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1.
混合岩型铀矿是康滇地轴上最有希望取得找矿突破的铀矿类型,海塔地区的铀矿化即是该类型铀矿的典型代表。本文针对区内的长英质脉矿石、富晶质铀矿石英脉矿石和含矿热液石英脉中的石英流体包裹体进行了研究。结果表明,海塔地区混合岩型铀矿的成矿作用可分为2个阶段:早期混合岩化热液成矿阶段为高温、中低盐度流体,流体包裹体均一温度集中在380~540℃,盐度变化范围为16.15%~23.18%NaCl eqv,是区内铀成矿的主要阶段;晚期热液叠加改造成矿阶段为中低温、低盐度流体,流体包裹体均一温度集中在140~220℃,盐度变化范围为5.56%~23.18%NaCleqv,是区内富铀矿的形成阶段。流体包裹体的气相成分测试表明,长英质脉矿石石英包裹体中以CH4、CO2为主,其次为H2O和N2;而富晶质铀矿石英脉及含矿热液石英脉石英包裹体中以H2为主,部分含有CO2、CH4、H2O。氢、氧同位素研究表明,早期混合岩化成矿阶段的成矿流体可能为岩浆水与变质水的混合,而晚期热液叠加改造成矿阶段成矿流体中可能有大气降水的加入。  相似文献   
2.
Evapotranspiration (ET) is an important parameter in hydrologic processes and modelling. In agricultural watersheds with competing uses of fresh water including irrigated agriculture, estimating crop evapotranspiration (ETc) accurately is critical for improving irrigation system and basin water management. The use of remote sensing-based basal crop coefficients is becoming a common method for estimating crop evapotranspiration for multiple crops over large areas. The Normalized Difference Vegetation Index (NDVI) and the Soil Adjusted Vegetation Index (SAVI), based on reflectance in the red and near-infrared bands, are commonly used for this purpose. In this paper, we examine the effects of row crop orientation and soil background darkening due to shading and soil surface wetness on these two vegetation indices through modelling, coupled with a field experiment where canopy reflectance of a cotton crop at different solar zenith angles, was measured with a portable radiometer. The results show that the NDVI is significantly more affected than the SAVI by background shading and soil surface wetness, especially in north–south oriented rows at higher latitudes and could lead to a potential overestimation of crop evapotranspiration and irrigation water demand if used for basal crop coefficient estimation. Relationships between the analysed vegetation indices and canopy biophysical parameters such as crop height, fraction of cover and leaf area index also were developed for both indices.  相似文献   
3.
This study considered the possibility of using visible and near infrared (VNIR) spectral absorption feature parameters (SAFPs) in predicting the concentration and mapping the distribution of heavy metals in sediments of the Takab area. In total, 60 sediment samples were collected along main streams draining from the mining districts and tailing sites, in order to measure the concentration of As, Co, V, Cu, Cr, Ni, Hg, Ti, Pb and Zn and the reflectance spectra (350–2500 nm). The quantitative relationship between SAFPs (Depth500nm, R610/500nm, R1344/778nm, Area500nm, Depth2200nm, Area2200nm, Asym2200nm) and geochemical data were assessed using stepwise multiple linear regression (SMLR) and enter multiple linear regression (EMLR) methods. The results showed a strong negative correlation between Ni and Cr with Area2200nm, a significant positive correlation between As and Asym2200nm, Ni and Co with Depth2200nm, as well as Co, V and total values with Depth500nm. The EMLR method eventuated in a significant prediction result for Ni, Cr, Co and As concentrations based on spectral parameters, whereas the prediction for Zn, V and total value was relatively weak. The spatial distribution pattern of geochemical data showed that mining activities, along with the natural weathering of base metal occurrences and rock units, has caused high concentrations of heavy metals in sediments of the Sarough River tributaries.  相似文献   
4.
陈震霆  孙晓兵  乔延利 《遥感学报》2018,22(6):996-1004
在卫星海洋遥感中,云作为海气耦合系统最重要的调节器之一,其检测结果对海洋上空云微物理特性的反演精度有较大影响。因此,快速而准确识别海洋上空的云像元是卫星遥感数据处理过程中首要解决的关键问题。以PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar)卫星搭载的POLDER3载荷遥感数据为研究对象,提出一种改进的海洋上空云检测方法。首先剔除海洋耀光;接着利用有云与晴空区近红外反射率差异检验识别有云像元,并利用偏振反射率检验进一步识别低反射率的云像元;然后利用近红外与可见光反射率比值检验识别晴空像元;最后建立多角度云检测结果空间融合规则,重新标记有云、晴空和未定像元。以印度洋海区为例进行实验分析,将云检测结果与Buriez方法进行对比,发现检测精度基本相当,而有云像元的识别速度却平均提高约3倍。结果表明:该方法能有效的检测出海洋上空的云像元,满足业务化数据处理的高精度及时效性要求,为后续云微物理特性反演提供可靠的数据源。  相似文献   
5.
