Mechanics and Morphology of Silk Drawn from Anesthetized Spiders

 CO₂ and N₂ anesthetized Nephila spiders produced dragline silk with mechanical properties that differed from control silk as a function of time under anesthesia. Silk from CO₂ spiders had a significantly lower breaking strain and breaking energy, significantly higher initial modulus, and marginally lower breaking stress. At the onset of anesthesia the silk diameter became highly variable. During deep anesthesia silk either became thinner or retained cross-section but fibrillated. Received: 26 August 1999 / Accepted in revised form: 22 December 1999     

A novel marine silk

The discovery of a novel silk production system in a marine amphipod provides insights into the wider potential of natural silks. The tube-building corophioid amphipod Crassicorophium bonellii produces from its legs fibrous, adhesive underwater threads that combine barnacle cement biology with aspects of spider silk thread extrusion spinning. We characterised the filamentous silk as a mixture of mucopolysaccharides and protein deriving from glands representing two distinct types. The carbohydrate and protein silk secretion is dominated by complex β-sheet structures and a high content of charged amino acid residues. The filamentous secretion product exits the gland through a pore near the tip of the secretory leg after having moved through a duct, which subdivides into several small ductules all terminating in a spindle-shaped chamber. This chamber communicates with the exterior and may be considered the silk reservoir and processing/mixing space, in which the silk is mechanically and potentially chemically altered and becomes fibrous. We assert that further study of this probably independently evolved, marine arthropod silk processing and secretion system can provide not only important insights into the more complex arachnid and insect silks but also into crustacean adhesion cements.     

Floral CO<Subscript>2</Subscript> emission may indicate food abundance to nectar-feeding moths

As part of a study of the roles of the sensory subsystem devoted to CO₂ in the nectar-feeding moth Manduca sexta, we investigated CO₂ release and nectar secretion by flowers of Datura wrightii, a preferred hostplant of Manduca. Datura flowers open at dusk and wilt by the following noon. During the first hours after dusk, when Manduca feeds, the flowers produce considerable amounts of nectar and emit levels of CO₂ that should be detectable by moths nearby. By midnight, however, both nectar secretion and CO₂ release decrease significantly. Because nectar production requires high metabolic activity, high floral CO₂ emission may indicate food abundance to the moths. We suggest that hovering moths could use the florally emitted CO₂ to help them assess the nectar content before attempting to feed in order to improve their foraging efficiency.Electronic Supplementary Material  Supplementary material is available in the online version of this article at     

CO<Subscript>2</Subscript>-fertilization and potential future terrestrial carbon uptake in India

There is huge knowledge gap in our understanding of many terrestrial carbon cycle processes. In this paper, we investigate the bounds on terrestrial carbon uptake over India that arises solely due to CO ₂ -fertilization. For this purpose, we use a terrestrial carbon cycle model and consider two extreme scenarios: unlimited CO₂-fertilization is allowed for the terrestrial vegetation with CO₂ concentration level at 735 ppm in one case, and CO₂-fertilization is capped at year 1975 levels for another simulation. Our simulations show that, under equilibrium conditions, modeled carbon stocks in natural potential vegetation increase by 17 Gt-C with unlimited fertilization for CO₂ levels and climate change corresponding to the end of 21st century but they decline by 5.5 Gt-C if fertilization is limited at 1975 levels of CO₂ concentration. The carbon stock changes are dominated by forests. The area covered by natural potential forests increases by about 36% in the unlimited fertilization case but decreases by 15% in the fertilization-capped case. Thus, the assumption regarding CO₂-fertilization has the potential to alter the sign of terrestrial carbon uptake over India. Our model simulations also imply that the maximum potential terrestrial sequestration over India, under equilibrium conditions and best case scenario of unlimited CO₂-fertilization, is only 18% of the 21st century SRES A2 scenarios emissions from India. The limited uptake potential of the natural potential vegetation suggests that reduction of CO₂ emissions and afforestation programs should be top priorities.     

