• Energy Research
• Closed Access close
• Restricted close
• 12. Responsible consumption close
• 15. Life on land close
• CN close
• US close
• CA close

Abstract Transportation de-carbonization is a complex problem involving the economy, population, technology and environment. Implementing the pathway simulation based on systematic methods will help to optimize the transportation sustainability plan. This study’s key motivation is that earlier research ignored the relationship between driving factors and the transmission process. To quantitatively identify the path and process of emission reduction, a hybrid system dynamics STIRPAT-SD model is proposed to explore the transportation optimization’s de-carbonization ability. This study fully considers the composition of elements and subsystems based on the STIRPAT theoretical model and visually shows the system’s feedback relationship. Transportation structural and technical optimization scenarios are set to identify the threshold reduction paths. It is found these optimization strategies have significant de-carbonization effects. And transportation structure policy has the highest de-carbonization efficiency, the emission intensity decreased by 9.1% under the TSS2 scenario (Transportation structure scenario). This study proposes a novelty model combining dynamic simulating processes with a significantly theoretical model to improve simulation and factor composition accuracy. And the joint scenario setting identifies the most effective de-carbonization pathway and clarifies the threshold of all possible pathways. Research findings can effectively track, test, predict the achievement of policy goals, and provide policy optimization references for the sustainable development related to the transportation system in practice.

China is the largest fruit producer and consumer market in the world. Understanding the growing conditions responses to climate change is the key to predict future site suitability of main cultivation areas for certain deciduous fruit trees. In this study, we used dynamic and growing degree day models driven by downscaled daily temperatures from 22 global climate models to project the effects of climate change on growing conditions for deciduous fruit trees under two representative concentration pathway (RCP) 4.5 and RCP8.5 scenarios over 2 future time periods (represented by central years 2050s and 2085s) in northern China. The results showed a general increase of available winter chill for all sites under RCP4.5 scenario, and the most dramatic increase in chill accumulation could reach up to 36.8% in northeast regions for RCP8.5. However, the forecasted chill will decrease by 6.4% in southeast stations under RCP8.5 by 2085s. Additionally, the increase rate of growing season heat showed spatially consistency, and the most pronounced increase was found in the RCP8.5 by 2085s. For the southwest station, median heat accumulation increased by 20.8% in the 2050s and 37.1% in the 2085s under RCP8.5. Similar increasing range could be found in the northeast station; the median growing season heat increased by 19.8% and 38.8% in the 2050s and 2085s under RCP8.5, respectively. Moreover, the date of last spring frost was expected to advance and the frequency of frost occurrences was projected to decline in the study area compared to the past. Overall, the present study improves understanding regarding site-specific characteristics of climatic suitability for deciduous fruit tree cultivation in main producing regions of northern China. The results could provide growers and decision-makers with theoretical evidence to take adaptive measure to ensure fruit production in future.

Purpose This study aims to consider environmental sustainability, a global challenge under the preview of sustainable development goals, highlighting the significance of knowledge economy in attaining sustainable aggregate demand behavior globally. For this purpose, 155 countries that have data available from 1995 to 2021 were selected. The purpose of selecting these countries is to test the global responsibility of the knowledge economy to attain environmental sustainability. Design/methodology/approach Results are estimated with the help of panel quantile regression. The empirical existence of aggregate demand-based environmental Kuznets curve (EKC) was tested using non-linear tests. Moreover, principal component analysis has been incorporated to construct the knowledge economy index. Findings U-shaped aggregate demand-based EKC at global level is validated. However, environmental deterioration increases with an additional escalation after US$497.945m in aggregate demand. As a determinant, the knowledge economy is reducing CO2 emissions. The knowledge economy has played a significant role in global responsibility, shifting the EKC downward and extending the CO2 reduction phase for every selected country. Further, urbanization, energy intensity, financial development and trade openness significantly deteriorate the environmental quality. Originality/value This study contains the empirical existence of aggregate demand-based EKC. The role of the knowledge economy is examined through an index which is calculated by using four pillars of the knowledge economy (technology, innovations, education and institutions). This study is based on a combined panel of all the countries for which the data was available.

Forest soil acidification caused by acid deposition is a serious threat to the forest ecosystem. To investigate the liming effects of biomass ash (BA) and alkaline slag (AS) on the acidic topsoil and subsoil, a three-year field experiment under artificial Masson pine was conducted at Langxi, Anhui province in Southern China. The surface application of BA and AS significantly increased the soil pH, and thus decreased exchangeable acidity and active Al in the topsoil. Soil exchangeable Ca2+ and Mg2+ in topsoil were significantly increased by the surface application of BA and AS, while an increase in soil exchangeable K+ was only observed in BA treatments. The soil acidity and active Al in subsoil were decreased by the surface application of AS. Compared with the control, soluble monomeric and exchangeable Al in the subsoil was decreased by 38.0% and 29.4% after 3 years of AS surface application. There was a minimal effect on soluble monomeric and exchangeable Al after the application of BA. The soil exchangeable Ca2+ and Mg2+ in the subsoil increased respectively by 54% and 141% after surface application of 10 t ha-1 AS. The decrease of soil active Al and increase of base cations in subsoil were mainly attributed to the high migration capacity of base cations in AS. In conclusion, the effect of surface application of AS was superior to BA in ameliorating soil acidity and alleviating soil Al toxicity in the subsoil of this Ultisol.