山地叶面积指数反演理论、方法与研究进展   总被引:2,自引:0,他引:2  
江海英  贾坤  赵祥  魏香琴  王冰  姚云军  张晓通  江波 《遥感学报》2020,24(12):1433-1449
叶面积指数LAI(Leaf Area Index)是表征叶片疏密程度和冠层结构特征的重要植被参数,在气候变化、作物生长模型以及碳、水循环研究中发挥着重要作用。遥感是获取区域及全球尺度LAI的一个重要手段,当前LAI产品主要基于遥感数据反演得到,但是多数LAI产品算法并未考虑地形特征的影响,导致山地LAI遥感反演精度不确定性大。提高山地LAI遥感反演精度亟需考虑地形因子对冠层反射率的影响,其中山地冠层反射率模型和遥感数据地形校正是提升山地LAI遥感反演精度的关键。本文围绕山地LAI遥感反演理论与方法,综合分析了国内外山地冠层反射率模型和地形校正模型的研究进展,总结了目前山地LAI遥感反演存在的问题,并讨论了未来研究的发展趋势。  相似文献   
6.
Determining sediment provenance allows a better understanding of fluvial palaeo-dynamics, and identifying involved watersheds, at broad spatio-temporal scales. Conventional approaches for source identification are usually based on the physical, mineralogical, geochemical, magnetic or isotopic properties of sediments. Rapid, non-destructive and, in well-established contexts, highly accurate, mid-infrared spectroscopy is an alternative method for investigating sediment sources. The present research objectives are: (i) to use the mid-infrared spectroscopy method to discriminate the provenance of fine sediments, by applying discriminant analysis on a large set of reference samples from three different watersheds in the Upper Rhine area (associated with the Rhine, Ill and Vosges tributaries); (ii) to clarify whether the provenance spectra signatures are influenced by riverine depositional contexts (bars versus banks) and, to some extent, by grain size and/or high organic matter content; and (iii) to apply the mid-infrared spectroscopy – discriminant analysis method to a study of fluvial palaeo-dynamics and determine the provenance of palaeo-channel infillings. Three main sedimentary sources, divided into eight sub-categories, have been characterized by 196 modern reference samples from 78 collecting sites. Discriminant analysis displayed a strong separating power by classifying correctly the origin of samples without any inter-group overlap, independently from the geomorphological context (bar or bank) and associated slight changes in organic matter contents or grain size. Mid-infrared spectroscopy – discriminant analysis investigations of the palaeo-channel infill, complemented by radiocarbon dates and mineralogical data, allowed reconstructing general trends for the local morpho-sedimentary dynamics over the last ca 12 millennia.  相似文献   
7.
拉曼光谱是一种快速无损的分析手段,它既可观察样品的显微结构构造,也可分析样品的成分和结构。为了丰富多金属结核的岩石矿物学特征,文章对西太平洋某海山区的多金属结核样品进行了X射线粉末衍射分析和拉曼光谱分析。X射线分析结果显示该区域样品主要含有水羟锰矿、钡镁锰矿、斜长石、钙十字沸石和石英,显微构造主要有纹层状构造、柱状构造、树枝状构造、充填构造等。通过分析对比潮湿样品和烘干样品铁锰质矿物的拉曼特征谱峰,得出结核中水羟锰矿的特征谱峰位于490 cm~(-1)、570 cm~(-1)和626 cm~(-1)附近,钡镁锰矿的特征谱峰则位于640 cm~(-1)附近,与陆地上对应矿物的特征拉曼谱峰不同。结核中的钡镁锰矿结构不稳定,经过风干或者抛磨后部分产生相变,不同显微结构中,相变情况不同。经与RRUFF数据库比对,识别出钙十字沸石、斜长石等自形晶,多分布于结核最内层,往结核外层总体减少。矿物微晶多见铁锰质矿物微晶和钙十字沸石微晶,铁锰质矿物绕其向外生长。  相似文献   
8.
