土地利用变化对西双版纳地区土壤及植被碳含量的影响

土地利用变化，尤其是热带地区森林生态系统土地利用方式的变化极大地改变了全球碳循环，对大气CO2浓度的升高，气候变暖等全球性环境问题起着不可忽视的作用。同时，森林的大面积破坏，引起土壤流失，营养元素含量降低，土壤健康状况恶化，最终大幅度降低生态系统的生产力。本文主要结合野外实地调查和室内分析的方法，研究森林砍伐后转变为农田和橡胶园对西双版纳热带地区土壤碳、氮、磷含量以及有机质化学结构的影响，天然次生林恢复、橡胶园建设对大气CO2的蓄积作用。 森林砍伐后转变为农田和橡胶园，显著地改变了土壤的理化特性。研究结果表明，与次生林相比，农田和橡胶园表层土壤容重、pH值升高，含水量降低，有机质、全氮、全磷、速效氮、有效磷含量显著降低。土地利用变化对土壤特性的影响主要发生在0-40 cm 表层土壤，而对40 cm以下土层影响较小。 土地利用变化改变土壤碳含量，同时影响土壤有机质的化学结构。胡敏酸紫外-可见光谱(UV-VIS)、傅利叶变换红外光谱 (FT-IR) 分析发现，不同生态系统表层土壤 (0-20 cm) 胡敏酸光谱学特性存在明显差异。次生林E4/E6值高于农田和橡胶园。与次生林相比，农田和橡胶园表层土壤有机质中酚基相对含量显著降低，脂肪族、芳香族、羧基以及多聚糖等化合物相对含量增加。 运用样地调查、生物量模型模拟和室内土壤样品分析方法，研究了次生林恢复和橡胶园建设对大气CO2的汇集作用。结果表明：退化土壤恢复为次生林、农田建设橡胶园能够有效促进植被和土壤中碳的汇集。次生林和橡胶林生物量增长速率分别为9.8，10.2 （9.4）t•ha-1•yr-1, 1 m表层土壤有机碳汇集速率分别为0.7和1.1 t•C•ha-1•yr-1。模拟结果显示，40年橡胶林生物量为327 (324) t•ha-1, 恢复50年后天然次生林生物量为395 t•ha-1。加之土壤有机碳，40年橡胶园约汇集碳190 t•ha-1, 次生林恢复50年碳汇集潜力为250 t•ha-1。

Quantifying global terrestrial carbon influx and storage as stimulated by an increase in atmospheric carbon dioxide concentration

EXTRACT (SEE PDF FOR FULL ABSTRACT): Measurements of spatial and temporal distributions of carbon dioxide concentration and carbon-13/carbon-12 ratio in the atmosphere suggest a strong biospheric carbon sink in terrestrial ecosystems. Quantifying the sink, however, has become an enormous challenge for Earth system scientists because of great uncertainties associated with biological variation and environmental heterogeneity in the ecosystems. This paper presents an approach that uses two driving parameters to bound terrestrial carbon sequestration associated with an increase in carbon dioxide concentration.

A high performance oxygen storage material for chemical looping processes with CO2 capture

Chemical looping combustion (CLC) is a novel combustion technology that involves cyclic reduction and oxidation of oxygen storage materials to provide oxygen for the combustion of fuels to CO2 and H2O, whilst giving a pure stream of CO2 suitable for sequestration or utilisation. Here, we report a method for preparing of oxygen storage materials from layered double hydroxides (LDHs) precursors and demonstrate their applications in the CLC process. The LDHs precursor enables homogeneous mixing of elements at the molecular level, giving a high degree of dispersion and high-loading of active metal oxide in the support after calcination. Using a Cu-Al LDH precursor as a prototype, we demonstrate that rational design of oxygen storage materials by material chemistry significantly improved the reactivity and stability in the high temperature redox cycles. We discovered that the presence of sodium-containing species were effective in inhibiting the formation of copper aluminates (CuAl2O4 or CuAlO 2) and stabilising the copper phase in an amorphous support over multiple redox cycles. A representative nanostructured Cu-based oxygen storage material derived from the LDH precursor showed stable gaseous O2 release capacity (∼5 wt%), stable oxygen storage capacity (∼12 wt%), and stable reaction rates during reversible phase changes between CuO-Cu 2O-Cu at high temperatures (800-1000 °C). We anticipate that the strategy can be extended to manufacture a variety of metal oxide composites for applications in novel high temperature looping cycles for clean energy production and CO2 capture. © The Royal Society of Chemistry 2013.

