Monitoring the concentration of N2O in the Fildes Peninsula, maritime Antarctica

Gases in the marine boundary layer in Fildes Peninsula, maritime Antarctica were sampled and analyzed for the first time. Sampling sites included areas covered by moss and lichen growth, penguin colonies and an area where scientific research stations are located. A total of 211 samples were analyzed for N2O concentrations, with an average of (321.33±3.07) nL/L. This is above the global average value of 314 nL/L. It is found that the N2O concentrations evidently increase during the summer months. Concentrations around the research stations are higher than at remote areas, indicating a potential source from human activities on the island. N2O concentrations at a large penguin colony on Barton Peninsula are the highest among the sampled areas. This may explain why N2O concentrations in Fildes Peninsula are higher than the global average. Our preliminary conclusions are that human activities and emissions from penguin dropping-amended soil and vegetation soil constitute the major sources of N2O in the maritime Antarctic atmosphere.     

A 2500-year sea level change record in Fildes Peninsula, Antarctica

A detailed record of sea level changes during the last 2500 years is preserved in the northernwest coast of Fildes Peninsula in Antarctica. Fourteen marine alga layers were deposited in the beach with an altitude of 2.80 m, and one diatom layer deposited in the ancient lake on the terrace with an altitude of 6.84 m. A radiocarbon age of 695±70 aBP was obtained for the modern marine alga, and the age was used in correction for the carbon reservoir effect of the marine alga. Sea level fell 4.98 m from the 4th century B.C. to the early 13th century, at an average of -0.31 cm/a, then rose about 0.78 m during the early 13th to the middle 18th century, at an average of 0.14 cm/a. It has risen about 0.16 m since the middle 18th century, at an average of 0.07 cm/a.     

Determination of dioxin-like polychlorinated biphenyls in soil and moss from Fildes Peninsula,Antarctica

Dioxin-like polychlorinated biphenyls(PCBs) are a class of toxic and persistent chemicals that are often found in the environment.The determination of dioxin-like PCBs in Fildes Peninsula,Antarctica,is reported in this paper.Dioxin-like PCBs were widely distributed in Antarctic soil and moss with concentration of 2.23-27.2 pg/g in soil and 10.4-812 pg/g in moss.The highest concentrations were found in the Ardley Island area and the lowest concentrations on the west coast.The contribution of PCB-118 to the ∑12PCBs ranged from 36.0% to 69.6% in soil,and 17.2% to 43.4% in moss.The congener specific patterns in soil and moss were similar.Long-range atmospheric transport is thought to be the main source of PCBs detected on King George Island.The ∑12PCBs toxic equivalent(TEQ) in soil was 0.400×10?3 to 516×10?3 pg(TEQ)/g with a mean value of 147×10?3 pg(TEQ)/g.PCB-126 had the largest contribution(81.1%) to the ∑12PCBs TEQ in soil.The ∑12PCBs TEQ in moss ranged from 2.90×10?3 to 1.19 pg/g with a mean value of 0.482 pg/g.PCB-126 was also the largest contributor(91.4%) to the ∑12PCBs TEQ in moss.The mean TEQ in moss was about 40 times that in soil.     

14C dating of moss peat banks in Fildes Peninsula, Antarctica

Based on the radiocarbon data of the moss peat banks in Fildes Peninsula, Antarctica, it was calculated that the mean rates of peat accumulation in the upper layer and the lower layer are 0.195 and 0.069 4 mm · a^™1 respectively. Based on the radiocarbon date (3 265 ± 120 aBP) and the mean rate of peat accumulation in the lower peat layer, it was calculated that the age of the coast terrace on which the moss peat bank occurs is earlier than 4 300 aBP. During the past 4 300 years the coast terrace has risen about 18 m without apparently being destroyed, and the age of the glacier retreating process in this area is also earlier than 4 300 aBP.     

Molecular organic geochemical peculiarities of lacustrine core sediments in Fildes Peninsula, King George Island, Antarctica

The peculiarities of lipids in lacustrine core sediments from Fildes Peninsula, King George Island, Antarctica, are reported. The origin of high-molecular-weight n-alkanes, alkenes,fatty acids, alcohols is supposed to be related to the abundant moss occurring in the sediments.Abundant iso-and anteiso-fatty acids that occur in the sediments indicate a relatively strong bacterial activity in non-ice-cover zone than in other regions in Antarctica. The C18:2 unsaturated fatty acids mainly originate from autochthonous algae in the sediment pool, and the C18:2/C18:0ratios in the profile are controlled more by paleotemperatures than source assemblies. Long-chain alkenones were identified in freshwater lacustrine sediment in Antarctica for the first time, of which Prymnesiophyceae is assumed to be the source organism. High relative abundance of C37:4honologue in long-chain alkenone well correlates to the severely cold climate in Antarctica.     

