蚯蚓和三叉苦对亚热带人工林土壤N2O和CH4通量的短期效应

在广东鹤山大叶相思(Acacia auriculaeformis)人工林内设置外来蚯蚓西土寒宪蚓(Ocnerodrilus occidentalis)和乡土植物三叉苦(Evodia lepta)野外控制实验,用静态箱-气相色谱法对土壤N2O和CH4通量进行15 d的原位测定,研究蚯蚓和三叉苦对土壤N2O和CH4通量的影响。结果表明,三叉苦并未明显增加土壤N2O和CH4的通量,而假植物(模拟三叉苦的物理效应)则显著促进了土壤N2O的释放通量。整个实验阶段,蚯蚓效应分别使无植物对照和三叉苦处理土壤N2O通量增加了26.7%和66.3%,而在种假植物条件下,添加蚯蚓使土壤N2O通量降低了39.7%;同时,蚯蚓效应使对照处理土壤CH4吸收通量增加了10.3%,使假植物处理土壤CH4吸收通量降低了90.6%,而使三叉苦处理土壤CH4释放通量增加了301.8%。可见,蚯蚓能够促进人工林土壤N2O释放;同时促进人工林土壤从CH4“汇”向“源”转变。三叉苦的物理过程促进土壤N2O的释放,而三叉苦的生物过程抑制土壤N2O的排放。如何减缓人工林中土壤N2O和CH4的排放,必须综合考虑植物物理过程、生物过程以及蚯蚓对土壤N2O和CH4排放过程影响的独立效应和交互效应。     

大气CO2浓度升高对土壤微生物的影响

自人类进入工业化时代以来,由于化石燃料的燃烧和森林的大面积破坏,大气中ＣＯ２的浓度已由工业革命以前的２８０μｌ·Ｌ－１增加到现在的３５０μｌ·Ｌ－１,仅从１９５７年至今的几十年间,大气中ＣＯ２的浓度就增加了２０％,预计到下个世纪下半叶,大气中ＣＯ２的...     

CO2浓度和土壤含水量对植物个体尺度短期水分利用效率的影响

分析植物个体短期水分利用效率(WUE_p)对CO₂浓度(C_a)和土壤含水量(SWC)的响应,可提高对气候变化下个体生存策略的认识。本研究以侧柏幼树为对象,在模拟气候箱中进行培养试验,设400(C₄₀₀)、600(C₆₀₀)和800 μmol·mol^-1CO₂(C₈₀₀)浓度处理和35%～45%田间持水量(FC)、50%～60%FC、60%～70%FC、70%～80%FC、95%～100%FC土壤含水量处理,共15个处理。WUE_p对C_a和SWC的响应用包裹式茎流计、称重法结合静态同化箱测定。结果表明: 个体日间(0.12～1.87 mol·h^-1)和夜间蒸腾速率(0.01～0.16 mol·h^-1)均在C₄₀₀×70%～80%FC时达到最大值,个体日间净光合速率(2.12～22.10 mmol·h^-1)在C₈₀₀×70%～80%FC时达到最大值,而个体夜间呼吸速率(0.84～4.41 mmol·h^-1)随SWC的增加而增加,随C_a的增加而减小,在C₄₀₀×95%～100%FC时达到最大值。WUE_p(5.37～24.35 mmol·mol^-1)在C₈₀₀×50%～60%FC时达到最大值,表明高C_a和干旱条件下,植物个体可通过生理可塑性调整,利用较少的水分固定更多的碳;此外,当个体间形态特征差异较小时,叶片瞬时水分利用效率可以较好地指示WUE_P的变化。     

不同尺度上植物叶气孔导度对升高CO2的响应

植物叶气孔导度对大气CO2浓度升高的响应可表现在以下几个层面：在叶水平上,叶气孔导度和气孔密度下降;在植物个体水平上,单位叶面积蒸腾下降,植株的水分利用率升高;在生态系统水平上,蒸散降低,土壤泾流和土壤水分含量增加;在全球尺度上,扩大了温室气体的增温效应,同时也降低了全球降雨量增加的趋势。正是因为植物叶气孔导度的变化会影响全球水循环,所以它在全球变化中起着非常重要的作用。但目前的研究结果还不能外推到更大的尺度上去。     

增施CO2对植物修复土壤DEHP污染的影响

修复效率低一直是植物修复技术需要解决的关键问题之一.基于我国的CO2减排压力和CO2对植物生长的必要性,选择C3植物绿豆和C4植物玉米作为修复植物,以DEHP为目标污染物,探索增施CO2对植物修复土壤DEHP污染的影响.结果表明:DEHP对两种植物生长和根际微环境都产生了抑制性影响.增施CO2后,两种植物地上干质量显著增加,叶片SOD酶活性明显下降,根际土壤碱性磷酸酶活性增加,根际微生物群落结构改变,根际耐DE-HP胁迫微生物数量增加,表明增施CO2对促进植物生长、增强植物抗DEHP胁迫能力、改善根际微环境有积极作用.增施CO2还促进了两种植物对DEHP的吸收,特别是植物地下部分.这些共同作用导致增施CO2后的两种植物根际DEHP残留浓度明显下降,土壤污染植物修复效率提高.整体上看,增施CO2对C3植物绿豆的影响明显大于C4植物玉米.可以将增施CO2作为强化植物修复过程的措施之一.     

