城市废弃物处理温室气体排放研究:以厦门市为例

城市废弃物处理是城市人为活动产生温室气体的来源之一.参考IPCC国家温室气体清单指南2006推荐的方法建立了厦门市废弃物处理的温室气体排放计算模型,对厦门市2005～2010年废弃物处理的温室气体排放情况进行了估算,包括固体废弃物填埋、焚烧以及污水处理等过程.结果表明,2005年温室气体总排放量折合二氧化碳当量(CO2e)为406.3 kt,2010年温室气体总排放量(以CO2e计)达到704.6 kt,随着废水处理工艺的提高和城市生活垃圾量的迅速增长,主要排放源由废水处理转变为固体废弃物填埋.2005年填埋产生的温室气体排放占固体废弃物处理排放量的90%左右,2010年所占比例下降到75%.厦门市废水处理温室气体排放量2007年最高,以CO2e计达到325.5 kt,化学原料及化学品制造业从2005～2010年一直是厦门市CH4排放量最高的产业,占工业废水处理CH4排放总量的55%以上.     

Global warming contributions from wheat,sheep meat and wool production in Victoria,Australia – a life cycle assessment

This paper compares the life cycle global warming potential of three of Australia’s important agricultural production activities – the production of wheat, meat and wool in grazed subterranean clover (sub-clover) dominant pasture and mixed pasture (perennial ryegrass/phalaris/sub-clover/grass and cape weed) systems. Two major stages are presented in this life cycle assessment (LCA) analysis: pre-farm, and on-farm. The pre-farm stage includes greenhouse gas (GHG) emissions from agricultural machinery, fertilizer, and pesticide production and the emissions from the transportation of these inputs to paddock. The on-farm stage includes GHG emissions due to diesel use in on-farm transport and processing (e.g. seeding, spraying, harvesting, topdressing, sheep shearing), and non-CO₂ (nitrous oxide (N₂O), and methane (CH₄)) emissions from pastures and crop grazing of lambs.The functional unit of this life cycle analysis is the GHG emissions (carbon dioxide equivalents – CO₂ -e) from 1 kg of wheat, sheep meat and wool produced from sub-clover, wheat and mixed pasture plots. The GHG emissions (e.g. CO₂, N₂O and CH₄ emission) from the production, transportation and use of inputs (e.g. fertilizer, pesticide, farm machinery operation) during pre-farm and on-farm stages are also included. The life cycle GHG emissions of 1 kg of wool is significantly higher than that of wheat and sheep meat. The LCA analysis identified that the on-farm stage contributed the most significant portion of total GHG emissions from the production of wheat, sheep meat and wool. This LCA analysis also identified that CH₄ emissions from enteric methane production and from the decomposition of manure accounted for a significant portion of the total emissions from sub-clover and mixed pasture production, whilst N₂O emissions from the soil have been found to be the major source of GHG emissions from wheat production.     

基于双层规划模型的城市固体废物管理系统优化研究

采用变权重组合模型和情景分析法,对北京市的城市固体废物(MSW)产量进行有效地预测.预测结果表明,北京市垃圾产量增幅不大但处理设施容量存在缺口.在科学预测的基础上,构建以温室气体(GHG)控制为上层目标,系统成本最小化为下层目标的双层规划模型(BLPMGMC).该模型的结果表明,焚烧和堆肥将是北京市MSW的主要处理方式;在3个规划时段内,GHG总排放量达到1.67×106t(以CO2当量计),填埋场的CH4和焚烧厂的N2O是GHG排放的主要贡献者;系统总成本达到7.0×109元,其中,65%的成本来自于焚烧厂和堆肥厂.4种模型结果的对比分析表明,双层规划能提供综合经济和环境因素的管理方案.     

