生物质炭及过氧化钙对旱地红壤CH4、CO2和N2O排放的影响

采用室内培养实验,在旱地红壤中添加生物质炭和过氧化钙,探究生物质炭和过氧化钙对旱地红壤CH_4、CO_2和N_2O排放及微生物活性的影响。本试验共设置4个处理,即CK(对照)、Ca(过氧化钙,1.72 g·kg~(-1))、C(生物质炭,21.46 g·kg~(-1))、C+Ca(生物质炭,21.46 g·kg~(-1);过氧化钙,1.72 g·kg~(-1))。结果表明:生物质炭和过氧化钙单施能够减少CO_2和N_2O通量,配施(C+Ca)对CH_4、CO_2和N_2O气体减排的效果更显著;从温室气体增温潜势(GWP)变化可以看出改良剂对温室效应具有明显的减轻作用。生物质炭和过氧化钙在一定程度上增加土壤pH、土壤微生物量碳和可溶性有机碳含量。土壤中添加生物质炭和过氧化钙均可以提高蔗糖酶、淀粉酶以及脲酶活性,其中配施(C+Ca)效果最好。因此,生物质炭和过氧化钙配施能够有效降低旱地红壤温室气体的排放量,对旱地红壤的减排可以起到一定作用。     

秸秆还田对稻田温室气体排放的影响:Meta分析——以长江中下游地区为例

全球气候变暖是人类面临的严峻挑战,稻田生态系统在全球气候变暖中起到重要的作用。目前已有许多学者通过大田试验的方法研究了不同秸秆还田方式下温室气体排放的特征,但由于试验地点等因素的不同导致最终的结果差异很大。通过整合这些结果来研究区域内不同秸秆还田方式(翻耕秸秆还田(CTS)、免耕秸秆还田(NTS)和旋耕秸秆还田(RTS))下稻田温室气体排放的特征,能够准确地反映一定区域内稻田生态系统的净减排潜力。本文基于长江中下游地区32篇关于秸秆还田对稻田温室气体排放的文献收集173组数据,利用Meta分析方法研究了3种秸秆还田方式下稻田CH_4和N_2O排放的特征,并估算出不同秸秆还田方式下稻田的全球增温潜势和净增温潜势。结果表明,CTS、NTS和RTS处理下稻田CH_4周年排放的效应值分别为0.76、0.37和0.68,稻田N_2O周年排放的效应值分别为0.44、0.36和0.52;在两熟制下,不同秸秆还田方式下稻田CH_4周年排放的效应值的大小为RTSCTSNTS,但N_2O周年排放的效应值的大小为RTSNTSCTS。在三熟制下,三种秸秆还田方式下稻田CH_4的周年排放的效应值的高低为CTSRTSNTS,而N_2O周年排放的效应值的高低为RTSNTSCTS。在相同的秸秆还田方式下,三熟制稻田温室气体周年排放的效应值都高于两熟制。此外,不同的还田秸秆种类影响稻田温室气体的排放;结合前期研究,估算出CTS、NTS和RTS处理下稻田的净增温潜势分别为12 375.55、11 232.36和15 982.87 kg CO_2-equivalent·hm~(-2)。因此,免耕秸秆还田是长江中下流地区稻田净减排条件下适宜的秸秆还田方式。     

全球变化对长江三角洲土地持续利用的影响及其对策

全球变化对区域土地持续利用的影响表现为其多方面内容从不同侧面直接或间接地对区域土地利用生产性、安全性、保持性、可行性和接受性产生影响。在长江三角洲地区 ,全球变化对土地持续利用的影响主要表现为不利的方面 :( 1)海平面上升导致土地面积减少及土壤性质恶化 ;( 2 )自然灾害增多导致土地利用安全性降低 ;( 3)酸雨危害加重导致土地生态环境恶化 ;( 4 )地表植被减少及湿润指数降低导致土地退化加剧。针对以上问题 ,应采取以下对策以促进长江三角洲土地持续利用 :( 1)加强全球变化监测与预警 ;( 2 )制定适应于全球变化的土地持续利用规划 ;( 3)增强土地利用对全球变化的应变能力 ;( 4 )加强全球合作 ,减缓不利于人类生存的全球变化速度。     