Changes in element composition along the spinning duct in a Nephila spider

The silk gland of the golden orb spider Nephila edulis connects to the exit spigot through a long S-shaped duct that assists in the formation of the thread. Previous evidence suggests that the epithelium of the distal (last) part of the duct is specialized for ion transport and that a proton pump is involved in this process. Here, we present evidence from SEM (scanning electron microscope)-EDAX (energy dispersive X-ray) microanalysis of rapidly frozen material maintained at approximately -150°C and from the use of pH indicators that the element composition and pH change progressively as the dragline silk dope (spinning solution) passes down the duct to form the thread. Na⁺ and Cl^- composition decreased while K⁺ and P and S increased. Indicators suggested that the pH dropped from 6.9ǂ.1 to 6.3ǂ.1. These novel findings suggest that the absorption of Na⁺ and secretion of the more chaotropic K⁺ may help the silk protein molecules to refold while the secretion of H⁺ may assist in this process and reduce the repulsive charges on them. This in turn may allow the molecules to approach one another more closely to crystallize. Thus precise control of the ionic environment within the spider's spinning duct may be important in forming a tough insoluble thread and when devising mimetic processes to spin silk proteins industrially.     

Relationship between CO<Subscript>2</Subscript> at a rural site and integral measures of atmospheric stagnation,recirculation, and ventilation

Integral quantities, wind run, S, and recirculation factor, R, useful for describing air flow, are calculated and combined with CO₂ mixing ratios. Meteorological observations were obtained from a RASS sodar and CO₂ mixing ratios from a continuous analyzer installed at a rural site in the upper Spanish plateau. The measuring campaign spread over 3 years and two approaches were followed. The first approach considered integral quantities on a daily basis and two classifications of air flow, to date scarcely used. The first classification distinguished among stagnation, recirculation, and ventilation, the second considering synoptic, meso-, and local scales. Moreover, 52.94% of daily values handled in this paper corresponded to ventilation and 49.70% to synoptic scale. The main goal of this approach is the subsequent link between the two classifications: the synoptic scale was associated with ventilation, mesoscale with recirculation and local scale partially with recirculation. CO₂ observations were distributed in air flow groups following these classifications and mesoscale processes were satisfactorily described since noticeable evidence of transport from nearby cities was observed. In the second approach, S and R pairs were used and CO₂ mixing ratios were distributed following percent intervals of ventilation, calculated by binning these pairs. The main goal of the second approach is to consider only three groups of mixing ratios. In the first group, with high ventilation, mixing ratios were low. With intermediate ventilation, mixing ratios were medium, and with low ventilation mixing ratios were high. A contrast of 21 ppm between the third and first groups was obtained at the 95th percentile. Finally, the second group provided a contrast of 3 ppm between north and south directions and also between east and west attributed to transport from nearby cities.     

CO<Subscript>2</Subscript> emission and economic growth of Iran

This research investigates the relationship between CO₂ emission and economic growth of Iran over 14 years from 1994 to 2007 using a national panel data set. The statistical and emission intensity methodologies are used for analyzing the data series. The study finds evidence supporting parameters which conclude the stability of significant correlation between CO₂ emission and economic development over time during the years under investigation in Iran. This relationship is investigated and discussed for the energy sectors of the country as well. The results confirm that in all sectors except of agricultural, there is a positive strong correlation between CO₂ emission and economic growth throughout the study period. In most sectors, CO₂ emission intensity (the emission per unit of GDP) doesn’t show increasing trends while the absolute emission is rapidly increasing by the economic growth.     

From Specialization in Spider Egg Predation to an Original Nesting Mode in a "Primitive" Ant: A New Kind of Lestobiosis

 Mature colonies of Discothyrea oculata were observed nesting in cribellatid spider oothecas where they found both shelter and food although these oothecas, installed in preexisting cavities, were protected with crimped silk. Workers of colonies bred in test tubes during laboratory experiments recuperated the silk from spider oothecas introduced into their foraging area, using their mandibles and forelegs, to operculate and line the test tubes. Also, colonies left the test tubes to shelter in the cribellatid spider oothecas. The term "arachnolesty" is proposed for this new kind of lestobiosis. Received: 20 April 1998 / Accepted in revised form: 16 October 1998     