基于EOF分析对南海西北海域水体光谱特性的研究   总被引:1,自引:0,他引:1  
This study presents an analysis of the spectral characteristics of remote sensing reflectance(R_(rs)) in northwestern South China Sea based on the in situ optical and water quality data for August 2018.R_(rs)was initially divided into four classes,classes A to D,using the max-classification algorithm,and the spectral properties of whole R_(rs) were characterized using the empirical orthogonal function(EOF) analysis.Subsequently,the dominant factors in each EOF mode were determined.The results indicated that more than 95% of the variances of R_(rs) are partly driven by the back-scattering characteristics of the suspended matter.The initial two EOF modes were well correlated with the total suspended matter and back-scattering coefficient.Furthermore,the first EOF modes of the four classes of R_(rs)(A-D R_(rs)-EOF_1) significantly contributed to the total variances of each R_(rs) class.In addition,the correlation coefficients between the amplitude factors of class A-D R_(rs)-EOF_1 and the variances of the relevant water quality and optical parameters were better than those of the unclassified ones.The spectral shape of class AR_(rs)-EOF_1 was governed by the absorption characteristic of chlorophyll a and colored dissolved organic matter(CDOM).The spectral shape of class B R_(rs)-EOF_1 was governed by the absorption characteristic of CDOM since it exhibited a high correlation with the absorption coefficient of CDOM(a_g(λ)),whereas the spectral shape of class C R_(rs)-EOF_1 was governed by the back-scattering characteristics but not affected by the suspended matter.The spectral shape of class D R_(rs)-EOF_1 exhibited a relatively good correlation with all the water quality parameters,which played a significant role in deciding its spectral shape.  相似文献   
9.
采用荧光光谱区域体积积分法定量研究洱海沉积物有色可溶性有机物(CDOM)三维荧光空间分布特性,结果表明,洱海沉积物CDOM中类腐殖酸组分占比最高(44.5%~74.2%),其次为溶解性微生物代谢产物(10.7%~20.4%)和类富里酸物质(8.19%~19.7%),而类蛋白组分占比最低,类腐殖酸占比与H/C和N/C均呈显著负相关;南部湖心平台区域沉积物类富里酸和类蛋白组分占比较高,其CDOM自生源占比较高;北部水生植物分布区溶解性微生物代谢产物占比较高,CDOM陆源性较强;中部深水区及南北湖湾区域类腐殖酸占比较高,随水深增加沉积物CDOM自生源特征增强.随沉积物深度增加类腐殖酸和溶解性微生物代谢产物占比呈下降趋势,类富里酸占比呈上升趋势,CDOM自生源特征增强,脂肪化程度增高.随湖泊富营养化程度增加沉积物CDOM受微生物代谢产物影响增强,陆源性增加,而自生源性降低,湖泊沉积物CDOM具有富营养化指示意义.  相似文献   
10.
为探究海湾扇贝(Argopecten irradians)、栉孔扇贝(Chlamys farreri)、虾夷扇贝(Patinopecten yessoensis)三种扇贝闭壳肌的挥发性风味物质差异,采用气相色谱-离子迁移谱(gas chromatography-ion mobility spectroscopy,GC-IMS)技术,对三种扇贝闭壳肌在新鲜(40℃)和加热(100℃)情况下进行挥发性成分分析。结果表明:在新鲜状态下,海湾扇贝(HWSB-F)、栉孔扇贝(ZKSB-F)、虾夷扇贝(XYSB-F)闭壳肌中,共定性出27种挥发性风味物质,其中醛类8种,醇类5种,酮类5种,酯类3种,以及醚类、苯类、酸类、烯类和噻唑等。在加热情况下,海湾扇贝(HWSB-C)、栉孔扇贝(ZKSB-C)、虾夷扇贝(XYSB-C)闭壳肌中共定性出52种挥发性风味物质,其中醛类20种,酯类5种,酮类7种,醇类8种,烯类4种,酸类2种,醚类2种,还包括吡嗪、胺类、苯类、含氧杂环等物质。对三种扇贝闭壳肌新鲜组和加热组指纹图谱进行分析,发现新鲜扇贝原有的挥发性风味物质加热后减少,且产生了新的其他种类的挥发性风味物质。扇贝闭壳肌加热组的挥发性风味物质种类较多,组成比较复杂,新鲜组的扇贝闭壳肌挥发性风味物质种类较少,组成简单。通过主成分分析,可在新鲜状态和加热状态下,有效区分三种扇贝闭壳肌组织。三种扇贝闭壳肌挥发性风味物质指纹图谱的建立,丰富了不同扇贝呈味物质的组成成分研究内容,证明GC-IMS技术可快速鉴别三种去壳扇贝闭壳肌的种类,为不同种扇贝闭壳肌以次充好提供检测依据。  相似文献   
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