杨柴对高CO2浓度和土壤干旱胁迫的响应

毛乌素优势植物杨柴 (HedysarummongolicumTurcz.)对高CO2 浓度和土壤干旱胁迫响应的研究结果表明 :干旱胁迫可使杨柴根系伸长 ,根生物量、地径、主茎高和茎生物量下降 ;高CO2 浓度使杨柴根和茎生物量明显增加 ,CO2 的“施肥效应”显著 ,干旱使CO2 的“施肥效应”减弱。同时 ,土壤干旱胁迫使杨柴的根 /冠比增加 ,说明在土壤干旱胁迫情况下根的生长比地上部分 (茎 )的生长更活跃 ,有利于提高杨柴在干旱沙漠地区的固沙作用 ;CO2 浓度升高和土壤干旱胁迫均使杨柴叶片的水势下降 ,叶片水势的下降使叶片细胞对水分的束缚力增强 ,从而减少植物蒸腾耗水 ,有利于提高水资源的利用效率     

大气CO2浓度升高对植物根系的影响

植物长期生长在CO2浓度不断升高的环境中,其结构和功能都将受到影响,这种影响不仅表现在植物的地上部分,同时也表现在植物的地下部分(根系),尤其是细根的长度、直径、产量、周转以及根与枝的分配模式等方面。植物根系结构和功能的改变影响植物地上部分和生态系统物质循环中的碳动态及土壤中碳库的变化。目前有关大气CO2浓度升高对根系动态影响的研究报道主要包括大气CO2浓度升高对根系结构(直径、分枝、长度、数量等)和根系生理(周转率、产量、碳分配模式等)的影响2个方面。目前,该领域研究还存在一些不足,例如在CO2浓度升高条件下,对植物根系内部的调控机制,以及由其引起的物质循环和能量流动的动态变化的了解较少;至今没有令人信服的证据说明大气CO2浓度升高使根系周转升高还是降低。今后应加强研究在CO2浓度升高条件下根系的周转变化和光合产物分配模式变化,CO2浓度升高和外界环境因素的共同作用对根系的影响,以及采用不同研究方法和研究对象在不同立地条件下开展升高CO2浓度对根系影响的对比研究等。     

CO2浓度升高对植物-土壤系统地下部分碳流通的影响

目前 ,由于化石燃料的燃烧和土地利用的改变 ,每年释放到大气中的碳大约有 7Ｇｔ[2 4 ] ,其中 ,有 3Ｇｔ留在大气中 ,2Ｇｔ被固定在深海中 ,另 2Ｇｔ被植物固定在生态系统中[19,4 8] ,事实上 ,陆地生态系统中的碳大部分都贮存在土壤中[4 4 ] ,所以植物与土壤之间的碳流通对全球碳循环极为重要。大气ＣＯ2 浓度升高有可能通过生态系统中的各种生理过程来改变植物 -土壤系统中碳通量的变化 ,使输入土壤的碳量增加 ,另一方面 ,地下部分碳通量的增加使土体成为一个潜在的碳汇 ,有可能缓解大气中ＣＯ2 浓度的升高。但有关高ＣＯ2 对地下部分植物…     

植物对沼泽湿地生态系统CO2和CH4排放的影响

利用静态暗箱/气相色谱法于2003~2005年在生长季对三江平原小叶章(Calamagrostis angustifolia)沼泽化草甸和毛果苔草(Carexlasiocarpa)沼泽地区CO2和CH4的排放通量进行野外对比观测实验。结果表明:2003~2005年生长季小叶章草甸土壤-植物系统CO2排放通量分别是土壤CO2排放通量的1.65、2.06和2.01倍,毛果苔草沼泽土壤-植物系统CO2排放通量分别是土壤CO2排放通量的2.58、2.27和4.21倍,表明沼泽湿地土壤-植物系统CO2排放通量的主要贡献者是植物地上部分的呼吸作用,且3个生长季小叶章草甸CO2排放通量均显著大于毛果苔草沼泽,主要是由于植物生物量的差异以及土壤微生物活性的不同。2003~2005年植物生长季,小叶章草甸土壤-植物系统CH4排放通量分别是土壤的4.84、3.55和6.45倍,毛果苔草沼泽土壤-植物系统CH4排放通量分别是土壤的2.60、1.25和3.22倍,且3个生长季小叶章草甸和毛果苔草沼泽CH4排放通量均具有显著差异,这主要是由于水位的差异以及植物对CH4排放能力的不同造成的。     