垃圾分类对碳减排的影响分析：以青岛市为例

城市生活垃圾(MSW)处理单元是重要的温室气体排放源,垃圾分类可以实现垃圾减量化和提高资源化利用率,但对于温室气体减排的影响还鲜见报道.以青岛市内4区为研究对象,基于生命周期评价方法,研究了垃圾分类前后不同生活垃圾处置模式下的温室气体排放情况.结果表明,垃圾分类可以显著降低处置全过程中的温室气体排放,模式1(混合收集+填埋)、模式2(混合收集+焚烧)、模式3(垃圾分类+厨余垃圾厌氧消化和其他焚烧)和模式4(垃圾分类+厨余垃圾厌氧消化、可回收垃圾资源化和其他焚烧)垃圾处理全过程净碳排放量(以CO₂/MSW计)分别为686.39、-130.12、-61.88和-230.17 kg·t^-1.提高厨余垃圾回收效率并不能显著降低碳排放.随着垃圾回收效率的提高,碳减排量呈线性增加,可回收垃圾回收效率每提高10%,其净碳排放量降低26.6%(16.5 kg·t^-1).适度分离餐厨垃圾、提高可回收垃圾回收效率和降低厨余垃圾厌氧消化沼气泄漏率是目前减少生活垃圾温室气体排放和社会成本的可行策略.     

Mitigation of greenhouse gas emissions in European conventional and organic dairy farming

Dairy farming is the largest agricultural source of the greenhouse gases methane (CH₄) and nitrous oxide (N₂O) in Europe. A whole-farm modeling approach was used to investigate promising mitigation measures. The effects of potential mitigation measures were modeled to obtain estimates of net greenhouse gas (GHG) emissions from representative dairy model farms in five European regions. The potential to reduce farm GHG emissions was calculated per kg milk to compare organic and conventional production systems and to investigate region and system specific differences. An optimized lifetime efficiency of dairy cows reduced GHG emissions by up to 13% compared to baseline model farms. The evaluation of frequent removal of manure from animal housing into outside covered storage reduced farm GHG emissions by up to 7.1%. Scraping of fouled surfaces per se was not an effective option since the reduction in GHG emissions from animal housing was more than out-weighed by increased emissions from the storage and after field application. Manure application by trail hose and injection, respectively, was found to reduce farm GHG emissions on average by 0.7 and 3.2% compared to broadcasting. The calculated model scenarios for anaerobic digestion demonstrated that biogas production could be a very efficient and cost-effective option to reduce GHG emissions. The efficiency of this mitigation measure depends on the amount and quality of organic matter used for co-digestion, and how much of the thermal energy produced is exploited. A reduction of GHG emissions by up to 96% was observed when all thermal energy produced was used to substitute fossil fuels. Potential measures and strategies were scaled up to the level of European regions to estimate their overall mitigation potential. The mitigation potential of different strategies based on a combination of measures ranged from −25 up to −105% compared to baseline model farms. A full implementation of the most effective strategy could result in a total GHG emission reduction of about 50 Mt of carbon dioxide (CO₂) equivalents per year for conventional dairy farms of EU(15) comparable to the defined model farms.     

Wood materials used as a means to reduce greenhouse gases (GHGs): An examination of wooden utility poles

There has been growing concern over the build-up of greenhouse gase(GHGs) in the atmosphere, particularly carbon dioxide (CO₂), as acause of global warming. The IPCC Third Assessment Report (2001) suggests two ways in which the choice of materials could berelevant. First, some materials, particularly wood, have the advantage thatthey continue to hold carbon (C)in their cells even after being convertedto products. The implications of this feature are well researched. Second,an area that is not well researched relates to the different energyrequirements for producing similar products made with different materials. Using the findings of recent research, this paper compares the energyrequirements and C emissions of manufacturing a product using wood withthat of other materials. The case study of utility poles demonstrates thepositive C and global warming consequences of the lower energyrequirements of wood in the U.S., compared to other materials such assteel or concrete. It demonstrates that GHG emissions associated withutility poles are a small but significant percent of total US annual emissions. Wood utility poles are associated with GHG emission reductions of 163Terragrams (Tg) of CO₂ when compared with steel poles. This isabout 2.8 percent of US annual GHG emissions, which are estimated atabout 5.28 Petragrams (Pg) of CO₂ annually. Thus, the use ofwooden utility poles rather than steel results in a small but significantreduction in total US emissions.     

