Understanding interactions between complex human and natural systems involved in urban carbon cycling is important when balancing the dual goals of urban development to accommodate a growing population, while also achieving urban carbon neutrality. This study develops a systems breakdown accounting method to assess the urban carbon cycle. The method facilitates greater understanding of the complex interactions within and between systems involved in this cycle, in order to identify ways in which humans can adapt their interactions to reduce net greenhouse gas emissions from urban regions. Testing the systems breakdown accounting method in Stockholm County, Sweden, we find that it provides new insights into the carbon interactions with urban green-blue areas in the region. Results show how Stockholm County can reduce its emissions and achieve its goal of local carbon net-neutrality, if the green areas protect its carbon sequestration potential and maintain it to offset projected remaining active emissions. Results also show that the inland surface waters and inner archipelago waters within Stockholm County are a considerable source of greenhouse gases to the atmosphere. A better understanding of these water emissions is necessary to formulate effective planning and policy measures that can reduce urban emissions. The insights gained from this study can also be applied in other regions. In particular, water bodies could play a significant role in the urban carbon cycle and using this knowledge for more complete carbon accounting, and a better understanding of green-blue interactions could help to reduce net urban emissions in many places.
keywords: انتشار گازهای گلخانه ای | جداسازی کربن | چرخه کربن شهری | تغییر استفاده از زمین | برنامه ریزی شهری پایدار | حسابداری کربن | Greenhouse gas emissions | Carbon sequestration | Urban carbon cycle | Land use change | Sustainable urban planning | Carbon accounting

As a result of carbon-pricing policies, a number of jurisdictions across the world claim to be decoupling their greenhouse gas (GHG) emissions from their gross domestic product (GDP). In British Columbia (BC), Canada, in what appears to be decoupling from 2007 to 2018, GHGs with respect to GDP declined by 16% ( BC Government 2020 ). This finding, however, is the result of a production-based method of accounting— the predominant global approach for allocating emissions—and not a consumption-based method. In this study, we compare these two accounting methods with respect to British Columbian decoupling. We cal- culate consumption-based emissions through a multi-regional input-output analysis from 2010 to 2015. In our results for 2015, we find total consumption emissions of 82.5Mt of CO 2 e; when compared to the total production emissions of 73.7Mt of CO 2 e, we find BC to be a net consumer of emissions by 8.8Mt of CO 2 e for 2015. Although BC has had this net consumer status since at least 2004 ( Dobson and Fellows, 2017 ), this orientation is in decline primarily due to the decarbonizing trends of China and the USA. In short, for BC from 2010–2015, on a per capita basis, both production and consumption accounts of emissions de- clined (even as GDP rose), but per capita consumption accounts declined more than production accounts and mostly due to emissions reductions from trade partners. Finally, this study may be of interest to policymakers and scientists, and like other scholars, we recommend that consumption-based inventories accompany production-based accounts when designing and assessing global GHG mitigation policy. © 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
keywords: انتشار گازهای گلخانه ای | تجزیه و تحلیل خروجی چند منطقه ای | معامله بین المللی | گازهای گلخانه ای | تغییرات اقلیمی | Embodied emissions | Multi-regional input-output analysis | International trade | Greenhouse gasses | Climate change

Transportation is one of the most influential factors in greenhouse gas emissions and global warming. This paper studies a network with an automotive supply chain that includes one supplier and one manufacturer next to a fuel supply chain consisting of a fuel manufacturer, operating under government intervention. The car manufacturer sells its green and non-green products under the dual-channel system with stochastic demand and demand leakage. To decrease greenhouse gas emissions, the car manufacturer invests in fuel-efficient technology for green products to reduce car fuel consumption. Moreover, due to increasing public awareness of environmental issues, the supplier invests in greening efforts to provide raw materials for fuel-efficient cars. The fuel manufacturer determines the fuel price under the government supervision and the government considers subsidies to support it. The fuel manufacturer has the opportunity to export the surplus fuel to other markets at a higher price. The government supports the production of fuel-efficient cars with two policies of subsidy-taxation and granting loans to customers. By doing so, the car manufacturer improves the level of fuel-efficient technology and the greening efforts of the supplier are increased. Additionally, the amount of fuel consumption in the internal market is reduced and the fuel manufacturer can export more fuel to the external market. As a result, the profit of all members increases simultaneously and environmental conditions improve. This model is studied under two scenarios for the distribution function of stochastic part of demand: (1) the Stackelberg scenario with complete information as a uniform distribution function and (2) the Nash scenario with partial information on a distribution-free approach. Some numerical examples based on real cases are provided to examine the capability of the proposed models. Finally, some sensitivity analyses are applied to the main parameters to extract several in-depth managerial concepts.
Keywords: Automotive supply chain | Fuel-efficient car | Greening efforts | Government intervention | Technology level | Distribution-free approach

