若尔盖高原花湖湖滨湿地甲烷排放研究

若尔盖高原湿地位于青藏高原东北部地区，平均海拔3,400-3,600m，是长江和黄河的自然分水区，区内发育了大面积的草本沼泽以及高寒沼泽化草甸、高寒湖泊。由于它所处的位置海拔高、气候波动较大，并处于我国三大自然区的交错过渡带，因而被认为是我国最为典型的脆弱湿地生态系统之一。由于地处偏远、自然环境条件恶劣等多方面的原因，针对若尔盖湿地的科学研究资料一直以来还非常缺乏。本文对国内外近年来在湿地生态系统甲烷排放过程、研究方法，以及关于湿地生态系统甲烷排放的影响因素进行了综述，并采用静态箱－气相色谱法，从湿地环境格局、湿地甲烷排放等方面，对若尔盖高原典型高寒湖泊湖滨不同类型湿地甲烷排放特征进行了研究，并进一步探讨了影响若尔盖高原高寒湖泊湖滨带甲烷排放的因素。得到如下结果：1．若尔盖高原花湖湖滨湿地在植物生长季（6 至8 月），甲烷排放平均速率为0.315 mg·m-2·h-1；不同月份间甲烷排放速率存在差异，分别为：-0.054、0.471、0.493 mg·m-2·h-1。不同类型湿地甲烷排放速率亦表现出差异，两栖蓼（Polygonum amphibium）湿地、滩涂和藏嵩草（Kobresia tibetica）草甸甲烷排放速率分别为：0.464、0.477、0.005mg·m-2·h-1。2．若尔盖高原花湖湖滨湿地甲烷排放速率与土壤10cm 温度显著相关。土壤温度是影响若尔盖高原花湖湖滨不同类型湿地甲烷排放的重要因素之一。随着土壤温度的升高，土壤微生物活性增强，使土壤中的氧消耗加快，氧化还原电位下降，有利于产甲烷菌的生长，从而增加土壤的甲烷产生量。3．地表水位与若尔盖高原花湖湖滨湿地甲烷排放速率相关性不显著。地表水覆盖，使得湿地土壤缺氧状况得到加强，增强了土壤中产甲烷菌的活性，促进甲烷形成，再通过植物、气泡或扩散的形式释放出土壤。但水层的加深，也使土壤中已产生的甲烷在通过气泡或扩散形式穿越水层时，被氧化的量增加，从而减少了甲烷向大气中的排放。4．植被高度以及植被地上生物量与若尔盖高原花湖湖滨带甲烷排放速率的相关性不显著。植物主要通过凋落物以及根系分泌物的输入为产甲烷菌提供基质，并作为土壤与大气之间的甲烷气体交换的传输途径；与其他环境因素共同影响湿地生态系统甲烷排放。The Zoige wetland on the eastern fringe of Qinghai-Tibetan Plateau, with averagealtitude between 3,400 and 3,600m, is the watershed of Yangtze River and YellowRiver. There are large area of peatland, subalpine meadow and lakes in this region.Due to its high elevation, transitional topology and high fluctuation of climate, theZoige wetlands represent one of the most fragile wetland ecosystems in China. And asa result of remote location and harsh environment conditions, the researches on theZoige wetland are relatively rare, especially the researches on the methane emissionfrom littoral zone of alpine lakes. Variations of methane emission rates as measuredby the method of static chamber – gas chromatography (GC) were detected fromlittoral zone of alpine lake on the Zoige Plateau. Relationships between methaneemission rates and environmental factors were analyzed. It is concluded that:1．The average methane emission rate in the littoral zone of Huahu Lake, ZoigePlateau is 0.315 mg·m-2·h-1, with evident spatial and temporal variations. The littoralzone has different methane effluxes with -0.054, 0.471, and 0.493 mg·CH4·m-2·h-1in June, July and August respectively. Different types of wetland have differentmethane emission rates, with value of 0.464, 0.477, and 0.005 mg·CH4·m-2·h-1 forPolygonum amphibium wetland ( PA ), Shoal ( S ) and Kobresi tibetica meadow ( KT ), respectively.2． The soil temperature at 10cm is significantly correlated with the methane effluxesin littoral zone of Huahu Lake, Zoige Plateau, and which is one of the most important factors influencing the methane emission from this region. The activities of soilmicroorganisms rise under higher soil temperature and increases oxygen consumptionand decreases Eh, which is in favor of the methanogensis, and enhances theproduction of methane in soil.3． The correlation between the standing water and methane effluxes from littoralzone of Huahu Lake is not significant. Because of the standing water, the anaerobicconditions of wetland soil have been enhanced, and are favor to the decomposition oforganic matter. And the anaerobic conditions strengthen the methanogensis’ activities,thus the methane production, which release to the atmosphere by diffusion, ebullitionand aerenchymal plants. With the water level’s increase, more methane produced insoil which is transferred by ebullitions or diffusion are oxidated, thus reduce themethane release to the atmosphere.4． The height and aboveground biomass of vegetation are not significant related tothe methane effluxes from littoral zone of Huahu Lake, Zoige Plateau. The vegetationprovides substrates for methanogensis by litter and root exudates; act as thetransportation way of methane between soil and atmosphere; influence the methaneemission of wetland ecosystems with other environment factors.

