Comparison of Life-Cycle Inventory Databases: A Case Study Using Soybean Production

Three established life-cycle inventories of agricultural operations were used to generate air emissions data for soybean production: the greenhouse gases, regulated emissions, and energy use in transportation (GREET) model; the economic input-output life-cycle assessment (EIO-LCA) model; and SimaPro software equipped with the Franklin database. EIO-LCA and GREET baseline data were compared to evaluate differences in boundary definitions that apply specifically to U.S. soybean agriculture and processing, which resulted in several major findings. The EIO model estimated for emissions of particulate matter less than 10 micrograms (PM10) resulting from wind erosion that were not included in GREET, but neglected indirect nitrous oxide (N2O) and nitrogen oxides (NOx) emissions from fertilizer application. EIO also assumed significantly lower process energy requirements and lower volatile organic compounds (VOC) for soybean crushing and oil extraction. The GREET and SimaPro models were compared using identical boundary and assumption data, to reveal major discrepancies in fundamental assumptions of energy inventories. Key emission factors varied by several orders of magnitude for basic energy generation and combustion processes, potentially impacting results for any inventory analysis that contains significant energy consumption. The Franklin database assumed VOC and sulfur oxides (SOx) emissions more than an order of magnitude higher than GREET for all categories investigated, with significantly lower N2O and methane (CH4) emission factors.     

中国居民消费隐含的碳排放量变化的驱动因素

应用基于投入产出技术的生命周期评价(EIO-LCA)核算了1997、2000、2002、2005和2007年5a的中国居民消费隐含的二氧化碳排放量,发现其呈现增加趋势。2007年达到18.53亿t,相当于1997年的1.61倍,年平均增长4.89%. 其次采用结构分解分析(SDA)分析了碳排放效率变化、经济内在结构变迁、消费结构转变、人均消费水平变化、城市化进程和人口总量变化等六项因素对碳排放总量变化的驱动作用。研究发现碳排放效率因素和人均消费水平变化是驱动碳排放变化的两大主要力量,并且作用相反。碳排放效率的持续提高,很大程度上缓解了居民消费的隐含碳排放急剧增加的趋势,是减缓碳排放量的主要因素;而人均消费水平的迅速提高成为推动碳排放增加的主要力量,是推动碳排放增加的主要因素。     

Decomposition of Emission Multipliers in a National Accounting Matrix Including Environmental Accounts

This study defines a linear model of emission multipliers through the use of a national accounting matrix including environmental accounts (NAMEA) for the Catalan economy that integrates the regional economic information with the greenhouse gas emissions. As in the model of income multipliers, emission multipliers can be divided into own effects, open effects, and circular effects. This decomposition shows the channels of income generation and their effects on regional greenhouse gas emissions. Our results reveal significant differences among the three gases analyzed as well as important asymmetries at a sectorial level.     

中国区域间隐含碳排放转移

利用投入产出模型,对消费视角下碳排放的核算方法及国际贸易中隐含碳排放转移的研究是当前国际学术界碳排放研究的焦点问题之一。在梳理国内外相关研究进展的基础上,利用区域间投入产出模型构建了区域间隐含碳排放转移的核算方法,并计算了1997年和2007年中国8个主要区域间隐含的碳排放转移及其变化。结果显示,不管是在规模还是空间上,中国区域间隐含碳排放转移都发生了很大变化,总体上呈现向西部地区延伸的趋势,尤其是西北地区成为最大的碳排放承接区域。而京津和东南沿海地区始终是主要的碳转出地区,尤其是东南沿海地区因出口而导致的碳排放向中西部地区转移的增加最为明显。因此,调整东部地区的出口结构,优化投资和消费结构,避免落后淘汰产能通过区域转移进一步发展,提高节能技术的应用是我国节能减排工作的重要内容。     

Improving the integrated hybrid LCA in the upstream scope 3 emissions inventory analysis

Purpose

The protocols of carbon footprints generally define three scopes for different greenhouse gas (GHG) emissions levels. The most important carbon footprint emissions source comes from upstream indirect emissions of scope 3 for products that do not consume energy during their use phase. Upstream scope 3 GHG inventory can usually be analyzed through input–output or hybrid LCA analysis. The economic input–output life cycle analysis (EIO-LCA) and the hybrid LCA model have been widely used for this purpose. However, a cutoff error exists in the hybrid model, and the lack of a truncation criterion between process and IO inventory may lead to a high level of uncertainty in the hybrid model. This study attempts to improve the problem of cutoff uncertainty in hybrid LCA and proposes a method to minimize the cutoff uncertainty.

