The impact of biofuel plantation on biodiversity: a review

Because plants convert solar energy into chemical energy stored in organisms, biomass production as an energy source can help to reduce the world＇s reliance on fossil energy and mitigate global warming. Biofuel production is a fast-growing industry that represents a new type of large-scale human disturbance on ecosystems. Thus, the benefits of biofuel production bring environmental risks that include its potential impact on biodiversity, which is still an open question. In this review, we start first with a brief overview of the evolution of biofuel concept; second, we review the state of biofuel production across the continents, with a major emphasis on the main species used and their major feedstock. For which, we found significant differences for land use and environmental cultural management of biofuel plantation between tropical and temperate regions. Third, we summarize the impacts of biofuel plantation on biodiversity at multiple scales, based on the case studied with respect to the corresponding issues. At the genetic level, introgression and contamination by aggressive genotypes are a primary risk. At the species level, habitat pollution, degradation, and disturbance caused by intensive management of biofuel plantation significantly raise the risk of habitat fragmentation, native extinction, and bio-invasion. At the ecosystem level, the large-scale homogeneous landscape of biofuel plantation results in simplified community and food web that severely damage ecosystem services, including ecosystem diversity. Finally, we compare the current and potential benefits and risks of biofuel plantations for the practical application of a biofuel industry of China. We emphasize the land use constraint from food security and biodiversity conservation, and the need for scientific research and systematic monitoring as a critical support for the sustainable development of biofuel production in China.     

China＇s sizeable and uncertain carbon sink： a perspective from GOSAT

Despite the agreement that China’s terrestrial ecosystems can provide a carbon sink and offset carbon dioxide(CO2)emissions from fossil fuels,the magnitude and spatial distribution of the sink remain uncertain.Accurate quantification of the carbon sequestration capacity of China’s terrestrial ecosystems has profound scientific and policy implications.Here,we report on the magnitude and patterns of China’s terrestrial carbon sink using the global monthly CO2flux data product from the Greenhouse gases Observing SATellite(GOSAT),the world’s first satellite dedicated to global greenhouse gas observation.We use the first year’s data from GOSAT(June 2009–May2010)that are currently available to assess China’s biospheric carbon fluxes.Our results show that China’s terrestrial ecosystems provide a carbon sink of-0.21 Pg C a-1.The consumption of fossil fuels in China leads to carbon dioxide emissions of 1.90 Pg C a-1into the atmosphere,approximately 11.1%of which is offset by China’s terrestrial ecosystems.China’s terrestrial ecosystems play a significant role in offsetting fossil fuel emissions and slowing down the buildup of CO2in the atmosphere.Our analysis based on GOSAT data offers a new perspective on the magnitude and distribution of China’s carbon sink.Our results show that China’s terrestrial ecosystems provide a sizeable and uncertain carbon sink,and further research is needed to reduce the uncertainty in its magnitude and distribution.     

2012年1月23日SEP事件的“twin-CME”爆发现象

"twin-CME"模型是Li等人提出的一种比单个CME更高效的产生SEP事件的模型。本文主要以"twin-CME"模型为出发点,综合运用SOHO/LASCO、STEREO-A/SECCHI、STEREO-B/SECCHI的日冕观测及CME的GCS模拟,Learmonth、BIRS和Wind/WAVES射电观测,以及SDO/AIA源区观测和SDO/HMI磁图资料,分析2012年1月23日爆发的极端SEP事件的源区爆发特征。结果表明:此SEP事件对应的源区观测到"twin-CME"爆发,即从同一源区先后相继爆发了2个CME,这2个CME在空间的传播方向基本一致,并在传播到一定高度时发生相互作用合并成一个更强的CME,此爆发过程CME和源区磁场特征与"twin-CME"模型的假设基本相似。"twin-CME"爆发及双CME合并可能是引起此极端SEP事件的原因。     

基于电镜的生物质成型燃料锅炉结渣机理研究

目前市场上已出现生物质成型燃料燃烧设备,由于结渣等因素影响,限制了这种生物质成型燃料燃烧设备的推广与应用.结渣不仅会对燃烧设备的热性能造成影响,而且危及燃烧设备的安全性.在生物质成型燃料炉渣电镜实验的基础上,揭示生物质成型燃料锅炉结渣的过程并得出预防和防止结渣措施.     