加强全球合作 寻求能源、环境与经济发展的最佳模式——联合国“能源、环境与经济发展”国际会议采访录

明确的宗旨共同的责任能源工业是国家经济发展的命脉,同时又是重要的环境污染源。随着各国工业化的发展,经济的增长、环境污染、生态破坏及由此引发的一系列气候变化已成为当前全球高度重视的问题。“气候变化,需要全球合作”为响应这一今年“世界环境日”的主题,加强我国与国外的对口     

全球变化对长江三角洲土地持续利用的影响及其对策

全球变化对区域土地持续利用的影响表现为其多方面内容从不同侧面直接或间接地对区域土地利用生产性、安全性、保持性,可行性和接受性产生影响,在长江三角洲地区,全球变化对土地持续利用的影响主要表现为不利的方面：（1）海平面上升导致土地面积减少及土壤性质恶化;（2）自然灾害增多导致土地利用安全性降低;（3）酸雨危害加重导致土地生态环境恶化;（4）地表植被减少及湿润指数降低导致土地退化加剧,针对以上问题,应采取以下对策以促进长江三角洲土地持续利用;（1）加强全球变化监测与预警;（2）制定适应于全球变化的土地持续利用规划;（3）增强土地利用对全球变化的应变能力;（4）加强全球合作,减缓不利于人类生存的全球变化速度。     

农田固碳措施对温室气体减排影响的研究进展

农田是CO2,CH4和N2O三种温室气体的重要排放源,在全球范围内农业生产活动贡献了约14%的人为温室气体排放量,以及58%的人为非CO2排放,不合理的农田管理措施强化了农田温室气体排放源特征,弱化了农田固碳作用。土壤碳库作为地球生态系统中最活跃的碳库之一,同时也是温室气体的重要源/汇。研究表明通过采取合理的农田管理措施,既可起到增加土壤碳库、减少温室气体排放的目的,又能提高土壤质量。农田土壤碳库除受温度、降水和植被类型的影响外,还在很大程度上受施肥量、肥料类型、秸秆还田量、耕作措施和灌溉等农田管理措施的影响。本文通过总结保护性耕作/免耕,秸秆还田,氮肥管理,水分管理,农学及土地利用变化等农田管理措施,探寻增强农田土壤固碳作用,减少农田温室气体排放的合理途径。农田碳库的稳定/增加,对于保证全球粮食安全与缓解气候变化趋势具有双重的积极意义。在我国许多有关土壤固碳与温室气体排放的研究尚不系统或仅限于短期研究,这也为正确评价各种固碳措施对温室气体排放的影响增加了不确定性。     

对当前全球气候变化问题的思考

全球气候变化问题已经超越了一般环境问题的范畴,而成为国际政治经济外交关系的重要考虑因素。随着《京都议定书》的实施以及气候变化问题谈判进程的加快．对我国未来经济社会发展提出了挑战。文章分析认为．要求主要发展中国家承诺减限排义务的压力与日俱增,而我国开始进入工业化中期．应对气候变化问题的能力还比较薄弱。因此．提出应对全球气候变化问题的一些思考：（1）充分认识全球气候变化问题的重要性和严峻性,准确把握国际谈判进程;（2）加快制定适应和减缓气候变化的国家战略。采取适合我国国情的有力措施积极应对气候变暖;（3）加强气候变化领域的能力建设．提高我国参与全球气候变化活动的能力;（4）充分利用国际合作机制,提高我国应对气候变化的技术水平与经济能力。     