Methods

The way to improve the cutoff uncertainty could follow two steps. First, through the IO inventory analysis of EIO-LCA, we can define the emissions by various tiers of product components. The IO inventory indicator can provide a definitive criterion for the process inventory of the hybrid model. Second, we connect the process- and IO-LCI according to the IO inventory result. The advantage of the process inventory is that it provides detailed manufacturing information on the target while the IO encompasses a complete system boundary. For improvements, the process inventory can catch the most important process of the GHG emissions, and the IO inventory could compensate for the remainder of the incomplete system inventory.

Results and discussion

In this case study, the printed circuit board production process is used to evaluate the efficiency of the improved method. The threshold M was set to 70 in this case study, and the IO inventory provides the remaining 30 %. For the integrated hybrid model, the tier 3 process inventory takes only 64 % while the incorporation of the proposed method can include 92 % of the total emissions, which shows the cutoff uncertainty can be reduced through the improvement.

Conclusions

This study provides a clear guideline for process and IO cutoff criteria, which can help the truncation uncertainty. When higher precision is required, process LCI will need to play an important role, and thus, a higher M value should be set. In this situation, the emissions from IO-LCI would be smaller than the emissions from the process LCI. The appropriate solution would attain a comfortable balance between data accuracy and time and labor consumption.     

Input‐Output‐based Life Cycle Inventory

An input‐output‐based life cycle inventory (IO‐based LCI) is grounded on economic environmental input‐output analysis (IO analysis). It is a fast and low‐budget method for generating LCI data sets, and is used to close data gaps in life cycle assessment (LCA). Due to the fact that its methodological basis differs from that of process‐based inventory, its application in LCA is a matter of controversy. We developed a German IO‐based approach to derive IO‐based LCI data sets that is based on the German IO accounts and on the German environmental accounts, which provide data for the sector‐specific direct emissions of seven airborne compounds. The method to calculate German IO‐based LCI data sets for building products is explained in detail. The appropriateness of employing IO‐based LCI for German buildings is analyzed by using process‐based LCI data from the Swiss Ecoinvent database to validate the calculated IO‐based LCI data. The extent of the deviations between process‐based LCI and IO‐based LCI varies considerably for the airborne emissions we investigated. We carried out a systematic evaluation of the possible reasons for this deviation. This analysis shows that the sector‐specific effects (aggregation of sectors) and the quality of primary data for emissions from national inventory reporting (NIR) are the main reasons for the deviations. As a rule, IO‐based LCI data sets seem to underestimate specific emissions while overestimating sector‐specific aspects.     

Development of the interregional I/O based LCA method considering region-specifics of indirect effects in regional evaluation