Relationship between luminescence and matrices in the system A12O3-B2O3-Ce2O3

The system Al₂O₃-B₂O₃-Ce₂O₃, with Al/B ratio varying from 4.5 to 2 and Ce/(Al+B) = 0.02, has been prepared at the temperature from 1 200 to 1 400°C. Relationship between luminescence and matrices in the system Al₂O₃-B₂O₃-Ce₂O₃ was investigated. It was found that some changes of the matrices occurred with Al/B ratio varying from 4.5 to 2. These results lead to a great change in luminescence properties, indicating variation of Ce-surroundings of crystal field. With the decrease of the ratio from 3 to 2, the excitation and emission peaks shift to shorter wavelengths. It was also found that a new type of rare earth luminescent materials was obtained with appropriate Al/B ratio.     

南极苔原近地面CO_2、CH_4、N_2O浓度和通量的相互关系

在南极苔原 ,首次系统地研究了近地面CO2 、CH4、N2 O浓度及通量的相互关系 ,结果表明 :天气条件对三种温室气体浓度日变化影响较大 ;在天气较晴稳及雪天条件下 ,CO2 与CH4、N2 O浓度日变化存在明显的消长关系 ;而在雨天这三种气体浓度日变化趋势基本一致 ;整个夏季CO2 与CH4浓度变化趋势基本一致 ,而N2 O却与二者浓度的变化趋势相反 ;另外 ,在雨、雪天气条件下CH4、N2 O通量日变化存在消长关系 ,整个夏季二者的通量变化也存在明显的消长关系 ;南极苔原土壤对CH4主要起着汇的作用 ,对N2 O主要起着源的作用 .此外 ,CO2 浓度变化对苔原CH4通量有较大影响 ,CO2 浓度增加会适当减缓CH4汇的作用 ,甚至使南极苔原由CH4的汇变为源     

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.     

CoFe2O4/SiO2纳米复合材料的制备及其磁性

采用溶胶-凝胶法制备（CoFe₂O₄）_x/（SiO₂）_1-x纳米复合材料. 利用X射线衍射（XRD）和振动样品磁强计（VSM）研究样品结构、 晶粒尺寸及磁性. 结果表明, 随SiO₂含量增加, 样品的晶粒尺寸减小, 比饱和磁化强度和矫顽力降低.      

Simulation experiments on the reaction system of CH4-MgSO4-H2O

H2S-rich gas in carbonate reservoirs is usually attributed to thermochemical sulfate reduction （TSR）. In this paper, thermal simulation experiments on the reaction system of CH4-MgSO4-H2O were carried out using autoclave at 425℃--525℃. The threshold temperature for initiating TSR is much lower than our previous studies （550℃）. Properties of the reaction products were analyzed by microcoulometry, gas-chromatography （GC）, Fourier transform-infrared spectrometry （FT-IR） and X-ray diffraction （XRD） methods. Thermodynamics and reaction kinetics of TSR processes were investigated on the basis of the experimental data. The results show that thermochemical reduction of magnesium sulfate with methane can proceed spontaneously to produce magnesium oxide, hydrogen sulfur, and carbon dioxide as the main products, and high temperature is thermodynamically favorable to the reaction. Ac- cording to the reaction model, the calculated activation energy of TSR is 101.894 kJ/mol, which is lower than that by most previous studies. Mg^2＋ may have played a role of catalytic action in the process of TSR. The elementary steps of TSR and reaction mechanism were discussed tentatively. The study can provide important information on the explanation of geochemical depth limit for natural gas and on the generation of high H2S gas in deep carbonates reservoirs.     

