凋落叶多样性对杉木幼苗生长及吸收~(15)N标记硫铵的影响

利用15N硫铵研究了凋落叶多样性对杉木幼苗生长及养分吸收的影响 .结果表明 ,凋落叶多样性的增加有利于盆栽杉木幼苗的生长 .杉木、火力楠、红栲和刺楸 4种凋落叶混合处理后 ,杉木幼苗的生长量最大 ;杉木、火力楠、刺楸 3种凋落叶混合处理后的杉木幼苗生长量次之 ,其它依次为杉木、火力楠、红栲 3种凋落叶混合处理 >杉木和刺楸凋落叶处理 >杉木和红栲凋落叶处理 >对照 >杉木和火力楠 2种凋落叶混合处理 >杉木凋落叶处理 .就杉木幼苗对硫铵氮的吸收率而言 ,不作任何处理的杉木幼苗吸收率最高 ,其次为杉木、火力楠、红栲和刺楸 4种凋落叶混合处理 ,其它依次为杉木、火力楠、刺楸 3种凋落叶混合处理和杉木、火力楠、红栲 3种凋落叶混合处理 >杉木和刺楸凋落叶处理 >杉木和红栲凋落叶处理>杉木和火力楠 2种凋落叶混合处理 >杉木凋落叶处理 .另外 ,用凋落叶处理后 ,土壤中硫铵氮的残留量比不作凋落叶处理的土壤多 ,硫铵氮的总回收量也比不作凋落叶处理的土壤大幅增加 ,而且凋落叶多样性的增加也会增加硫铵氮的残留量 .

Structure and oxygen permeability of a dual-phase membrane

The dual-phase membrane of La0.15Sr0.85Ga0.3Fe0.7O3-delta-Ba0.5Sr0.5Fe0.2Co0.8O3-delta (LSGF-BSCF) was prepared successfully. This membrane was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe micro-analyzer (EPMA). This membrane has a dense dual-phase structure: LSGF being the dense body of this membrane and BSCF as another phase running along the LSGF body. This structure is favorable for the oxygen permeation through the membrane. The oxygen permeation test shows that the oxygen permeation flux of LSGF-BSCF membrane (Jo(2) = 0.45 ml/min cm(2), at 915 degreesC) is much higher than that of LSGF membrane (Jo(2) = 0.05 ml/min cm(2)). Thickness dependence of oxygen permeation indicates that the oxygen permeation is controlled by the bulk diffusion. Compared to pure BSCF the dual-phase membrane of LSGF-BSCF is stable in reducing atmosphere. (C) 2003 Elsevier B.V. All rights reserved.

Oxidative dehydrogenation of propane in a dense tubular membrane reactor

Oxidative dehydrogenation of propane (ODP) to propylene was investigated in a dense tubular membrane reactor made of Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) at 700degreesC and 750degreesC. The propylene selectivity in the membrane reactor (44.2%) is much higher than that in the fixed-bed reactor (15%) at the similar propane conversion (23-27%). Higher propylene selectivity in the membrane reactor was attributed to the lattice oxygen (O2-) supplied through the membrane.

Trends in heavy metal levels in the dissolved and particulate phase in the Dutch rhine-meuse (MAAS) delta*

Levels of the heavy metals Cd, Cr, Cu, Pb and Zn, in both the dissolved and particulate phase, were determined in two sampling campaigns in August 1978 and August 1984 in the Dutch Rhine-Meuse (Maas) Delta. Besides the heavy metal concentrations, other important parameters were determined, such as the concentrations of seston, chlorophyll and nutrients. The concentrations of dissolved Cd and of Cd, Pb and Cu in particulate matter were much higher in 1978 than in 1984, especially for Cd. This may be due to the strict regulations implemented in Germany to reduce the pollution of natural waters by heavy metals. The correlation between the high Cd content and the chlorophyll content is explained by the binding of Cd to living and dead organisms. The distribution of the metals between the dissolved and the particulate phase, indicated by the distribution quotient Kd , increases from low values of Kd for Cu and Zn, to higher values for Cd and Cr, and the highest values for Pb. The differences are explained by various binding forms of each of these metals in natural waters

