Carbon isotope fractionation of Thermoanaerobacter kivui in different growth media and at different total inorganic carbon concentration

Chemolithotrophic homoacetogenic bacteria apparently express a characteristic stable carbon isotope fractionation and may contribute significantly to acetate production in anoxic environments. However, fractionation factors (ε) in bacterial cultures have rarely been determined and the effect of substrate availability has not been assessed. We therefore studied the kinetic carbon isotope effect in cultures of Thermoanaerobacter kivui grown at 55 °C. The fractionation factor in HCO₃⁻ buffered medium was ca. 15‰ more negative than that in PO₄³⁻ buffered medium. To test whether the difference was caused by the initial substrate ratio of H₂ and total inorganic carbon (TIC; 0.5 in HCO₃⁻ vs. 4.0 in PO₄³⁻ buffered medium), T. kivui was grown in either [3-(N-morpholino) propanesulfonic acid, MOPS] buffered or PO₄³⁻ buffered media with different HCO₃⁻ concentration. Indeed, the fractionation factor became more negative with increasing HCO₃⁻ concentration and decreasing H₂/TIC ratio. While pH had only a small effect, the fractionation was generally more negative in MOPS buffered than in phosphate buffered media, indicating that the buffer system also affected fractionation. Collectively, the results show that substrate availability and other environmental factors affect the magnitude of isotope fractionation during acetate production by chemolithotrophic homoacetogenesis.     

Sources of polycyclic aromatic hydrocarbons (PAHs) to northwestern Saskatchewan lakes east of the Athabasca oil sands

The past several decades have witnessed a significant expansion of mining activities in the Athabasca oil sands region, raising concerns about their impact on the surrounding boreal forest ecosystem. To better understand the extent to which distal sites are impacted by oil sands-derived airborne contaminants, we examine sources of polycyclic aromatic hydrocarbons (PAHs) in surface sediments and dated sediment cores from Saskatchewan lakes situated ∼100–220 km east–northeast of the main area of bitumen mining activities. The concentrations and fluxes of both parent and alkylated PAHs are low and show considerable variability over the past 70–100 years. Small yet discernible increases in PAH concentrations and fluxes occurred over the past 30 years, a trend which coincides with the rapid growth in bitumen production. However, several lines of evidence point to wildfires as the principal source of PAHs to these lakes: (1) the significant co-variations in most cores between retene (1-methyl-7-isopropyl phenanthrene) and other groups of parent and alkylated PAHs, (2) the similarity in compound specific δ¹³C signatures of the parent PAHs phenanthrene and pyrene in recently deposited surficial sediments and those corresponding to time intervals considerably pre-dating the large scale development of the oil sands and (3) the discernible up-core increases in the proportion of refractory carbon (i.e., char) in Rock-Eval 6 data. The collective evidence points to softwood combustion from boreal forest fires as the principal source of retene in sediments and the general increase in forest fire activity in this region over the past several decades as the source of refractory carbon. Mining activities associated with the Athabasca oil sands are thus not considered a major source of PAHs to these lakes.     

Methodological comparison for quantitative analysis of fossil and recently derived carbon in mine soils with high content of aliphatic kerogen

In mine soil, quantification of soil organic carbon (OC) derived recently from biomass decomposition is complicated by the presence of fossil (geogenic) C derived from coal, oil shale, or similar material in the overburden. The only reliable method for such measurement is ¹⁴C analysis (i.e. radiocarbon dating) using instrumentation such as accelerator mass spectrometry, which is too expensive for routine laboratory analysis. We tested two previously used and two new methods for recent C quantification and compared them with ¹⁴C AMS radiocarbon dating as a reference using a set of soil samples (n = 14) from Sokolov, Czech Republic: (i) ¹³C isotope ratio composition, (ii) cross polarization magic angle spinning ¹³C nuclear magnetic resonance (CPMAS ¹³C NMR) spectroscopy, (iii) near infrared spectroscopy (NIRS) coupled with partial least squares regression and (iv) Rock–Eval pyrolysis. Conventional methods for OC determination (dry combustion, wet dichromate oxidation, loss-on-ignition) were also compared to quantify any bias connected with their use. All the methods provided acceptable recent carbon estimates in the presence of mostly aliphatic fossil C from kerogen. However, the most accurate predictions were obtained with two approaches using Rock–Eval pyrolysis parameters as predictors, namely (i) S₂ curve components and (ii) oxygen index (OI). The S₂ curve approach is based on the lower thermal stability of recent vs. fossil organic matter. The OI approach corresponded well with ¹³C NMR spectra, which showed that samples rich in recent C were richer in carboxyl C and O-alkyl C. These two methods showed the greatest potential as routine methods for recent C quantification.     