Assessments on emergy and greenhouse gas emissions of internal combustion engine automobiles and electric automobiles in the USA

Increasing energy consumption in the transportation sector results in challenging greenhouse gas (GHG) emissions and environmental problems. This paper involved integrated assessments on GHG emissions and emergy of the life cycle for the internal combustion engine (ICE) and electric automobiles in the USA over the entire assumed fifteen-year lifetime. The hotspots of GHG emissions as well as emergy indices for the major processes of automobile life cycle within the defined system boundaries have been investigated. The potential strategies for reducing GHG emissions and emergy in the life cycle of both ICE and electric automobiles were further proposed. Based on the current results, the total GHG emissions from the life cycle of ICE automobiles are 4.48E + 07 kg CO₂-e which is 320 times higher than that of the electric automobiles. The hotspot area of the GHG emissions from ICE and electric automobiles are operation phase and manufacturing process, respectively. Interesting results were observed that comparable total emergy of the ICE automobiles and electric automobiles have been calculated which were 1.54E + 17 and 2.20E + 17 sej, respectively. Analysis on emergy index evidenced a better environmental sustainability of electric automobiles than ICE automobiles over the life cycle due to its higher ESI. To the authors’ knowledge, it is the first time to integrate the analysis of GHG emissions together with emergy in industrial area of automobile engineering. It is expected that the integration of emergy and GHG emissions analysis may provide a comprehensive perspective on eco-industrial sustainability of automobile engineering.     

基于投入产出法的北京能源消耗温室气体排放清单分析

城市是一个巨大能源物资消耗体和温室气体排放体,相关研究受到广泛关注.本文以2007年为例基于投入产出法研究北京市能源消耗的温室气体排放量,计算得出CH4和N2O这两种常规温室气体排放量.结果表明,北京市2007年能源消耗温室气体排放量为3531.72万tCO2当量,其中CO2排放量为3514.40万t,CH4排放量为1734.32t,N2O排放量为435.83t.北京市工业部门仍然是主要的温室气体排放部门,其排放的温室气体占CO2总量的98.96%,CH4总量的88.48%和N2O总量的98.99%.不同最终使用部门中,政府部门消费产生的温室气体排放量超过总量的15%,高于城镇消费和农村消费之和;调出和出口部门的碳排放量超过总量的40%,所占比例最大.贸易中,隐含在调出和出口部门中温室气体排放量是隐含在调入和进口部门的十几倍.北京市不同行业的温室气体排放强度略优于全国水平.降低北京市温室气体排放量可从进一步优化产业结构,发挥科技减排的作用,提高不同产业的能源利用率等方面采取措施.     

Effects of aeration method and aeration rate on greenhouse gas emissions during composting of pig feces in pilot scale

The aim of this study was to uncover ways to mitigate greenhouse gas(GHG) emissions and reduce energy consumption during the composting process. We assessed the effects of different aeration rates(0, 0.18, 0.36, and 0.54 L/(kg dry matter(dm)·min)) and methods(continuous and intermittent) on GHG emissions. Pig feces and corn stalks were mixed at a ratio of 7:1. The composting process lasted for 10 weeks, and the compost was turned approximately every 2 weeks. Results showed that both aeration rate and method significantly affected GHG emissions. Higher aeration rates increased NH3 and N2O losses,but reduced CH4 emissions. The exception is that the CH4 emission of the passive aeration treatment was lower than that of the low aeration rate treatment. Without forced aeration,the CH4 diffusion rates in the center of the piles were very low and part of the CH4 was oxidized in the surface layer. Intermittent aeration reduced NH3 and CH4 losses, but significantly increased N2 O production during the maturing periods. Intermittent aeration increased the nitrification/denitrification alternation and thus enhanced the N2 O production. Forced aeration treatments had higher GHG emission rates than the passive aeration treatment. Forced aeration accelerated the maturing process, but could not improve the quality of the end product. Compared with continuous aeration, intermittent aeration could increase the O2 supply efficiency and reduced the total GHG emission by 17.8%, and this reduction increased to 47.4% when composting was ended after 36 days.     