The evolution of CO<Subscript>2</Subscript> emissions in international trade for major economies: a perspective from the global supply chain

Employing global multi-regional input–output models, this paper revisits the carbon dioxide (CO₂) emission trade (including exports and imports) and assesses their positions in the national emissions of 14 major countries with large national emissions or large emission trades during 1995–2009. It especially explores the evolution of the emission trades of these countries from both continuous time series and comparative perspectives, in order to provide an explanation for CO₂ emission spillovers across countries. The main findings obtained were as follows: (1) China was the largest CO₂ exporter to other countries, accounting for over 20 % of global exports since 2005; the CO₂ exports of the United States of America (USA), Germany, and Japan varied slightly over this time period, but overall, their proportions had decreased. (2) The CO₂ imports of the USA were the largest, occupying around 20 % of the global CO₂ imports; meanwhile, China’s CO₂ imports increased rapidly and ranked the second largest. (3) For Chinese Taiwan, its proportion of CO₂ exports in production-based emissions ranked the highest while that of the USA ranked the lowest; highly CO₂ import-dependent countries with an over 40 % proportion of CO₂ imports in its consumption-based emissions included France, Germany, Italy, and Spain, while China, India, and Russia remained the lowest, distinguished from their physical energy imports. These results suggested that the global policy makers should take the CO₂ emissions in trade into consideration when carefully accounting for national emissions inventories.     

CO2泄漏对稻田水基础水质指标的影响研究

碳捕集与封存（CCS）技术是当前抑制大气中CO₂过快增长的有效方法,但在CCS项目实施过程中仍存在CO₂泄漏而影响地表环境及生态的风险.本研究以龙粳31号和龙稻18号为实验对象,模拟研究地质封存CO₂以不同速率泄漏对稻田水环境基础水质指标D_CO2、pH、DO和ORP的影响,探讨稻田水对地质封存CO₂泄漏的响应规律.结果表明：CO₂泄漏对稻田水的D_CO2、pH、DO和ORP长期影响显著,不同CO₂泄漏速率对稻田水质指标的影响差异显著.在各指标平衡后,稻田水各水质指标均呈现明显的日变化规律,其中D_CO2呈早晚高、午间低的先减后增规律,而pH、DO和ORP均呈早晚低、午间高的先增后减规律.根据各指标差异性分析,建议将稻田水D_CO2作为稻田系统CO₂泄漏监测的主要指标,将pH、DO、ORP作为CO₂泄漏监测的辅助指标.     

Factors affecting CO<Subscript>2</Subscript> efflux rates and the stability of soil organic carbon storage in volcanic soils of the Canary Islands

Because volcanic soils store large amounts of soil organic carbon (SOC), they play a far more important role in the carbon (C) cycle than their limited global coverage suggests. We analysed the C released as CO₂ from a range of volcanic soils under natural conditions and analysed the influence of environmental variables (moisture and temperature), substrate availability (as assessed from the contents of various SOC fractions and the inputs of plant residues from litterfall), respiratory agents (roots, microorganisms and decomposing enzymes) and other pedological features of the topsoils (0–30 cm depth) on the CO₂ efflux rates over a 2-year experimental period. High CO₂ efflux rates (419 g C-CO₂ m^?2 y^?1 as the average for Andisols) were obtained that were related to significant decreases in the amount of SOC stored. CO₂ release was strongly controlled by soil moisture, although it was inhibited in the Andisols with the highest moisture levels (above 50 kg m^?2 in topsoil). It was not responsive to the availability of decomposing microorganisms or enzymes and appeared more related to the inputs of easily decomposable plant residues than to the amount of either labile or recalcitrant SOC. Among the SOC pools, only the water-soluble C in saturated paste extracts (WSC_se) of air-dried soil samples was consistently correlated with the CO₂ efflux rates. The desiccation of Andisols appeared to induce the release of previously stabilised SOC, which was readily mineralised when the moisture conditions became favourable. The results of this study indicate that SOC storage in Andisols is highly vulnerable to drying-wetting processes even in unmanaged natural ecosystems and that microclimate conditions can be critical for successful C sequestration in these soils.     

