黄淮海平原河北省范围内农田土壤二氧化碳和氧化亚氮排放量的估算

以黄淮海平原河北省范围内的农田土壤为研究对象,通过与田间实际观测数据进行比较发现,DNDC模型能够较好地反映农田土壤温室气体CO2和N2O的排放通量,可以用来模拟估算农田土壤CO2和N2O的排放通量.根据模型估算,2003年河北省111个县市农业土壤CO2排放量约3.758×106tC,各县市总的N2O排放量40.345×106kgN.全省释放的CO2和N2O中有40%左右来自冬小麦/夏玉米地.因此,减少该地区农业土壤CO2和N2O排放量的措施,应集中用于排放量高的县市和这些地区的冬小麦/夏玉米地,进行大范围的普遍减排可能收效甚微,并且没有必要.     

低浓度CO2对水车前和黑藻光合特性的影响

本实验通过对沉水植物水车前（offelia alismoides）和黑藻（Hydrilla verticillata）进行低浓度C02诱导,研究其光合特性的变化。研究显示,诱导后,水车前的PEPC／Rubisco活性比值由0．45上升到4．17,黑藻由0．47上升到4．17,两种植物的C4途径光合酶PEPC和NAD—ME的活性升高了10倍左右,其他C4光合酶如NAD—MDH和PPDK的活性也大幅升高;诱导后,水车前和黑藻的其他光合特性也发生了显著变化：净光合速率比对照分别提高了50．8％和74．1％,O2对处理组光合速率的抑制分别为对照组的35％和60％,叶绿素荧光基本参数也有显著性变化。研究结果表明,经低浓度C02诱导,水车前和黑藻光合碳同化途径可能由C3转变成为C4。     

Isoprene emission rates under elevated CO2 and O3 in two field-grown aspen clones differing in their sensitivity to O3

Isoprene is the most important nonmethane hydrocarbon emitted by plants. The role of isoprene in the plant is not entirely understood but there is evidence that it might have a protective role against different oxidative stresses originating from heat shock and/or exposure to ozone (O(3)). Thus, plants under stress conditions might benefit by constitutively high or by higher stress-induced isoprene emission rates. In this study, measurements are presented of isoprene emission from aspen (Populus tremuloides) trees grown in the field for several years under elevated CO(2) and O(3). Two aspen clones were investigated: the O(3)-tolerant 271 and the O(3)-sensitive 42E. Isoprene emission decreased significantly both under elevated CO(2) and under elevated O(3) in the O(3)-sensitive clone, but only slightly in the O(3)-tolerant clone. This study demonstrates that long-term-adapted plants are not able to respond to O(3) stress by increasing their isoprene emission rates. However, O(3)-tolerant clones have the capacity to maintain higher amounts of isoprene emission. It is suggested that tolerance to O(3) is explained by a combination of different factors; while the reduction of O(3) uptake is likely to be the most important, the capacity to maintain higher amounts of isoprene is an important factor in strengthening this character.     

加气灌溉对不同施氮水平的设施甜瓜土壤CO2和N2O排放的影响

为探讨不同加气灌溉施氮模式下设施甜瓜土壤CO₂和N₂O排放的动态变化规律及其与土壤温度、湿度的关系,本研究采用密闭静态箱-气相色谱法对加气灌溉不同施氮水平下土壤CO₂和N₂O排放进行监测,并分析了加气灌溉对不同施氮量下土壤CO₂和N₂O排放的影响.试验采用加气灌溉(AI)和不加气灌溉(CK)两种灌溉方式,施氮量设不施氮(N₁)、传统施氮量的2/3(150 kg·hm^-2,N₂)和传统施氮量(225 kg·hm^-2,N₃)3个施氮水平.结果表明:加气灌溉土壤CO₂和N₂O排放量高于不加气灌溉处理,但是差异不显著;相同灌溉模式下,CO₂和N₂O排放量随施氮量的增加而显著增加,施氮量是土壤CO₂和N₂O排放的主要影响因素.加气灌溉条件下,不同施氮处理N₂O排放通量与土壤温度和湿度呈显著正相关,CO₂排放通量与土壤温度呈显著正相关.加气减氮处理在氮肥减少1/3的情况下,甜瓜产量提高了6.9%,温室气体排放引起的增温潜势值从9544.82 kg·hm^-2下降到9340.72 kg·hm^-2.综上,通过加气灌溉减少氮肥施用量来抑制农业生产系统中温室气体排放是可行的.     

