Responses of rice growth to copper stress under free-air CO2 enrichment （FACE）

The responses of rice to the second degree contamination of copper were studied by pot experiments under free-air CO2 enrichment （FACE） with 570 μmol ·mol^-1 of CO2. The results showed that the content of copper in rice leaves was reduced with the CO2 concentration reaching 570 μmol· mol^-1 and this happened more significantly under the second degree contamination of copper. Under FACE, activities of superoxide dismutase （SOD） enzyme in rice leaves treated by copper contamination were induced, whereas the contents of glutathione （GSH） and glutathione disulfide （GSSG） had no significant difference from the control. In the presence of ambient CO2, activities of SOD enzyme treated by copper pollution were suppressed during the whole rice growth, however, the contents of GSH and GSSG were induced at tillering and jointing stages, and then restored to the control levels in later growth under the second degree contamination of copper. With the rice growing, the content of malondialdehyde （MDA） rises continuously, but there had been no significant difference between the treatments at the same growth stage. Further studies are needed on the response mechanism of rice to Cu stress under elevated CO2.     

Diurnal and monthly variations of carbon dioxide flux in an alpine shrub on the Qinghai-Tibet Plateau

Long-term flux observation is an efficient approachto collect CO2 emission or assimilation data in an ecosys-tem. In cooperation with a series of international coopera-tion programs including those sponsored by IGBP (Inter-national Geosphere-Biosphere Program), WCRP (WorldClimate Research Program), IHDP (International HumanDimension of Global Environment Change), GCTE(Global Change and Terrestrial Ecosystem) and LUCC(Land Use and Land Cover Change), a lot of researchwork conce…     

Coral reef ecosystems in the South China Sea as a source of atmospheric CO<Subscript>2</Subscript> in summer

Field measurements of air-sea CO2 exchange in three coral reef areas of the South China Sea (i.e. the Yongshu Reef atoll of the Nansha Islands, southern South China Sea (SCS); Yongxing Island of Xisha Islands, north-central SCS; and Luhuitou Fringing Reef in Sanya of Hainan Island, northern SCS) during the summers of 2008 and 2009 revealed that both air and surface seawater partial pressures of CO2 (pCO2) showed regular diurnal cycles. Minimum values occurred in the evening and maximum values in the morning. Air pCO2 in each of the three study areas showed small diurnal variations, while large diurnal variations were ob-served in seawater pCO2. The diurnal variation amplitude of seawater pCO2 was ~70 μmol mol–1 at the Yongshu Reef lagoon, 420–619 μmol mol–1 on the Yongxing Island reef flat, and 264–579 μmol mol–1 on the reef flat of the Luhuitou Fringing Reef, and 324–492 μmol mol–1 in an adjacent area just outside of this fringing reef. With respect to spatial relations, there were large differences in air-sea CO2 flux across the South China Sea (e.g. ~0.4 mmol CO2 m–2 d–1 at Yongshu Reef, ~4.7 mmol CO2 m–2 d–1 at Yongxing Island, and ~9.8 mmol CO2 m–2 d–1 at Luhuitou Fringing Reef). However, these positive values suggest that coral reef ecosystems of the SCS may be a net source of CO2 to the atmosphere. Additional analyses indicated that diurnal variations of surface seawater pCO2 in the shallow water reef flat are controlled mainly by biological metabolic processes, while those of deeper water lagoons and outer reef areas are regulated by both biological metabolism and hydrodynamic factors. Unlike the open ocean, inorganic metabolism plays a significant role in influencing seawater pCO2 variations in coral reef ecosystems.     

The contribution of root respiration to soil CO2 efflux in Puccinellia tenuiflora dominated community in a semi-arid meadow steppe

Rising atmospheric CO2 and temperature are altering ecosystem carbon cycling. Grasslands play an important role in regional climate change and global carbon cycle. Below-ground processes play a key role in the grassland carbon cycle because they regulate …     

Changes of photosynthetic capacity of some plant species under very high CO2 concentrations in Biosphere 2

Conclusions The initial slope of A/ light curve became steep under high CO₂ (700 μmol · mol^-1) compared with that under low CO₂ (350 μmol · mol^-1) for the C₃ species growing in very high CO₂(>2 200 μmol · mol^-1) for a long period. The light compensation points remained unchanged, but the light saturation points were found increased. The ϕ_m,_app and A_max of the C₃ species increased respectively by 79 % and 80 %, while those of C₄ species decreased by 10% and 14%, respectively. The shape of A/light curve of C₄ species did not change. Such results indicated that C₃ species increased the capacity of photosynthesis, while C₄ did not change, otherwise it decreased a little. This work only compared the changes of capacity in photosynthesis of some species under different CO₂ levels in Biosphere 2. We need further investigation on the effects of high CO₂ on the same species outside Biosphere 2, in order to fully undertand the effects and mechanism of response of plants to the elevated CO₂.     