The oxidation of ammonia by autotrophic bacteria is a central part of the nitrogen cycle and a fundamental aspect of biological nutrient removal (BNR) during wastewater treatment. Autotrophic ammonia oxidation produces protons and results in net-CO2 production due to the neutralizing effect of bicarbonate alkalinity. Attention must be paid to the propensity for this produced CO2 to be transferred to the atmosphere where it can act as a greenhouse gas (GHG). In the context of BNR systems, bicarbonate-derived CO2 emissions should be considered distinct from the biogenic CO2 that arises from cellular respiration, though this distinction is not made in current GHG accounting practices. The aim of this study was to evaluate the performance of two experimental systems operated under autotrophic mode and buffered with bicarbonate, to investigate the rela- tionship between ammonia removal and gaseous CO2 emissions. The first system consisted of continuously aerated lab-scale batch reactors, which were effective in demonstrating the important link between ammonia oxidizer activity, pH, and gaseous CO2 production. Depletion of the buffer system always led to a rapid decline in system pH and cessation of CO2 emissions when the pH fell below 7.0. The second system was a tubular continuous-flow biofilm reactor which permitted comparison of ammonia removal and CO2 emission rates. A linear relationship between ammonia removal and CO2 emissions was demonstrated and the quantified CO2 production was relatively close to that which was predicted based on the stoichiometry of nitrification, with this CO2 being detected in the gas phase. It was apparent that this system offered minimal resistance to the mass transfer of CO2 from the liquid to gas, which is an important factor that determines how much of the bicarbonate- derived CO2 may contribute to greenhouse gas emissions in engineered systems such as those used for BNR.
keywords: اکسیداسیون آمونیاک اتوتروفیک | بیوفیلم های autotrophic | حذف مواد مغذی زیستی | قلیایی کربنات | انتشار گاز CO2 | انتشار گازهای گلخانه ای | Autotrophic ammonia oxidation | Autotrophic biofilms | Biological nutrient removal | Carbonate alkalinity | CO2 emissions | Greenhouse gas emissions

In this study, multi-criteria assessment technique is used to predict the methane generation from large municipal solid waste landfills in Ontario, Canada. Although a number of properties determine the gas generation from landfills, these parameters are linked with empirical relationships making it difficult to generate precise information concerning gas production. Moreover, available landfill data involve sources of uncertainty and are mostly insufficient. To fully characterize the chemistry of reaction and predict gas generation volumes from landfills, a fuzzy-based model is proposed having seven input parameters. Parameters were identified in a linguistic form and linked by 19 IF-THEN statements. When compared to measured values, results of the fuzzy based model showed good prediction of landfill gas generation rates. Also, when compared to other first order decay and second order decay models like LandGEM, the fuzzy based model showed better results. When plotting the LandGEM and Fuzzy model values to the actual measured data, the fuzzy model resulted in a better fit to actual data than the LandGEM model with a coefficient of determination R2 of 0.951 for fuzzy model versus 0.804 for LandGEM model. The results show how multi-criteria assessment technique can be used in modelling of complicated processes that take place within the landfills and somehow accurately predicting the landfill gas generation rate under different operating conditions
Keywords: Municipal solid waste | Landfill gas | Life-cycle assessment | Waste to energy | Greenhouse gas emissions | Fuzzy model