The geometry of the NO2- anion: ab initio calculations and Franck-Condon analysis

Geometry optimization and harmonic vibrational frequency calculations have been performed on the (X) over bar (2)A(1) state of NO2 and (X) over bar (1)A(1) state of NO2-. Franck-Condon analyses and spectral simulations were carried out on the NO2((X) over bar (2)A(1))-NO2-((X) over bar (1)A(1)) photo detachment process. In addition, the equilibrium geometry parameters, r(NO)= 1.248 +/- 0.005 Angstrom and angle(ONO) 116.8 +/- 0.5degrees, of the (X) over bar (1)A(1) state of NO2-, are derived by employing an iterative Franck-Condon analysis procedure in the spectral simulation. Our conclusions regarding the anion geometry suggest a reinterpretation of the results of Woo et al. (C) 2004 Published by Elsevier B.V.

长期高浓度CO_2处理对长白赤松土壤硝化酶、反硝化酶和固氮酶活性的影响(英文)

在吉林省长白山地区模拟检测了大气CO2浓度升高对土壤氮循环关键过程的影响。试验采用完全随机区组设计的开顶箱系统模拟环境CO2和高浓度CO2,起始于1999年春。选取长白山特有树种长白松(Pinus sylvestris var.sylvestri-formu),种子播种于1999年5月份,萌芽后开始CO2熏蒸处理。CO2熏蒸处理始于每年4月末止于10月末。分别在2006年6月、8月和2007年6月采集土壤样品,并检测土壤硝化酶(NEA)、反硝化酶(DEA)和固氮酶活性。结果表明,高浓度C02使土壤硝化酶(NEA)活性显著提高,提高幅度2006年6月为30.3%,2006年8月为30.9%,2007年6月为11.3%;土壤反硝化酶活性(DEA)在2006年6月份(P<0.012)和2006年8月份(P<0.005)被C02浓度升高显著抑制;在整个研究过程中没有发现C02浓度升高对固氮酶活性产生显著影响。因此,本研究认为C02浓度升高显著影响了土壤硝化酶(NEA)和反硝化酶活性(DEA)。图3表1参44。

潮棕壤免耕农田土壤酶活性的动态变化

研究了潮棕壤免耕和常规耕作农田土壤蔗糖酶、脲酶和酸性磷酸酶活性在玉米不同生育时期和不同土层深度的动态变化.结果表明,免耕可显著提高表层(0~10cm)土壤酶活性,其蔗糖酶活性在玉米拔节期、大喇叭口期和成熟期显著高于常规耕作,脲酶活性在拔节期和孕穗期显著高于常规耕作,酸性磷酸酶活性在孕穗期和成熟期显著高于常规耕作(P<0·05);在10~20cm土层,免耕土壤蔗糖酶活性在苗期、拔节期和大喇叭口期与常规耕作差异显著,脲酶活性除孕穗期外均显著高于常规耕作(P<0·05);在20~30cm土层,免耕土壤蔗糖酶活性在玉米各生育期均显著低于常规耕作,土壤脲酶活性在苗期、酸性磷酸酶活性在成熟期与常规耕作差异显著(P<0·05).随土层深度的增加,免耕农田土壤酶活性总体呈下降趋势;常规耕作农田土壤蔗糖酶和酸性磷酸酶活性总体呈上升趋势,而脲酶活性呈下降趋势.

杉木与阔叶树叶凋落物混合分解对土壤活性有机质的影响

通过室内培养,研究了杉木叶凋落物及与桤木、刺楸和火力楠混合叶凋落物对土壤活性有机质的影响.结果表明:添加叶凋落物显著地增加了土壤微生物碳、氮及土壤呼吸强度和可溶性有机碳含量.其中,添加杉-阔混合叶凋落物对土壤活性有机质的增加效应大于纯杉木叶凋落物.在培养后期(第135天),添加纯杉木叶凋落物和杉-阔混合叶凋落物处理土壤微生物碳含量分别比对照土壤高49%和63%,微生物氮高35%和75%,土壤呼吸强度高65%和100%,可溶性有机碳含量高66%和108%.添加叶凋落物对土壤微生物熵和微生物C/N的影响不显著(P>0·05).