科尔沁沙地15种禾本科植物种子萌发特性比较

在实验室条件下,观测了科尔沁沙地乌兰敖都地区禾本科植物当年新采种子的萌发特点。15种植物中,披碱草、糙隐子草、冠芒草、大油芒、芦苇、虎尾草、野古草、狼尾草的发芽率超过80％,水稗草、牛鞭草、虱子草、狗尾草的发芽率不足10％。1～3d开始发芽的植物有大油芒、画眉、芦苇、虎尾草、披碱草、冠芒草、毛马唐、糙隐子草、超过10d基本不发芽的植物包括狗尾草、虱子草、牛鞭草.发芽持续期小于10d的植物包括毛马唐、水稗草、芦苇、画眉草、大油芒;发芽持续期21～30d的植物有披碱草、冠芒草。发芽种子超过总发芽种子的50％需要天数为虎尾草2d,芦苇3d,大油芒4d,披碱草5d,糙隐子草5d,野古草7d,冠芒草7d,狼尾草10d。与英国Sheffield地区相比,乌兰敖都地区一年生禾草发芽率低的所占比重更大,发芽更为缓慢;乌兰敖都地区多年生禾草的发芽率差别很小,但发芽更为缓慢。杂草植物萌发的风险分摊能力相对明显,因此抗干扰能力相对较强。

the ebb-tidal delta of the venice lagoon,Italy

Very high-resolution seismic lines were collected offshore the Venice Lagoon in the framework of the Co.Ri.La'New very high resolution seismic methods to study the Venice Lagoon subsoil' project. The 140 km boomer profiles led to the identification of a convex-upward,lens-shaped body just outside the Lido inlet,one of the three lagoon inlets,which has been interpreted as an ebb-tidal delta.The comparison between the scismostratigraphic setting og this deposit, as revealed by the seismic lines,and the analyses of historicalbathymetric maps highlighted the key role of human interventions in the formation and evolution of the Lido inlet cbb-tidal delta.To preserve the lagoon environment but also to ensure a navigable way, human interventions at the Lidoinlet,performed since the fourteenth centtury, caused profound variations in the inlet dynamics,ldading to a progressive increase in the sediment dispersion from the lagoon interior towards the sea. The ebb-tidal delta of the Lido nilet is thus a very recent feature compared with the formation of the Venice lagoon and formed mainly as a consequence of the construction of the two jetties that have bound the inlet form AD 1886 to the present day.

水分和氮磷水平对小麦碳同位素分辨率和水分利用效率的影响

依据盆栽试验数据 ,利用植物稳定性碳同位素分辨率的理论模型 ,研究了水分和氮磷营养对小麦叶片碳同位素分辨率 (Carbon- isotope discriminationΔ)的影响。结果表明 :水分差异引起碳同位素分辨率较大变异 ,碳同位素分辨率随土壤相对含水量 (Soil relative water content)的提高而提高 ,在土壤相对含水量为 6 0 %～ 70 %条件下碳同位素分辨率最高。缺水时磷水平提高 ,碳同位素分辨率提高。水分利用效率 (Water use efficiency)与碳同位素分辨率关系受土壤水分和养分水平的影响。缺水条件下水分利用效率与碳同位素分辨率之间为负相关 ,充分供水下为正相关 ;在低氮水平下的关系不明显 ,施氮 15 0 kg· hm- 2时相关性显著。

稳定性核素~(15)N在农业研究中的应用

稳定性核素示踪是现代农业研究中一门新兴技术。稳定性核素15N作为一种有效手段在农业施肥研究、氮素循环研究中发挥着极为重要的作用。本文介绍了15N的相关概念,列举了20世纪80年代以来15N在氮肥研究、氮素转化研究以及农业环境保护中的应用进展,阐明了应用15N的新技术已解决的问题,以及将要解决的问题,并展望了性核素示踪技术的应用前景。

抑制剂及其组合对尿素~(15)N在小麦土壤系统中的行为和归宿的影响

应用加有脲酶抑制剂 (HQ)、硝化抑制剂 (DCD)及其组合的标记尿素进行春小麦盆栽试验 .结果表明 ,在生长季节结束时 ,小麦回收 ,土壤残留和损失的肥料N各占施入N量的 1 7.65～ 2 3.69%、43.72～ 56.32 %和 1 9.99～ 36.77% .其中 ,与单施尿素相比 ,两种抑制剂配合使用处理的肥料N总回收率高 1 6.78% ,小麦回收高 5.96% .施用氮肥对籽粒贡献最大 ,占吸收肥料N量 43.3～ 62 .0 % .