Fluxes of CH4 and N2O in aspen stands grown under ambient and twice-ambient CO2

The objectives of this study were: (1) to quantify the effects of plant species' loss from designed calcareous grassland communities at a field site in northwestern Switzerland on the size and composition of earthworm communities, and (2) to evaluate how exposure of plant communities to elevated atmospheric CO2 might alter the effects of plant species' loss on earthworm communities. We non-destructively censused earthworm communities in each of 24 1.2 m2 experimental plots in autumn 1996 when soils were wet and earthworms were active. Each plot contained an experimental plant community with 31, 12 or 5 native plant species (eight plots each). Half of the plots in each species treatment were exposed to ambient CO2 concentrations (350 μL CO2 L-1) and half to elevated CO2 (600 μL CO2 L-1) using screen-aided CO2 control. The study was conducted in the fourth year after community establishment and the third year of CO2 treatment as part of a long-term study on the interactive effects of plant species' loss and elevated CO2 on grassland communities. The size (density and biomass) of earthworm communities declined linearly when the number of plant species in the community was reduced from 31 to 5 species (e.g. 32 ± 1 g m-2 to 23 ± 2 g m-2) due mainly to a decline in the endogeic worm species Allolobophora rosea which was the most abundant of nine earthworm species observed (nearly half of all worms in each plot). However, no changes in the relative contribution of individual species or the three main earthworm ecological groups (anecics, endogeics, epigeics) to the entire earthworm community were observed with declining number of plant species. The responses of earthworm communities to plant species'; loss appear to reflect changes in community fine root biomass in the topsoil (e.g. declining worm biomass with declining fine root biomass) observed in parallel studies conducted at this site. Further the results of this study demonstrate that a loss of plant species from these calcareous grassland communities may also alter the age structure of earthworm communities, but not significantly influence their diversity or composition. Our data also indicate that rising atmospheric CO2 may not greatly impact the size and composition of worm communities or alter the effects of plant species' loss on earthworm communities. Therefore, the disappearance of plant species from these native grasslands, as a result of ever increasing human activities, may be expected to lead to reductions in the size of earthworm communities and the ecosystem services they provide. This revised version was published online in July 2006 with corrections to the Cover Date.     

影响煤生物气化的物化特征及煤预处理的研究进展

在“双碳”目标引领下,传统化石能源将逐渐被取代。我国煤炭资源储量多、分布广,将不可开采的煤炭资源生物气化可作为天然气资源的重要补充。因此,研究生物成因煤层气的增产机理具有重要的理论和现实意义。煤生物气化的发展前景广阔,但难点在其缓慢的动力学特征。为揭示生物煤层气的生成潜力和内部因素,本文就煤的物理化学特征对生物气化的影响、煤的物化性质对生物作用的响应以及预处理煤提高其生物有效利用性进行系统论述。生物作用降解煤的内部因素和环境条件已通过室内研究查明,发现低阶煤比高阶煤更具生物气增产潜力。产甲烷微生物群落对煤的生物转化过程势必引起煤的各项物理化学性质的变化。为产甲烷菌持续提供可用底物是煤生物气化的主要限制因素,研究多以化学预处理手段提高煤生物气化的效率和产量,而超临界CO2萃取以物理方式溶解大分子网格中小分子有机物用于生物气化。生物成因煤层气的增产潜力巨大,但室内实验条件与储层环境差异明显,原位增产有待深入研究,煤层有机物生物转化的微生物学研究亦有待完善。不同煤阶、不同储层环境对生物气化影响的主控因素研究是实现煤的生物气化商业化开发的关键。     

盐碱胁迫对巨菌草根际土壤微生物多样性及酶活性的影响

为探明盐碱胁迫对巨菌草根际土壤微生物多样性及酶活性的影响,该文设置了7个盐碱梯度,利用SPSS和Illumina高通量测序分析巨菌草根际土壤生理指标和微生物多样性.结果表明:(1)各处理间,巨菌草根际土壤真菌和细菌结构均存在差异;12‰盐碱浓度下,真菌优势菌纲为粪壳菌纲(68.5％)、散囊菌纲(16.3％),细菌优势菌...     

The respiratory source of CO2

Abstract Approximately half of the carbon plants fix in photosynthesis is lost in dark respiration. The major pathways for dark respiration and their control are briefly discussed in the context of a growing plant. It is suggested that whole-plant respiration may be largely ADP-limited and that fine control of the respiratory network serves to select the respiratory substrate and to partition carbon between the numerous possible fates within the network. The striking stoichiometry between whole-plant growth and respiration is reviewed, and the relationships between substrate-limited growth and ADP-limited respiration are discussed.     