Background and Aims  Recently, Life Cycle Assessment (LCA) has been recognized as an effective tool for evaluating the environmental impacts of regional activities. The main issue, when applying LCA to region-based studies, is how best to consider and reflect the regional characteristics, as they need to be as close to reality as possible. Several Life Cycle Inventory (LCI) analysis and Life Cycle Impact Assessment (LCIA) studies have been undertaken to study site-specific considerations. However, due to practicalities, very few attempts have been made at identifying the regions affected by regional activities and consider their regional characteristics. Therefore, the purpose of this study is to suggest the direction of a forthcoming study by showing the necessity of regional characteristic consideration in regional evaluation, and to suggest a synthetic, region-based LCA method which can reflect the differences of regional characteristics for direct and indirect effects of regional activities. Methods  In this study, the Life Cycle Region-specific Assessment Method (LCRAM) was proposed as a new site-specific LCA method. As an example, we used LCRAM to observe the effects of 4 environmental burdens (CO₂, NO_x, SO_x, and SPM) to human health (DALY) in 47 regions (prefectures in Japan). LCRAM consists of a regional database and an analysis method (EIOM). In order to reflect the regional characteristics, including structural (regional production and consumption, interregional trade, and the structure of energy consumption) and environmental features (geographical location, climate, natural conditions, and population density), we first constructed a regional database. This includes an Interregional Trade Matrix (ITM), Regional Environmental Burden Coefficients (REBC), and Regional Damage Factors (RDF). Second, for considering the regional characteristics by using the regional database to the each region, it is a necessary to identify the environmental burden emitting regions (Emitting Regions) of indirect effects due to regional activity. To do this, we developed the Expanded Interregional Input Output Method (EIOM) to take the place of the Multi-Regional Input Output method (Multi-Regional IO) by applying the Two-Regional IO method and the ITM. This is because it is difficult to apply Multi-Regional IO to many regions and industries owing to practical constraints. Results and Discussion  Upon comparison between the regional database, it was found to show considerable differences due to regional characteristics. It is possible to identify how much the difference of REBC influences the evaluation results by calculating the Deviation Effect Index with REBC and, thus, it was found that the effects from the iron and steel, and electric power industries were more than three times that of other industries. Also the size of RDF varies according to the property of the Environmental Burden (EB) and region; and the more site-specific EB, such as SPM in this study shows, the more distinct the difference. Therefore, it seems reasonable to recommend that the proper regional database is applied to the Emitting Regions. Meanwhile, a comparison with a 9-region IO table (a Multi-Regional IO table made by the Ministry of Economy, Trade and Industry in Japan) was performed to verify the reliability of EIOM. The results indicated a high consistency of over 95%, which verifies that EIOM can be used instead of a Multi-Regional IO method. Finally, as a comparison between LCRAM and Region-Generic Method (RGM) for nine activity regions, we confirmed that the results produced by RGM may be an underestimation or overestimation; as an example, the largest difference among the regions for DALY reached 48% of the RGM result. Conclusions and Outlook  In this study, it was clearly shown that the evaluation results will be different depending on the structure and environmental features of each region. It is necessary to reflect the proper regional characteristics to evaluate the actual regional activity. LCRAM is an efficient method to consider the regional characteristics for direct and indirect effects to regions, through all stages of the activities. Also, it is possible to apply a regional evaluation for more regions and more detail in the industry classification. Furthermore, it discusses the interdependence and transportation effects due to interaction between the regions. Thus, it may enable us to make an appropriate decision in region-based evaluations such as nourishment and inducement of industry, infrastructure, recycle system, etc. Finally, it is also expected that further discussion and continuous examination will contribute to enabling us to frame an actual and efficient policy based on the regional structural features and environmental features for a sustainable community.     

水资源投入产出方法研究进展

从扩展建模技术、系数调整2条线索回顾国内外的水资源投入产出研究进展, 并讨论水资源的投入产出研究的不足和发展趋势。因为水资源投入产出表反映的是水资源与经济结构的关系,如果研究人员自己编制一张水资源投入产出表是不容易的事情。通常情况下都是以研究地域的投入产出表为基础,与其他模型相结合来研究水资源投入产出,但是水资源投入产出建模技术因为数据的限制而只能建立年度模型,具有很强的前提假定,使得投入产出建模技术缺乏灵活性,因而在运用中有对模型改进的必要。水资源投入产出扩展建模技术在这些方面就分别形成了与地区投入产出表结合的投入产出建模技术、与水资源供给相结合的投入产出扩展建模技术、与延长表结合的投入产出扩展建模技术。时效性缺乏一直就成为影响IO模型研究的最主要的瓶颈之一,为此,对各种用于建立新的 IO 表技术的研究一直受到普遍的重视。目前, IO 表系数调整方法已从消耗系数不变的系数调整方法、以RAS为代表的比例法, 发展到多种手段相结合的优化法。算法的改进和求解非线性规划问题的大量计算机软件的出现使得非线性优化模型得到了广泛的应用。     

The Waste Input-Output Approach to Materials Flow Analysis

Abstract: A general analytical model of materials flow analysis (MFA) incorporating physical waste input-output is proposed that is fully consistent with the mass balance principle. Exploiting the triangular nature of the matrix of input coefficients, which is obtained by rearranging the ordering of sectors according to degrees of fabrication, the material composition matrix is derived, which gives the material composition of products. A formal mathematical definition of materials (or the objects, the flow of which is to be accounted for by MFA) is also introduced, which excludes the occurrence of double accounting in economy-wide MFAs involving diverse inputs. By using the model, monetary input-output (IO) tables can easily be converted into a physical material flow account (or physical input-output tables [PIOT]) of an arbitrary number of materials, and the material composition of a product can be decomposed into its input origin. The first point represents substantial saving in the otherwise prohibitive cost that is associated with independent compilation of PIOT. The proposed methodology is applied to Japanese IO data for the flow of 11 base metals and their scrap (available as e-supplement on the JIE Web site).     

