大气CO₂富集对根际NaCl盐渍的人参果植株干物质生产和水分利用的影响     

陈凯  胡国谦  KEUTGEN Norbert  KEUTGEN Ann  JANSSENS Mar  LENZ Fritz 《大气科学学报》2012,35(2):129-139

对单株砂培盆栽的半木质化枝条扦插生根的一月龄人生果(Solanum muricatum Ait.)栽培品种"Xotus",每周浇两次200mL NaCl质量浓度分别为0mg·L^-1和25mg·L^-1的Hoagland营养液处理2个月,第二个月在控制空气CO₂体积分数为(350±10)×10^-6、(700±10)×10^-6和(1050±10)×10^-6的植物生长箱内试验。结果表明,人参果植株干物质生产量和耗水量受根际NaCl盐渍而下降,又随大气CO₂升高而增加。根际NaCl盐渍能增大植株叶片蒸腾系数、根/冠比和干物质向枝干和根部分配的比例及积累量,降低根系吸收水分的效率和耗水量。升高大气CO₂能促进叶片发育及干物质向地上部其他器官和地下部组织分配,增加总叶面积、比叶干重和各种器官中干物质增长量,提高干物质生产率和水分利用率。根际经25mg·L^-1NaCl盐渍处理的植株,总干物质增长量和水分利用率相应下降50%～54%和24%～37%;与350×10^-6CO₂的处理的植株相比,700×10^-6及1050×10^-6CO₂的处理分别使这两项指标提高到79%～106%和61%～88%以及133%～189%和99%～142%。大气CO₂富集能改善受NaCl盐渍的植株干物质生产力、提高水分利用率。根际NaCl盐渍和大气CO₂富集对人参果植株干物质生产和水分利用有生物互作效应。它们的共同作用会促进植株干物质的增长及叶片中合成的干物质向其他器官分配,提高干物质生产率和水分利用率,同时减少总叶面积、枝条和根系干重、根系吸水效率、植株耗水量和叶片蒸腾系数。因此,全球大气CO₂富集将有利于该作物的干物质生产和水分利用。  相似文献   

Analysis of spatial and temporal extreme monsoonal rainfall over South Asia using complex networks   总被引：2，自引：1，他引：1  

Nishant Malik  Bodo Bookhagen  Norbert Marwan  Jürgen Kurths 《Climate Dynamics》2012,39(3-4):971-987

We present a detailed analysis of summer monsoon rainfall over the Indian peninsular using nonlinear spatial correlations. This analysis is carried out employing the tools of complex networks and a measure of nonlinear correlation for point processes such as rainfall, called event synchronization. This study provides valuable insights into the spatial organization, scales, and structure of the 90th and 94th percentile rainfall events during the Indian summer monsoon (June–September). We furthermore analyse the influence of different critical synoptic atmospheric systems and the impact of the steep Himalayan topography on rainfall patterns. The presented method not only helps us in visualising the structure of the extreme-event rainfall fields, but also identifies the water vapor pathways and decadal-scale moisture sinks over the region. Furthermore a simple scheme based on complex networks is presented to decipher the spatial intricacies and temporal evolution of monsoonal rainfall patterns over the last 6 decades.  相似文献   

Fractionation of rare-earth elements in plants during experimental growth in varied clay substrates     

Khadija Semhi  Sam Chaudhuri  Norbert Clauer 《Applied Geochemistry》2009

The distribution and content of rare-earth elements (REEs) were determined in two radish species, the cultivated Raphanus sativus and the wild Raphanus raphanistrum, that were grown under laboratory-controlled conditions, in three substrates consisting of illite for one and two smectite substrates for the others, with the two smectite substrates being characterised by different porosities. The plants were split into leaves and stems + roots for analysis. The results indicate that both species take up systematically higher amounts of REEs when grown in the illite substrate, even considering that the smectite equivalent contains about three times more REEs. The REE uptake is also more plant species than mineral composition dependent: R. raphanistrum takes up 3.5–6.7 times more REEs than R. sativus, depending on the substrate, its porosity and the considered plant segments. Increased substrate porosity favours the take up of the REEs, but no specific uptake is observed in leaves relative to that in the combined stems and roots. The transfer of the REEs from minerals to plant organs does not appear to induce systematically identical patterns: (1) in the case of R. sativus, a positive Eu anomaly is visible in all patterns from both segment groups grown in both substrates. When grown in illite, the heavy REEs are also enriched in the stems and roots, which has not been observed in any other organ or in the other substrate and (2) in the case of R. raphanistrum, a very significant positive Gd anomaly, which is not expected to fractionate relative to the other REEs as do Ce and Eu, is observed in all segments of the plants grown in both substrates. A slight negative Ce anomaly is also visible in some of the REE patterns, suggesting some changes in the oxidation–reduction conditions in the substrates near the roots during plant growth. The comparison of the REE patterns from leaves relative to those of the roots + stems shows that those of R. raphanistrum grown in illite provide a spectrum that is very specific with significant deficits in La, Ce, Gd, Tm, Yb and Lu in the leaves. In the other cases, the patterns do not outline significant differences except for R. sativus grown in illite, in which the leaves are enriched in light and medium REEs from La to Gd relative to the stems + roots.  相似文献   

