Remote estimation of water quality parameters of Himalayan lake (Kashmir) using Landsat 8 OLI imagery

The overarching aim of this study was to derive simple and accurate algorithms for the retrieval of water quality parameters for the Wular Lake using Landsat 8 OLI satellite data. The water quality parameters include pH, COD, DO, alkalinity, hardness, chloride, TDS, total suspended solids (TSS), turbidity, electric conductivity and phosphate. Regression analysis was performed using atmospherically corrected true reflectance values of original OLI bands, images after applying enhancement techniques (NDVI, principal components) and the values of the water quality parameters at different sample locations to obtain the empirical relationship. Most of the parameters were well correlated with single OLI bands with R² greater than 0.5, whereas phosphate showed a good correlation with NDVI image. The parameters like pH and DO showed a good relation with the principal component I and IV, respectively. The high concentration of pH, COD, turbidity and TSS and low concentration of DO infers the anthropogenic impact on lake.     

2012-2015年中缅油气管道重要节点土地利用/覆被时空变化分析

"中缅油气管道"是我国陆上第三大能源通道,该项目的建设将改变其沿线周边的土地利用/覆盖现状,同时对沿线地区的自然环境和社会经济发展产生重要影响。本文选取中缅油气管道沿线的国内11个重要节点和缅甸境内4个重要节点作为研究区,以2012年和2015年2期Landsat7 ETM+和Landsat8 OLI影像数据作为数据源,利用决策树分类算法提取2012年和2015年2期中缅油气管道沿线重要节点的土地利用/覆被信息,分析2012年和2015年2个时期的中缅油气管道沿线15个重要节点土地利用/覆被的时空变化。研究结果表明：①15个节点中,除德宏芒市、保山隆阳区、缅甸若开邦外,其他11个节点的土地覆被变化均在20%左右;②15个节点中,最主要的土地覆被变化为植被和裸土的相互转换,其次为其他土地覆被类型向建筑的转换;③由于中缅油气管道项目的辐射作用,带动当地经济发展,改变当地的经济作物结构,因此造成大量的植被和裸土的相互转换,并造成建筑用地需求增加,出现大量的其他地表覆被类型向建筑的转换。     

基于Landsat8 OLI遥感影像冰湖边界分类叠加提取

青藏高原特殊的地理及其气候环境适合冰湖变化研究。传统的方法由于受到冻湖、冰川以及山体的阴影的影响,提取冰湖边界时会出现大量的错分和误分。本文基于NDWI(Normalized Difference Water Index,水体指数法)、DEM(数字高程模型)、RGI(Randolph Glacier Inventory)6.0全球冰川编目数据提出针对不同状态下的冰湖边界提取的分类叠加提取方法。结果表明,分类叠加提取方法能够实现未结冰、半结冰以及全结冰三种状态下的冰湖边界提取,并且能减少冰川以及山体阴影的影响,使用该方法提取三种状态下的冰湖的错分和漏分误差均小于2%且Kappa系数均大于0.81。     

Glacial oscillations during the Bølling–Allerød Interstadial–Younger Dryas transition in the Ruda Valley,Central Pyrenees

The Upper Garonne Basin included the largest glacial system in the Pyrenees during the last glacial cycle. Within the long-term glacial retreat during Termination-1 (T-1), glacier fluctuations left geomorphic evidence in the area. However, the chronology of T-1 glacial oscillations on the northern slopes of the Central Pyrenees is still poorly constrained. Here, we introduce new geomorphological observations and a 12-sample dataset of ¹⁰Be cosmic-ray exposure ages from the Ruda Valley. This U-shaped valley, surrounded by peaks exceeding 2800 m a.s.l., includes a sequence of moraines and polished surfaces that enabled a reconstruction of the chronology of the last deglaciation. Following the maximum ice extent, warmer conditions prevailing at ~15–14 ka, during the B8;lling–Aller8;d (B–A) Interstadial, favoured glacial retreat in the Ruda Valley. Within the B–A, glaciers experienced two phases of advance/stillstand with moraine formation at 13.5 and 13.0 ka. During the early Younger Dryas (YD), glacial retreat exposed the highest surfaces of the Saboredo Cirque (~2300–2350 m) at 12.7 ka. Small glaciers persisted only inside the highest cirques (~2470 m), such as in Sendrosa Cirque, with moraines stabilising at 12.6 ka. The results of this work present the most complete chronology for Pyrenean glacial oscillations from the B–A to the YD.     

青海迎庆沟—景忍东多金属矿区矿带划分

迎庆沟-景忍东矿区圈出8条矿带,多条主矿体,规模几近大型。成因类型复杂,从接触交代到热液型均有,亦发现斑岩型、层控型矿床类型的迹象。     

新疆北山地区侵入岩遥感识别方法

基于ASTER数据、Landsat 8数据及WorldView-2数据,采用波段组合法、最小噪声分离法、主成分分析法以及波段比值法,结合岩石光谱曲线,综合提取了新疆北山地区侵入岩的岩性特征。对WorldView-2进行主成分分析和最小噪声分离,并将R(PCA2)G(PCA1)B(PCA4)、R(MNF2)G(MNF1)B(PCA1)、OLI数据R(B7)G(B6)B(B5)进行假彩色合成,利用OLI数据中的B5/B2、B2/B1突出花岗岩。这些方法解决了复杂岩性的影像色调差异较小、细节不清晰等问题,降低了岩性划分及解译的难度,使各种岩性界线更加明晰。结合前人的区域地质调查成果,对研究区侵入岩岩性进行了系统解译及分析。多源遥感数据的综合利用,有助于更有效地识别复杂岩性并进行更详细的岩性分类,提高遥感岩性识别的正确率。     

Tephras in lacustrine sediments of the Sarliève marsh (French Massif Central): age and preservation