中国“一带一路”倡议投资对降低共建国家气候风险的影响

“一带一路”倡议是实践人类命运共同体理念的重要平台。然而,许多“一带一路”倡议共建国家处于气候变化敏感区,部分西方国家对“一带一路”倡议建设存在一些质疑与污蔑,认为“一带一路”倡议的基建项目可能增加了共建国家的气候变化脆弱性。该研究从应对气候变化的视角探究中国对外直接投资对“一带一路”倡议共建国家气候变化风险的影响,进而考察其内在机理。基于2004—2020年65个共建国家的面板数据,以各国气候变化脆弱性风险为被解释变量,评估中国对外直接投资对东道国应对气候变化风险能力的影响。研究发现：(1)中国对“一带一路”倡议地区的直接投资显著减轻了共建国家的气候变化脆弱性风险;在全球气候变化危机加剧的背景下,提高了共建国家气候风险应对能力。(2)对于“一带一路”倡议国家中的中低收入国家、中国邻国以及与中国建立自由贸易协定的国家而言,中国“一带一路”倡议投资降低当地气候变化脆弱性风险的作用更为明显。(3)中国“一带一路”倡议投资的作用可以通过收入增长效应、政治稳定效应部分解释,符合“一带一路”倡议共享发展成果、推进全球治理的重要理念。(4)中国“一带一路”倡议投资在降低共建国家气候变化脆弱性的同时...     

全球气候变化对中国森林影响的研究进展

通过梳理现有文献表明,全球气候变化对社会经济和自然生态系统造成了重大影响,气候变化将显著地改变森林生态服务的供给水平和质量,对森林和以林为生的人口都会造成重要的生态、经济和社会影响,甚至威胁到人类的生存.我国是受气候变化影响较大而适应能力较弱的发展中国家,森林适应气候变化的科学、社会经济及对策研究相对滞后,因此,笔者从气候变化对历史上森林生态系统的影响着手,阐述了气候变化对森林分布、森林演替、森林生产力、生物多样性、森林火灾、森林水文调节和水质、森林生态系统的未来、森林生态服务的水平和质量等方面产生的影响,分析了现有气候变化对森林影响的研究存在的不足:忽略了其它环境因子的作用;忽略了不同物种之间的竞争机制;缺乏对极端气候事件的考虑;缺乏森林自身变化对气候变化的反馈;缺乏森林生态系统对全球气候变化相应机制更深入的认识;研究模型及数据的不完善性.文章最后提出了可将气候变化对森林造成的危害降到最低限度的政策建议.     

青藏高原NPP时空演变格局及其驱动机制分析

青藏高原植被生态系统对全球变化的响应较为敏感。该研究引入重心模型等方法分析和探讨了2000～2015年青藏高原NPP时空变化格局及其驱动机理,并定量区分了NPP变化过程中气候变化和人类活动的相对作用。结果发现:(1)2000～2015年,青藏高原NPP年均值总体上呈现从东南向西北递减的趋势。在年际变化方面,近16年青藏高原不同生态子区的NPP均呈现不同程度的增加趋势。(2)近16年青藏高原NPP重心总体向西南方向移动,表明西南部NPP在增量和增速上大于东北部。(3)NPP与降水显著相关的区域主要位于青藏高原中部、青藏高原东南部及雅鲁藏布江流域中下游,而NPP与气温显著相关的区域主要位于藏南地区、横断山区北部、青藏高原中部和北部。(4)气候变化和人类活动在青藏高原NPP变化过程中的相对作用存在显著的时空差异性,在空间上呈现"四线-五区"的格局。研究成果可为揭示青藏高原区域生态系统对全球变化的响应机制提供理论和方法支撑。     

Soil management practices for sustainable agro-ecosystems

A doubling of the global food demand projected for the next 50 years poses a huge challenge for the sustainability of both food production and global and local environments. Today’s agricultural technologies may be increasing productivity to meet world food demand, but they may also be threatening agricultural ecosystems. For the global environment, agricultural systems provide both sources and sinks of greenhouse gases (GHGs), which include carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). This paper addresses the importance of soil organic carbon (SOC) for agro-ecosystems and GHG uptake and emission in agriculture, especially SOC changes associated with soil management. Soil management strategies have great potential to contribute to carbon sequestration, since the carbon sink capacity of the world’s agricultural and degraded soil is 50–66% of the historic carbon loss of 42–72 Pg (1 Pg=10¹⁵ g), although the actual carbon storage in cultivated soil may be smaller if climate changes lead to increasing mineralization. The importance of SOC in agricultural soil is, however, not controversial, as SOC helps to sustain soil fertility and conserve soil and water quality, and organic carbon compounds play a variety of roles in the nutrient, water, and biological cycles. No-tillage practices, cover crop management, and manure application are recommended to enhance SOC storage and to contribute to sustainable food production, which also improves soil quality. SOC sequestration could be increased at the expense of increasing the amount of non-CO₂ GHG emissions; however, soil testing, synchronized fertilization techniques, and optimum water control for flooding paddy fields, among other things, can reduce these emissions. Since increasing SOC may also be able to mitigate some local environmental problems, it will be necessary to have integrated soil management practices that are compatible with increasing SOM management and controlling soil residual nutrients. Cover crops would be a critical tool for sustainable soil management because they can scavenge soil residual nitrogen and their ecological functions can be utilized to establish an optimal nitrogen cycle. In addition to developing soil management strategies for sustainable agro-ecosystems, some political and social approaches will be needed, based on a common understanding that soil and agro-ecosystems are essential for a sustainable society.     