基于多区域投入产出分析的京津冀地区虚拟水核算

通过贸易与消费调控实现区域水资源优化配置已成为缓解地区水资源压力的途径之一。跨区域投入产出分析可为地区间虚拟水贸易战略提供依据。基于2012年京津冀地区投入产出表与生产用水量构建了跨地区虚拟水核算模型,计算了隐含在经济贸易中的虚拟水总量及各地区各部门的直接用水系数、完全用水系数和拉动系数,分析了各部门虚拟水进出口情况,识别了重点耗水部门。结果表明:京津冀地区呈现虚拟水净出口状态,其中净出口部门主要为北京的服务与交通业,河北的农业和制造业。京津冀的农业、矿业和水供应业在生产过程中直接消耗水量大,应注重提升用水效率及节水技术的开发;三地制造业、建筑业和服务与交通业的平均拉动系数较大,这说明其他部门生产活动对该部门依赖性较大,其单位产出的提高将带动整个地区更多虚拟水量的投入。此外,河北的农业和制造业为京津冀各部门输送了大量虚拟水,为各部门生产提供了支撑,是节水的重点部门,应着重调整其产业结构,并从直接和间接用水两方面入手减少水资源消耗。计算了京津冀地区不同部门的直接、间接水资源消耗、水资源消耗拉动系数,以及部门间的虚拟水贸易情况,结果可为该地区部门间水资源配置和虚拟水战略的制定提供基础。     

Identify sectors’ role on the embedded CO2 transfer networks through China’s regional trade

This study developed a framework for combining multi-regional input-output analysis and network indicators to assess the interregional CO₂ flows in China. The interregional CO₂ flows of eight regions were calculated and visualized based on a multiregional input-output (MRIO) model for China. The focus of the research was intermediate use. The results of the network indicators showed that refined petroleum, coke, nuclear fuel and chemical products (07), and basic metals and fabricated metal sectors (09) played key roles in the complex networks. and these sectors in most regions controlled a large share of CO₂ transfer by functioning as key hubs and authorities. They along with commerce, transport, storage, and post (16) acted as agents that brokered the CO₂ flows within and between regions. The roles of some other industrial sectors were also identified, e.g., construction (15) functioned as the largest authority. The results demonstrated the importance and effectiveness of network indicators for identifying the characteristics of CO₂ emissions embedded in the domestic supply chain, and provided new information relevant to policy implementation.     

Product Environmental Life-Cycle Assessment Using Input-Output Techniques

Life-cycle assessment (LCA) facilitates a systems view in environmental evaluation of products, materials, and processes. Life-cycle assessment attempts to quantify environmental burdens over the entire life-cycle of a product from raw material extraction, manufacturing, and use to ultimate disposal. However, current methods for LCA suffer from problems of subjective boundary definition, inflexibility, high cost, data confidentiality, and aggregation.
This paper proposes alternative models to conduct quick, cost effective, and yet comprehensive life-cycle assessments. The core of the analytical model consists of the 498 sector economic input-output tables for the U.S. economy augmented with various sector-level environmental impact vectors. The environmental impacts covered include global warming, acidification, energy use, non-renewable ores consumption, eutrophication, conventional pollutant emissions and toxic releases to the environment. Alternative models are proposed for environmental assessment of individual products, processes, and life-cycle stages by selective disaggregation of aggregate input-output data or by creation of hypothetical new commodity sectors. To demonstrate the method, a case study comparing the life-cycle environmental performance of steel and plastic automobile fuel tank systems is presented.     

煤电一体化开发对锡林郭勒盟环境经济的影响

国家“十二五”规划确定将在内蒙古锡林郭勒盟建设国家重点大型煤电基地.煤电一体化开发将大大地推动锡盟的区域经济发展,但也可能会对这一典型草原地区和重要生态屏障地区的生态环境造成不利影响.采用物料平衡法和指数增长模型对2001-2009年锡林郭勒盟SO2排放量与人均GDP做了相关性分析,发现二者关系基本符合环境库兹涅茨曲线,呈较缓和倒U型曲线,拐点在人均GDP35000-40000元,目前已过曲线拐点,SO2排放量缓步下降.对锡盟煤电一体化开发情景下(2012-2020)的SO2排放及人均GDP进行预测,结果显示SO2排放量将随经济发展呈上升趋势,表明煤电一体化开发会使环境库兹涅茨曲线的拐点后延,虽然到2020年SO2排放量仍然没有超出区域大气环境容量,但将接近环境容量极限,会给当地环境带来明显压力;基于以上判断,进而从制度、技术、市场三方面出发,探讨了促进锡盟煤电一体化产业建设与环境保护协调发展的对策.     