LCI1, a Chlamydomonas reinhardtii plasma membrane protein,functions in active CO2 uptake under low CO2

In response to high CO₂ environmental variability, green algae, such as Chlamydomonas reinhardtii, have evolved multiple physiological states dictated by external CO₂ concentration. Genetic and physiological studies demonstrated that at least three CO₂ physiological states, a high CO₂ (0.5–5% CO₂), a low CO₂ (0.03–0.4% CO₂) and a very low CO₂ (< 0.02% CO₂) state, exist in Chlamydomonas. To acclimate in the low and very low CO₂ states, Chlamydomonas induces a sophisticated strategy known as a CO₂‐concentrating mechanism (CCM) that enables proliferation and survival in these unfavorable CO₂ environments. Active uptake of C_i from the environment is a fundamental aspect in the Chlamydomonas CCM, and consists of CO₂ and HCO₃^– uptake systems that play distinct roles in low and very low CO₂ acclimation states. LCI1, a putative plasma membrane C_i transporter, has been linked through conditional overexpression to active C_i uptake. However, both the role of LCI1 in various CO₂ acclimation states and the species of C_i, HCO₃^– or CO₂, that LCI1 transports remain obscure. Here we report the impact of an LCI1 loss‐of‐function mutant on growth and photosynthesis in different genetic backgrounds at multiple pH values. These studies show that LCI1 appears to be associated with active CO₂ uptake in low CO₂, especially above air‐level CO₂, and that any LCI1 role in very low CO₂ is minimal.     

采后梨果实皮层和髓中EFE活性、ACC和多胺含量变化及其与乙烯生成的关系

菊水梨皮层和髓的乙烯合成酶（ＥＦＥ）活性和氨基环丙烷羧酸（ＡＣＣ）含量及其果实乙烯释放量均分别高于二十世纪梨。在同一品种果实的皮层和髓中,ＡＣＣ含量无明显差异,但髓的ＥＦＥ活性明显高于皮层。梨果实内含有丁二胺、亚精胶和精胺３种内源多胺,而以丁二胺和亚精胺含量为最高,精胺含量虽低但较稳定。果实在乙烯释放高峰出现前,其皮层和髓中的丁二胺和亚精胺含量变化有明显差异。采后梨果实的乙烯生成与果实内ＥＦＥ活性,ＡＣＣ含量、多胺含量的变化有密切关系,而乙烯生成的差异不仅表现在品种间,而且在果实的皮层和髓之间也存在差异,梨果实的髓似乎对整个果实的乙烯生成有更重要的影响。     

Intermediates Adsorption Engineering of CO2 Electroreduction Reaction in Highly Selective Heterostructure Cu‐Based Electrocatalysts for CO Production

The challenge in the artificial CO₂ reduction to fuel is achieving high selective electrocatalysts. Here, a highly selective Cu₂O/CuO heterostructure electrocatalyst is developed for CO₂ electroreduction. The Cu₂O/CuO nanowires modified by Ni nanoparticles exhibit superior catalytic performance with high faradic efficiency (95% for CO). Theoretical and experimental analyses show that the hybridization of Cu₂O/CuO nanowires and Ni nanoparticles can not only adjust the d‐band center of electrocatalysts to enhance the intrinsic catalytic activity but also improve the adsorption of COOH* intermediates and suppress the hydrogen evolution reaction to promote the CO conversion efficiency during CO₂ reduction reaction. An in situ Raman spectroscopic study further confirms the existence of COOH* species and the engineering intermediates adsorption. This work offers new insights for facile designing of nonprecious transition metal compound heterostructure for CO₂ reduction reaction through adjusting the reaction pathway.     