Greenhouse Gas Fluxes in Tropical and Temperate Agriculture: The need for a Full-Cost accounting of Global Warming Potentials

Agriculture's contribution to radiative forcing is principally through its historical release of carbon in soil and vegetation to the atmosphere and through its contemporary release of nitrous oxide (N_2O) and methane (CHM₄). The sequestration of soil carbon in soils now depleted in soil organic matter is a well-known strategy for mitigating the buildup of CO₂ in the atmosphere. Less well-recognized are other mitigation potentials. A full-cost accounting of the effects of agriculture on greenhouse gas emissions is necessary to quantify the relative importance of all mitigation options. Such an analysis shows nitrogen fertilizer, agricultural liming, fuel use, N_2O emissions, and CH₄ fluxes to have additional significant potential for mitigation. By evaluating all sources in terms of their global warming potential it becomes possible to directly evaluate greenhouse policy options for agriculture. A comparison of temperate and tropical systems illustrates some of these options.     

甲烷排放与应对气候变化国家战略探析

甲烷的全球变暖潜势是二氧化碳的72倍(20年水平),但其在大气中的寿命短于二氧化碳,可以作为优先减排对象。中国的甲烷排放十分突出,甲烷减排在应对气候变化国家战略中具有重要的基础性地位,然而在政策研究中,甲烷受到的关注程度远低于二氧化碳。本文基于甲烷排放研究的相关进展,首次系统性地论述了中国甲烷排放与应对气候变化国家战略之间的关系。主要结论是:甲烷排放的有效控制和减缓可以成为中国温室气体减排的重要组成部分,甲烷等温室气体的减排战略要用"系统减排"思路替代传统的"末端减排"思路;甲烷系统减排的策略和实施措施不仅需要重视主要排放部门(如煤炭开采与洗选业,农业)的直接末端减排,更需要突出强调建设活动、城市消费、资本投资和出口贸易等消费端的间接体现减排;在国际气候谈判中通过纳入甲烷排放,可以至少在五个方面丰富和支撑中国的国家立场,如从承诺"单位GDP二氧化碳减排"向承诺"单位GDP温室气体减排"转变。     

Global estimates of soil carbon sequestration via livestock waste: a STELLA simulation

It has become increasingly well documented that human activities are enhancing the greenhouse effect and altering the global climate. Identifying strategies to mitigate atmospheric carbon dioxide emissions on the national level are therefore critical. Fossil fuel combustion is primarily responsible for the perturbation of the global carbon cycle, although the influence of humans extends far beyond the combustion of fossil fuels. Changes in land use arising from human activities contribute substantially to atmospheric carbon dioxide; however, land use changes can act as a carbon dioxide sink as well. A soil carbon model was built using STELLA to explore how soil organic carbon sequestration (SOC) varies over a range of values for key parameters and to estimate the amount of global soil carbon sequestration from livestock waste. To obtain soil carbon sequestration estimates, model simulations occurred for 11 different livestock types and with data for eight regions around the world. The model predicted that between 1980 and 1995, United States soils were responsible for the sequestration of 444–602 Tg C from livestock waste. Model simulations further predicted that during the same period, global soil carbon sequestration from livestock waste was 2,810–4,218 Tg C. Our estimates for global SOC sequestration are modest in proportion to other terrestrial carbon sinks (i.e. forest regrowth); however, livestock waste does represent a potential for long-term soil carbon gain. SOC generated from livestock waste is another example of how human activities and land use changes are altering soil processes around the world. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Sea to air transport of trace gases in the coastal zone: a literature review