沈阳城市森林绿量测算

借助ARC/GIS地理信息系统,以“平面量推算平面量”的方法,测算了沈阳市城市森林的绿量.结果表明:沈阳市城市森林不同类型单位面积绿量以风景游憩林最高,为3·86m2·m-2;生态公益林最低,为2·27m2·m-2;城市森林分布区单位面积绿量为2·99m2·m-2;城区单位面积绿量为0·25m2·m-2.沈阳城市森林总体绿量约为1·13×108m2·其中,附属林为4·15×107m2,占36·64%;生态公益林2·72×107m2,占23·99%;风景游憩林2·20×107m2,占19·38%;道路林1·84×107m2,占16·20%;生产经营林0·43×107m2,占3·79%.经检验,平面量推算平面量方法测算精度达到91·81%(α=0·05).

热带森林植被生物量与遥感地学数据之间的相关性分析

以我国云南省西双版纳的热带森林为例,对热带森林植被生物量与遥感地学数据之间的相关性进行了分析。首先,利用森林资源连续清查的林业固定样地数据计算出各样地的森林植被生物量,并建立其GIS数据库。然后,对遥感图像进行几何校正,并对遥感图像进行主成分变换、缨帽变换以及植被指数的计算来产生其派生数据。其次,将样地数据、遥感数据及其派生数据,地形和气象数据转换到统一的坐标系和投影下,并将其内插为30米分辨率的格网数据。最后,进行样地森林植被生物量与其遥感地学数据之间的相关性分析。该分析表明,森林植被的生物量与年降雨量和第二主成分在0·01的水平上相关显著,而与中红外植被指数、LANDSATTM5、缨帽变换的亮度、湿度以及第一主成分在0·05的水平上相关显著。其中,与年降雨量的相关性最高,达到0·308;其次是与第二主成分,达到-0·231;再次是与中红外植被指数和LANDSATTM5,其相关系数分别为0·203和-0·201。

Stable isotopic compositions in Australian precipitation

Stable deuterium (delta D) and oxygen-18 (delta O-18) isotopes in 1962 to 2002 precipitation from the seven Australian stations of the Global Network of Isotopes in Precipitation (GNIP) were used to investigate isotope characteristics including temporal and spatial distributions across different regions of Australia. On the basis of 1534 samples, the local meteoric water line (LMWL) was established as delta D = 7.10 delta O-18 + 8.21. delta O-18 showed a depletion trend from north and south to central Australia (a continental effect) and from west to east. Precipitation amount effects were generally greater than temperature effects, with quadratic or logarithmic correlations describing delta/T and delta/P better than linear relationships. Nonlinear stepwise regression was used to determine the significant meteorological control factors for each station, explaining about 50% or more of the delta O-18 variations. Geographical control factors for delta O-18 were given by the relationship delta O-18 (parts per thousand) = -0.005 longitude (degrees) - 0.034 latitude (degrees)-0.003 altitude (m) - 4.753. Four different types of d-excess patterns demonstrated particular precipitation formation conditions for four major seasonal rainfall zones. Finally, wavelet coherence (WTC) between delta O-18 and SOI confirmed that the influence of ENSO decreased from east and north to west Australia.

Determination of atenolol and metoprolol by capillary electrophoresis with Tris(2,2 '-bipyridyl)ruthenium(II) electrochemiluminescence detection

Capillary electrophoresis (CE) coupling with a tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)(3)(2+)) electrochemiluminescence (ECL) detection technique was developed for the analysis of two 8-blockers, atenolol (AT) and metoprolol (ME). The parameters that influence the separation and detection, including the buffer pH and concentration, the separation voltage, the detection potential and Ru(bpy)(3)(2+) concentration, were optimized in detail. The calibration curve was linear over a concentration range of two or three orders of magnitude for the two beta-blockers. The detection limits for AT and ME were 0.075 and 0.005 mu M (S/N = 3). The relative standard deviations (n = 8) of the ECL intensity and the migration time were 2.65 and 0.22% for AT, 2.82 and 0.34% for ME, respectively. The proposed method was applied to determine AT and ME in spiked urine samples; satisfactory results were obtained.

