Historical analysis of heavy metal pollution in three estuaries on the north coast of Galicia (NW Spain)     

F. Lorenzo  A. Alonso  M. J. Pellicer  J. L. Pagés  M. Pérez-Arlucea 《Environmental Geology》2007,52(4):789-802

This research focuses on the development of metal pollution in sediment cores from three estuaries in Northwest Spain: Viveiro, Ortigueira and Barqueiro. Pb, Cu, Co, Cr, Cd and Zn and total organic carbon were assessed using principal component analysis (PCA) in order to obtain background values, measure pollution levels and identify pollution sources. Results were interpreted by considering the local industrial history, grain size and C/N relationship. The pollution levels obtained bear a strong resemblance to those documented for of a moderately industrialised area. PCA identifies factors that reflect mainly temporal associations with metals. Sedimentation rates between 0.9 and 1.1 cm/year were determined. In Viveiro core levels of Cr pollution are associated with tanneries. In Ortigueira, high core levels of Cu and Co are linked to mining, and Cr levels to adjacent ultramafic rocks. Erosion of Holocene sediment causes high values of Co and Cr in the Barqueiro core. Cu increase in the three estuaries is related to fungicide use since 1910. Sea level rise appears to be affecting the marine characteristics of the sediments in Barqueiro. In Viveiro, the nature of the sediment reflects engineering work and land reclamation.  相似文献   

基于最小噪声分离变换的遥感影像融合方法   总被引：4，自引：0，他引：4  

顾海燕  李海涛  杨景辉 《国土资源遥感》2007,18(2):53-55

针对主成分分析（PCA）融合算法的不足和最小噪声分离（MNF）变换的优势，以IKONOS新型高分辨率观测卫星提供的全色和多光谱数据为实验数据，提出了基于最小噪声分离变换的遥感影像融合方法，并与其它融合方法进行定量和视觉比较，结果表明该方法能得到更好的融合效果。  相似文献   

一种运用纹理和光谱特征消除投影差影响的建筑物变化检测方法     

袁修孝  宋妍 《武汉大学学报(信息科学版)》2007,32(6):489-493

针对不同时期高分辨率遥感影像变化检测中城区建筑物因投影差差异所产生的误检测现象,提出了一种综合应用光谱和纹理特征的建筑物变化检测方法。以变化和未发生变化地物影像的散度作为可分性依据,首先对光谱差分影像在混合高斯密度模型下建模,并采用马尔可夫最小错误概率准则提取初始变化区域,往往含有错判的建筑物。然后将误判建筑物影像类和真实变化影像类构成训练集,通过引入多通道Gabor滤波器,提取训练集的纹理差分特征,并采用分类别PCA变换实施纹理差分特征的选择。最后对选择出的纹理差分特征依据高斯混合密度模型建模,并用马尔可夫最小错误概率提取真变化区域,即可去除光谱信息检测所产生的伪变化。试验表明,本文方法能够较好地解决建筑物变化的错判问题,提高了影像变化检测的精度。  相似文献   

SHALLOW SEAWATER DEPTH RETRIEVAL BASED ON BOTTOM CLASSIFICATION FROM REMOTE SENSING IMAGERY     

PANGLei ZHANGMing-bo ZHANGJi-xian ZHENGZhao-qing LINZong-jian 《中国地理科学(英文版)》2004,14(3):258-262

Remote sensing technique, replacing conventional sonar bathymetry technique, has become an effective complementary method of mapping submarine terrain where special conditions make the sonar technique difficult to be carried out. At the same time, as one kind of data set, multispectral remote sensing data has the disadvantage of being influenced by the variable bottom types in shallow seawater, when it is applied in bathymetry. This paper puts forward a new method to extract water depth information fi‘om multispectral data, considering the bottom classification and the true water depth accuracy. That is the Principal Component Analysis (PCA) technique based on the bottom classification. By the least square regression with significance, the experiment near Qingdao City has obtained more satisfactory bathymetry accuracy than that of the traditional single-band method, with the mean absolute error about 2.57m.  相似文献   

基于PCA的井间地震偏振分析方法及其应用     

金聪  林松  邓小虎  程飞  程邈 《大地测量与地球动力学》2021,41(12):1300-1305

基于主成分分析(principal component analysis, PCA)方法构建理论模型进行三分量地震偏振分析试算,获得较准确的检波器的水平方位角和垂直倾角,然后对地震响应进行坐标旋转,从而校正检波器方向。将该方法应用于跨孔井间弹性波波速测试,对实测资料进行偏振分析可知,初至P波与初至S波分别在H_P分量和R分量中得到加强,不仅有利于初至起跳的拾取,还可以获得较准确的波速资料,为岩土工程设计提供更精确的动力学参数。  相似文献   

南洛河流域洛南盆地表土孢粉与植被的关系(英文)     