The Sarli8;ve marsh sediments (Massif Central, France) contain two tephras. The first tephra [, ca. 12 000 BP], regionally well known, enables to date the beginning of lacustrine infill to the Lateglacial. The second tephra, the ȁ8;tephra de Sarli8;ve’, the emitting volcano of which is unknown, would be dated to around the Early Subboreal from pollen data. This occurrence, after the discovery of the ȁ8;tephra de Beaunit’, emphasizes that volcanic eruption(s) occurred in the ȁ8;Chaîne des Puys’ or in the volcanic Cézallier more than 1000 years after the last known eruption (Pavin) in the ȁ8;Chaîne des Puys’ at around 6.6/6.7 ka (5800/5900 BP). In the Sarli8;ve piles, these tephras, well preserved in thick and more silicated deposits of deltas, were not observed in carbonated basin sediments where they were altered. The abundance of authigenic zeolites formed during the Lateglacial in restricted depocentre lacustrine waters allows us to detect initial CF1 tephra occurrence. To cite this article: A. Fourmont et al., C. R. Geoscience 338 (2006).     

NaAlSi3O8熔体粒子扩散行为压力效应的分子动力学研究

为了研究压力对钠长石成分熔体粒子微观扩散行为的影响,本文用分子动力学方法,探讨了2001．5K温度下,压力由50MPa上升到19862MPa的过程中,熔体的微观结构、粒子自扩散系数随压力的变化规律。研究表明,在升压过程中,低次配位体Al和Si向5次和6次配位体转变,Al的含量在15GPa达到极大值,而Si含量的极大值在20GPa仍未出现。Na的自扩散系数随压力升高单调下降,Al、Si和O的自扩散系数随压力升高先增后减,在8～10GPa左右达到极大值。网架形成粒子自扩散系数的极大值与Al和Si含量的极大值对应的压力点不一致。所有粒子的自扩散系数与它们与O之间键的寿命呈线性负相关。     

What do Δ14C changes across the Gerzensee oscillation/GI‐1b event imply for deglacial oscillations?

High‐resolution studies were performed on late‐glacial sediments from a small lake in western Denmark with respect to lithology, geochemistry, stable isotopes, pollen stratigraphy and radiocarbon dating on terrestrial macrofossils. One purpose was to detect the so‐called Gerzensee oscillation, or the GI‐1b event, in the later part of the Aller8;d warm period, and to describe the environmental impact of this short cooling. The other aim was to test the hypothesis that considerable Δ¹⁴C changes occur over this time, which can be related to ocean ventilation/thermohaline circulation changes. We find that the GI‐1b event had a major impact on both terrestrial and limnic ecosystems: large vegetation changes, increased soil erosion and lowered aquatic production. By correlations to events in the GRIP ice‐core and ¹⁴C patterns in the Cariaco basin we also transformed our ¹⁴C dated record into calendar years to calculate Δ¹⁴C values. The ¹⁴C dates show that the GI‐1b event both preceded, and was part of, the 11 400–11 300 ¹⁴C yr BP radiocarbon plateau, and was followed by the 11 000–10 900 ¹⁴C yr BP plateau; thus the later part of the event coincides with a distinct age decline. This delayed age drop (Δ¹⁴C rise) in relation to the hypothetical triggering mechanism behind the event, decreased ocean ventilation, could be explained by redeposited macrofossils at the onset of GI‐1b. This phenomenon, also seen at the onset of Younger Dryas, may also reflect increased soil erosion and redeposition at the start of cold periods. The independent Cariaco Basin record, however, implies that the very end of the cool GI‐1b event is related to a distinct rise in Δ¹⁴C. Likewise, the ¹⁰Be record from GISP2 shows a distinct rise in the middle of the event, precluding decreased solar forcing as the trigger of the climate event, but making it likely that high cosmic ray flux (low solar activity) may be the cause of the rising atmospheric ¹⁴C content. We thus conclude that the Δ¹⁴C changes over the Gerzensee oscillation (GI‐1b), being one of several coolings during the Last Termination, does not seem to be related to ocean ventilation changes. The reason behind this lack of coincidence between rising Δ¹⁴C and a fairly distinct Northern Hemisphere cooling may be due to the fact that the oceanic changes during some of these coolings are too subtle to give an atmospheric ¹⁴C imprint, or that an anti‐phase relationship between the two hemispheres blurs the Δ¹⁴C signal, or, finally, that a partly unknown mechanism may lie behind such coolings. Copyright © 2000 John Wiley & Sons, Ltd.     

Towards a Higher Comparability of Geothermometric Data obtained by Raman Spectroscopy of Carbonaceous Material. Part I: Evaluation of Biasing Factors

Raman spectroscopy of carbonaceous material (RSCM) is frequently used to determine metamorphic peak temperatures from the structural order of carbonaceous material enclosed in metasediments. This method provides a quick, robust and relatively cheap geothermometer. However, the comparability of the RSCM parameter is low as there are at least three major sources of biasing factors. These sources are the spectral curve‐fitting procedure, the sample characteristics itself and the experimental design including the used Raman system. To assess the impacts of the biasing factors on RSCM, a series of experiments was performed. The experiments showed that curve‐fitting is strongly influenced by individual operator‐bias and the degrees of freedom in the model, implying the need for a standardised curve‐fitting procedure. Due to the diversity of components (optics, light detection device, gratings, etc.) and their combinations within the Raman systems, different Raman instruments generally give differing results. Consequently, to estimate comparable metamorphic temperatures from RSCM data, every Raman instrument needs its own calibration. This demands a reference material series that covers the entire temperature calibration range. Although sample heterogeneity will still induce some variation, a reference material series combined with standardised curve‐fitting procedures will significantly increase the overall comparability of RSCM data from different laboratories.