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One proposed strategy to solve current environmental challenges is industrial and urban symbiosis (I/UrS); however, appropriate evaluation methods are needed so that the potential benefits of I/UrS can be quantified. Several evaluation methods have been applied separately to study I/UrS, but no integrated studies have been conducted by applying different methods in the same case study area. Therefore, this study aimed to establish a comprehensive framework to evaluate I/UrS by combining the material flow analysis (MFA), carbon footprint (CF) and emergy methods. First, we developed a unified database and step-by-step process to clarify the waste distribution and recycling processes in an industrial city. Then a baseline scenario and an I/UrS scenario were set up to define the baselines and effects of I/UrS and compare the results. Finally, the three methods were applied to identify physical features in the I/UrS system. The MFA-based results showed that the use of I/UrS led to a 6.4% reduction in the physical value of material use. The CF-based results indicated that reduction of waste and by-products results in a 13.8% reduction in CO 2 e emissions. The emergy-based results showed that, with the implementation of I/UrS, the value of the emergy sustainability index (excluding labor and services) improved greatly (a 49.2% emergy reduction) as compared with the baseline case (a 14.3% reduction). In addition, the effects of implementing I/UrS by waste and by-product exchanges for blast furnace slag, scrap steel, waste paper, and waste plastic were evaluated. Whereas the CF reductions of unit ton of blast furnace slag is relatively low, emergy reductions of that is comparatively high. If policymakers only consider CF results when addressing the issue of climate change, the effects on emergy will be underestimated in this case. We conclude that the main actors in this area release huge emissions, but they also have a high potential to reduce their environmental loads. In addition, with appropriate designs, waste paper and plastics recycling could be highly efficient. Finally, the integration of the three evaluation methods should contribute to creating a low carbon and more resource independent society. [ABSTRACT FROM AUTHOR]

• Recent research on the B&R eco-environment is reviewed. • The B&R is likely to face environmental challenges due to its fragile background. • Four key aspects of the ecological environment are studied. • Sustainable development should be promoted under socioeconomic frameworks for the B&R. • Future research directions for improving the B&R eco-environments are proposed. The Belt and Road Initiative (BRI) will play an essential role in boosting the world's economy. However, the main portion of the Belt and Road (B&R) is in arid, semi-arid, or sub-humid fragile ecological regions, which with global climate change and the intensification of human activities will face many pressing environmental challenges in the future. Despite this, in the existing research on the B&R, papers in the field of natural sciences are less than 1.2–4.3% of the total number of papers on the main databases, which is far lower than the coverage in humanities and social sciences. And those focused on the ecological and environmental issues along the B&R are even fewer, so necessary understanding of both the risks and adequate mitigation measures remains unclear. This paper systematically reviews the relevant research on the eco-environments along the B&R, and summarizes it in terms including of spatial patterns and cognition, cost efficiency and evaluation, ecological security and evaluation, ecological footprint and carrying capacity. It further suggests that a better understanding of environmental changes and their effects on the B&R is needed. Additionally, it is essential that the potential positive socio-economic impacts for the future under the BRI are sustainable. Finally, future research directions are proposed to improve for the better eco-environments in B&R regions with consideration of global changes. [ABSTRACT FROM AUTHOR]

Human activities create more reactive nitrogen than is created through natural processes every year. The excess reactive nitrogen in the environment causes various negative effects including eutrophication, climate change, acidification, and human health problems. The sources of the excess nitrogen are mainly fertilizers and animal and human waste generated by food production and consumption. Therefore, our food choices have major effects on the nitrogen load to the environment. To quantify the load, a consumption-based accounting tool, called the nitrogen footprint, has been recently developed. In current nitrogen footprint models, seafood is calculated as a single category using the same simple assumptions as livestock. However, there is a variety of types and methods of production of seafood. In addition, world per capita consumption of seafood is projected to continue expanding. In this paper, we propose a new nitrogen footprint model to evaluate the impact of seafood in detail, present the results of the model applied to Japan as a case study, and explain the important parameters that are needed to accurately evaluate the load of seafood consumption. Our model tracks the feeding steps in detail, considering differences among fed aquacultured seafood, non-fed aquacultured seafood (mainly bivalves and filter-feeding carp), and captured seafood. Our model evaluates the Japanese food nitrogen footprint of fed aquacultured seafood as 0.7 kg-N/capita/year, ca. 45% of that of all seafood, whereas the previous model evaluates it as 3.36 kg-N/capita/year. Our results demonstrate that the key factors for assessing the nitrogen load of seafood are the proportions of fed aquaculture and of plant protein in feed. In order to enable food choices that will effectively reduce nitrogen release, we provide the virtual N factors (per intake nitrogen release during production) for different seafood as 0.2 (non-fed aquacultured and captured), 4.8 (freshwater and diadromous fish), 3.9 (demersal fish), 3.4 (pelagic fish and other marine fish), and 8.2 (crustaceans). Our results show that eating more non-fed aquacultured and captured seafood and less fed-aquacultured shrimps and prawns could reduce our nitrogen load from food consumption as effectively as choosing poultry instead of beef. Although its evaluation is limited to nitrogen load related to food itself and not including the load from energy use, etc., our detailed nitrogen footprint model for different seafood categories and production sources can quantify the effectiveness of policies and actions that link sustainable consumption and sustainable fisheries and aquaculture, contributing toward the Aichi Biodiversity Targets. [ABSTRACT FROM AUTHOR]