Fourier-transform Infrared Spectroscopy (FTIRS), a New Method to Infer Past Changes in Tree-line Position and TOC using Lake Sediment     

Peter Rosén  Per Persson 《Journal of Paleolimnology》2006,35(4):913-923

This study tests the hypothesis that Fourier-transform infrared spectroscopy (FTIRS) of lake sediments can be used to infer past changes in tree-line position and total organic carbon (TOC) content of lake water. A training set of 100 lakes from northern Sweden spanning a broad altitudinal and TOC gradient from 0.7 to 14.9 mg/l was used to assess whether vegetation zones and TOC can be modelled from FTIR spectra of surface sediments (0–1 cm) using principal component analysis (PCA) and partial least squares (PLS) regression. Preliminary results show that FTIRS of lake sediments can be used to reconstruct past changes in tree line and the TOC content of lake water, which is hardly surprising since FTIRS registers the properties of organic and minerogenic material derived from the water mass and the drainage area. The FTIRS model for TOC gives a root mean squared error (RMSECV) of calibration of 1.4 mg/l (10% of the gradient) assessed by internal cross-validation (CV) yielding an R_cv² of 0.64. This should be compared with a near-infrared spectroscopy (NIRS) and diatom transfer function for TOC from the same set of lakes, which have a R_cv² of 0.61 and 0.31, and RMSECV of 1.6 and 2.3 mg/l, respectively. The FTIRS-TOC model was applied to a Holocene sediment core from a tree-line lake and the results show similar trends as inferences from NIRS and pollen from the same core. Overall, the results indicate that changes in FTIR spectra from lake sediments reflect differences in catchment vegetation and TOC, and that FTIRS-models based on surface-sediment samples can be applied to sediment cores for retrospective analysis.  相似文献   

Adsorption and stabilization of organic carbon by mineral surfaces in soils     

Seunghun KANG Saikat Ghosh Baoshan XING 《中国地球化学学报》2006,25(B08):263-264

Soils are the largest carbon reservoir in the terrestrial system. Soils contain about three times more carbon than vegetation and twice as much as that present in the atmosphere. Soil organic matter （SOM） is very complex in composition and structure, formed of heterogeneous substances and generally associated with minerals in soils. SOM is classified as labile and stable fractions on the basis of residence time, determined not only by the chemical composition of SOM, but also by types of protection or bonds within soils. The stable carbon fraction is protected either physically or chemically. To understand the process of SOM stabilization, physicochemical properties of organic-mineral complexes were determined by Fourier transformed infrared （FTIR） with attenuated total reflectance （ATR） and diffuse reflectance （DRIFT）, atomic force microscopy （AFM）, and nuclear magnetic spectroscopy （NMR）. Humic acids and carboxylic acids with relatively short carbon chains were used as sorbates, and goethite, kaolinite, and montmorillonite as adsorbents. Humic acid was fractionated during adsorption on the minerals, which was highly influenced by the characteristics of minerals. For instance, long-chain aliphatic carbon was likely to be adsorbed onto the surface of kaolinite and montmorillonite, while goethite surface attracted carboxylic functional groups of humic acid.  相似文献   

表生循环水向成矿溶液转变条件的模拟实验──表生循环水向成矿溶液演变机理之(一)     

陈福  王中刚  朱笑青 《矿物学报》1997,(4)

对成矿溶液性质的认识是成矿理论和成矿预测的基础。本文用云南腾冲热泉水、勐野并钾盐卤水、青岛海洋水、贵州赤天化含油气水、贵阳雨水以及从贵阳森林公园腐殖土中提取的含腐植酸的水溶液，和自配的pH＝1．0的含氯酸性水，对西南地区不同岩性的四种矿源岩样进行了加温浸泡溶解实验。另外还利用表生风化淋滤模拟实验装置对该四种矿源岩样进行了三种不同大气雨水的风化淋滤模拟实验。实验结果表明酸雨和酸性水最容易形成高含量的成矿溶液；含腐植酸的水有时对多种金属也能形成较高含量的合矿溶液。但现代雨水、腾冲火山热泉水、勐野井钾盐卤水、青岛海洋水、贵州赤天化含油气水等近中性和偏碱性的表生水对Fe、Mn、Cu、Pb、Zn、等常量金属元素几乎不能形成高含量的合矿溶液；当溶液中存在强络合剂时，可能对某些贵金属和稀有、分散元素的搬运和成矿具有较重要意义。  相似文献   

土壤圈在全球变化中的意义与研究内容   总被引：17，自引：0，他引：17  

赵其国 《地学前缘》1997,(Z1)

土壤圈是地圈系统的重要组成部分，它处于地圈系统，即气圈、水圈、生物圈与岩石圈的交界面，是最活跃、最富生命力的圈层。土壤圈的物质循环是全球变化中物质循环的重要内容，因此，研究土壤圈及其物质循环的结构与功能，对全球变化，特别对全球土壤变化有密切关系。土壤圈在全球土壤变化中的研究内容包括：土壤圈与地圈各圈层的物质循环；水土资源的时空变化；土壤肥力变化与农业持续发展，区域治理与环境建设等，这些都是全球土壤变化，特别是中国全球变化的主题，应引起高度重视。  相似文献   

