庐山风景区碳源、碳汇的测度及均衡

旅游目的地系统碳源、碳汇的计算与分析,不仅是旅游业节能减排政策制定的重要依据,也是旅游与环境相互关系研究的一个新的科学命题.以庐山风景区为例,计算并分析了2010年的碳源及碳汇.结果表明:(1)2010年庐山风景区包括本地居民和旅游者的总碳排放为108 697 t.其中,本地居民占碳排放总量的19.52％,旅游者占碳排放总量的80.48％.在旅游者碳排放中,旅游交通碳排放占50.24％,旅游住宿碳排放占38.04％,旅游食物消费碳排放占10.65％,旅游活动碳排放仅占1.07％;(2)2010年庐山风景区内陆地生态系统碳吸收为9447 t;(3)从碳源、碳汇均衡角度看,庐山陆地生态系统的固碳量吸收了区内碳排放的23.47％.但由于旅游者的区际流动和旅游业的产业关联性强,陆地生态系统的碳吸收仅占区内和区外碳排放总量的8.69％,旅游业使庐山成为一个显著的碳源.     

中国航空碳排放及其效率时空演化特征分析

航空碳排放不仅影响空气质量且可造成温室效应。中国正处于从民航大国向民航强国迈进的关键时期,提高航空碳排放效率是行之有效的航空碳减排手段。运用可拓展随机性环境影响评估模型(STIRPAT)对中国2004—2019年航空碳排放总量的时空演变特征进行分析,以探明不同尺度区域航空碳排放的空间差异与空间关联表现;运用基于非期望产出的超效率松弛变量模型(SBM)和标准差椭圆分析法(SDE)对中国航空碳排放效率的时空分布与格局演化过程进行判定,以分析各省域航空碳排放效率的差异,并给出有效的航空碳减排方略。研究发现：2004—2019年,中国航空碳排放总量持续增长,航空碳排放增长率和航空碳排放强度均呈波动下降趋势;四大经济区航空碳排放总量分布总体表现为“东部>西部>中部>东北”的格局,东部仍是中国航空碳排放的主要区域;高碳排放区较分散,还未形成省域之间连片的碳排放高值区。2004—2019年,中国航空碳排放效率总体呈现“M”型波动上升趋势,各省域航空碳排放效率均不同程度的提高,但主要以低效率区、中效率区为主;各省域之间的航空碳排放效率差异性经历了逐渐减小到逐步增大的过程,但总体航空碳...     

秦岭山地碳中和空间服务范围及其模拟预测

在当前碳中和背景下,秦岭山地碳中和的量化及其空间服务范围的测算对于碳中和合理规划和快速实现具有重要意义。采用IUEMS （Intelligent Urban Ecosystem Management System）系统对秦岭山地的固碳量进行核算,利用DMSP/OLS （Defense Meteorological Satellite Program/Operational Linescan System）和NPP-VIIRS （Net Primary Productivity-Visible infrared Imaging Radiometer）夜间灯光数据和各地市的能源消耗数据通过模型拟合对秦岭山地碳排放量进行空间量化,基于固碳量和碳排放量得到秦岭山地空间碳中和量。利用PLUS （Patch-generating Land Use Simulation Model）模型模拟了2030和2050年的碳中和空间分布,结合常见气体扩散系数计算得到常温常压下秦岭山地碳中和对周边区域的服务范围。结果表明：2000-2020年秦岭山地固碳量呈现上升的趋势,大部分区域不同时间尺度上的固碳速率呈正向趋势,空间上秦岭山地中西部区域固碳量整体较大;对秦岭固碳量影响较大的地形特征为海拔1200m左右、斜坡、半阳坡和半阴坡;研究区内碳排放量空间上整体较低,碳排放低值区面积占到了秦岭总面积的90%,碳排放较大区域主要位于秦岭北坡的城区区域,时间上碳排放量最大值为先增加后减少的变化趋势;2000-2050年秦岭山地碳汇服务范围为174-262.63km,服务范围在空间上呈逐渐扩大趋势,2030年后其扩大程度将略有减少。     

中国农业系统近40年温室气体排放核算

基于排放因子法构建了包含种植业和牲畜养殖业的农业系统温室气体排放核算体系,系统核算了1980-2020年我国全国尺度上的农业系统温室气体排放总量和变化趋势,并在区县级尺度下对1980、2000、2011年的中国农业系统的温室气体排放量进行核算,对比不同阶段农业系统温室气体排放变化的时空异质性规律。研究发现：1980-2020年我国农业系统温室气体排放量呈波动增长趋势,增长了近46%。CH₄是农业系统排放贡献最大的温室气体,占总排放量的47.33%。我国农业系统温室气体排放与不同地区农业生产方式有关,CH₄排放量高的地区主要位于我国主要水稻产区以及旱地作物产区。CO₂排放量高的地区主要位于东北、西北等地区以及华东地区。N₂O排放量较高地区主要位于西北的主要畜牧养殖地区,以及我国农业经济发展水平高的中南部地区。研究有助于揭示我国农业温室气体排放的动态特征,现状规律,以及空间差异性特征,从农业减排角度为实现双碳目标提供科学参考。     