Refractory Black Carbon Results and a Method Comparison between Solid-state Cutting and Continuous Melting Sampling of a West Antarctic Snow and Firn Core

This work presents the refractory black carbon(rBC)results of a snow and firn core drilled in West Antarctica(79°55'34.6"S,94°21'13.3"W)during the 2014?15 austral summer,collected by Brazilian researchers as part of the First Brazilian West Antarctic Ice Sheet Traverse.The core was drilled to a depth of 20 m,and we present the results of the first 8 m by comparing two subsampling methods—solid-state cutting and continuous melting—both with discrete sampling.The core was analyzed at the Department of Geological Sciences,Central Washington University(CWU),WA,USA,using a single particle soot photometer(SP2)coupled to a CETAC Marin-5 nebulizer.The continuous melting system was recently assembled at CWU and these are its first results.We also present experimental results regarding SP2 reproducibility,indicating that sample concentration has a greater influence than the analysis time on the reproducibility for low rBC concentrations,like those found in the Antarctic core.Dating was carried out using mainly the rBC variation and sulfur,sodium and strontium as secondary parameters,giving the core 17 years(1998?2014).The data show a well-defined seasonality of rBC concentrations for these first meters,with geometric mean summer/fall concentrations of 0.016μg L^?1 and geometric mean winter/spring concentrations of 0.063μg L^?1.The annual rBC concentration geometric mean was 0.029μg L^?1(the lowest of all rBC cores in Antarctica referenced in this work),while the annual rBC flux was 6.1μg m^?2 yr^?1(the lowest flux in West Antarctica records so far).     

城镇化背景下中国长期低碳转型路径研究

在中国经济步入新常态之际,为了研究城镇化背景下的长期碳排放趋势,构建了人口变动与能源系统互动的综合分析框架与社会经济-能源系统模型。结果显示,从2014年至2050年,预计有3亿人口从农村流向城市,并呈现从中小型城市逐步向大型和特大型城市汇集的趋势。人口流动趋势与人民生活质量改善结合,推动中国基础设施建设、工业产品生产和能源服务需求增长。基准情景下,2050年中国一次能源消费总量达到84亿tce,能源相关CO₂排放达到176亿t,比2013年增长83%;而在低碳转型情景下,通过技术创新,2050年中国一次能源消费需求可以控制在61亿tce左右,CO₂排放在2020—2025年间达峰,2050年比基准情景降低78%。低碳转型过程中,非化石能源电力和能效技术的减排潜力最大,工业和电力部门率先在2020年达峰,建筑和交通 ^①（①按照国际通行的能源系统部门划分标准和能耗概念,工业、建筑、交通均属于终端能源消费部门,其中建筑部门能耗指建筑运行能耗,而非建筑建造过程中的能耗;交通部门能耗指所有交通活动能耗,既包括交通运输业营运类运输工具的交通能耗,也包括私人、公务非营运类运输工具的交通能耗 ^[1]。）将在2030年左右达峰。实现低碳转型所需新增固定投资占GDP的1.5%,不会给国民经济带来重大负担。中国实施新型城镇化战略具有技术和经济可行性。     

隐形碳关税:概念辨析与国际治理

碳关税是各国高度关注的贸易问题,因涉及各国经贸利益,南北国家在碳关税问题上分歧很大。任何有关碳关税的政策措施,都会引起发展中国家的强烈反对。因此,部分发达国家试图另辟蹊径,在国际贸易中通过增加生产标准、碳标签等技术要求,以比较隐蔽的方式实现执行碳关税的目的。文中将这些隐蔽的但能起到碳关税执行效果的政策措施归纳为隐形碳关税,并定义隐形碳关税是指那些虽然没有在边境环节征收碳关税,但与征收碳关税起到相同贸易壁垒作用的,对发展中国家出口产品和服务构成限制的政策和措施。隐形碳关税比较典型的表现形式包括生产标准、碳标签等措施。这些措施本身是政策中性的,并不构成隐形碳关税,但如果叠加了转移应对气候变化成本、限制发展中国家产业发展等目的,这些措施的性质便不再中性,而成为现实中的贸易壁垒。隐形碳关税的治理应该是国际气候治理进程的一个部分,《联合国气候变化框架公约》则应是隐形碳关税治理的主要国际平台。无论是在气候公约内还是气候公约外的治理机制,隐形碳关税的国际治理都应遵循气候公约的相关原则,尤其是共同但有区别责任原则,区别对待发达和发展中国家的责任和义务,充分发挥生产标准、碳标签等措施的积极环境效用,同时约束其不当使用,建立公平、互信、务实的国际合作模式,实现气候治理与经济发展的协同。     

山西省煤矿采空地下空间评估与再利用研究

山西省煤炭资源丰富,年煤炭产量占全国产量的近1/4,煤炭资源开采形成大量的采空地下空间。随着碳中和目标的提出和山西风电、光伏发电的大力发展,如何合理利用煤矿采空地下空间,尤其是将地下空间与新能源结合将成为煤炭产业低碳发展的关键。本次研究运用比例系数法和采空地下空间守恒定律,测算出2022年山西省开采煤矿井巷可利用空间为1.54亿m3,“十五”到“十三五”期间关闭/退出煤矿的井巷可利用空间为1.05亿m3,估算1949至2021年山西省煤矿因工作面开采形成的采空地下空间约38.98亿m3,预测到2030年山西省煤矿工作面开采还可形成采空地下空间约19.56亿m3。根据山西省能源低碳发展需求提出了山西省煤矿采空地下空间未来可利用的四种模式：煤矿地下旅游或地下仓储、煤矿地下抽水蓄能、煤矿地下压缩空气储能和煤矿地下封存二氧化碳等。     