Exchange of trace gases between the oceans and the atmosphere affects the atmospheric content and cycling of a range of chemical species which are related to climate change, ozone layer depletion, acid deposition, eutrophication, atmospheric particle formation, photo-oxidants, trace metals and persistent organic pollutants (POPs). The effects and impacts of air–sea exchange of these gases can be local, regional and global. Until now, most of the research has concentrated on the sea–air exchange of trace gases in the open ocean. The flux rates of the trace gases from the coastal waters to the air are much higher than the rates for the open ocean and the contribution of the coastal areas to the total oceanic emissions of these trace gases can be significant on a global scale. This contribution can be as high as 50% and more for nitrous oxide and COS. Concerning the contribution of the trace gas production in the coastal areas to the total global production of these gases, it can be concluded that this contribution seems to be below 2% except for nitrous oxide. However, it should be pointed out that on the local and even regional scale the emissions in the coastal areas can be very important, contributing substantially to the total emission of these gases in a studied area. Thus, there is a need to carry out studies in the future with the aim to provide more accurate understanding of the production and sea–air exchange processes for these gases around the world. Electronic Publication     

气候变化对长江源地区高寒草甸生态系统的影响

近十几年来，长江源区气候暖干化趋势明显，冰川退缩、湖泊萎缩、草场退化、土地沙漠化、水土流失等环境问题日益严重。高寒草甸是长江源地区主要的植被类型之一，在全球变化影响下，以耐低温寒冷的嵩草属（Kobresia）植物为建群种的高寒草甸将面临更严重的生态胁迫。以长江源地区高寒草甸生态系统为研究对象，采用国际通用的生物地球化学模型模拟高寒草甸生物量、生产力和土壤有机质等的动态变化，并综合考虑人类活动对生态系统生产力和营养元素生物地球化学循环的影响，探讨了全球气候变化对高寒草甸生态系统可能造成的影响。     

Bound to lead?Rethinking China's role after Paris in UNFCCC negotiations

As the biggest global emitter of greenhouse gases, China is an extremely important actor in international climate negotiations. During the climate summit in Copenhagen, China was blamed for its uncooperative positions particularly from the US side. However, in the Paris climate process, China's participation in international negotiations is more active, and has become a wellrecognized promoter of the Paris Agreement. To understand China's climate policy, the economic and diplomatic strategy should be taken into consideration, especially the changes in the ideas of China's global governance rooted from domestic politics discourse. Moreover, China's symmetrical changes within domestic and international dimension possibly bring out more balanced climate policies and thus the constructive role of China will be the normalcy in the future United Nations Framework Convention on Climate Changenegotiations. However, the negotiations after the US presidential elections may change dramatically and yields great uncertainty for global action. Thus, the vacuum of power may be a possible scenario. Will China reinforce its role toward leadership or go back to group politics? This article examines China's concerns, motives, and possible path to climate leadership in the current debate.     

Methane and Nitrogen Oxide Fluxes in Tropical Agricultural Soils: Sources, Sinks and Mechanisms