Ageing effect on the mineral and chemical composition of Opalinus Clays (Mont Terri,Switzerland) after excavation and surface storage     

Isabelle Techer  Norbert Clauer  Nicole Liewig 《Applied Geochemistry》2009

Samples of Opalinus Clays from Mont Terri Underground Research Laboratory in the Swiss Jura were analyzed repetitively relative to the duration of their exposure to atmosphere. The objective was the evaluation of such a progressive exposure on the chemical composition of whole-rock samples, and on the chemical and Sr isotopic compositions of leachates obtained by leaching the rock powders with dilute acetic acid. This chemical study was complemented by scanning electron microscope observations to identify the related mineral alterations. The chemical data for the rock powders remained quite constant whatever the duration of the storage, whereas significant changes were observed for the leachates. Similar changes were observed in the leachates of samples collected progressively closer to the walls of a previously excavated niche. When storage time or distance to gallery wall increases, the main variations are: (1) a progressive decrease of the element contents and of the ⁸⁷Sr/⁸⁶Sr ratio in the leachates, (2) an alteration of pyrite followed by precipitation of Ca-sulfate in the rocks, both observed by SEM, and (3) a probable precipitation of new mineral phases in the rocks, such as Fe-oxyhydroxides and/or jarosite that could not be visualized by electron microscopic observation because of their very limited amount and very small grain size. The modifications call for an oxidation of pyrite that probably induced also an oxidation of the organic matter. It could also be shown that the reactions were enhanced by temperature increase, and that they were less pronounced in the samples behind the gallery wall than in the cores stored in laboratory conditions.  相似文献   

Plasmaspheric electron density reconstruction based on the topside sounder model profiler     

Ivan Kutiev  Pencho Marinov  Anna Belehaki  Norbert Jakowski  Bodo Reinisch  Chris Mayer  Ioanna Tsagouri 《Acta Geophysica》2010,58(3):420-431

We apply a model-assisted technique to construct the topside electron density profile based on Digisonde measurements. This technique uses the Topside Sounder Model (TSM), which provides the plasma scale height, O⁺-H⁺ transition height, and their ratio Rt = H _T /h _T , derived from topside sounder data of Alouette and ISIS satellites. The Topside Sounder Model Profiler (TSMP) incorporates TSM and uses the model quantities as anchor points for the construction of topside density profiles. TSMP provides its model ratios with transition height and plasmaspheric scale height. The analysis carried out indicates that Digisonde derived F-region topside scale height Hm is systematically lower than one derived from topside sounder profiles. To construct topside profiles by using Hm, a correction factor of around 3 is needed to multiply the neutral scale height in the α-Chapman formula. It was found that the plasmaspheric scale height strongly depends on latitude and its ratio with the F-region scale height expresses large day-to-day variability.  相似文献   

Verification of the TSMP-assisted digisonde topside profiling technique     

Anna Belehaki  Ivan Kutiev  Bodo Reinisch  Norbert Jakowski  Pencho Marinov  Ivan Galkin  Chris Mayer  Ioanna Tsagouri  Themistocles Herekakis 《Acta Geophysica》2010,58(3):432-452

The purpose of this paper is to evaluate the performance of the TSMP-assisted Digisonde (TaD) topside profiling technique. We present systematic comparisons between electron density profiles and TEC parameters extracted from TaD model with (a) CHAMP-derived TEC parameters, (b) CHAMP reconstructed profiles, (c) ground based GPSderived TEC parameters, and (d) profiles reconstructed from RPI/IMAGE plasmagrams. In all cases, TaD follows the general trend of plasmaspheric observations derived from the above datasets. Especially during storm cases, TaD shows remarkable agreement with the variations of the ground based GPS-derived TEC parameters. Overall, the comparison results shows that TaD method can be adopted by EURIPOS to provide the electron density distribution up to plasmaspheric heights in real-time.  相似文献   

