Yutao Wang

Environmental performance of straw-based pulp making: A life cycle perspective

Agricultural straw-based pulp making plays a vital role in pulp and paper industry, especially in forest deficient countries such as China. However, the environmental performance of straw-based pulp has scarcely been studied. A life cycle assessment on wheat straw-based pulp making in China was conducted to fill of the gaps in comprehensive environmental assessments of agricultural straw-based pulp making. On average, the global warming potential (GWP), GWP excluding biogenic carbon, acidification potential and eutrophication potential of wheat straw based pulp making are 2299kg CO2-eq, 4550kg CO2-eq, 16.43kg SO2-eq and 2.56kg Phosphate-eq respectively. The dominant factors contributing to environmental impacts are coal consumption, electricity consumption, and chemical (NaOH, ClO2) input. Chemical input decrease and energy recovery increase reduce the total environmental impacts dramatically. Compared with wood-based and recycled pulp making, wheat straw-based pulp making has higher environmental impacts, which are mainly due to higher energy and chemical requirements. However, the environmental impacts of wheat straw-based pulp making are lower than hemp and flax based pulp making from previous studies. It is also noteworthy that biogenic carbon emission is significant in bio industries. If carbon sequestration is taken into account in pulp making industry, wheat straw-based pulp making is a net emitter rather than a net absorber of carbon dioxide. Since wheat straw-based pulp making provides an alternative for agricultural residue management, its evaluation framework should be expanded to further reveal its environmental benefits.

Evaluating renewable natural resources flow and net primary productivity with a GIS-Emergy approach: A case study of Hokkaido, Japan

Renewable natural resources, such as solar radiation, rainfall, wind, and geothermal heat, together with ecosystem services, provide the elementary supports for the sustainable development of human society. To improve regional sustainability, we studied the spatial distributions and quantities of renewable natural resources and net primary productivity (NPP) in Hokkaido, which is the second largest island of Japan. With the help of Geographic Information System (GIS) software, distribution maps for each type of renewable natural resource were generated by kriging interpolation based on statistical records. A composite map of the flow of all types of renewable natural resources was also generated by map layer overlapping. Additionally, we utilized emergy analysis to convert each renewable flow with different attributes into a unified unit (i.e., solar equivalent joules [sej]). As a result, the spatial distributions of the flow of renewable natural resources of the Hokkaido region are presented in the form of thematic emergy maps. Thus, the areas with higher renewable emergy can be easily visualized and identified. The dominant renewable flow in certain areas can also be directly distinguished. The results can provide useful information for regional sustainable development, environmental conservation and ecological management.

Strategic assessment of fuel taxation in energy conservation and CO2 reduction for road transportation: a case study from China

Road transportation has attracted extensive attention throughout the world because of its high energy demands and numerous externalities. Sustainable road transportation has thus become a great challenge for politicians and decision-makers all over the world. There have been a series of studies indicating that appropriate pricing of fuel can be both effective and efficient for reducing overconsumption of transport fuel. However, relatively little research has been done on fuel price approaches in developing country contexts. For a country like China, where road traffic today is growing more than in other countries, there is a strategic interest to do more economic analyses of fair and efficient pricing of fuel. In this study, we present a strategic assessment of fuel pricing in energy conservation and CO2 reduction from road transportation in China, both in a retrospective and a prospective perspective. First of all, the correlation between fuel price and road transport gasoline demand, based upon data from 1995 to 2007, was examined with an econometric model. Secondly, on basis of the elasticity model, the potential reductions with respect to fuel demand and Green House Gas (GHG) emissions as a consequence of a strategic fuel tax implementation in China were examined up to 2030. The results indicate that such strategic fuel taxation can play a considerable role in steering the growth of road transport gasoline demand, and thus also Chinese GHG emissions.

Sustainability of the use of natural capital in a city: Measuring the size and depth of urban ecological and water footprints

The Sustainable Development Goals (SDGs) are limited in their ability to measure progress towards environmental sustainability especially at the city level. The aim of this paper is to provide insights into an integrated assessment of urban sustainability, with emphasis on the significance of the maintenance of natural capital stocks. The use of water and land as critical natural capital in Guiyang, a southeast city in China was investigated by bringing together the ecological footprint (EF), water footprint (WF) and corresponding capacity indicators into an improved three-dimensional (i3D) model. Results showed that Guiyang has long been operating in a state of overshoot due to shortage of annual natural capital flows and accumulated depletion of stocks. This is particularly true for land use, whose stocks maintained a relatively stable level of depletion between 2000 and 2014. As of 2014, an EF depth of 6.45 was accumulated. With respect to water use, a shift in the citys role from creditor to debtor was observed in 2004. Industrial use of natural capital has more than tripled over the past 15u202fyears and replaced agriculture to be the main driver of water unsustainability. Overall, Guiyangs economic growth did not show signs of decoupling from the EF and WF. These findings highlight the need for effective policies that would help Guiyang reduce dependency on the use of critical natural capital. Finally, this paper provided an in-depth discussion of the methodological strengths and limitations of the i3D model and concluded that it is able to track the structural and characteristic dynamics of both flows and stocks while avoiding burden shifting across various components within single forms of natural capital from a strong sustainability perspective. Our study enhances understanding of the critical role of natural capital in ensuring urban sustainability and improving human welfare in connection with SDGs.

The Effects of Bridge Abutments on the Benthic Macroinvertebrate Community

A river ecosystem is a treasure that is home to a wide variety of wetland species. The construction of bridges might have a deep impact on diversity of such an ecosystem. The ecological consequence of bridge abutments was studied by monitoring the benthic macroinvertebrate community at six main bridges on the Tuhai and Majia rivers in eastern China. We collected samples of macroinvertebrates from upstream to downstream during the summer hight-water period, and we monitored water quality at each site. The macroinvertebrate community of under-bridge sites was signifi cantly correlated with that of reference sites in abundance, biomass, and richness. The benthic macroinvertebrate communities were not signifi cantly different between under-bridge sites and reference sites in terms of abundance and biomass, while they were signifi cantly different in terms of richness and the Shannon-Wiener index. This pattern outlined a major impact of bridge abutments on benthic macroinvertebrate communities for the fi rst time, indicating the importance of habitat restoration after river construction was fi nished. Suitable measures should be taken to minimize the impact of bridge abutments.