Public acceptance and risk-benefit perception of CO<Subscript>2</Subscript> geological storage for global warming mitigation in Japan

CO₂ geological storage will be one of the cost-effective options for global warming mitigation, and this technology is under development widely in the world. However, the technology may face the challenge of public acceptance before its implementation. In order to evaluate the public acceptance, questionnaire surveys were conducted among Japanese university students. A cognitive map of geological storage, together with other major global warming mitigation options, everyday life activities, etc., was constructed by means of a statistical analysis of the responses to the questionnaire. The risk-benefit cognitive map consists of the following factors: “risk perception,” “benefit perception,” and “public acceptance.” The risk perception is further disaggregated into “dread risk” and “unknown risk.” Additionally, a second survey was conducted after providing the students with additional information on global warming and CO₂ geological storage, and the effects of the information on their perceptions were evaluated. The effects of risk and benefit perceptions on public acceptance were evaluated and discussed based on the cognitive maps representing the perceptions before and after providing the information. The analyses revealed that the benefit perception was more influential than the risk perception on the public acceptance of CO₂ geological storage. The benefit perception increased greatly after providing the information; however, the unknown risk remained considerably large. Further, RD&D relating unknown risk, for example, the monitoring technology for stored CO₂ and the risk assessment of CO₂ leakage, and the supply of related information to the public would be beneficial for increasing the public acceptance.     

CO<Subscript>2</Subscript> Mitigation and Renewable Oil from Photosynthetic Microbes: A New Appraisal

The only major strategy now being seriously considered for biological mitigation of atmospheric CO₂ relies entirely on terrestrial plants. Photosynthetic microbes were the focus of similar consideration in the 1990s. However, two major government-sponsored research programs in Japan and the USA concluded that the requisite technology was not feasible, and those programs were terminated after investing US$117 million and US$25 million, respectively. We report here on the results of a privately funded US$20 million program that has engineered, built, and successfully operated a commercial-scale (2 ha), modular, production system for photosynthetic microbes. The production system couples photobioreactors with open ponds in a two-stage process – a combination that was suggested, but never attempted – and has operated continuously for several years to produce Haematococcus pluvialis. The annually averaged rate of achieved microbial oil production from H. pluvialis is equivalent to <420 GJ ha ^-1 yr^-1, which exceeds the most optimistic estimates of biofuel production from plantations of terrestrial ``energy crops.' The maximum production rate achieved to date is equivalent to 1014 GJ ha^-1 yr^-1. We present evidence to demonstrate that a rate of 3200 GJ ha^-1 yr^-1 is feasible using species with known performance characteristics under conditions that prevail in the existing production system. At this rate, it is possible to replace reliance on current fossil fuel usage equivalent to ∼300 EJ yr^-1 – and eliminate fossil fuel emissions of CO₂ of ∼6.5 GtC yr^-1 – using only 7.3% of the surplus arable land projected to be available by 2050. By comparison, most projections of biofuels production from terrestrial energy crops would require in excess of 80% of surplus arable land. Oil production cost is estimated at $84/bbl, assuming no improvements in current technology. We suggest enhancements that could reduce cost to $50/bbl or less.     

融冰期与非融冰期水库CO2逸出昼夜变化及CO2分压影响因素研究

以位于黄土高原北洛河流域的南沟水库为研究对象，采用Li-850静态箱法，于融冰期（3月）、非融冰期（5月）对水体CO₂分压（p（CO₂））和水-气界面CO₂逸出（F（CO₂））分别进行了5 d 40次昼夜监测，同时测定了各种水体理化指标，着重对比了水体p（CO₂）在两个时期间的差异和两时期内的昼夜变化特征，系统分析了水体p（CO₂）的影响因素.结果表明：融冰期p（CO₂）（（324.8±59.4）Pa）比非融冰期（（124.9±14.1）Pa）高出近3倍，差异性显著（p<0.05），但两个时期内昼夜p（CO₂）值并无显著性差异（p>0.05）；水体p（CO₂）与水温、pH、叶绿素（Chla）、溶解氧（DO）呈显著负相关，与溶解无机碳（DIC）、溶解有机碳（DOC）呈显著正相关，水体p（CO₂）受流域碳酸盐体系和水温影响最大，相关系数分别达0.92和-0.91，光合呼吸作用的影响其次；研究区小水库F（CO₂）范围为101~1589 g·m^-2·a^-1，是大气持续碳"源"，其平均排放量与个别温带、亚热带小型水库接近，但低于热带水库.     

