 were 4.32 × 104 DALY and 4.62 × 103 Species·yr, respectively. The total economic cost was $ 2.15 × 1011, which included an internal cost of $ 5.99 × 1010 and external cost of $ 1.55 × 1011. Key factor analysis demonstrates that diesel and fertilizer production dominated the reduction in ecological and external cost burdens. Direct water consumption and labor cost played leading roles in human health and internal cost, respectively. The spatiotemporal variation assessment indicates that Inner Mongolia and Heilongjiang were the hotspots for water footprint and economic impact assessment results after considering the yield factor. The national average water footprint and economic impact caused by producing 1 ton of maize showed an upward trend from 2008 to 2015, however, a significant decline transpired later. Overall, improving the resource efficiency (i.e., diesel and freshwater), scientific application of fertilizer and reducing labor input can further lessen the water footprint and economic impact of maize production. Developing the social environment can also generate indirect environmental and economic benefits to China's maize production.