The carbon budget of California

The carbon budget of a region can be defined as the sum of annual fluxes of carbon dioxide (CO₂) and methane (CH₄) greenhouse gases (GHGs) into and out of the regional surface coverage area. According to the state government's recent inventory, California's carbon budget is presently dominated by 115 MMTCE per year in fossil fuel emissions of CO₂ (>85% of total annual GHG emissions) to meet energy and transportation requirements. Other notable (non-ecosystem) sources of carbon GHG emissions in 2004 were from cement- and lime-making industries (7%), livestock-based agriculture (5%), and waste treatment activities (2%). The NASA-CASA (Carnegie Ames Stanford Approach) simulation model based on satellite observations of monthly vegetation cover (including those from the Moderate Resolution Imaging Spectroradiometer, MODIS) was used to estimate net ecosystem fluxes and vegetation biomass production over the period 1990–2004. California's annual NPP for all ecosystems in the early 2000s (estimated by CASA at 120 MMTCE per year) was roughly equivalent to its annual fossil fuel emission rates for carbon. However, since natural ecosystems can accumulate only a small fraction of this annual NPP total in long-term storage pools, the net ecosystem sink flux for atmospheric carbon across the state was estimated at a maximum rate of about 24 MMTCE per year under favorable precipitation conditions. Under less favorable precipitation conditions, such as those experienced during the early 1990s, ecosystems statewide were estimated to have lost nearly 15 MMTCE per year to the atmosphere. Considering the large amounts of carbon estimated by CASA to be stored in forests, shrublands, and rangelands across the state, the importance of protection of the natural NPP capacity of California ecosystems cannot be overemphasized.     

The analysis of greenhouse gas emissions/reductions in waste sector in Vietnam

The global waste sector produces, on average, 2–5 % of global anthropogenic greenhouse gas (GHG) emissions. The amount of GHG emissions has grown steadily and is predicted to increase considerable in the forthcoming decades because of the increases in population and gross domestic product (GDP). However, the GHG mitigation opportunities for the sector are still fully not exploited, in particularly in developing countries. A series of initiatives were highly successful and showed that large reductions in emissions are possible. This study aims to propose a holistic quantification model, which can be used for estimation of waste generation and evaluation of the potential reduction of GHG emissions in waste sector for developing countries with a particular application to Vietnam. The two scenarios set for the study were business as usual (BaU) which waste management is assumed to follow past and current trends and CounterMeasure (CM) which alternative waste treatment and management are assessed. Total emissions in the BaU scenario are projected to increase from 29.47 MtCO₂eq in 2010 to 85.60 MtCO₂eq by 2030 and 176.32 MtCO₂eq by 2050. The highest emissions are due to methane (CH₄) released by disposal sites, accounting for about 60 % of the GHG emissions from waste in Vietnam in 2030. This emission is projected to increase significantly (67 % in 2050), unless more of the methane is captured and used for energy generation. The CM scenario gives emission reductions from 25.7 % (2020), 40.5 % (2030) to 56.6 % (2050) compared to the BaU scenario. The highest GHG reduction is achieved through recycling, followed by methane recovery to optimize the co-benefit for climate change mitigation.     