Explaining the doubling of N2O emissions under elevated CO2 in the Giessen FACE via in‐field 15N tracing

Rising atmospheric CO₂ concentrations are expected to increase nitrous oxide (N₂O) emissions from soils via changes in microbial nitrogen (N) transformations. Several studies have shown that N₂O emission increases under elevated atmospheric CO₂ (eCO₂), but the underlying processes are not yet fully understood. Here, we present results showing changes in soil N transformation dynamics from the Giessen Free Air CO₂ Enrichment (GiFACE): a permanent grassland that has been exposed to eCO₂, +20% relative to ambient concentrations (aCO₂), for 15 years. We applied in the field an ammonium‐nitrate fertilizer solution, in which either ammonium () or nitrate () was labelled with ¹⁵N. The simultaneous gross N transformation rates were analysed with a ¹⁵N tracing model and a solver method. The results confirmed that after 15 years of eCO₂ the N₂O emissions under eCO₂ were still more than twofold higher than under aCO₂. The tracing model results indicated that plant uptake of did not differ between treatments, but uptake of was significantly reduced under eCO₂. However, the and availability increased slightly under eCO₂. The N₂O isotopic signature indicated that under eCO₂ the sources of the additional emissions, 8,407 μg N₂O–N/m² during the first 58 days after labelling, were associated with reduction (+2.0%), oxidation (+11.1%) and organic N oxidation (+86.9%). We presume that increased plant growth and root exudation under eCO₂ provided an additional source of bioavailable supply of energy that triggered as a priming effect the stimulation of microbial soil organic matter (SOM) mineralization and fostered the activity of the bacterial nitrite reductase. The resulting increase in incomplete denitrification and therefore an increased N₂O:N₂ emission ratio, explains the doubling of N₂O emissions. If this occurs over a wide area of grasslands in the future, this positive feedback reaction may significantly accelerate climate change.     

开放式空气CO2增高对稻田CH4和N2O排放的影响

在FACE(free aircarbondioxideenrichment)平台上 ,采用静态暗箱 气相色谱法观测研究了大气CO2 浓度增加对稻田CH4和N2 O排放的影响 .结果表明 ,在 15 0和 2 5 0kgN·hm-2 两种氮肥水平下大气CO2 浓度增加 2 0 0 μmol·mol-1均明显促进水稻生长 ,水稻生物量积累 .大气CO2 浓度增加对 15 0和 2 5 0kgN·hm-2 两种氮肥水平下稻田CH4排放均无显著影响 ,并简要分析了与现有文献报道结果不一致的原因 .大气CO2 浓度增加也未导致 15 0和 2 5 0kgN·hm-2 两种氮肥水平下稻田N2 O排放的明显变化 ,与大多数研究结果一致 .     

N2O排放规律及其影响因子

采用野外静态箱-气相色谱法,研究了小兴安岭典型阔叶林沼泽生长季节土壤CO2、CH4和N2O排放季节变化规律、源/汇功能及主要影响因子。结果表明：①苔草沼泽、毛赤杨沼泽和白桦沼泽生长季节土壤CO2、CH4、N2O排放分别集中在夏季、夏秋季、春夏季,平均排放通量依次为514.63、487.89、382.27 mgm-2h-1,1.88、1.03、0.04 mgm-2h-1,58.61、11.73、3.70µgm-2h-1。②三者生长季节土壤CO2排放通量与气温和0~20 cm土壤温度均呈显著正相关;苔草沼泽CH4排放通量与30~40 cm土壤温度呈显著正相关,毛赤杨沼泽CH4排放通量与地表温度呈显著负相关;白桦沼泽N2O排放通量与地表温度呈显著正相关。苔草沼泽N2O排放与水位呈显著负相关;毛赤杨沼泽CH4排放与水位呈显著正相关;白桦沼泽CO2排放与水位呈显著负相关。③三者生长季节土壤均为CO2、CH4、N2O排放源（17.56、13.76、18.53 thm-2;67.54、37.05、1.30 kghm-2;0.13、2.11、0.42 kg.hm-2）,三者CO2排放量相近（5.5%~21.6%）;苔草沼泽为CH4的强排放源,毛赤杨沼泽为中排放源,白桦沼泽为弱排放源;毛赤杨沼泽为N2O的强排放源,白桦沼泽为中排放源,苔草沼泽为弱排放源。     

Chlorophyll a fluorescence and CO2 exchange of Umbilicaria aprina under extreme light stress in the cold