张文超  李春海  鹿化煜  田先华  张红艳  雷昉  唐领余 《地理学报(英文版)》2014,24(3):427-445

The catchment of South Luohe River in Central China is an important region for investigating modern pollen-environment relationship, because it is located in the transitional zone between south and north China, an environment which is sensitive to climate changes. In this study, 40 surface samples under ten vegetation types were collected to reveal the relationship between pollen assemblages and vegetation. The results show that the surface pollen assemblages reflect the vegetation quite well. In forest topsoils, the average of arboreal pollen content is greater than 40%, and the Selaginella sinensis spore is high. As to sparse forest grassland and shrub community, the average arboreal pollen is 13.2% and 16.6% respectively, and the shrub pollen is relatively higher than that of grassland samples. The grassland and farmland are characterized by low percentage of tree and shrub pollen(<10% and <1%), and high percentage of herbs(>80%). Pinus, Quercus and some other arboreal pollen can indicate the regional vegetation because of their dispersal ability. Quercus pollen is under-representative and so is Pinus. Artemisia pollen is significantly over-represented, has poor correlation with the plant coverage, and may reflect human disturbance. Gramineae can indicate plant quite well, but with low representation. High content of Chenopodiaceae probably suggests human impact. Predominant Selaginella sinensis can be used as an indicator of forest environment. Cluster analysis and principal components analysis of pollen assemblages can distinguish forest and non-forest vegetation well. The former method is better at separating pine and mixed forests, while the latter is more stable and could better differentiate farmland and other non-forest area. The first axis of PCA mainly reflects the humidity.  相似文献   

1993—2011年北大西洋与北太平洋的波浪变化及其原因探究     

石永芳  杨永增  吴克俭  尹训强 《海洋与湖沼》2014,45(4):685-694

基于1993—2011年的7套卫星高度计数据,分析北大西洋和北太平洋的波浪变化趋势;利用NCEP/NCAR提供的月平均风场及SLP(Surface Level Pressure)数据,分析风场和SLP的空间变化特征,并通过主成分分析进一步考察了波浪变化与SLP的相关关系。结果表明:北大西洋波浪变化趋势的空间分布呈偶极子形态,西南区域为增大趋势,东北区域为减小趋势;而北太平洋波浪变化的主要特征是在中纬度带呈明显的减小趋势;比较而言,波浪变化趋势的空间形态与SLP变化的空间分布特征更接近,波浪主要模态的空间分布及时间系数与SLP距平场的震荡特征十分吻合,大尺度背景场SLP的变化对波浪的长期变化趋势有重要的影响。  相似文献   

基于SPEI的1960—2018年赣江流域干旱特征          下载免费PDF全文

刘喆玥  韩会明  赖亮  杨立苑  胡丽丽 《气象与减灾研究》2021,44(2):133-140

基于赣江流域39个气象站点逐月降水和气温数据,计算不同时间尺度标准化降水蒸散发指数(SPEI),采用Mann-Kendall突变检验、主成分分析(PCA)等方法,分析了赣江流域1960—2018年干旱时空变化特征.研究表明:不同时间尺度SPEI均有微弱升高的趋势,干旱形势有所缓解,SPEI能够较好地表征赣江流域旱涝情况.赣江流域中部的轻旱和特旱发生频率要高于其他地区,中旱主要高发地区主要分布在南部和西部区域,重旱主要集中在东部和北部.赣江流域干旱的空间分布具有较好的一致性,旱涝变化整体保持一致,南部与北部旱涝状态存在相反的纵向差异,且中部与南部、北部旱状况涝存在空间差异.  相似文献   

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伍吉仓  孙亚峰  刘朝功 《大地测量与地球动力学》2008,28(4):97-101

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Geochemical Characteristics and Sources of Some Chemical Components in Sediments of Zhuiiang（Pearl） River Estuary     

周怀阳彭晓彤  潘建明 《中国海洋湖沼学报》2004,22(1):34-43

Sediment cores with length of 25 - 45cm at 12 stations in Zhujiang(Pearl) River Estuary were sampled in summer of 1999. Chemical components (Al2O3 , Fe2O3, CaO, TiO2, Cu, Pb, Cr, Zn, Co, Ni, V, Ba, Sr and Y) and grain sizes were analyzed. Sediments in Zhujiang River Estuary are characterized by relatively coarse grain size. The grain sizes of the sediments in the area outside the estuary are relatively finer than those in the north part of the estuary but coarser than those in the middle of Lingdingyang and have a trend similar to the spatial distribution trend of some chemical components such as Fe2O3, Al2O3, TiO2, V, Cu, Ni, Zn and Y. This showed that grain size is an important factor that controls the spatial distribution and depth profile of chemical elements in the Zhujiang River Estuary. Frequent re-suspension, re-transportation and redistribution of settled sediment on estuary floor could be deduced from the spatial distributions and depth profiles of chemical components. Except for CaO and Sr, the chemical components always enrich at the west side of, in the middle of, and at the north side of, the estuary. Fe2O3, Al2O3, Ti, V, Cr, Ni, Zn, Cu and Y in Zhujiang River Estuary sediments mainly result from rock and soil weathering except that parts of Cr, Ni, Zn Cu and Y are anthropogenic. CaO and Sr in sediments originate from marine source. Although Co as well as Pb derives from anthropogenic sources, human activities related to Co might differ from the activities related to Pb.  相似文献