2010年中国机动车CH4和N2O排放清单

中国大部分机动车温室气体排放研究都集中于CO₂排放,对于CH₄和N₂O等排放的研究鲜见. 以中国机动车污染防治年报(2011年)、中国汽车工业年鉴(2011年)、中国统计年鉴(2011年)以及交通运输部发布的相关信息和数据(2011年)等为基础,结合文献调研和2008─2010年对北京、广州等国内10余座典型城市的实地调查结果,获得2010年我国机动车活动水平及排放特征. 基于上述基础信息,解析得到按不同车型、燃料和车龄分布的机动车保有量、年均行驶里程及排放因子,建立2010年中国机动车CH₄和N₂O排放清单. 结果表明:2010年中国机动车CH₄和N₂O排放量分别为23.90×104和6.01×104t,折算成CO₂分别为501.99×104和1862.51×104t. 不确定性分析则显示,中国CH₄排放量在18.21×104～27.52×104t之间,N₂O排放量在4.32×104～7.62×104t之间. 在机动车中,汽车CH₄和N₂O排放量最大,分担率(某车型污染物排放量占机动车排放总量的比例)分别为77.99%和94.22%,而摩托车和农用车排放分担率较小. 在各类汽车中,CH₄排放主要来源于轻型汽油车和天然气出租车,二者的排放分担率分别为47.98%和23.42%;N₂O排放则主要源于轻型汽油车,其分担率为73.09%. 因此,轻型汽油车是削减机动车CH₄和N₂O排放的重点车型,同时天然气出租车也应作为控制CH₄排放的主要车型.      

Environmental impacts of distributed energy systems—The case of micro cogeneration

Distributed generation in micro cogeneration systems, e.g. reciprocating or Stirling engines and fuel cells, is of increasing interest in the energy market. This paper investigates environmental impacts of micro cogeneration by carrying out a detailed life cycle assessment and an analysis of local air quality impacts of micro cogeneration systems.Most micro cogeneration systems are superior, as far as the reduction of GHG emissions is concerned, not only to average electricity and heat supply, but also to state-of-the art separate production of electricity in gas power plants and heat in condensing boilers. The GHG advantages of micro cogeneration plants are comparable to district heating with CHP. Under the assumption that gas condensing boilers are the competing heat-supply technology, all technologies are within a very narrow range. Looking at the GHG reduction potential on the level of a supply object (e.g. a single-family house) by modeling the operation with a CHP optimization tool, the achievable mitigation potential is somewhat lower, because the micro cogeneration systems do not supply the whole energy demand. Here, fuel cells offer the advantage of a higher power-to-heat ratio.Environmental impacts other than those related to climate and resource protection relate more specifically to technology. In addition to investigating the emissions side, analysis of the air quality situation of a residential area supplied by reciprocating engines was carried out. The analysis shows that for the selected conditions, the additional emission of NO_x due to the engines do not create severe additional environmental impacts.     

杭州市城市生活垃圾处理主要温室气体及VOCs排放特征

为了解城市生活垃圾处理过程中主要温室气体及VOCs排放的变化特征,基于《2006年IPCC国家温室气体清单指南》《浙江省市县温室气体清单编制指南》和《大气挥发性有机物源排放清单编制技术指南》推荐的方法,估算了2005-2016年杭州市生活垃圾处理主要温室气体及VOCs排放量.结果表明:2005-2016年杭州市生活垃圾处理过程中温室气体排放占绝对主导地位,VOCs排放只占极少一部分.杭州市生活垃圾处理主要温室气体和VOCs排放量总体上呈上升趋势,与2005年相比,2016年杭州市生活垃圾处理主要温室气体排放量增长了68.8%,VOCs排放量增长了134.0%.从生活垃圾处理方式来看,杭州市生活垃圾填埋处理的温室气体排放量远高于焚烧处理方式,但填埋处理的VOCs排放量却低于焚烧处理方式（2007年和2008年除外）.杭州市生活垃圾填埋处理和焚烧处理的温室气体排放强度分别为0.72~0.86、0.18~0.23.从排放贡献和排放强度来看,采用填埋处理方式有利于减少垃圾处理过程中VOCs的排放,而采用焚烧处理方式更有利于温室气体的减排.随着人均生活垃圾产生量的上升,无论是温室气体还是VOCs,杭州市人均垃圾处理排放量总体呈现稳步上升的态势.研究显示,深入垃圾分类回收、控制人均生活垃圾产生量、优化垃圾焚烧处理方式,可以实现生活垃圾处理主要温室气体和VOCs的协同减排.      