Investigation of the cross-reaction mechanism of C<Subscript>6</Subscript>H<Subscript>5</Subscript>F-HNO<Subscript>2</Subscript> aqueous solution irradiated at 355 nm by transient absorbance spectrum technique

The transient absorption spectrum technique was employed to investigate the cross-reaction mechanism of C6H5F-HNO2 aqueous solution irradiated at 355 nm. The characteristic and the kinetic parameters of transient species were also detected. Hydroxyl radical derived from the photolysis of HNO2 was added to monofluorobenzene with a second-order rate constant of （5.83±0.17）×10^9 L·mol^-1·s^-1 to form an adduct, C6H5F…OH, which was able to react with HNO2 as the main reaction pathway with a rate constant of （8.3±0.1）×10^7 L·mol^-1·s^-1. The C6F6…OH adduct can also be decayed by elimination of H2O to yield monofluorophenyl radical C6H4F-. By GC-MS technique, the final products were identified to be monofluorophenol, nitro-monofluorobenzene, nitro-monofluorophenol and para-fluorobiphenyl.     

Kinetic studies of the decomposition reaction of adducts of dinuclear Fe(Ⅱ)/O2

Kinetic studies of the decomposition reaction of dinuclear Fe(Ⅱ) adducts [Fe₂(N-Et-HPTB){O₂P(OPh)₂}](Cl- O₄)₂ (1) and [Fe₂(N-Et-HPTB) {O₂P(Ph)₂}] (ClO₄)₂ (2) with O₂ have been carried out at low temperature using UV-vis spectra. The decomposition reaction of Fe(Ⅱ)/O₂ adducts was first-order in the experimental conditions, and the activation parameters were obtained. ?H^¹ = 85.62 kJ·mol^-1, ?S¹ = 19.43 J·mol^-1·K^-1 for compound (1) and ?H^¹ = 97.97 kJ·mol^-1, ?S^¹ = 55.68 J·mol^-1·K^-1 for compound (2). These results are similar to those of dioxygen adducts of other metals complexes and natural enzymes such as methane mono- oxygenase (MMOH).     

Effect of CO<Subscript>2</Subscript> concentrations on the activity of photosynthetic CO<Subscript>2</Subscript> fixation and extracelluar carbonic anhydrase in the marine diatom <Emphasis Type="Italic">Skeletonema costatum</Emphasis>

The growth and activity of photosynthetic CO2 uptake and extracellular carbonic anhydrase (CAext) of the marine diatom Skeletonema costatum were investigated while cultured at different levels of CO2 in order to see its physio-logical response to different CO2 concentrations under either a low (30 靘ol·m-2·s-1) or high (210 靘ol·m-2·s-1) irradiance. The changes in CO2 concentrations (4—31 靘ol/L) affected the growth and net photosynthesis to a greater extent under the low than under the high light re-gime. CAext was detected in the cells grown at 4 mol/L CO2 but not at 31 and 12 靘ol/L CO2, with its activity being about 2.5-fold higher at the high than at the low irradiance. Photo- synthetic CO2 affinity (1/ K1/2(CO2)) of the cells de-creased with increased CO2 concentrations in culture. The cells cultured under the high-light show significantly higher photosynthetic CO2 affinity than those grown at the low-light level. It is concluded that the regulations of CAext activity and photosynthetic CO2 affinity are dependent not only on CO2 concentration but also on light availability, and that the de-velopment of higher CAext activity and CO2 affinity under higher light level could sufficiently support the photosyn-thetic demand for CO2 even at low level of CO2.     

Comparative study of the net exchange of CO<Subscript>2</Subscript> in 3 types of vegetation ecosystems on the Qinghai-Tibetan Plateau

Using the eddy covariance method, from 1 July 2003 to 30 June 2004, we conducted the observation and analysis of ecosystem CO2 flux in 3 types of alpine meadow vegetation （Kobresia humilis, Potentilla fruticosa shrub and Kobresia tibetica swamp meadows） on the Qinghai-Tibetan Plateau. The results show that the Kobresia humilis meadow, the shrub meadow and the swamp meadow＇s highest CO2 uptake rates are 16.78, 10.42 and 16.57 μmol·m^-2·-s^-1 respectively, while their highest CO2 release rates are 8.22, 7.73 and 18.67μmol·m^-2·-s^-1 respectively. The Kobresia humilis meadow and shrub meadow＇s annual atmospheric uptakes are 282 g CO2/m^2 and 53 g CO2/m^2, respectively, while swamp meadow＇s annual atmospheric release is 478 g CO2/m^2. This proves that the Kobresia humilis meadow and the shrub meadow on the Qinghai-Tibetan Plateau have relatively low potential for CO2 uptake and release compared to C4 grasslands, a number of lowland grasslands, and forests. Moreover, swamp meadow has relatively high release potential. This, in turn, reveals clear differences in carbon source/sink between different types of vegetation in the Qinghai-Tibetan Plateau alpine meadow ecosystem. These differences are mainly brought by differences in the vegetations＇ photosynthetic capacity and soil respiration.     