Response of microbial communities of Lake Baikal to extreme temperatures

The survival rate, metabolic activity, and ability for growth of microbial communities of Lake Baikal have been first studied after exposure to extremely low temperatures (freeze-thawing) for different lengths of time. It has been shown that short-term freezing (1–3 days) inhibits the growth and activity of microbial communities. The quantity of microorganisms increased after 7-and 15-day freezing. In the periods of maximums, the total number of microorganisms in the test samples was twice as high as in the control. It was established that after more prolonged freezing the microorganisms required more time after thawing to adapt to new conditions. In the variants with 7-and 15-day freezing, the activities of defrosted microbial communities were three or more times higher than in the control. The survival rate and activity of Baikal microorganisms after freeze-thawing confirms the fact that the Baikal microbial communities are highly resistant to this type of stress impact.     

玉米秸秆还田对黑土微生物群落功能多样性的影响

为了解玉米秸秆还田对土壤微生物群落功能多样性的影响,采用ECO-Biolog微平板法,分析了以无玉米秸秆还田为对照(CK),6000 kg·hm^-2(S1)、9000 kg·hm^-2(S2)、12000 kg·hm^-2(S3)和15000 kg·hm^-2(S4)四个秸秆还田量的土壤微生物碳源代谢特征。结果表明:随着玉米秸秆还田量的增加,土壤微生物平均颜色变化率(AWCD)也随之增加,24~96 h的AWCD值变化迅速,96 h后进入平稳期,S4处理AWCD值始终大于其他处理;秸秆还田对Shannon指数与Simpson指数没有显著影响(P>0.05),但与CK相比,S4处理McIntosh指数显著增加了57.5%(P<0.05);主成分分析结果显示,秸秆还田影响着土壤微生物群落碳代谢能力,S1、CK、S2和S3处理在PC1和PC2上出现显著的分异,糖类、多聚物类、羧酸类碳源是研究区域内土壤微生物利用的主要碳源。因此,在东北黑土区增加玉米秸秆还田量能够提高土壤微生物对碳源的利用能力,提升黑土肥力。     

玉米秸秆还田对黑土微生物群落功能多样性的影响

为了解玉米秸秆还田对土壤微生物群落功能多样性的影响,采用ECO-Biolog微平板法,分析了以无玉米秸秆还田为对照(CK),6000 kg·hm^-2(S1)、9000 kg·hm^-2(S2)、12000 kg·hm^-2(S3)和15000 kg·hm^-2(S4)四个秸秆还田量的土壤微生物碳源代谢特征。结果表明:随着玉米秸秆还田量的增加,土壤微生物平均颜色变化率(AWCD)也随之增加,24~96 h的AWCD值变化迅速,96 h后进入平稳期,S4处理AWCD值始终大于其他处理;秸秆还田对Shannon指数与Simpson指数没有显著影响(P>0.05),但与CK相比,S4处理McIntosh指数显著增加了57.5%(P<0.05);主成分分析结果显示,秸秆还田影响着土壤微生物群落碳代谢能力,S1、CK、S2和S3处理在PC1和PC2上出现显著的分异,糖类、多聚物类、羧酸类碳源是研究区域内土壤微生物利用的主要碳源。因此,在东北黑土区增加玉米秸秆还田量能够提高土壤微生物对碳源的利用能力,提升黑土肥力。     

The effect of carbon dioxide,aeration rate and sodium chloride on the secretion of proteins from growing bakers' yeast (Saccharomyces cerevisiae)

Since yeast may be an important microorganism for industrial use when its genes are modified by recombinant DNA techniques to overproduce certain proteins, (particularly those which are glycosylated), it is desirable to study how environmental variables affect its protein secretion ability. It is also of interest to understand how proteins such as proteases, lipases and amylases are excreted in solid matrices to develop a basis for learning more about solid fermentations. With these two applications in mind, the total protein excreted by both aerated and non-aerated Saccharomyces cerevisiae growing in a liquid batch culture (with varying levels of CO₂ and NaCl) was tracked. Using a modified Bradford method (Coomassie Blue dye-binding assay) for the concentration of total proteins in the extracellular fermentation broth, it has been determined that by 24 h of the run, excreted proteins rose to levels of about 10% of the total cell protein (500 μg ml^?1 protein from about 10 g of yeast, containing about 5 g total protein). No cell lysis was observed during the 24 h run. The highest protein levels at the top of the fermentor seemed to be those achieved in response to CO₂ alone. Additions of NaCl did not seem to enhance the secreted protein level. Large inconsistencies in replicating anaerobic runs for protein concentration appeared to be explained by noting that rising CO₂ bubbles may cause ‘foam fractionation’ of the proteins in the broth.