Tropical soils are important sources and sinks of atmospheric methane (CH₄) and major sources of oxides of nitrogen gases, nitrous oxide (NM_2O) and NO_x (NO+NO₂). These gases are present in the atmosphere in trace amounts and are important to atmospheric chemistry and earth's radiative balance. Although nitric oxide (NO) does not directly contribute to the greenhouse effect by absorbing infrared radiation, it contributes to climate forcing through its role in photochemistry of hydroxyl radicals and ozone (O₃) and plays a key role in air quality issues. Agricultural soils are a primary source of anthropogenic trace gas emissions, and the tropics and subtropics contribute greatly, particularly since 51% of world soils are in these climate zones. The soil microbial processes responsible for the production and consumption of CH₄ and production of N-oxides are the same in all parts of the globe, regardless of climate. Because of the ubiquitous nature of the basic enzymatic processes in the soil, the biological processes responsible for the production of NO, N_2O and CH₄, nitrification/denitrification and methanogenesis/methanotropy are discussed in general terms. Soil water content and nutrient availability are key controls for production, consumption and emission of these gases. Intensive studies of CH₄ exchange in rice production systems made during the past decade reveal new insight. At the same time, there have been relatively few measurements of CH₄, N_2O or NO_x fluxes in upland tropical crop production systems. There are even fewer studies in which simultaneous measurements of these gases are reported. Such measurements are necessary for determining total greenhouse gas emission budgets. While intensive agricultural systems are important global sources of N₂O and CH₄ recent studies are revealing that the impact of tropical land use change on trace gas emissions is not as great as first reports suggested. It is becoming apparent that although conversion of forests to grazing lands initially induces higher N-oxide emissions than observed from the primary forest, within a few years emissions of NO and N₂O generally fall below those from the primary forest. On the other hand, CH₄ oxidation is typically greatly reduced and grazing lands may even become net sources in situations where soil compaction from cattle traffic limits gas diffusion. Establishment of tree-based systems following slash-and-burn agriculture enhances N₂O and NO emissions during and immediately following burning. These emissions soon decline to rates similar to those observed in secondary forest while CH₄ consumption rates are slightly reduced. Conversion to intensive cropping systems, on the other hand, results in significant increases in N₂O emissions, a loss of the CH₄ sink, and a substantial increase in the global warming potential compared to the forest and tree-based systems. The increasing intensification of crop production in the tropics, in which N fertilization must increase for many crops to sustain production, will most certainly increase N-oxide emissions. The increase, however, may be on the same order as that expected in temperate crop production, thus smaller than some have predicted. In addition, increased attention to management of fertilizer and water may reduce trace gas emissions and simultaneously increase fertilizer use efficiency.     

Mitigating Greenhouse Gas Emissions from Rice-Wheat Cropping Systems in Asia

The rice-wheat belt comprises nearly 24–27 million ha in South and East Asia. Rice is generally grown in flooded fields whereas the ensuing wheat crop requires well-drained soil conditions. Consequently, both crops differ markedly in nature and intensity of greenhouse gas (GHG) fluxes, namely emission of (1) methane (CH₄) and (2) nitrous oxide (N_2O) as well as the sequestration of (3) carbon dioxide. Wetland rice emits large quantities of CH₄; strategies to CH₄ emissions include proper management of organic inputs, temporary (mid-season) field drainage and direct seeding. As for the wheat crop, the major GHG is N_2O that is emitted in short-term pulses after fertilization, heavy rainfall and irrigation events. However, N_2O is also emitted in larger quantities during fallow periods and during the rice crop as long as episodic irrigation or rainfall result in aerobic-anaerobic cycles. Wetland rice ensures a relatively high content of soil organic matter in the rice-wheat system as compared to permanent upland conditions. In terms of global warming potential, baseline emissions of the rice-wheat system primarily depend on the management practices during the rice crop while emissions from the wheat crop remain less sensitive to different management practices. The antagonism between CH₄ and N_2O emissions is a major impediment for devising effective mitigation strategies in rice-wheat system - measures to reduce the emission of one GHG often intensify the emission of the other GHG.     

Developing sustainable practices to adapt to the impacts of climate change: a case study of agricultural systems in eastern England (UK)

The weight of scientific evidence suggests that human activities are noticeably influencing the world's climate. However, the effects of global climate change will be unevenly spread, due to local variations in vulnerability and adaptive capacity. Using downscaled projections of future UK climates over the next 50 years, this paper investigates the impacts of, and possible responses to, climate change in one small area in eastern England, selected as a test-bed for sustainable agriculture. It shows that local agricultural systems are vulnerable to changes in the climate. At present, however, these considerations have a limited effect on agricultural operations, which are mainly driven by short-term events and 'non-climate' policies, such as agricultural price support. The capacity of agricultural systems to adapt successfully to climate change will be determined by the ability of producers to integrate climate change into their planning strategies with a view to ultimately ensuring sustainable agricultural practices in the long term. Electronic Publication