Quantitative assessment of tidal wetlands using remote sensing

Effective management of tidal wetlands requires periodic data on the boundaries, extent, and condition of the wetlands. In many states, wetlands are defined wholly, or in combination with other criteria, by the presence of particular emergent halophytic plants. Many important characteristics of the wetlands ecosystem are related directly to the production of emergent plant material or may be inferred from knowledge of the distribution of emergent plant species. Remote-sensing techniques have been applied to mapping of the distribution of wetland vegetation but not to quantitative evaluation of the condition of that vegetation.Recent research in the tidal wetlands of Delaware and elsewhere has shown that spectral canopy reflectance properties can be quantitatively related to the emergent green biomass ofSpartina alterniflora (salt marsh cord grass) throughout the peak growing season (April through September, in Delaware). Periodic measurements of this parameter could be applied to calculations of net aerial primary productivity for large areas ofS. alterniflora marsh in which conventional harvest techniques may be prohibitively time consuming. The method is species specific and, therefore, requires accurate discrimination ofS. alterniflora from other vegetation types. Observed seasonal changes in species spectral signatures are shown to have potential for improving multispectral categorization of tidal wetland vegetation types.     

氮沉降与生物炭对土壤可溶性有机质的影响

利用盆栽实验，探讨氮沉降与生物炭（BC）施用对杉木幼苗土壤可溶性有机碳（DOC）含量和可溶性有机质（DOM）光谱学特征的短期影响.氮沉降处理为0（对照）、40（低氮）和80kgN/（hm²·a）（高氮），在不同氮沉降下BC施用水平分别为0（对照）、12（低量BC）和36t/hm²（高量BC）.结果表明：相比对照处理，单独低氮与单独高氮处理3个月后土壤pH值分别下降了0.06和0.09（P<0.05），但单独施用BC和氮沉降背景下施用BC处理的土壤pH值均呈上升趋势，增加了0.32~0.94（P<0.05）.与对照处理相比，单独低氮处理的土壤DOC含量显著降低，单独高氮处理的则显著升高且DOM结构趋于简单；单独施用BC和氮沉降背景下施用BC处理中，低量BC处理的土壤DOC含量无明显变化，但高量BC处理的显著提高了30.1%~95.6%，并且DOM结构趋于复杂.冗余分析发现，土壤pH值是导致不同处理DOM存在差异的关键因素.因此，氮沉降背景下施用高量BC短期内可以减缓土壤酸化，提高土壤DOC含量并使DOM更加稳定.     

浅析泥石流堆积物的光谱特征——以蒋家沟泥石流堆积物为例

运用 10 0 BXMTS野外光谱仪探测了小江支流蒋家沟新、老泥石流堆积物的光谱反射率 ,总结了新、老堆积物的反射光谱特性 ,分析了影响泥石流堆积物反射光谱特性的因素 (岩性、水分含量、植被覆盖 ) ,最后讨论了应用高空间分辨率遥感图像解译泥石流堆积物的可能性。     

昆仑山口西地震激发的地球环型振荡

利用中国数字地震台网(CDSN)改造后的7个台站3天的VHE、VHN波形资料,采用功率谱密度估计方法,在没有对资料进行去固体潮处理的情况下,提取了2001-11-14昆仑山口西地震激发的0T2～0T40地球环型自由振荡,并与地球初步参考模型(PREM)的理论自由振荡周期进行对比,发现环型振荡振型周期与PREM预测的环型自由振荡周期符合得很好。频率与PREM模型略微不一致的环型振荡振型可以解释为地球介质的横向不均匀性和各向异性所致。因此地球自由振荡信息可用于揭示地球的三维不均匀结构信息或各向异性信息,并可能对区分地幔对流模式(全地幔对流或上地幔对流)有所帮助。     

基于ASD和FISS的植被叶片氮素含量反演研究

地面成像光谱系统能够在更为微观的尺度上满足多元化应用需求,实现对植物群体、单个植株的快速精细探测,获取精细的植被生理参量的空间信息,从而弥补大尺度远距离遥感难以发挥作用的领域。本文采用ASD地物光谱仪和新型地面成像光谱系统FISS,以大豆叶片为研究对象,获取大豆叶片ASD光谱及FISS成像光谱数据,探讨大豆植株叶片的图像特征、反射率光谱、导数光谱、光谱指数等光谱特征变量与叶片氮素含量的相关性,建立植株叶片氮素含量的估算模型。研究结果表明：FISS地面成像光谱仪和ASD地面非成像光谱仪对氮素具有敏感指示的波段区间一致,480~520 nm和680~720 nm区间的波段范围与氮素含量具有较高的相关性;导数光谱特征所得精度要比原始光谱特征所得精度高,说明导数光谱对氮素含量的指示更为敏感,可以更加有效地提取氮素含量信息;反演模型对氮素含量反演精度的影响低于光谱特征对精度的影响。研究表明FISS数据由于其独特的测量方式和图谱合一的特点,可以更加准确地用于植被氮素含量的反演,实现植被叶片氮素含量的快速实时无损监测及图像可视化表达。     