Paper mill sludge (PMS) is a residual biomass that is generated at paper mills in large quantities. Currently, PMS is commonly disposed in landfills, which causes environmental issues through chemical leaching and greenhouse gas production. In this research, we are exploring the potential of fast pyrolysis process for converting PMS into useful bio-oil and biochar products. We demonstrate that by subjecting PMS to a combination of acid hydrolysis and torrefaction pre-treatment processes it is possible to alter the physicochemical properties and composition of the feedstock material. Fast pyrolysis of pretreated PMS produced bio-oil with significantly higher selectivity to levoglucosenone and significantly reduced the amount of ketone, aldehyde, and organic acid components. Pretreatment of PMS with combined 4% mass fraction phosphoric acid hydrolysis and 220 °C torrefaction processed prior to fast pyrolysis resulted in a 17 times increase of relative selectivity towards levoglucosenone in bio-oil product along with a reduction of acids, ketones, and aldehydes combined from 21 % to 11 %. Biochar, produced in higher yield, has characteristics that potentially make the solid byproduct ideal for soil amendment agent or sorbent material. This work reveals a promising process system to convert PMS waste into useful bio-based products. More in-depth research is required to gather more data information for assessing the economic and sustainability aspects of the process.

Seagrass systems of the Western Pacific region are biodiverse habitats, providing vital services to ecosystems and humans over a vast geographic range. SeagrassNet is a worldwide monitoring program that collects data on seagrass habitats, including the ten locations across the Western Pacific reported here where change at various scales was rapidly detected. Three sites remote from human influence were stable. Seagrasses declined largely due to increased nutrient loading (4 sites) and increased sedimentation (3 sites), the two most common stressors of seagrass worldwide. Two sites experienced near-total loss from of excess sedimentation, followed by partial recovery once sedimentation was reduced. Species shifts were observed at every site with recovering sites colonized by pioneer species. Regulation of watersheds is essential if marine protected areas are to preserve seagrass meadows. Seagrasses in the Western Pacific experience stress due to human impacts despite the vastness of the ocean area and low development pressures.

Abstract The Chinese government has taken measures to realize energy-savings and emission reductions, such as promoting innovations, adjusting the industrial structure, balancing regional development, and reforming markets. The aim of this paper is to assess the effects of these measures on China's CO2 emissions by using a newly proposed decomposition approach, which identified eight new factors related to the above realistic measures, i.e., energy saving and production technologies, industrial energy and production efficiencies, regional energy and production efficiencies, and pure energy and production efficiencies. The main findings indicate benefits from considerable technological progress in energy-saving and production during 2000–2016 period, and two technological factors contributed the most to emissions abatement and cumulatively reduced 5372.43 Mt and 1291.72 Mt CO2 emissions. The efforts of industrial restructuring promoted energy and production efficiency improvement, which further facilitated emission reduction. In contrast, the pure energy and production efficiency changes cumulatively led to 1080.26 Mt and 1135.85 Mt CO2 emissions growth during the whole sample period, suggesting that severe resource misallocation problems may exist in both the energy market and output market. Additionally, the Chinese government failed to narrow the technology gap between developed regions and underdeveloped regions, further restricting emission reduction.

This study focused on the effects of plant compositions on removal rates of pollutants in microcosms through investigating rhizosphere microbial populations, photosynthetic efficiency and growth characteristics. Mixed-culture groups improved the removal efficiency of TN and TP significantly but exhibited lower COD removal rates. Total plant biomasses were improved as the species richness increased, but the N/P content in the plants was mainly affected by the type of species. The mixed-culture groups showed lower photosynthesis rates and oxygen supply generated from roots under high irradiation. Microbial communities of the cultured groups in the rhizosphere exhibited significant differences. According to principal component analysis (PCA), the fungi were the typical microbes of SPA, SPAB, and SPABC, resulted in improvement in nutrient accumulation. These results demonstrated that a mixed culture strategy can represent the overyielding of biomass, promote the photo-protection mechanism, and will further increase the removal rates of pollutants in a constructed wetland.

Net primary production (NPP), the difference between CO2 fixed by photosynthesis and CO2 lost to autotrophic respiration, is one of the most important components of the carbon cycle. Our goal was to develop a simple regression model to estimate global NPP using climate and land cover data. Approximately 5600 global data points with observed mean annual NPP, land cover class, precipitation, and temperature were compiled. Precipitation was better correlated with NPP than temperature, and it explained much more of the variability in mean annual NPP for grass- or shrub-dominated systems (r2 = 0.68) than for tree-dominated systems (r2 = 0.39). For a given precipitation level, tree-dominated systems had significantly higher NPP (approximately 100-150 g C m(-2) yr(-1)) than non-tree-dominated systems. Consequently, previous empirical models developed to predict NPP based on precipitation and temperature (e.g., the Miami model) tended to overestimate NPP for non-tree-dominated systems. Our new model developed at the National Center for Ecological Analysis and Synthesis (the NCEAS model) predicts NPP for tree-dominated systems based on precipitation and temperature; but for non-tree-dominated systems NPP is solely a function of precipitation because including a temperature function increased model error for these systems. Lower NPP in non-tree-dominated systems is likely related to decreased water and nutrient use efficiency and higher nutrient loss rates from more frequent fire disturbances. Late 20th century aboveground and total NPP for global potential native vegetation using the NCEAS model are estimated to be approximately 28 Pg and approximately 46 Pg C/yr, respectively. The NCEAS model estimated an approximately 13% increase in global total NPP for potential vegetation from 1901 to 2000 based on changing precipitation and temperature patterns.