Effect of cerium on microstructure and electrochemical performance of Ti-V-Cr-Ni electrode alloy

Effect of cerium on the microstructure and electrochemical performance of the Ti0.25V0.35-xCexCr0.1Ni0.3 (x = 0, 0.005) electrode alloy was investigated by X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectrometry (FESEM-EDS), and electrochemical impedance spectroscopy (EIS) measurements. On the basis of XRD and FESEM-EDS analysis, the alloy was mainly composed of V-based solid solution with body-centered-cubic structure and TiNi-based secondary phase. Ce did not exist in two phases, instead, it existed as Ce-rich small white particles, with irregular edges, distributed near the grain boundaries of the V-based solid solution phase. Discharge capacity, cycle stability, and high-rate discharge ability of the alloy electrode were effectively improved with the addition of Ce at 293 K. It was very surprising that the charge retention was abnormal with larger discharge capacity after standing at the open circuit for 24 h. EIS indicated that addition of Ce improved the dynamic performance, which caused the charge transfer resistance (R-T) to decrease and exchange current density (I-0) to increase markedly. The exchange current density of the electrochemical reaction on the alloy surface with Ce addition was about 2.07 and 3.10 times larger than that of the alloy without Ce at 303 and 343 K, respectively.

Capillary electrophoresis with solid-state electrochemiluminescence detector

We report capillary electrophoresis coupling to a solid-state electrochemiluminescence (ECL) detector for the first time. The solid-state ECL detector was fabricated by immobilizing the ECL reagent tris(2,2'-bipyridyf)ruthenium (TBR) in poly-(p-styrenesulfonate)-silica-poly(vinyl alcohol) grafting 4-vinylpyridine copolymer films. The excellent stability of the solid-state ECL detector in the phosphate solution satisfied application in CE. The CE with solid-state ECL detector system was characterized using tripropylamine (TPA) and proline. The influences of detection potential, the concentration of TBR in the film, and pH value of ECL buffer were investigated. The linear range for TPA and proline was 0.005-10 muM and 5-10 mM with correlation coefficients of 0.997 and 0.998, respectively. The detection limit (signal-to-noise ratio S/N = 3) was estimated to be 0.002 and 2.0 muM for TPA and proline, respectively. The relative standard deviations for 1.0 pm TPA and 1.0 mm proline were 8.7% and 7.5% with theoretical plate numbers of 70 000 and 16 000, respectively. Compared with the CE-ECL of TBR in aqueous solution, the CE coupling with solid-state ECL detector system gave the same sensitivity of analysis.

Enhanced surface plasmon resonance immunosensing using a streptavidin-biotinylated protein complex

In this paper, we present a novel strategy for improving the sensitivity of surface plasmon resonance immunosensing using a streptavidin-biotinylated protein complex. This amplification strategy is based on the construction of a molecular complex between streptavidin and biotin labeled protein. The complex can be formed in a cross-linking network of molecules so that the amplification of the response signal will be realized due to the big molecular size of the complex. The results show that the amplification strategy causes a dramatic improvement of the detection sensitivity. hIgG protein could be detected in the range of 0.005-10 mug ml(-1).

Determination of the impurities elements in high-purity cadmium by inductively coupled plasma mass spectrometry

A method for the determination of impurity elements in high purity cadmium by inductively coupled plasma mass spectrometry was developed. The spectral interference arising from Cd was discussed and the magnitude of interference by the polyatomic ion of Cd was compared. The effect of the high concentration Cd on the analyte signal was studied. The results showed that Cd possessed both significant suppression effects on the light mass elements signal and enhancement effects on the heavy mass elements signal,and the effects can be corrected by the use of internal standard elements. In this paper, Y and Bi was employed for the light mass elements and the heavy mass elements,respectively. As, Be, Co, Cu, Ga, Ge, Mn, Mo, Pb, Ni, Sr, Au, Tl, Th, V and U in high purity cadmium were determined. Detection limits are 0.005-0.052 mu g L-1,and the recoveries of standard addition are 82%-108%.

Oxidation of NADH by dopamine incorporated in lipid film cast onto a glassy carbon electrode

Stable lipid film was made by casting lipid in chloroform onto a glassy carbon electrode. This model of a biological membrane was used to investigate the oxidation of dihydronicotinamide adenine dinucleotide (NADH) by dopamine. After this electrode had been immersed in dopamine solution for 10 h, it was found that some dopamine had been incorporated in the film. The cyclic voltammogram was obtained for the oxidation of 2.0 X 10(-3) mol 1(-1) NADH with dopamine incorporated in the films. All electrochemical experiments were performed in 0.005 mol 1(-1) phosphate buffer (pH 7.0) containing 0.1 mol 1(-1) NaCl without oxygen. The oxidation current increased gradually with successive sweeps and reached steady state. It was a different phenomenon from previous results. The anodic overpotential was reduced by about 130 mV compared with that obtained at a bare glassy carbon electrode. The diffusion coefficient for 2.0 X 10(-3) mol 1(-1) NADH was 6.7 X 10(-6) cm(2) s(-1). (C) 1999 Elsevier Science S.A. All rights reserved.