SOI sensing technologies for harsh environment

This paper reviews and addresses certain aspects of Silicon-On-Insulator (SOI) technologies for a harsh environment. The paper first describes the need for specialized sensors in applications such as (i) domestic and other small-scale boilers, (ii) CO2 Capture and Sequestration, (iii) oil & gas storage and transportation, and (iv) automotive. We describe in brief the advantages and special features of SOI technology for sensing applications requiring temperatures in excess of the typical bulk silicon junction temperatures of 150oC. Finally we present the concepts, structures and prototypes of simple and smart micro-hotplate and Infra Red (IR) based emitters for NDIR (Non Dispersive IR) gas sensors in harsh environments. © 2012 IEEE.

Steel and aluminium in a low carbon future

Production of steel and aluminium creates 10% of global carbon emissions from energy and processes. Demand is likely to double by 2050, but climate scientists are recommending absolute reductions of at least 50% and these are Increasingly entering law. How can reductions of this order happen? Only 10-20% savings can be expected in liquid metal production, so the primary industry is pursuing carbon sequestration as the main solution. However, this Is as yet unproven at scale, and as well as carrying some risk, the capital and operating costs are likely to be high, but are as yet unknown. In parallel with these strategies we can also examine whether we can reduce demand for liquid metal. 'Material efficiency' may allow delivery of existing services with less requirement for metal, for instance through designing products that use less metal, reducing process scrap, diverting scrap for other use, re-using components or delaying end of life. Overall demand reduction could occur if goods were used more intensely, alternative means were used to deliver the same services, or total demand were constrained. The paper analyses all possible options, to define and evaluate scenarios that meet the 2050 target, and discuss the steps required to bring them about. The paper concludes with suggestions for key areas where future research In metal forming can support a future low carbon economy. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA. Weinheim.

铵态氮肥对黄土高原典型土壤氮素激发效应的影响

以黄土高原从北向南不同地区典型土壤类型为对象,采用Bremner淹水培养法,研究铵态氮肥对黄土高原典型土壤氮素的激发效应。结果表明,在测定NH4+-N的激发效应时,只有考虑粘土矿物对有机氮矿化产物或者添加NH4+-N的固定,才可获得可靠结果。在培养20 d和60 d时,NH4+-N对不同土类氮素激发效应存在极显著和显著的影响(P≤0.01和<0.05);培养40 d时,尽管不同土类氮素激发效应也存在很大差异,但统计检验不显著。从整体评价,NH4+-N对土垫旱耕人为土和黄土正常新成土表现出正的激发效应,而对干润砂质新成土表现出负的激发效应,对简育干润均腐土在培养20 d和40 d时无激发效应,而在培养60 d时,表现出显著的负激发效应。结果还看出,在培养40 d和60 d时,NH4+-N对农田土壤表现出负激发效应,对林地和裸地土壤表现出正激发效应,而草地土壤在培养40 d时为正激发效应;培养20 d和60 d时无激发效应。添加有机物料在培养20 d和40 d时对激发效应的影响不显著(P=0.0872和0.1641),培养时间延长至60 d时影响显著(P=0.049)。添加紫花苜蓿(Medicago sati-v...

CO_2地质埋存后的逃逸问题研究进展

中国的温室气体排放目前已排世界第一,对环境是严重的威胁.CO_2地质埋存是温室气体资源化利用及减少大气温室气体排放量的有效途径之一,但是在地质埋存后,CO_2一旦逃逸会引起地表的隆起或凹陷、污染水源、破坏海洋生态系统等系列灾害,并使温室气体埋存效果毁于一旦.本文在对CO_2埋存问题简要介绍的基础上,重点对埋存后CO_2逃逸问题的研究现状作综述.阐述了CO_2埋存后通过盖层渗流和扩散、废弃井的渗透等逃逸方式,以及主要的控制参数,包括盖层渗透逃逸、扩散逃逸、油井及裂隙逃逸等方面的参数.通过分析,提出了需要进一步研究的问题,主要有:(1)控制CO_2逃逸的主要参数需要通过模型实验确定;(2)需要建立考虑化学反应、地层特征和井口分布特征的多相渗流模型;(3)在CO_2逃逸方面除要考虑扩散、渗流效应外,还要考虑井口分布、高气压引起的劈裂导致的渗透性急剧增加的效应等因素的影响