广东货船水运的温室气体排放和低碳发展对策

作为我国港口大省和低碳试点省,广东需先行测算船舶水运的GHG(温室气体)排放量基线,以探究低碳水运对策. 通过文献调研收集适用数据和资料,基于引擎功率法,测算了广东抵港货船在2010年的GHG排放量. 结果表明:广东专属经济区海域内货船水运的GHG总排放量为2887×104t,不确定性在-36%~45%之间,其中在领海区域内的排放量为730×104t;远洋集装箱船是GHG最大排放源,占总排放量的43%;集装箱船、干散货船、油轮和其他货船的GHG排放量不确定性均介于-30%~50%之间,远洋货船的主引擎在正常航行模式下输出功率是最主要的不确定性源. 基于分析船舶水运的GHG排放特征,提出船舶减速、向远洋货船供应岸电和内河货船主引擎转用天然气共3项低碳节能措施,共可减排40%的GHG排放量.该研究结果不仅为广东低碳水运发展提供基础性的GHG排放数据,也可为其他港口地区提供估算水运业GHG排放量的技术方法参考和实践经验.      

Greenhouse gas balances of molasses based ethanol in Nepal

This paper evaluates life cycle greenhouse gas (GHG) balances in production and use of molasses-based ethanol (EtOH) in Nepal. The total life cycle emissions of EtOH is estimated at 432.5 kgCO_2eq m⁻³ ethanol (i.e. 20.4 gCO_2eq MJ⁻¹). Avoided emissions are 76.6% when conventional gasoline is replaced by molasses derived ethanol. A sensitivity analysis was performed to verify the impact of variations in material and energy flows, and allocation ratios in the GHG balances. Market prices of sugar and molasses, amount of nitrogen-fertilizers used in sugarcane production, and sugarcane yield per hectare turn out to be important parameters for the GHG balances estimation. Sales of the surplus electricity derived from bagasse could reduce emissions by replacing electricity produced in diesel power plants. Scenario analysis on two wastewater processes for treatment of effluents obtained from ethanol conversion has also been carried out. If wastewater generated from ethanol conversion unit is treated in pond stabilization (PS) treatment process, GHG emissions alarmingly increase to a level of 4032 kgCO_2eq m⁻³ ethanol. Results also show that the anaerobic digestion process (ADP) and biogas recovery without leakages can significantly avoid GHG emissions, and improve the overall emissions balance of EtOH in Nepal. At a 10% biogas leakage, life cycle emissions is 1038 kgCO_2eq m⁻³ ethanol which corresponds to 44% avoided emissions compared to gasoline. On the other hand, total emissions surpass the level of its counterpart (i.e. gasoline) when the leakage of biogas exceeds 23.4%.     

Greenhouse gas mitigation and offset options for suckler cow farms: an economic comparison for the Swiss case

We assessed the economic suitability of 4 greenhouse gas (GHG) mitigation options and one GHG offset option for an improvement of the GHG balance of a representative Swiss suckler cow farm housing 35 Livestock units and cultivating 25 ha grassland. GHG emissions per kilogram meat in the economic optimum differ between the production systems and range from 18 to 21.9 kg CO₂-eq./kg meat. Only GHG offset by agroforestry systems showed the potential to significantly reduce these emissions. Depending on the production system agroforestry systems could reduce net GHG emissions by 66% to 7.3 kg CO₂-eq./kg meat in the most intensive system and by 100% in the most extensive system. In this calculation a carbon sequestration rate of 8 t CO₂/ha/year was assumed. The potential of a combination of the addition of lipids to the diet, a cover of the slurry tank and the application of nitrification inhibitors only had the potential to reduce GHG emissions by 12% thereby marginal abatement costs are increasing much faster than for agroforestry systems. A reduction of the GHG emissions to 7.5 kg CO₂-eq./kg meat—possible with agroforestry only—raised costs between 0.03 CHF/kg meat and 0.38 CHF/kg meat depending on the production system and the state of the system before the reduction. If GHG emissions were reduced maximally average costs ranged between 0.37 CHF/kg meat, if agroforestry had the potential to reduce net GHG emissions to 0 kg CO₂-eq., to 1.17 CHF/kg meat if also other options had to be applied.     