Flow-injection microcolumn on-line preconcentration for the determination of chromium (VI)

A rapid and sensitive on-line preconcentration method for spectrophotometric determination of chromium (VI) in nature water is described. Preconcentration and determination are based on (i) the quantitative and fast adsorption of chromium (VI) on the high surface area nanometer-size TiO₂ (anatase) powders, which prepared by a sol-gel method from hydrolysis of TiCl₄ and (ii) the quantitative and reproducible elution of Cr (VI) by 2.0 mol·L⁻¹ HCl. A mini-column system for preconcentration is developed, Cr(VI) on the mini-column is eluted and merged with a stream water and DPCB (1,5-diphenylcarbazide) as the chromogenic reagent. The proposed system permits throughputs of 6 sample h⁻¹ (0.001 μg·mL⁻¹ Cr(VI)) or 20 sample h⁻¹ (0.1 μg·mL⁻¹ Cr(VI)). The preconcentration factor is 55. The detection limit is 0.8 ng · mL⁻¹ Cr(VI). The reproducibility is satisfactory with a relative standard deviation of less than 3.35% (0.01 μg·mL⁻¹ Cr(VI),n=5). Supported by the National Natural Science Foundation of China Ma Wanhong: born in 1961, Ph. D. Graduate student, Associate professor     

An acetylcholinesterase inhibitor, 3-benzidino-5-methyl-6-phenylpyridazine, blocking outward potassium currents in acutely isolated rat hippocampal pyramidal neurons

3-benzidino-5-methyl-6-phenylpyridazine (BMP) inhibited electric eel acetylcholinesterase (AChE), with IC50 being 0.58 μmol·L-1. As an AChE inhibitor, the effects of BMP on delayed rectifier potassium current (IK(DR)) and transient outward potassium current (IK(A)) in acutely isolated rat hippocampal pyramidal neurons were studied using the whole cell patch-clamp technique. BMP (0.1―50 μmol·L-1) inhibited IK(DR) and IK(A) in a concentration-dependent and voltage-independent manner. The IC50 value for the bl...     

CO2 background concentration in the atmosphere over the Chinese mainland

Based on the long-term monitoring data on CO₂ concentration, variation trend and characteristics of CO₂ background concentration in the atmosphere over the Chinese mainland are analyzed. Results show that the increasing trend of CO₂ background concentration in the atmosphere over the Chinese mainland has appeared during the period of 1991–2000. The average annual CO₂ growth increment is 1.59 μL/L, and the average annual CO₂ growth rate is 0.44%. Distinct seasonal variations of CO₂ background concentration are observed, and the averaged amplitude of CO₂ seasonal variations is 10.35 μL/L. Regional variation characteristics of CO₂ background concentration in the atmosphere and possible impact of human activities on these variations over the Chinese mainland are discussed as well.     

Coordination behavior between zinc salts and L-α-methionine

The solubility properties of ZnCl\-2/ZnAc\-2/ZnSO\-4_Met_H\-2O systems at 25℃ in the whole cocentration range have been investigated by phase equilibrium method. The results indicate that ZnAc\-2 and ZnSO\-4 systems are both simple systems, which do not exist any compound; there are 2 complexes formed in ZnCl\-2 system: Zn(Met)Cl\-2 and Zn(Met)\-2Cl\-2·2H\-2O. Under the direction of phase equilibrium result, 2 solid complexes have been prepared in water and characterized by chemical analysis, IR, X_ray diffraction. Their combustion energies have also been determined by means of a RBC_type_1 rotating_bomb calorimeter, and their standard enthalpies of formation, Δ f, coor(s)H O-, have been calculated which are (-828.32±3.00) kJ·mol -1 and (-1 117.08±6.15) kJ·mol -1, respectively.     

Fluxes of CO2, N2O and CH4 from a typical temperate grassland in Inner Mongolia and its daily variation

Using a dark enclosed chamber technique, the fluxes of CO₂, N₂O and CH₄ from nature and disturbed grassland were measured on the spot in Inner Mongolian Temperate Grassland along the annual rainfall gradient section ranging from 450 to 200 mm. The results showed that the measured mean fluxes of CO₂, N₂O and CH₄ were (1 180.4 ± 308.7), (0.010 ± 0.004) and (−0.039 ± 0.016) mg · m⁻²/h, respectively. The decrease of the fluxes of CO₂, N₂O and CH₄ follows with that of annual rainfall gradient in the measurement area. Human activities, such as grazing and reclamation are also critical factors to affect the fluxes of these gases from grassland. Daily continuous measurement of CO₂, N₂O and CH₄ fluxes showed a strong diurnal variation with higher emission in the daytime. A good relationship between the fluxes of CO₂, N₂O, CH₄ and temperature was exposed in this study.     