农田土壤有机碳的影响因素及其研究

大气温室效应气体N2O、CO2增多与全球气温变暖有着密切的关系,由于农业活动导致的碳排放量占碳总排放量的25%,因此研究农田土壤有机碳的影响因素,对增加农田碳素固定和保持,减少由于不合理的土地使用而导致大量CO2的排放,维持农业和生物圈生态系统的可持续发展有着重要意义。本文分析了温度、水分、土地开垦、休闲和撩荒、耕翻、轮作、秸秆还田、肥料管理等对土壤有机碳的影响。减少翻耕次数,增加秸秆还田,优化氮、磷、钾等养分用量及配比,是提高农田,尤其是旱地农田土壤有机碳含量,培肥、改良土壤的重要途径。

Identification and analysis of a Scophthalmus maximus ferritin that is regulated at transcription level by oxidative stress and bacterial infection

Ferritins are conserved Iron storage proteins that exist in most living organisms and play an essential role in Iron homeostasis. In this study, we reported the identification and analysis a ferritin M subunit, SmFerM, from turbot Scophthalmus maximus. The full length cDNA of SmFerM contains a 5'-untranslated region (UTR) of 232 bp, an open reading frame (ORF) of 531 bp, and a 3'-UTR of 196 bp The ORF encodes a putative protein of 176 amino acids, which shares extensive sequence identities with the M terrains of several fish species. In silico analysis identified in SmFerM both the ferroxidase center of mammalian H ferritins and the iron nucleation site of mammalian L ferritins. Quantitative real time reverse transcriptase-PCR analysis indicated that SmFerM expression was highest in muscle and lowest in heart and responded positively to experimental challenges with bacterial pathogens and poly(I center dot C) Exposure of cultured turbot hepatocytes to treatment of stress inducers (iron, copper, and H2O2) significantly upregulated the expression of SmFerM in a dose dependent manner. Iron chelating analysis showed that recombinant SmFerM purified from Escherichia coli exhibited apparent iron binding activity. These results suggest that SmFerM is a functional M ferritin and is likely to play a role in iron sequestration and protection against oxidative stress and microbial infection (C) 2010 Elsevier Inc All rights reserved

Ocean urea fertilization for carbon credits poses high ecological risks

The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed. (C) 2008 Elsevier Ltd. All rights reserved.

Temperature and biomass influences on interannual changes in CO2 exchange in an alpine meadow on the Qinghai-Tibetan Plateau

Three years of eddy covariance measurements were used to characterize the seasonal and interannual variability of the CO2 fluxes above an alpine meadow (3250 m a.s.l.) on the Qinghai-Tibetan Plateau, China. This alpine meadow was a weak sink for atmospheric CO2, with a net ecosystem production (NEP) of 78.5, 91.7, and 192.5 g C m(-2) yr(-1) in 2002, 2003, and 2004, respectively. The prominent, high NEP in 2004 resulted from the combination of high gross primary production (GPP) and low ecosystem respiration (R-e) during the growing season. The period of net absorption of CO2 in 2004, 179 days, was 10 days longer than that in 2002 and 5 days longer than that in 2003. Moreover, the date on which the mean air temperature first exceeded 5.0 degrees C was 10 days earlier in 2004 (DOY110) than in 2002 or 2003. This date agrees well with that on which the green aboveground biomass (Green AGB) started to increase. The relationship between light-use efficiency and Green AGB was similar among the three years. In 2002, however, earlier senescence possibly caused low autumn GPP, and thus the annual NEP, to be lower. The low summertime R-e in 2004 was apparently caused by lower soil temperatures and the relatively lower temperature dependence of R-e in comparison with the other years. These results suggest that (1) the Qinghai-Tibetan Plateau plays a potentially significant role in global carbon sequestration, because alpine meadow covers about one-third of this vast plateau, and (2) the annual NEP in the alpine meadow was comprehensively controlled by the temperature environment, including its effect on biomass growth.