甲醇对甲醇汽油混合燃料发动机碳氢排放贡献率的定量研究

在一台JL368Q3型汽油机上,通过考察发动机燃用体积分数分别为10%、20%和85%的甲醇汽油混合燃料时甲醇和碳氢(HC)的排放特性,研究了甲醇和汽油各自的排放率随发动机排气温度的变化规律和甲醇掺混比的影响,以及甲醇对发动机碳氢排放的贡献率。试验结果表明:甲醇掺混比对甲醇排放率的影响不大,在各掺混比下,甲醇排放率均不超过8g/kg,且随发动机排气温度的升高呈现指数降低的趋势;汽油的碳氢排放率比甲醇排放率高一个数量级,甲醇体积分数为10%时发动机的碳氢排放率在中高负荷时最低,约为40g/kg;在各甲醇掺混比下,汽油均是发动机碳氢排放的主要来源,甲醇对发动机碳氢排放的贡献率不超过8%。     

橡胶聚合物在碳氢溶剂中的膨胀特性

为了验证碳氢有机溶剂在橡胶中的运输机理及运输特性,并为后期研究吸热型碳氢燃料与橡胶的相容性做准备,用浸泡/称量法对硫磺硫化体系(分别填充快压出炭黑和SiO2)、过氧化物硫化体系和混合硫化体系的天然橡胶在有机溶剂中的膨胀现象进行了研究。膨胀达到平衡时,快压出炭黑填充的硫磺硫化体系具有最小的溶剂吸收量,过氧化物硫化体系具有最大的溶剂吸收量。分别研究了交联密度、溶剂分子和温度对有机溶剂在橡胶中扩散的影响规律,并从热力学角度进行了详细分析。结果表明:实验所用橡胶-溶剂系统中,扩散结果偏离了Fick模型,为无规则扩散,且扩散系数随溶剂摩尔体积、相对分子质量、分子链的长度增加而减小;交联密度增加时溶剂的扩散减少,橡胶吸收溶剂的量减小;对二甲苯和丙苯比实验所用的烷烃有机溶剂更易使橡胶膨胀;在实验温度范围内,温度升高时橡胶的吸收量增加。     

生物质快速热解制车用燃料过程的能值分析

基于能值分析理论和考虑环境投入,从可持续发展的角度对玉米秸秆热解加氢制精制油过程的2个方案进行综合评价,获得生产效率、环境影响、可持续性方面的能值指标.方案1中的氢气来自初级生物油水相重整,方案2中氢气来自外部市场购买.结果表明:2个方案能值转换率分别为5.00×105sej/J和1.37×105sej/J,从能值转换率的角度分析,与方案1、玉米燃料乙醇及生物柴油相比,方案2生产等量燃料消耗的太阳能最少,更有优势;2个方案的能值产出率均为1.07,生产效率较低;环境负载率分别是1.02和1.05,对环境影响较小;可持续发展系数分别是1.05和1.02,可持续性属于中等水平.     

国外期刊亮点

正发现新分子标靶有助治疗阿尔兹海默症香港科技大学理学院院长叶玉如领导的研究团队,发现了可以治疗阿尔兹海默症的新分子标靶,有机会进一步开发成为治疗该症的新药。研究团队针对导致患者认知障碍的EphA4蛋白异常活化,成功从传统中药中筛选出一种天然化合物,证实可以抑制EphA4的活性,并改善阿尔兹海默症病症。这项研究6月4日在线发表于PNAS上。阿尔兹海默症主要影响65岁以上的人士,患者在出现认知能力下降等症状前就已经患上了阿尔兹海默症。淀粉样蛋白被视为导致患者出现认知功能障碍的主因。研究发现,淀粉样蛋白会过度激活EphA4蛋白,     

一种高效清洁燃烧纯甲醇燃料的新方法探索

在一台点火式电喷汽油机上进行了甲醇裂解燃料高效清洁燃烧的探索研究．研制了甲醇裂解装置和控制单元及其控制策略．发动机用汽油起动后,电控单元判别排气温度当其温度达到320℃以上时,电控单元自动从汽油燃料切换到甲醇裂解燃料下工作．在甲醇燃料模式下,通过ECU的标定,实现了自动运行．试验结果表明：与汽油和M20甲醇汽油相比,甲醇裂解燃料可以有效地提高点火式电喷发动机的效率,显著增高发动机的经济性,而且降低了尾气中有害气体排放．可见燃用甲醇裂解燃料是电喷发动机高效清洁燃烧的新方式．     

Latitude migration of solar activity at high latitudes

Utilized here is the Carte Synoptique solar filament archive, namely the catalogue of solar filaments from March 1919 to December 1989, corresponding to solar rotation numbers 876 to 1823 to study latitudinal migration of solar activity at high latitudes. Except the well-known poleward migration of solar activity from middle latitudes to the poles, an equatorward migration is found from the solar poles toward middle latitudes （about 40°） within a normal cycle, which is neglected before, and the time interval for the former migration （4.4 years） is about 2.2 years shorter than that for the latter （6.6 years）, indicating that the change from one migration to the other takes place around the maximum time of a normal cycle. In the future, a dynamo model should represent the migration from the poles toward middle latitudes of the Sun, besides the migration in ＂butterfly diagrams＂ and the ＂rush to the poles＂. The traditional extended activity cycle is actually a part of the period of the successive migration from the poles toward the solar equator.