辅以纹理特征的HJ-CCD海上溢油信息提取 ——以PL19-3溢油为例

鉴于依赖光谱特征的传统溢油信息提取方法面临信息提取精度低的困境,提出采用光谱特征与纹理分析结合的方法应用于溢油监测.选择位于渤海的蓬莱19-3油田溢油事故为研究对象,基于覆盖溢油事故阶段的8景30m分辨率HJ-CCD数据,在溢油目标提取过程中,引入了方向性纹理特征分析,将主成分光谱降维、方向梯度边缘检测等技术相结合,形成了基于光谱与纹理特征的溢油信息提取技术.所述方法经8组数据检验后,用类间分歧度方法进行了对比评价.结果表明:将纹理分析方法应用于溢油信息提取,类间分歧度提高到1.9999,提高了油膜影响边界和油膜厚度分区识别能力.     

基于冠层多维光谱的水稻镉污染胁迫诊断模型研究

鉴于镉对水稻各种生理特征参数的影响具有复杂隐蔽性,导致冠层光谱特征变化微小,需要采用一些方法增强和提取隐含在光谱中的污染弱信息.在水稻冠层高光谱数据和各种实测生化参数的支持下,利用主成分分析、独立分量分析和分形分析技术从高光谱遥感数据中提取镉污染弱信息,获取水稻镉污染敏感光谱因子,包括第一主成分F1、独立分量ICA1和光谱分维D.利用3个敏感因子分别构建水稻镉污染一维诊断模型,获得较好的诊断效果.进一步将3个光谱因子进行组合构建二维诊断模型和三维诊断模型,使污染胁迫诊断结果更稳定直观.     

石家庄地区大气细粒子增长特征初步研究

为研究石家庄地区大气细粒子的微物理特征,2010年5月在石家庄市气象局观测站,对大气颗粒物、NOx和SO2进行了外场观测.结果表明:石家庄地区粒径小于1.0μm的大气颗粒物中,0.01~0.1μm粒径范围的粒子所占比例高达89.3%,大气细粒子污染较为严重.0.01~0.02μm和0.02~0.1μm粒径范围的颗粒物具有大致相似的变化规律,且与0.1~1.0μm粒径范围的粒子数浓度变化趋势明显不同.通过对典型粒子增长事件的研究发现,0.01~0.02μm的粒子数浓度在上午8:00左右会急剧升高,并达到全天的最大值.其后,0.01~0.02μm的颗粒物粒径会不断增长,由于增长消耗,其数浓度会迅速下降,使得0.02~0.04μm的粒子数浓度在上午12:00前会迅速升高.通过对气象要素和污染气体的分析,发现在相对湿度较低、风速风向变化不大,太阳辐射增加的情况下,SO2气相成核参与颗粒物增长的可能性较大.     

Multiscale Indicators of Land Degradation in the Patagonian Monte,Argentina

Depletion of vegetation by overgrazing in arid environments has long-lasting effects on the environmental quality over extended geographic areas. An adequate inspection of habitat changes requires scaled up procedures that would allow assessing end-points of environmental status in broad areas that would be based on processes occurring at the plant canopy level. Our purpose was to find indicators of land degradation–conservation status for use in land monitoring programs and in planning management practices that would be amenable to further up-scaling for use with remotely sensed imagery. In several sites of the Patagonian Monte differing in the impact of grazing management, we evaluated vegetation attributes at three spatial scales. At the population scale, we found that the severity of grazing impact was characterized by the reduction of the palatable grass, P. ligularis, outside and inside shrub canopies. At the vegetation patch scale, we found that land degradation by domestic herbivore impact was characterized by changes in attributes of patch shape (radius, height, internal canopy cover) and patch abundance. At the plant community scale, we found that the structure of the plant canopy as described using Fourier analysis of cover data changed after long-term grazing impact consistently with the modifications in plant population and patch structures. We present a conceptual multiscale scenario of structural changes triggered by domestic herbivore impact, and quantitative indicators of plant structure and processes useful to develop management strategies of the Patagonian-Monte that would conserve its natural habitats. The developed end-points are also amenable for use in land conservation assessment through remotely sensed imagery.     

Multicolour spectral karyotyping for complex chromosomal rearrangements in repeated abortion or congenital anomalies

Advances in molecular cytogenetics, especially the technique of fluorescence in situ hybridization (FISH), have allowed more precise definition of chromosomal structures, which are difficult to identify using conventional G-banding. Recently, a novel approach based on hybridization of 24 fluorescent-labelled chromosome painting probes was developed, termed spectral karyotyping (SKY), which allows the simultaneous and differential colour display of all human chromosomes. We have used SKY to identify not only five parental complex translocation carriers but also minute chromosome rearrangements in the fetus. Here, we concentrate attention on the clinical application of SKY for prenatal diagnosis. Copyright © 2001 John Wiley & Sons, Ltd.