近15年海南岛林地资源时空动态特征及政策驱动

遥感(RS)和地理信息系统(GIS)技术的发展为林地资源的调查和时空变化分析提供了有效手段。该文在遥感与地理信息系统技术支持下,利用中国资源环境数据库中1985年、1995年和2000年3期林地类型空间分布数据,通过建立林地资源时空演变模型,对海南岛林地资源变化的时空特征进行了定量分析,结果表明:1985年～2000年15年内,海南岛林地发生了大幅度的变化,而且空间差异非常明显,其中最近5年林地变化的广度和深度都远远超过了前10年。1985年～1995年海南岛林地资源总量出现大幅度增加,尤其是有林地的增长特别明显;而1995年～2000年大量的林地转为耕地和城镇建设用地,该时期有林地、灌木林和疏林地都出现大幅度减少。从空间格局来看,海口市在整个15年内,林地的变化始终最为突出,东部沿海县市,如文昌、琼海、万宁、陵水、保亭等林地变化的动态度和减少的数量都远远大于其他地区。文章还进一步分析了政策因子对林地资源变化的影响。

Nitrogen-15 signals of leaf-litter-soil continuum as a possible indicator of ecosystem nitrogen saturation by forest succession and N loads

National Key Research and Development Program [2010CB833502]; National Natural Science Foundation of China [30600071, 40601097, 30590381]; Chinese Academy of Sciences [KZCX2-YW-432, O7V70080SZ, LENOM07LS-01]; GUCAS [O85101PM03]

Landscape change detection of the newly created wetland in Yellow River Delta

Four models are employed in the landscape change detection of the newly created wetland. The models include ones for patch connectivity. ecological diversity, human impact intensity and mean center of land cover. The landscape data of the newly created wetland in Yellow River Delta in 1984, 1991, and 1996 are produced from the unsupervised classification and the supervised classification on the basis of integrating Landsat TM images of the newly created wetland in the four seasons of the each year. The result from operating the models into the data shows that the newly created wetland landscape in Yellow River Delta had a great chance. The driving focus of the change are mainly from natural evolution of the newly created wetland and rapid population growth, especially non-peasant population growth in Yellow River Delta because a considerable amount of oil and gas fields have been found in the Yellow River Delta. For preventing the newly created wetland from more destruction and conserving benign Succession of the ecosystems in the newly created wetland, six measures are suggested on the basis of research results. (C) 2003 Elsevier Science B.V. All rights reserved.

Application of rough set-based analysis to extract spatial relationship indicator rules: An example of land use in Pearl River Delta

Spatial relations, reflecting the complex association between geographical phenomena and environments, are very important in the solution of geographical issues. Different spatial relations can be expressed by indicators which are useful for the analysis of geographical issues. Urbanization, an important geographical issue, is considered in this paper. The spatial relationship indicators concerning urbanization are expressed with a decision table. Thereafter, the spatial relationship indicator rules are extracted based on the application of rough set theory. The extraction process of spatial relationship indicator rules is illustrated with data from the urban and rural areas of Shenzhen and Hong Kong, located in the Pearl River Delta. Land use vector data of 1995 and 2000 are used. The extracted spatial relationship indicator rules of 1995 are used to identify the urban and rural areas in Zhongshan, Zhuhai and Macao. The identification accuracy is approximately 96.3%. Similar procedures are used to extract the spatial relationship indicator rules of 2000 for the urban and rural areas in Zhongshan, Zhuhai and Macao. An identification accuracy of about 83.6% is obtained.

Mo掺杂对高纯Ce_(1-x)Nd_xO_(2-x/2)(x=0.10,0.15)体系烧结温度及晶界电性能的影响

用柠檬酸硝酸盐法制备高纯Ce1-xNdxO2-x/2(x=0.10,0.15)固溶体,加入摩尔分数为5%的Mo,研究了Mo掺杂对烧结温度、结构及电性能的影响.通过X射线衍射、电感偶合等离子体和场发射扫描电镜等手段对氧化物进行了结构表征,采用交流阻抗谱测试其电性能.柠檬酸硝酸盐法制备的前驱体经1450℃烧结24 h得到致密度大于96%的陶瓷材料;加入5%Mo,在1250℃下烧结8 h即可达到理想的致密度(>95%).加入Mo在烧结过程中可加快晶界迁移,促进晶粒生长,显著提高了晶界电导率.在600℃时Ce0.85Nd0.15O1.925的晶界电导率为2.56 S/m,加入Mo后材料的电导率增加到5.62 S/m.