安徽无为盆地平衡地质剖面研究   总被引：1，自引：0，他引：1  

胡德昭  徐鸣洁 《高校地质学报》1996,2(4):431-436

本文对无为盆地一条代表性地震剖面进行了平衡剖面计算，从而建立了盆地基本构造模型及其演化模式。计算结果表明：剖面跨的仑头背斜实际上是一外多重推覆构造，是由志系地层形成的；志留系地层叠置造成地层缩短量灰７．９ｋｍ，地层缩短率为１７．３％；推覆构造形成的背斜在后期演化过程中经受的剥蚀量达２．５ｋｍ；盆地边界正断层造成的拉张量为５．４ｋｍ，盆地基底的沉一达３．４ｋｍ，所得结果与盆地周边边地质及深部构造所反  相似文献   

福建宁化湖村盆地构造解析及其地质意义   总被引：4，自引：0，他引：4  

陈爱根  吴正文 《地质论评》1996,42(3):193-199

湖村盆地位于闽西宁化县境内，是闽西北地区变质岩系之上，几个零星出露上古生界的和下三叠统地区之一。本文运用平衡剖面的基本原理及构造解析方法，论证了湖村盆地既不是闽西北隆起之上的断陷盆地，也不是简单的“构造窗”而是在早三叠世末－中株罗世，闽西地区自北西向南发生叠瓦式逆冲推覆作用而形成的残存构造盆地。  相似文献   

Reconstructing the iron cycle from the horizontal distribution of metals in the sediment of Baldeggersee     

Tobias Schaller  H. Christoph Moor  Bernhard Wehrli 《Aquatic Sciences - Research Across Boundaries》1997,59(4):326-344

In Baldeggersee, the distributions of solid phase Fe, Mn, V, Cr, As and Mo were determined in different sediment strata, deposited under various deep-water oxygen conditions. Iron concentrations are correlated with water depth when an anoxic sediment is in contact with an oxic water column. Benthic redox gradients trigger iron transport towards the deepest site (geochemical focusing) and loss of iron from the shallower parts through the outflow. Fe cycling in the lake is inhibited by oxygen penetration into the sediment. Vanadium and arsenic can be used as tracers for the internal Fe cycle. Their distribution patterns are highly correlated with iron. In case of a stable oxycline in the deep water, Mo is enriched in the sediment and correlates with Mn. The horizontal distribution patterns of Fe, V, As and the correlation of Fe and Mn with trace metals are promising proxy indicators for the reconstruction of deep-water oxygen conditions during deposition.  相似文献   

Comparison of geostrophic and nonlinear balanced winds from LIMS data and implications for derived dynamical quantities     

T. Miles  W. L. Grose 《Pure and Applied Geophysics》1989,130(2-3):319-342

Nimbus 7 LIMS geopotential height data are utilized to infer the rotational wind distribution in the Northern Hemisphere stratosphere and lower mesosphere during a period of substantial wave-mean flow interaction in January, 1979. Rotational winds are derived from the application of a successive relaxation numerical procedure which incorporates the spherical polar coordinate iterative algorithm ofPaegle andTomlinson (1975) for the nondivergent nonlinear balance equation. Optimum convergence of the numerical solutions is found to occur when under-relaxation is utilized. The LIMS height analyses were also latitudinally smoothed and constrained to obey the ellipticity criterion for spherical coordinates. The balanced winds are compared with geostrophically derived values and within situ radiosonde reports for 100 mb to 10 mb over Berlin.From a localized perspective, the Berlin-LIMS comparison indicates that radiosonde and balanced wind vectors exhibit somewhat closer agreement in direction than is associated with the geostrophic estimates. However, substantial quantitative differences between radiosonde, balanced, and geostrophic wind speeds are also evident, suggesting that caution should be exercised in the local application of derived winds, as for example in the quantitative interpretation of trajectories derived from satellite height analyses during periods of enhanced stratospheric wave activity.On a longitudinally averaged basis, balanced zonal-mean wind speeds are typically 20% weaker than geostrophic values in polar latitudes, and as much as 50% weaker in tropical and midlatitude regions. Meridional balanced wind velocities, at a given longitude, are generally within ±10% of geostrophic values. Although these alterations in horizontal wind components result in only modest differences between balanced and geostrophic meridional eddy heat fluxes, a more substantial change appears in the meridional eddy momentum flux analysis. The corresponding patterns of Eliassen-Palm flux divergence are found to be somewhat more (less) intense for the balanced wind case in the stratosphere (lower mesosphere) in polar latitudes.  相似文献   

The Geochemistry of Lake Joyce, McMurdo Dry Valleys, Antarctica     

Joseph A. Shacat  William J. Green  Eric H. Decarlo  Silvia Newell 《Aquatic Geochemistry》2004,10(3):325-352

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Trimble 5700卫星定位仪在油田井位勘定中的应用     

刘霞 《全球定位系统》2003,28(3):37-41

本文主要介绍了Trimble 5700测地型卫星定位仪的主要性能、在油田井位勘定中的应用及其软件数据处理统计分析。  相似文献