一维热扩散湖模式在太湖的应用研究

利用在太湖获得的2010年8月11-28日的观测资料研究了一维热扩散湖模式在太湖的适用性,通过对比模拟进一步研究了影响太湖湖表温度模拟的主要因子。该湖模式对太湖最初的模拟结果并不理想,模拟的湖表面温度与观测有较大的系统性偏差,温度的日变化幅度与观测相比也偏小。通过分析该模式对太湖的模拟效果不理想的可能原因,针对太湖的生态环境和污染情况,设计了18个测试参数的敏感性试验,从敏感性试验的结果分析得到,适用于太湖的、依赖于湖泊类型的3个参数应做如下修改:消光系数（η₀）应放大3倍,湖泊表层吸收的太阳辐射系数（β）应取0.8,粗糙长度（z₀）采用公式计算得到。用新得到的适用于太湖的3个参数,模拟得到的结果与最初的模拟结果和观测资料对比,发现采用新的参数后,模拟结果比最初的模拟结果有了很大的改进,模拟的湖表温度基本接近观测,模拟的湖水垂直剖面时间序列图也跟观测吻合得较好,随之的感热、潜热通量的模拟也都与观测接近。最后,对输入湖模式的主要大气参量（太阳辐射、2 m气温及风场）±10%的误差引起的模式模拟的湖表面温度误差进行分析,结果表明该湖模式对大气强迫场的误差敏感度不高;相比之下,模拟结果对风场敏感性最小,对辐射和气温的敏感度相当。     

Applying personal carbon trading: a proposed ‘Carbon,Health and Savings System’ for British Columbia,Canada

Addressing climate change requires the synergy of technological, behavioural and market mechanisms. This article proposes a policy framework that integrates the three, deploying personal carbon trading as a key element within a policy portfolio to reduce personal carbon footprints. It draws on policy and human motivation literatures that address the behavioural changes that may be needed in the context of a long-term threat such as climate change. This proposal builds on an analysis of the British Columbia carbon tax, international examples of carbon pricing instruments and strategies for behavioural change such as social networks, loyalty management, mobile apps and gamification. Interviews were conducted with experts in financial services, energy conservation and clean technology, as well as with specialists in climate, health and taxation policy. Their input, together with a review of the theoretical literature and practical case studies, informed the proposed design of a Carbon, Health and Saving System for promoting individual engagement and collective action by linking long-term climate mitigation measures with short-term personal and social goals, including health, recreation and social reinforcement.

Policy Relevance

This article identifies areas for climate policy innovation and recommends policies that can support, promote and enable personal carbon budgeting and collective action. Although this study is focused on British Columbia, both the input provided by key opinion leaders and the proposed framework are applicable to other jurisdictions.

This policy proposal shows how personal carbon trading could work in the context of a Canadian province with an existing climate mitigation policy. It also specifies a minimum viable product approach to establishing the economic, social and technological foundations for personal carbon trading.

The Carbon, Health and Saving System identifies the technologies and stakeholders needed to implement personal carbon trading, and offers the possibility of motivating a widespread conscious human response in the event that carbon taxation proves insufficient to generate economic adaptation in a changing climate.     

Landscape for change? International climate policy and energy transitions: evidence from sub-Saharan Africa

What is the role of the climate regime in facilitating rapid decarbonization of the world’s energy systems? We examine how core assumptions concerning the roles of the nation state, carbon markets and finance and technology in international climate policy are being challenged by the realities of how transitions in the energy systems are unfolding. Drawing on the critical region of sub-Saharan Africa, we examine the potential for international climate policy to foster new trajectories towards decarbonization.

Policy relevance

The international regime for climate policy has been in place for some twenty years. Despite significant changes in the landscape of energy systems and drivers of global GHG emissions over this time, the core principles and tools remain relatively stable – national governments, carbon markets, project-based climate finance and the transfer of technological hardware. Given the diversity of actors and drivers and the limited direct reach and influence of international climate policy, however, there is an urgent need to consider how the climate regime can best support the embryonic transitions that are slowly taking form around the world. To do this effectively requires a more nuanced understanding of the role of the state in governing these transitions beyond the notion of a cohesive state serving as rule-enforcer and transition manager. It also requires a broader view of technology, not just as hardware that is transferred, but as a set of practices and networks of expertise and enabling actors. Likewise, though markets have an important role to play as vehicles for achieving broader ends, they are not an end in themselves. Finally on finance, while acknowledging the important role of climate aid, often as a multiplier or facilitator of more ambitious private flows, it is critical to differentiate between the types of finance required for different transitions, many of which will not be counted under, or directed by, the climate regime. In sum, the (low-) carbon economy is being built in ways and in numerous sites that the climate regime needs to be cognizant of and engage with productively, and this may require fundamental reconsideration of the building blocks of the international climate regime.