Elevated CO2 reduces the response of Sitobion avenae (Homoptera: Aphididae) to alarm pheromone

The aphid alarm pheromone (E)-β-farnesene (EβF) is an efficient signal that warns aphids of attack by natural enemies. In this field study, eight open-top chambers (OTCs) located in Beijing, China (40°11′N, 116°24′E) with spring wheat Triticum aestivum were used to examine the response of the grain aphid Sitobion avenae to CO₂ (ambient vs. double ambient) and EβF (applied zero, two, or five times each day). We experimentally tested the hypotheses that, depending on frequency of EβF release, elevated CO₂ reduces the response (in terms of population density) of S. avenae to EβF, and that lower activity of acetylcholinesterase (AChE) in S. avenae may be involved in its reduced sensitivity to EβF under elevated CO₂. Numbers of S. avenae declined with increased frequency of EβF application under ambient CO₂ but were unaffected by EβF application under elevated CO₂. Additionally, the mean relative growth rate (MRGR) and the dry material and amino acid content of S. avenae increased with elevated CO₂ but declined when with EβF application. Activities of superoxide dismutase and catalase were higher in S. avenae under elevated vs. ambient CO₂. Under elevated CO₂, however, AChE activity remained low when S. avenae was exposed to the lower EβF frequency, while the highest AChE activity occurred in aphids exposed to the higher EβF frequency. These results indicate that aphids become insensitive to EβF under elevated CO₂, perhaps because of decreased AChE activity.     

Can the envisaged reductions of fossil fuel CO<Subscript>2</Subscript> emissions be detected by atmospheric observations?

The lower troposphere is an excellent receptacle, which integrates anthropogenic greenhouse gases emissions over large areas. Therefore, atmospheric concentration observations over populated regions would provide the ultimate proof if sustained emissions changes have occurred. The most important anthropogenic greenhouse gas, carbon dioxide (CO(2)), also shows large natural concentration variations, which need to be disentangled from anthropogenic signals to assess changes in associated emissions. This is in principle possible for the fossil fuel CO(2) component (FFCO(2)) by high-precision radiocarbon ((14)C) analyses because FFCO(2) is free of radiocarbon. Long-term observations of (14)CO(2) conducted at two sites in south-western Germany do not yet reveal any significant trends in the regional fossil fuel CO(2) component. We rather observe strong inter-annual variations, which are largely imprinted by changes of atmospheric transport as supported by dedicated transport model simulations of fossil fuel CO(2). In this paper, we show that, depending on the remoteness of the site, changes of about 7-26% in fossil fuel emissions in respective catchment areas could be detected with confidence by high-precision atmospheric (14)CO(2) measurements when comparing 5-year averages if these inter-annual variations were taken into account. This perspective constitutes the urgently needed tool for validation of fossil fuel CO(2) emissions changes in the framework of the Kyoto protocol and successive climate initiatives.     

湖泊碳循环及碳通量的估算方法

湖泊由于其特殊的地理位置,较高的生产力,在碳循环中具有重要作用。作为湖泊营养元素的碳在湖泊水体中的赋存形态主要包括:碳酸盐系统(CO2,CO32-,HCO3-,H2CO3)、溶解态有机碳、生物死亡残体颗粒碳及生物体有机碳等。研究表明包括有机碳和溶解态无机碳在内的全世界湖泊总碳汇为0.077Gt/a,其中对大气的汇达到0.0532Gt/a。湖泊除从地表径流、地下水获得碳以外,还可从空气物质中获得碳。估算及测定水气界面CO2通量的方法主要有:①赖利估算法;②单侧扩散法;③同位素估算法;④涡度相关法;⑤静态箱式法。     