Urgency,development stage and coordination degree analysis to support differentiation management of water pollution emission control and economic development in the eastern coastal area of China

The eastern coastal areas of China have high-density population, developed society and economy, and large water pollution emissions. How to reduce water pollution and realize the coordinated development of the economy and environment has become the national focus. Effective environmental policies should consider regional differences in development stage and sustainability performance. Here, we first analyzed the water pollution emissions intensity of the eastern coastal areas of China and the urgency of emissions reduction using 8-year environmental statistics from 2003 to 2010. We characterized development stages of the eastern coastal areas based on the relationships between water pollution emissions intensity and economic development. Further, we built a coordination degree index of economic development and water environment protection as a measure of sustainability. Results show that water pollution emissions intensity decreases as the economy grows from 2003 to 2010. The less-developed regions have a better coordination degree than some more-developed regions, especially those most-developed ones (e.g., Shanghai show more pressures on long-term sustainability than Hebei). The less-developed regions should take advantage of economic growth to invest more advanced environment protection technologies. The more-developed regions need to upgrade its economic structures and municipal infrastructures. Overall, the study provided a comprehensive approach to understand regional difference in development stage and sustainability performance in the eastern coastal region of China as well as the need of different environmental policies to reduce water pollution emissions.     

Impacts of energy-related CO2 emissions: Evidence from under developed,developing and highly developed regions in China

A large accumulation of carbon dioxide and other greenhouse gases have caused great concern around the world. A great deal of general literature focus on the impact factors of CO₂ emissions at the national, regional and city levels. However, there is little specific guidance on regional difference in CO₂ emissions. In this paper, 30 provincial-level administrative units of China are divided into three different levels of economic development regions according to the GDP per capita from 1997 to 2012. A STIRPAT (Stochastic Impacts by Regression on Population, Affluence and Technology) model is used to examine the impact factors on energy-related CO₂ emissions, including population, economic level, technology level, urbanization level, industrialization level and foreign trade degree. The results indicate that the effect of energy intensity is the greatest in highly developed region. Nevertheless, the impact of urbanization, industry structure and foreign trade degree in under developed region is higher than the other two regions. Population and GDP per capita have greater effect on carbon emissions in developing region than the others. Finally, differentiated measures for CO₂ reductions should be adopted according to local conditions of different regions.     

Towards an Integrated Regional Materials Flow Accounting Model

A key challenge in attaining regional sustainability is to reduce both the direct and the indirect environmental impacts associated with economic and household activity in the region. Knowing what these flows are and how they change over time is a prerequisite for this task.
This article describes the early development of an integrated regional materials flow accounting framework. The framework is based on a hybrid (material and economic) multiregional input-output model. Using readily available economic and materials data sets together with transport and logistics data, the framework attempts to provide estimates of household resource flows for any U.K. region at quite detailed levels of product and material disaggregation. It is also capable of disaggregating these flows according to specific socioeconomic criteria such as income level or occupation of the head of household. Allied to appropriate energy and life-cycle assessment data sets, the model could, in addition, be used to map both direct and indirect environmental impacts associated with these flows.
The benefits of such an approach are likely to be a considerable reduction of uncertainties in (1) our knowledge of the household metabolism, and hence our predictions of regional household waste generation; (2) our assessment of the impacts of contemplated changes in industrial process siting, and thereby on other aspects of local and regional planning; and (3) our understanding of the impacts of changes in the pattern of demand for different materials and products. It is concluded that the use of such an integrated assessment tool has much to contribute to the debate on regional sustainability.     

Environmental Assessment of Freight Transportation in the U.S. (11 pp)

Goal, Scope and Background This study provides a life cycle inventory of air emissions (CO2, NOx, PM10, and CO) associated with the transportation of goods by road, rail, and air in the U.S. It includes the manufacturing, use, maintenance, and end-of-life of vehicles, the construction, operation, maintenance, and end-of-life of transportation infrastructure, as well as oil exploration, fuel refining, and fuel distribution. Methods The comparison is performed using hybrid life cycle assessment (LCA), a combination of process-based LCA and economic input-output analysis-based LCA (EIO-LCA). All these components are added by means of a common functional unit of grams of air pollutant per ton-mile of freight activity. Results and Discussion Results show that the vehicle use phase is responsible for approximately 70% of total emissions of CO2 for all three modes. This confirms that tailpipe emissions underestimate total emissions of freight transportation as infrastructure, pre-combustion, as well as vehicle manufacturing and end-of-life account for a sizeable share of total emissions. Differences between tailpipe emissions and total system wide emissions can range from only 4% for road transportation's CO emissions to an almost ten-fold difference for air transportation's PM10 emissions. Conclusion Rail freight has the lowest associated air emissions, followed by road and air transportation. Depending on the pollutant, rail is 50-94% less polluting than road. Air transportation is rated the least efficient in terms of air emissions, partly due to the fact that it carries low weight cargo. It emits 35 times more CO2 than rail and 18 times more than road transportation on a ton-mile basis. It is important to consider infrastructure, vehicle manufacturing, and pre-combustion processes, whose life-cycle share is likely to increase as new tailpipe emission standards are enforced. Recommendation and Outlook Emission factors, fuel efficiency, and equipment utilization contribute the most to uncertainty in the results. Further studies are necessary to address all variables that influence these parameters, such as road grade, vehicle speed, and vehicle weight. A focus on regional variation, end-of-life processes, fuel refining processes, terminals, as well as more accurate infrastructure allocation between freight and passenger transportation would strengthen the model.     