黄土丘陵区不同土地利用下土壤释放N2O潜力的影响因素

采用室内培养试验,研究了不同水热条件对黄土丘陵区林地、草地和果园土壤释放N2O的影响,同时测定了土壤中不同氮素形态的变化,旨在探讨影响土壤释放N2O潜力的因素。结果表明：土样中N2O通量与温度显著相关（r=0.1599, P<0.05）,均随温度的升高不断增大,35℃时达到最大。N2O通量与土壤水分含量极显著相关（r=0.2499,P<0.0001）,在土壤水分含量较低时,各土样中N2O通量与土壤水分含量呈正相关,土壤水分接近田间持水量时N2O通量最大,超过田间持水量时N2O通量急剧下降。土壤水分和温度对N2O通量的影响可用拟合方程F=a bT cT^2 dT^3 eT^4 fW来描述。在培养条件下,土壤中N2O的释放总量大小依次为：果园土>林地土>草地土,果园土释放N2O的总量分别比林地土和草地土的释放总量多30%,14%。土壤氮素形态与N2O的释放量有一定关系,但规律不明显。     

Energy and Carbon Management Systems

This article examines an important class of information system that serves as the foundation for corporate energy and greenhouse gas (GHG) accounting: energy and carbon management systems (ECMS). Investors, regulators, customers, and employees increasingly demand that organizations provide information about their organizational energy use and GHG emissions. However, there is little transparency about how organizations use ECMS to meet such demands. To shed light on ECMS implementation and application, we collected extensive qualitative interview data from two service‐sector organizations: one that uses a spreadsheet‐based ECMS and another that implemented an ECMS provided by a third‐party vendor. Our analysis of collected data revealed numerous challenges in the areas of business processes, managerial capabilities, data capture and integration, and data quality. Though our study is built on only two organizations and requires confirmation in large‐sample surveys, we provide several recommendations for organizations regarding ECMS. We also provide suggestions for future studies to build on our tentative results.     

Terrestrial fluxes of carbon in GCP carbon budgets

The Global Carbon Project (GCP) has published global carbon budgets annually since 2007 (Canadell et al. [2007], Proc Natl Acad Sci USA, 104, 18866–18870; Raupach et al. [2007], Proc Natl Acad Sci USA, 104, 10288–10293). There are many scientists involved, but the terrestrial fluxes that appear in the budgets are not well understood by ecologists and biogeochemists outside of that community. The purpose of this paper is to make the terrestrial fluxes of carbon in those budgets more accessible to a broader community. The GCP budget is composed of annual perturbations from pre‐industrial conditions, driven by addition of carbon to the system from combustion of fossil fuels and by transfers of carbon from land to the atmosphere as a result of land use. The budget includes a term for each of the major fluxes of carbon (fossil fuels, oceans, land) as well as the rate of carbon accumulation in the atmosphere. Land is represented by two terms: one resulting from direct anthropogenic effects (Land Use, Land‐Use Change, and Forestry or land management) and one resulting from indirect anthropogenic (e.g., CO₂, climate change) and natural effects. Each of these two net terrestrial fluxes of carbon, in turn, is composed of opposing gross emissions and removals (e.g., deforestation and forest regrowth). Although the GCP budgets have focused on the two net terrestrial fluxes, they have paid little attention to the gross components, which are important for a number of reasons, including understanding the potential for land management to remove CO₂ from the atmosphere and understanding the processes responsible for the sink for carbon on land. In contrast to the net fluxes of carbon, which are constrained by the global carbon budget, the gross fluxes are largely unconstrained, suggesting that there is more uncertainty than commonly believed about how terrestrial carbon emissions will respond to future fossil fuel emissions and a changing climate.     