三峡库区高水位运行期典型干支流水体CO2分压及其水面通量特征

本文以三峡库区典型干支流作为研究对象,重点研究高水位运行期库湾水体及库区干流CO2分压(p CO2)的分布规律,计算CO2的扩散通量和释放总量。本研究于2013年9月至11月利用走航式观测系统对库区奉节段干支流表层水体及定点剖面水体中p CO2和相关水质参数进行了逐月观测。研究结果表明,干支流表层水体p CO2的分布和扩散通量差异显著。干流CO2扩散通量(F-CO2)9月至11月变化不大,为28.19±0.80mmol/(m2·d);支流在观测期内,扩散通量由负变正,其中朱衣河F-CO2从-6.86增至32.05mmol/(m2·d);梅溪河从-6.94增至37.85mmol/(m2·d),草堂河从-6.97增至31.05mmol/(m2·d)。由10至11月的数据推广到全年的高水位运行阶段(10月至次年1月),全库区CO2排放量可达166 450t,其中支流占30.17%。     

三峡库区典型河流水-气界面CO2通量日变化观测及其影响因素分析

为研究河流水-气界面CO_2通量的季节和日变化特征;于2016年7月15～17日以及2017年11月4～6日对三峡库区嘉陵江支流竹溪河进行定点定时采集表层水样,并同步监测关键环境因子,采用亨利定律结合薄边界层模型计算其水-气界面CO_2通量F(CO_2).结果表明,竹溪河表层水CO_2分压p(CO_2)及界面CO_2脱气通量呈现出显著的日间和季节变化,以及明显的日内变化特征:在上午09:00前后达到释放高峰,随后波动下降;水-气界面CO_2通量日间均值分别为(100. 9±31. 6)、(78. 6±12. 1)、(83. 9±29. 7)、(137. 5±42. 1)、(147. 6±34. 0)、(132. 4±21. 7) mmol·(m~2·d)~(-1);并表现出夏季表层水体CO_2释放通量明显低于秋季,其均值分别为(87. 8±27. 5) mmol·(m~2·d)~(-1)和(139. 2±34. 0) mmol·(m~2·d)~(-1);总体表现出大气CO_2源的特征.竹溪河p(CO_2)和F(CO_2)受到诸多环境因子的影响,相关分析表明,pH、碱度、水温和气温是主要环境影响因子,CO_2释放通量可以用pH和碱度预测.     

Toward a framework of environmental risk management for CO<Subscript>2</Subscript> geological storage in china: gaps and suggestions for future regulations

China encourages the demonstration of carbon capture and storage (CCS) projects. In an effort to identify gaps and provide suggestions for environmental risk management of carbon dioxide (CO₂) geological storage in China, this article presents a concise overview of potential health, safety and environmental (HSE) risks and environmental management regulations for CO₂ geological storage in Australia, Japan, the United States (USA), the European Union (EU), and the United Kingdom (UK). The environmental impact assessment (EIA) experience of Shenhua Ordos Coal-to-Liquid (CTL) Project and PetroChina Jilin Oil Field enhanced oil recovery (EOR) is subsequently analyzed in light of our field investigation, and gaps in current EIA guidelines that are applicable to CO₂ geological storage projects are identified. It is found that there are no specific environmental risk regulations suitable for CO₂ storage in China, and environmental risk management lags behind the development of CCS technology, which presents a challenge to demonstration enterprises in terms of assessing environmental risk. One major challenge is the overestimation or underestimation of this risk on the part of the enterprise, and another is a lack of applicable regulations for government sectors to supervise the risk throughout CCS projects. Therefore, there is a pressing need for China to formulate environmental management regulations that include environmental risk assessment, mandatory monitoring schemes, environmental emergency plans, and related issues.     