A lichen growing in a continental Antarctic region with low temperatures and strong irradiance in summer was investigated for evidence of photoinhibition. Field experiments with Umbilicaria aprina from a sheltered site with heavy snowpack showed no effects of photoinhibition when the lichen was exposed to strong sun irradiance for nearly 11 h a day. This was evident from CO₂ exchange and simultaneous chlorophyll a fluorescence measurements. CO₂ exchange was also not affected if quartz glass allowing greater UV penetration, was used as a lid for the cuvette. The dependency of net photosynthesis on photosynthetic photon flux density suggests that the lichen is photophilous. Received: 2 April 1997 / Accepted: 11 August 1997     

Atmospheric CO2 and O3 alter competition for soil nitrogen in developing forests

Plant growth responses to rising atmospheric CO₂ and O₃ vary among genotypes and between species, which could plausibly influence the strength of competitive interactions for soil N. Ascribable to the size‐symmetric nature of belowground competition, we reasoned that differential growth responses to CO₂ and O₃ should shift as juvenile individuals mature, thereby altering competitive hierarchies and forest composition. In a 12‐year‐long forest FACE experiment, we used tracer ¹⁵N and whole‐plant N content to assess belowground competitive interactions among five Populus tremuloides genotypes, between a single P. tremuloides genotype and Betula papryrifera, as well as between the same single P. tremuloides genotype and Acer saccharum. Under elevated CO₂, the amount of soil N and ¹⁵N obtained by the P. tremuloides genotype common to each community was contingent on the nature of belowground competition. When this genotype competed with its congeners, it obtained equivalent amounts of soil N and tracer ¹⁵N under ambient and elevated CO₂; however, its acquisition of soil N under elevated CO₂ increased by a significant margin when grown in competition with B. papyrifera (+30%) and A. saccharum (+60%). In contrast, elevated O₃ had no effect on soil N and ¹⁵N acquisition by the P. tremuloides genotype common in each community, regardless of competitive interactions. Under elevated CO₂, the rank order of N acquisition among P. tremuloides genotypes shifted over time, indicating that growth responses to CO₂ change during ontogeny; this was not the case under elevated O₃. In the aspen‐birch community, the competitive advantage elevated CO₂ initially conveyed on birch diminished over time, whereas maple was a poor competitor for soil N in all regards. The extent to which elevated CO₂ and O₃ will shape the genetic structure and composition of future forests is, in part, contingent on the time‐dependent effects of belowground competition on plant growth response.     

Changes in Stomatal Conductance,Transpiration and Water Use Efficiency of Ten Species Experienced in High CO2 Concentrations in Biosphere 2

The stomotal conductance, transpiration and water use efficiency (WUE) were measured using a LI-6400 portable photosynthesis system for 5 tropical rain forest species and 5 desert species in Biosphere 2, USA. All the species have experienced in very high CO2 ( > 2 200 μmol• mol- 1 ) for more than 4.5 years. The results showed that the stomatal conductance and transpiration of rain forest species decreased from ( 127.4 ± 65.6) and (2.04 ± 0.61 ) mmol• m- 2•s- 1 to (61.3 + 30.5) and ( 1.54 ± 0.65 ) mmol• m-2• s -1 respectively, while WUE increased from (2.90 ± 0.55) to (8.45 ± 2.71) μmol CO2 •mmo1-1 H2O, with CO2 increasing from 350 – 400 to 700 – 820 μmol• mol-l. For the desert species, stomatal conductance and transpiration decreased from respectively (142.8±94.6) and (2.09±0.71) mmol•m-2•s-1 to (57.7±35.8) and (1.36±0.52) mmolm-2•s-l, but WUE increased from (4.69 ± 1.39) to (9.68 ± 1.61) μmol CO2•mmo1-1 H2O, with the CO2 increase from 320 - 400 to 820 – 850 μtmol• mol- 1. The stomatal conductance, transpiration and WUE were less influenced by light intensity under high CO2 than low CO2 concentrations. Most rain forest species reached their light saturation points at light intensity of 500 μmol• m-2•s-1, while desert species at 1 000 μmol•m-2•s-1. Among different species, the desert C3 tree, Nicotiana glauca Grah., had the highest decrease in stomatal conductance and transpiration and the highest increase in WUE, by 78%, 69% and 310% respectively. The enhancement of increasing CO2 to the stomatal, transpiration and WUE of species with different photosynthesis pathway and life forms in Biosphere 2 could be concluded as: C3 species > C4 species, and desert C3 species > rain forest C3 species.     