Sustainable intensification of crop residue exploitation for bioenergy: Opportunities and challenges

Crop residue exploitation for bioenergy can play an important role in climate change mitigation without jeopardizing food security, but it may be constrained by impacts on soil organic carbon (SOC) stocks, and market, logistic and conversion challenges. We explore opportunities to increase bioenergy potentials from residues while reducing environmental impacts, in line with sustainable intensification. Using the case study of North Rhine‐Westphalia in Germany, we employ a spatiotemporally explicit approach combined with stakeholder interviews. First, the interviews identify agronomic and environmental impacts due to the potential reduction in SOC as the most critical challenge associated with enhanced crop residue exploitation. Market and technological challenges and competition with other residue uses are also identified as significant barriers. Second, with the use of agroecosystem modelling and estimations of bioenergy potentials and greenhouse gas emissions till mid‐century, we evaluate the ability of agricultural management to tackle the identified agronomic and environmental challenges. Integrated site‐specific management based on (a) humus balancing, (b) optimized fertilization and (c) winter soil cover performs better than our reference scenario with respect to all investigated variables. At the regional level, we estimate (a) a 5% increase in technical residue potentials and displaced emissions from substituting fossil fuels by bioethanol, (b) an 8% decrease in SOC losses and associated emissions, (c) an 18% decrease in nitrous oxide emissions, (d) a 37% decrease in mineral fertilizer requirements and emissions from their production and (e) a 16% decrease in nitrate leaching. Results are spatially variable and, despite improvements induced by management, limited amounts of crop residues are exploitable for bioenergy in areas prone to SOC decline. In order to sustainably intensify crop residue exploitation for bioenergy and reconcile climate change mitigation with other sustainability objectives, such as those on soil and water quality, residue management needs to be designed in an integrated and site‐specific manner.     

Straw utilization for biofuel production: A consequential assessment of greenhouse gas emissions from bioethanol and biomethane provision with a focus on the time dependency of emissions

The shift from straw incorporation to biofuel production entails emissions from production, changes in soil organic carbon (SOC) and through the provision of (co‐)products and entailed displacement effects. This paper analyses changes in greenhouse gas (GHG) emissions arising from the shift from straw incorporation to biomethane and bioethanol production. The biomethane concept comprises comminution, anaerobic digestion and amine washing. It additionally provides an organic fertilizer. Bioethanol production comprises energetic use of lignin, steam explosion, enzymatic hydrolysis and co‐fermentation. Additionally, feed is provided. A detailed consequential GHG balance with in‐depth focus on the time dependency of emissions is conducted: (a) the change in the atmospheric load of emissions arising from the change in the temporal occurrence of emissions comparing two steady states (before the shift and once a new steady state has established); and (b) the annual change in overall emissions over time starting from the shift are assessed. The shift from straw incorporation to biomethane production results in net changes in GHG emissions of (a) ?979 (?436 to ?1,654) and (b) ?955 (?220 to ?1,623) kg CO₂‐eq. per t_{dry matter} straw converted to biomethane (minimum and maximum). The shift to bioethanol production results in net changes of (a) ?409 (?107 to ?610) and (b) ?361 (57 to ?603) kg CO₂‐eq. per t_{dry matter} straw converted to bioethanol. If the atmospheric load of emissions arising from different timing of emissions is neglected in case (a), the change in GHG emissions differs by up to 54%. Case (b) reveals carbon payback times of 0 (0–49) and 19 (1–100) years in case of biomethane and bioethanol production, respectively. These results demonstrate that the detailed inclusion of temporal aspects into GHG balances is required to get a comprehensive understanding of changes in GHG emissions induced by the introduction of advanced biofuels from agricultural residues.     

Evaluating atmospheric CO2 inversions at multiple scales over a highly inventoried agricultural landscape

An intensive regional research campaign was conducted by the North American Carbon Program (NACP) in 2007 to study the carbon cycle of the highly productive agricultural regions of the Midwestern United States. Forty‐five different associated projects were conducted across five US agencies over the course of nearly a decade involving hundreds of researchers. One of the primary objectives of the intensive campaign was to investigate the ability of atmospheric inversion techniques to use highly calibrated CO₂ mixing ratio data to estimate CO₂ flux over the major croplands of the United States by comparing the results to an inventory of CO₂ fluxes. Statistics from densely monitored crop production, consisting primarily of corn and soybeans, provided the backbone of a well studied bottom‐up inventory flux estimate that was used to evaluate the atmospheric inversion results. Estimates were compared to the inventory from three different inversion systems, representing spatial scales varying from high resolution mesoscale (PSU), to continental (CSU) and global (CarbonTracker), coupled to different transport models and optimization techniques. The inversion‐based mean CO₂‐C sink estimates were generally slightly larger, 8–20% for PSU, 10–20% for CSU, and 21% for CarbonTracker, but statistically indistinguishable, from the inventory estimate of 135 TgC. While the comparisons show that the MCI region‐wide C sink is robust across inversion system and spatial scale, only the continental and mesoscale inversions were able to reproduce the spatial patterns within the region. In general, the results demonstrate that inversions can recover CO₂ fluxes at sub‐regional scales with a relatively high density of CO₂ observations and adequate information on atmospheric transport in the region.