重庆西部山区典型湖泊水-气界面CO2交换通量及其影响因素

为了解我国西南山区湖泊水体CO_2的释放/吸收特征,于2017年7月对重庆西部山区典型9个湖泊表层水体溶解性无机碳进行调查,并同步监测关键环境因子,运用薄边界层法和静态箱法对其水-气界面CO_2通量[F(CO_2)]进行比较研究.结果表明,渝西山区湖泊夏季表层水p(CO_2)介于2.1~45.0 Pa之间,均值为(18.1±12.1) Pa;模型法和静态箱法计算的CO_2通量均值分别为(-8.0±2.9)、(-3.4±3.6)和(-7.1±22.3) mmol·(m2·d)-1,总体表现出大气CO_2汇的特征.水体p(CO_2)和F(CO_2)与关键环境因子的相关分析,表明表层水p(CO_2)和F(CO_2)与风速和ORP显著正相关,与pH显著负相关.     

Potential effects of climate change and rising CO2 on ecosystem processes in northeastern U.S. forests

Forest ecosystems represent the dominant form of land cover in the northeastern United States and are heavily relied upon by the region’s residents as a source of fuel, fiber, structural materials, clean water, economic vitality, and recreational opportunities. Although predicted changes in climate have important implications for a number of ecosystem processes, our present understanding of their long-term effects is poor. In this study, we used the PnET-CN model of forest carbon (C), nitrogen (N) and water cycling to evaluate the effects of predicted changes in climate and atmospheric carbon dioxide (CO₂) on forest growth, C exchange, water runoff, and nitrate ( $ {\text{NO}}^{ - }_{3} $ ) leaching at five forest research sites across the northeastern U.S. We used four sets of statistically downscaled climate predictions from two general circulation models (the Hadley Centre Coupled Model, version 3 and the Parallel Climate Model) and two scenarios of future CO₂ concentrations. A series of model experiments was conducted to examine the effects of future temperature, precipitation, CO₂, and various assumptions regarding the physiological response of forests to these changes. Results indicate a wide range of predicted future growth rates. Increased growth was predicted across deciduous sites under most future conditions, while growth declines were predicted for spruce forests under the warmest scenarios and in some deciduous forests when CO₂ fertilization effects were absent. Both climate and rising CO₂ contributed to predicted changes, but their relative importance shifted from CO₂-dominated to climate-dominated from the first to second half of the twenty-first century. Predicted runoff ranged from no change to a slight decrease, depending on future precipitation and assumptions about stomatal response to CO₂. Nitrate leaching exhibited variable responses, but was highest under conditions that imposed plant stress with no physiological effects of CO₂. Although there are considerable uncertainties surrounding predicted responses to climate change, these results provide a range of possible outcomes and highlight interactions among processes that are likely to be important. Such information can be useful to scientists and land managers as they plan on means of examining and responding to the effects of climate change.     

A decomposition analysis of carbon dioxide emissions in the Chinese nonferrous metal industry

The nonferrous metal industry (NMI) of China consumes large amounts of energy and associated emissions of carbon dioxide (CO ₂) are very high. Actions to reduce CO ₂ emissions and energy consumption are warranted. This study aims to analyze current China NMI trends of CO ₂ emissions and energy consumption including the underlying regional driver characteristics. We analyze the changes of CO ₂ emissions in the NMI based on the Logarithmic Mean Divisia Index (LMDI) method from 2000 to 2011. Then, a classification system is used to study the regional differences in emission changes from the NMI. The results show that the emissions of the Chinese NMI increased rapidly at an average annual growth rate of 31 million metric tons. The economic scale and energy intensity are the main driving factors responsible for the change in the emissions, while carbon emission coefficients make only a small contribution toward decreasing the emissions, and the energy structure has a volatile effect. Emissions and energy intensity of 29 China provinces were divided into five categories. The change in the trend of each region is indicated in this paper. Hebei is one of the provinces that achieved the best performance, and Chongqing achieved the worst performance among all of the regions. The analysis suggests that the main emphasis of CO ₂ emission mitigation should be focused on controlling the economic scale and improving the energy intensity. Developing the use of clean energy technologies and policies in both the NMI and power industries is important.