利用甲硝唑及外加氧方法筛选耐氧产氢Klebsiella oxytoca HP1突变菌株

氢酶是生物制氢的关键酶, 大多数氢酶因对氧极敏感而易失活, 因此提高氢酶的氧耐受性对生物制氢有重要意义。本研究利用1%甲基磺酸乙酯对Klebsiella oxytoca HP1进行了两轮诱变, 经40 mmol/L 甲硝唑和21%氧联合处理1 h(第一轮诱变)或2 h(第二轮诱变)进行筛选。所得突变菌株经产氢测试, 结果在15%氧浓度条件下, 第一代突变菌株HP1-A15产氢活性为出发菌株Klebsiella oxytoca HP1的3.70倍, 在21%氧浓度条件下第二代突变菌株 HPA15-37产氢活性为HP1-A15菌株的2.75倍, 是出发菌株的11倍。突变菌株HP1-A15和 HPA15-37具有较好的遗传稳定性。本试验结果说明利用MNZ和外加氧的方法适用于兼性厌氧菌耐氧产氢突变菌株的筛选。     

利用甲硝唑及外加氧方法筛选耐氧产氢Klebsiella oxytoca HP1突变菌株

摘氢酶是生物制氢的关键酶,大多数氢酶因对氧极敏感而易失活,因此提高氢酶的氧耐受性对生物制氢有重要意义。本研究利用1％甲基磺酸乙酯对Klebsiella oxytoca HPl进行了两轮诱变,经40mmol／L甲硝唑和21％氧联合处理1h（第一轮诱变）或2h（第二轮诱变）进行筛选。所得突变菌株经产氢测试,结果在15％氧浓度条件下,第一代突变菌株HPl-A15产氢活性为出发菌株Klebsiella oxytoca HPl的3.70倍,在21％氧浓度条件下第二代突变菌株HPAl5-37产氢活性为HPl-A15菌株的2.75倍,是出发菌株的11倍。突变菌株HPl-A15和HPAl5-37具有较好的遗传稳定性。本试验结果说明利用MNZ和外加氧的方法适用于兼性厌氧菌耐氧产氢突变菌株的筛选。     

裂殖酵母Pap1应答H2O2氧化胁迫的机制

转录因子Pap1是裂殖酵母(Schizosaccharomyces pombe)应答H2O2氧化胁迫反应中的关键调控因子.高浓度的H2O2激活蛋白激酶Sty1途径清除过量的H2O2,使H2O2降至较低浓度再活化Pap1;低浓度的则直接氧化活化Pap1,导致Pap1快速向细胞核内运输从而激活Pap1相关基因的表达.本文综述了裂殖酵母中转录因子Pap1在不同浓度H2O2胁迫下的激活途径,以及蛋白激酶Sty1对Pap1激活的重要作用     

Effects of dissolved CO2 levels on the growth of Mannheimia succiniciproducens and succinic acid production

A capnophilic rumen bacterium Mannheimia succiniciproducens produces succinic acid as a major fermentation end product under CO(2)-rich anaerobic condition. Since succinic acid is produced by carboxylation of C3 compounds during the fermentation, intracellular CO(2) availability is important for efficient succinic acid formation. Here, we investigated the metabolic responses of M. succiniciproducens to the different dissolved CO(2) concentrations (0-260 mM). Cell growth was severely suppressed when the dissolved CO(2) concentration was below 8.74 mM. On the other hand, cell growth and succinic acid production increased proportionally as the dissolved CO(2) concentration increased from 8.74 to 141 mM. The yields of biomass and succinic acid on glucose obtained at the dissolved CO(2) concentration of 141 mM were 1.49 and 1.52 times higher, respectively, than those obtained at the dissolved CO(2) concentration of 8.74 mM. It was also found that the additional CO(2) source provided in the form of NaHCO(3), MgCO(3), or CaCO(3) had positive effects on cell growth and succinic acid production. However, growth inhibition was observed when excessive bicarbonate salts were added. By the comparison of the activities of key enzymes, it was found that PEP carboxylation by PEP carboxykinase (PckA) is the most important for succinic acid production as well as the growth of M. succiniciproducens by providing additional ATP.