ESR/U-series chronology of the Lower Palaeolithic palaeoanthropological site of Visogliano, Trieste, Italy     

Christophe Falgures  Jean-Jacques Bahain  Carlo Tozzi  Giovanni Boschian  Jean-Michel Dolo  Norbert Mercier  Hlne Valladas  Yuji Yokoyama 《Quaternary Geochronology》2008,3(4):390-398

The Visogliano shelter, in north-eastern Italy, is an important Middle Pleistocene occupation site where human remains were found together with an archaic lithic industry, including choppers, chopping tools and a few protobifaces. It is of utmost importance to try to document this period, when a second wave of settlement colonised Western Europe, carrying new flaking techniques and tools.Combined ESR/U-series analyses, integrated with biostratigraphical and environmental data, define a chronological frame for the layers from which the artefacts were unearthed. The lower levels, including human remains, can be dated to the 350–500 kyr time span, in agreement with micromammal and stratigraphical studies.These data make Visogliano one of the oldest palaeoanthropological sites in Italy, where human remains are directly associated with protobifaces, choppers and chopping tools. In Western Europe, Visogliano is contemporaneous to the G soil of the Arago Cave, France, with which it shares several similarities in faunal assemblages and radiometric data, and which contains human remains also. These data make Visogliano as one of the oldest sites in Europe where the Acheulian culture is observed.  相似文献   

Effective Photoinactivation of Alpha‐Amylase,Catalase and Urease at 222 nm Emitted by an KrCl‐Excimer Lamp     

Marcus Clauß  Norbert Grotjohann 《洁净——土壤、空气、水》2008,36(9):754-759

The inactivation of enzymes is of great interest for many industrial applications. The effectiveness of photoinactivation of alpha‐amylase, catalase, and urease with 222 nm radiation was investigated in comparison to that at 254 nm. The enzymes were irradiated with different fluence rates of 222 nm radiation emitted by a KrCl‐excimer lamp and with 254 nm radiation produced by a low‐pressure mercury lamp. The relative activities were calculated before and after irradiation. Degradation caused by UV‐radiation was assessed by SDS‐PAGE analysis. The results clearly demonstrated that inactivation of the proteins is much more effective with the 222 nm excimer lamp compared to the 254 nm mercury lamp. Irradiation with the excimer lamp and a UV‐fluence rate of 1000 J/m² was sufficient to reduce the relative activities of amylase and urease to 15% and that of catalase to 60%. After irradiation with 4000 J/m², the enzyme activity was almost completely inhibited. In contrast, after irradiation with the mercury lamp with an UV‐fluence rate of 4000 J/m², the relative activity was still above 85%. The gel patterns showed no visible degradation after irradiation at 254 nm, but a strong and unspecific degradation was obvious after treatment at 222 nm, presumably caused by cleavage of the peptide bonds.  相似文献   

40Ar-39Ar ages of Dellen,Jänisjärvi,and Sääksjärvi impact craters     

Norbert Müller  Jack B. Hartung  Elmar K. Jessberger  Wolf U. Reimold 《Meteoritics & planetary science》1990,25(1):1-10

Abstract— ⁴⁰Ar-³⁹Ar age measurements were made for three whole rock melt samples produced during impact events which formed the Dellen, Jänisjärvi, and Sääksjärvi craters on the Baltic Shield. An age of 109.6 ± 1.0 Ma was obtained for the Dellen sample based on an age spectrum plateau. The age spectrum shows a small (7%) loss of radiogenic ⁴⁰Ar from low temperature fractions. Ages of 698 ± 22 Ma and 560 ± 12 Ma were obtained from isochrons for the Jänisjärvi and Sääksjärvi samples, respectively. Data obtained by laser degassing support the Sääksjärvi result. The presence of excess ⁴⁰Ar is indicated in lower temperature fractions for both samples and is correlated with K concentrations in the Sääksjärvi sample. Models explaining these results may require a change in the local “atmospheric” Ar isotopic composition as cooling of melt rocks proceeded. However, it cannot be excluded that devitrification and/or alteration changed the Ar budget. A crater production rate on the Baltic Shield based on measured ages of 6 craters is (0.3 ± 0.2) · 10^?14 20-km-and-larger craters per km² per year, in satisfactory agreement with previous estimates.  相似文献   

Utilisation de la methode rubidium-strontium pour la datation d'une schistosite de sediments peu metamorphises: Application au Precambrien II de la boutonniere de Bou Azzer-El Graara (Anti-Atlas,Maroc)     

Norbert Clauer 《Earth and Planetary Science Letters》1974,22(4):404-412

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