Quantifying and managing regional greenhouse gas emissions：Waste sector of Daejeon, Korea

A credible accounting of national and regional inventories for the greenhouse gas （GHG） reduction has emerged as one of the most significant current discussions. This article assessed the regional GHG emissions by three categories of the waste sector in Daejeon Metropolitan City （DMC）, Korea, examined the potential for DMC to reduce GHG emission, and discussed the methodology modified from Intergovernmental Panel on Climate Change and Korea national guidelines. During the last five years, DMC＇s overall GHG emissions were 239 thousand tons C02 eq./year from eleven public environmental infrastructure facilities, with a population of 1.52 million. Of the three categories, solid waste treatment/disposal contributes 68%, whilst wastewater treatment and others contribute 22% and 10% respectively. Among GHG unit emissions per ton of waste treatment, the biggest contributor was waste incineration of 694 kg CO2 eq./ton, followed by waste disposal of 483 kg CO2 eq./ton, biological treatment of solid waste of 209 kg CO2 eq./ton, wastewater treatment of 0.241 kg CO2 eq./m3, and public water supplies of 0.067 kg CO2 eq./m3. Furthermore, it is suggested that the potential in reducing GHG emissions from landfill process can be as high as 47.5% by increasing landfill gas recovery up to 50%. Therefore, it is apparent that reduction strategies for the main contributors of GHG emissions should take precedence over minor contributors and lead to the best practice for managing GHGs abatement.     

Water regime-nitrogen fertilizer incorporation interaction: Field study on methane and nitrous oxide emissions from a rice agroecosystem in Harbin, China

Water regime and nitrogen (N) fertilizer are two important factors impacting greenhouse gases (GHG) emission from paddy field, whereas their effects have not been well studied in cold region. In this study, we conducted a two-year field experiment to study the impacts of water regime and N fertilizer on rice yields and GHG emissions in Harbin, China, a cold region located in high latitudes. Our results showed that intermittent irrigation significantly decreased methane (CH₄) emission compared with continuous flooding, however, the decrement was far lower than the global average level. The N₂O emissions were very small when flooded but peaked at the beginning of the disappearance of floodwater. The N fertilizer treatments increased CH₄ emissions at low level (75kgN/ha). But both CH₄ and N₂O emissions were uninfluenced at the levels of 150kgN/ha and 225kgN/ha. Rice yields increased under intermittent irrigation and were highest at the level of 150kgN/ha. From our results, we recommended that the intermittent irrigation and 150kgN/ha as the ideal water regime-nitrogen fertilizer incorporation for this area to achieve low GHG emissions without impacting rice yields.     

中国核电能源链的生命周期温室气体排放研究

应用全能源链分析(PCA)和生命周期分析(LCA)方法,采用第一手调查数据和一些新的参数,对我国核电能源链的生命周期温室气体排放进行评价计算.结果表明,现阶段我国核电能源链(包括核燃料循环前段、核电站)的实际温室气体排放量为6.2g CO2,eq/(k W·h),若考虑核燃料循环后段(乏燃料后处理与废物处置)则总的温室气体排放量为11.9g CO2,eq/(k W·h).核电是低碳能源,发展核电代替一定规模的煤电提供一次能源,每1k W·h电力生产能够减排大约1kg二氧化碳.推进核电产业链的技术升级和持续节能降耗,鼓励材料再循环再利用,核电能源链的温室气体排放仍有进一步降低的空间.