Preparation and magnetic properties of CoFe2O4/TiO2 composite films

Using （Ti（OC4H9）4） and metal chlorates as starting materials, CoFe2O4/TiO2 composite films were prepared by sol-gel method. The effects of heat treatment temperature and pH of the precursor on microstructure and magnetic properties were studied. The phase structure of the samples was examined by X-ray diffraction. The microstructure was examined by scanning electron microscope, atomic force microscope and polarized microscope. The magnetic property was measured by vibrating sample magnetometer. The results show that the crystals of different phases grow up independently. CoFe2O4 is uniformly embedded into the TiO2 matrix in the prepared composite films, and the growth of composite films is dependent on the heat treatment temperatures and PH of the precursor. The average size of CoFe2O4 crystal is 19 nm in Nanocomposite film prepared when the heat treatment temperature is 800℃ and the pH of the precursor is between 2 and 3. The magnetism of the composite films is enhanced as the heat treatment temperature increases.     

Structural and microstructural transformations in Bi2Sr2Ca1 −xYxCu2O8 + y system

Conclusions With the substitution of Y for Ca in BSCYCO system, both the hole concentration and structure parameters change. The superconductor-nonsuperconductor transition at x_c = 0.4 is more sensitive to the structure transformation than the variation in the hole concentration. Microanalysis reveals an inhomogeneous substitution of Y for Ca. So a much sharper drop of T, is expected at transition point by ideal monophase samples of BSCYCO. A ratio of lattice constants c / o. 5 (a + b) is found to be a very good parameter of describing the SC-AF transition of ISCYCO, reflecting the degree of the localization of Cu-3d electrons on the CuOz plane.     

The P2O5 content of feldspars from the Yashan granites, Jiangxi Province, South China

The P₂O₅ contents of feldspars in the Yashan F-rich and P-rich granite yield a maximum value of 0.93% (In albite) and a maximum average value of 0.65% (hereinafter weight percent) (in K-feldspar), and is generally between 0.10% and 0.35%. Most of the distribution coefficient D_p[Ab/Kt] values are greater than 1(1.13–28.9). The study shows that phosphorus could preferably enter the albite structure mainly by PAISi₂ substitution relative to K-feldspar.     

Harmonic mixing of Bi2Sr2CaCu2O8+x intrinsic junction at millimeter waveband

Using intrinsic Josephson junctions in Ba₂Sr₂CaCu₂O_8+x single crystal, harmonic frequency mixing at 8 and 3 mm wavebands was successfully demonstrated at liquid nitrogen temperatures with harmonic numbers up to 68 and 50 respectively. The dependences of intermediate frequency output on the local oscillator power and dc bias were carefully studied.     

碳封存工程泄漏超高CO2浓度对植被影响的多光谱遥感监测应用

利用天然CO_2气田模拟碳封存工程泄漏超高浓度CO_2后对生态环境影响研究基地,借助多光谱高分辨率遥感技术,在获取多个时相的卫星影像基础上,监测当地植被指数及变化趋势。结果表明:多光谱遥感技术能很好的应用于因高浓度CO_2泄漏造成的植被影响监测,既适用于微小尺度的精细监测,同时也对宏观范围内植被监测起到很好的效果,为完善我国二氧化碳地质封存工程环境影响监测技术方法体系提供科学支撑。     

An in-situ DRIFTS study in the reaction between NO x and soot on BaAl2O4

The interactions between NO, O2 and their mixture on BaAl2O4, as well as the reaction of NOx with soot in the presence of O2, have been investigated using Diffuse Reflectance Infrared Fourier Transform Spectroscopy （DRIFTS）. NO adsorption produces only nitrites species in the absence of O2. NO2 adsorption produces nitrates species besides nitrites species. The produced nitrites will further react with O2, Osurf^-. and Olattice^2- to form nitrates. The reaction of NOx with soot begins with the reaction of nitrates with soot oxygenated complex （C（O））, which is regarded as the key and rate determining step. A reaction pathway is proposed for the catalyzed reaction of NOx with soot in the presence of O2.     

Fractal analysis for root growth of plant seedlings under doubled CO2 concentration

Fractal geometry was applied and box dimension was used as an indicator to analyze the effects of doubled CO₂ concentration on the root growth of plant seedlings. Results showed that doubled CO₂ concentration displayed different effects on root branching characteristics of C₃ and C₄ plants. There was an obvious increase of root branches in spring wheat while there were no significant effects on roots of sweet sorghum. In different soil layers, root branching of spring wheat was stimulated and this promotion was most significant in the second layer (10–20 cm), which denoted that elevated CO₂ altered the root branching pattern. That means higher CO₂ concentration influences not only root growth but also its differentiation and development.