转SOD基因烟草的光合特性初探

 以转基因Fe-SOD,Mn-SOD高表达、转基因Mn-SOD反义低表达烟草及非转基因品系为供试材料,比较CO₂光强对烟草光合作用和蒸腾作用的影响及不同叶位叶片的光合差异.在相同条件下,Mn-SOD高表达烟草CO₂补偿点最高(105μmol·mol^-1),Mn-SOD低表达烟草最低(78μmol·mol^-1),CO₂浓度对非转基因烟草蒸腾作用的影响比对其他三个转基因品系的影响要强.Mn-SOD低表达烟草的光补偿点最高(45μmol·m^-2·s^-1),而Mn-SOD高表达烟草最低(25μmol·m^-2·s^-1),并且强光对非转基因烟草的光合作用抑制大,转基因品系对强光具有较强的耐受力.同一叶位叶片,转基因烟草的光合速率、蒸腾速率更强.但转基因SOD高表达烟草在整体上并没有表现出明显的光合作用优势.     

Effects of lithium chloride on outward potassium currents in acutely isolated hippocampal CA1 pyramidal neurons

Lithium is best known for its therapeutic efficacy in the treatment of manic-depressive illness. Its clinical profile includes the antimanic and antidepressant ac- tions as well as prophylaxis of both mania and depres- sion. Despite its efficacy, the mole…     

Study on the reaction of carbon disulfide with hydroxyl radical in aqueous solution

Carbon disulfide is an important sulfur-containing compound in the environment, and its oxidation produces about 30% of the atmospheric COS[1]. In situ measure- ments show that CS2 is widespread in the sea surface wa- ters[2―4], and more recently, the continental water seems to be especially rich sources of CS2 due to industrial waste- water effluents. It is generally accepted that the ocean is an important source for atm. CS2, and Xie et al.[5] found that marine photochemical reaction of…     

Regional Δ<Superscript>14</Superscript>C patterns and fossil fuel derived CO<Subscript>2</Subscript> distribution in the Beijing area using annual plants

The level of atmosphericΔ14C and the fossil fuel derived CO 2 concentration in the Beijing area from May to September,2009, were systematically analyzed based on radiocarbon(14C)measurements of annual plants by accelerator mass spectrometry(AMS). The results show that the maximumΔ14C in Beijing was 29.6‰±2.2‰,and the minimum was–28.2‰±2.5‰,with a trend of decreasingΔ14C from the outer suburbs to inner suburbs to the urban center.This trend correlates well with increases in fossil fuel derived CO2 caused by human activities such as population density,industrial emissions and traffic,with lower values of atmosphericΔ14C associated with more intensive human activities.The fossil fuel derived CO 2 concentrations from May to September, 2009,ranged from 3.9±1.0 ppm to 25.4±1.0 ppm.It was calculated that each additional 1 ppm of CO2 from fossil fuels depleted the atmosphericΔ14C by approximately 2.70‰.This study suggests that 14C measurements of annual plants by AMS provide an effective method to rapidly trace fossil fuel derived CO2.     

A novel Pd/silicalite-1 composite membrane for hydrogen separation

A novel Pd/silicalite-1 composite membrane supported on the macroporous tubular stainless steel substrate was successfully fabricated by electroless plating at 303 K. The structure, morphology and gaseous permeability of the membrane were detected by X-ray diffractiometry （XRD）, scanning electron microscopy （SEM） and single-gas permeation test, respectively. Results confirm the formation of a thin, smooth, and continuous Pd/silicalite-1 composite membrane. The obtained composite membrane shows a high H2 permeance of 1.15×10^-6 mol. m^-2. s^-1. Pa^-1 with moderate H2 selectivity of 250 for H2/N2 at 773 K, at 0.1 MPa pressure drop, suggesting the potential application for H2 separation.     

Application of Nanometer-Size Titanium Dioxide in Extreme-Trace V（Ⅴ） Analysis

0Introduction Vanadiumplaysanimportantroleinmodernindustry,es peciallyinsteelandchemicalindustry.Forinstance,itscompoundsarewidelyappliedintheproceduresofvitrioland petroleumchemicalmanufactureascatalyzers[14].Vanadium hasseveralvalences,butgenerallyitslowvalencesturnintohighoneseasilyinenvironment[5].BecauseV(Ⅴ)isthemost stableandpoisonousone,weoftenlayemphasisonitinenvi ronmentalpollutioncontrol.Vanadiumexistsinenvironmentalwaterwithextremelylowconcentration.Inseawateritscontentislessthan…