燃油锅炉运行与监测的分析与探讨

近年来燃油锅炉的数量在不断增加,由此引出一系列的监测问题。在实际操作基础上,结合燃油锅炉的运行与现场监测,提出了一些观点和建议。     

On the value of temporary carbon: a comment on Kirschbaum

A recent paper by Miko Kirschbaum (Mitigat Adapt Strategies Glob Change 11(5–6):1151–1164, 2006) argues that temporary carbon (C) storage has “virtually no climate-change mitigation value.” However, temporary carbon has value in delaying global warming that needs to be recognized in carbon accounting methodologies. The conclusions reached are very sensitive to any value that is attached to time. Basing analysis exclusively on the maximum temperature reached within a 100-year time frame ignores other important impacts of global warming that also need to be included when mitigation strategies are assessed. The relative weightings for long-term versus short-term impacts represent policy choices that result in a greater or a lesser value being attributed to temporary carbon, but that value should not be zero. Global warming is too formidable an enemy to allow us the luxury of discarding part of our arsenal in fighting against it. Both reducing fossil-fuel combustion and increasing biosphere carbon stocks are needed.     

Sustainable development as a framework for developing country participation in international climate change policies

The paper presents a number of ideas on how climate change policy implementation in developing countries can be supported by alternative international cooperation mechanisms that are based on stakeholder interests and policy priorities including broader economic and social development issues. It includes a brief review of current development policies, technological research and promotion efforts, and climate change that demonstrates that mutual policy initiatives undertaken by governments and the private sector actually have major positive impacts on climate change without being initiated by this global policy concern. Furthermore a number of examples are given on how future development objectives in Brazil, China, and India jointly can support economic and social goals and global climate change concerns if these goals are taken into consideration and supported by international cooperative mechanisms. The paper proposes international cooperative mechanisms that can support the implementation of integrated development and climate change policies. The mechanisms include an international sustainable development (SD) and Climate Finance Mechanism (SDCFM), technology development and transition programmes, technology standards, and other measures.

Cadaver decomposition in terrestrial ecosystems

A dead mammal (i.e. cadaver) is a high quality resource (narrow carbon:nitrogen ratio, high water content) that releases an intense, localised pulse of carbon and nutrients into the soil upon decomposition. Despite the fact that as much as 5,000 kg of cadaver can be introduced to a square kilometre of terrestrial ecosystem each year, cadaver decomposition remains a neglected microsere. Here we review the processes associated with the introduction of cadaver-derived carbon and nutrients into soil from forensic and ecological settings to show that cadaver decomposition can have a greater, albeit localised, effect on belowground ecology than plant and faecal resources. Cadaveric materials are rapidly introduced to belowground floral and faunal communities, which results in the formation of a highly concentrated island of fertility, or cadaver decomposition island (CDI). CDIs are associated with increased soil microbial biomass, microbial activity (C mineralisation) and nematode abundance. Each CDI is an ephemeral natural disturbance that, in addition to releasing energy and nutrients to the wider ecosystem, acts as a hub by receiving these materials in the form of dead insects, exuvia and puparia, faecal matter (from scavengers, grazers and predators) and feathers (from avian scavengers and predators). As such, CDIs contribute to landscape heterogeneity. Furthermore, CDIs are a specialised habitat for a number of flies, beetles and pioneer vegetation, which enhances biodiversity in terrestrial ecosystems.     

四氯化碳显色法测定溶解氧

本文介绍了一种测定溶解氧的新方法。此方法快速、准确、分析结果直观、适合应急监测。     

喷雾塔中氨水吸收CO2的速率

为考察氨水细喷雾吸收CO2的能力,对喷雾塔中氨水细喷雾吸收CO2的反应过程进行了实验研究,测定了氨水吸收CO2的速率.实验结果表明,CO2的吸收速率随着氨水浓度、气体流量的升高而明显增大,随氨水流量升高也有所增加,CO2的吸收速率随CO2进口浓度的升高呈线性增加.当喷雾塔中温度低于40℃时,CO2的吸收速率随着塔内温度...     

碳源强化对人工湿地反硝化过程的影响研究

反硝化是人工湿地去除硝酸盐氮的主要机制,高含氮污水中低碳氮比是导致脱氮效果低的主要原因.研究了添加碳源对人工湿地反硝化过程的强化效果,结果表明,外界温度对湿地内的反硝化影响不大,而碳源则是重要的影响因素,对湿地投加碳源可以显著提高湿地的硝氮去除能力,在进水硝氮浓度25～45mg.L-1,24h水力停留时间的条件下,投加...