China’s water footprint by province,and inter-provincial transfer of virtual water

Water shortages and the uneven distribution of water resources restrict China’s sustainable development. The concepts of virtual water and water footprints provide a new approach to alleviate regional shortages of Chinese water resources by the inter-provincial allocation of commercial water resources. In this study, an interregional input-output model was applied to quantitatively estimate the water footprint of each province in China and to quantify the inter-provincial transfer of virtual water. The results indicated that there was considerable diversity in the water footprints of the various provinces. Provinces with larger populations and greater GDP had larger water footprints, and developed regions had higher proportions of external water footprints. From the perspective of final demand, local consumption was the main factor driving the water footprints of these provinces. From the perspective of sectoral structure, the agricultural water footprint had a larger proportion in these provinces. The transfer of virtual water in China did not occur from regions with abundant water resources to those suffering from water shortages, but it generally occurred from west to east, from inland to coastal areas, and from underdeveloped to developed regions. Many water-deficient regions also had large net virtual water exports. Water shortages in China will be alleviated by the enhancement of industrial water-use efficiency in water-deficient regions, the transfer of water-intensive industries to regions with abundant water resources, and the development of tertiary industries with low water consumption.     

Carbon balances in US croplands during the last two decades of the twentieth century

Carbon (C) added to soil as organic matter in crop residues and carbon emitted to the atmosphere as CO₂ in soil respiration are key determinants of the C balance in cropland ecosystems. We used complete and comprehensive county-level yields and area data to estimate and analyze the spatial and temporal variability of regional and national scale residue C inputs, net primary productivity (NPP), and C stocks in US croplands from 1982 to 1997. Annual residue C inputs were highest in the North Central and Central and Northern Plains regions that comprise ~70% of US cropland. Average residue C inputs ranged from 1.8 (Delta States) to 3.0 (North Central region) Mg?C?ha^?1?year^?1, and average NPP ranged from 3.1 (Delta States) to 5.4 (Far West region) Mg?C?ha^?1?year^?1. Residue C inputs tended to be inversely proportional to the mean growing season temperature. A quadratic relationship incorporating the growing season mean temperature and total precipitation closely predicted the variation in residue C inputs in the North Central region and Central and Northern Plains. We analyzed the soil C balance using the crop residue database and the Introductory Carbon Balance regional Model (ICBMr). Soil C stocks (0–20?cm) on permanent cropland ranged between 3.07 and 3.1?Pg during the study period, with an average increase of ~4?Tg?C?year^?1, during the 1990s. Interannual variability in soil C stocks ranged from 0 to 20?Tg?C (across a mean C stock of 3.08?±?0.01?Pg) during the study period; interannual variability in residue C inputs varied between 1 and 43?Tg C (across a mean input of 220?±?19?Tg). Such interannual variation has implications for national estimates of CO₂ emissions from cropland soils needed for implementation of greenhouse gas (GHG) mitigation strategies involving agriculture.     

环境投入产出分析在产业生态学中的应用

综述了环境投入产出分析的基本知识及其在产业生态学领域的应用。环境投入产出分析的核心是投入产出模型,包括价值型投入产出模型、实物型投入产出模型和混合型投入产出模型。环境投入产出分析在产业生态学领域主要用于环境压力核算、生命周期评估、社会经济因素相对贡献分析、产业链路径分析、风险影响分析和环境网络分析。同时,相关学者进行环境投入产出数据库开发,给环境投入产出分析提供便捷、标准化的数据渠道。讨论了环境投入产出分析的若干发展趋势。