Robust multivariate procedures applied to the interpretation of atypical individuals of a Cretaceous foraminifer

Robust multivariate statistical methods are applied to samples of the Cretaceous bolivinid foraminifer Afrobolivina afra, in which individuals from microspheric and megalospheric generations dominate, but which also contain some pseudo-megalospheric specimens. Pseudo-megalospheric tests may cause values which are atypical in the statistical sense but which are fully normal biologically. Other atypical values derive from crushed specimens, microspheric individuals and unusual normal megalospheres with exceptionally wide shells and pointed last chambers. A wrongly punched specimen was also found by the procedure. The method employed here consists of plotting the generalized statistical distances calculated from robust estimates of means and of covariances against the quantiles of a Gaussian distribution; the presence of an atypical observation(s) is readily exposed by its departure from the main trend of the plot.     

基于多元非线性回归和BP神经网络的滑坡滑动距离预测模型研究

滑坡灾害严重威胁着人类的生命财产安全, 对土地资源造成了一定影响。滑坡滑动距离直接表明了滑坡的冲击、堆积范围大小, 是估算滑坡受灾面积、评估滑坡潜在风险的重要参数, 也是滑坡防灾减灾工作中需要重点关注的指标。为了更准确高效地预测滑坡危害范围, 分别采用多元非线性回归和BP神经网络2种模型对影响滑坡滑动距离的因子进行了评估和建模, 并对天水地区的滑坡实例进行研究。研究结果表明, 2种模型均可用于滑坡滑动距离的预测。相较而言, BP神经网络的预测结果与实际情况有更高的拟合度, 准确性更高。     

论油气资源的多元勘探

油气资源勘探的常规方案大致是普查—详查—细测、物探—地质—钻井等。本研究团队在前人研究与应用基础上,经过多年的资源勘探实践,逐步形成了油气资源的多元勘探理论。该理论体系是由受控区域构造不同地质时代构造运动叠合作用下的多构造属性单元、不同油气属性特征的目标单元、不同物源属性的多学科多尺度地球物理勘探单元,以及不同作用的地球物理方法技术单元等所组构。本文以松辽盆地滨北地区、佳伊断裂上的汤伊地堑带为例论述了该勘探理论。松辽盆地自古生代至中新生代受控于古亚洲洋、蒙古—鄂霍茨克洋、西太平洋构造域的顺时针以挤压应力场为主的作用,同时该应力场作用具有一定的叠合表现。由区域地球物理、精细地球物理、石油地质、岩石物理、计算地球物理等不同学科的联合研究,对深层、探查程度低的油气新层系新领域目标进行了多尺度方法技术探查,最终提出目标区的油气性新认识。上述勘探新理论的建立延展了油气勘探思路,补充了已有的勘探方案,同时这一勘探理论也有益于固体矿产资源的探查。     

Identifying sources and hazardous risks of heavy metals in topsoils of rapidly urbanizing East China

With rapid economic and social development, soil contamination arising from heavy metals has become a serious problem in many parts of China. We collected a total of 445 samples (0–20 cm) at the nodes of a 2 km×2 km grid in surface soils of Rizhao city, and analyzed sources and risk pattern of 10 heavy metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn). The combination of Multivariate statistics analysis and Geostatistical methods was applied to identify the sources and hazardous risk of heavy metals in soils. The result indicated that Cr, Ni, Co, Mn, Cu, and As were mainly controlled by parent materials and came from natural sources. Cd and Hg originated from anthropogenic sources. Pb and Zn, belonging to different groups in multivariate analysis, were associated with joint effect of parent materials and human inputs. Ordinary Kriging and Indicator Kriging suggested that single element and elements association from the same principal components had similar spatial distribution. Through comprehensive assessment on all elements, we also found the high risk areas were located in the populated urban areas and western study area, which could be attributed to the higher geological background in the western part and strong human interference in the eastern part.     

长岛周边海域浮游植物分布及其环境影响因素

2013年春季和夏季对长岛周边海域进行了环境与生物综合调查,利用多元统计分析对长岛周边海域浮游植物分布及其影响因素进行分析。根据水环境分析结果对调查海域进行聚类分析,结果表明,春季(M1、M2)与夏季(A1、A2)均可分为两大类。M1与A2为高温高营养盐区,M2与A1为低温低营养盐区。调查期间,共发现69种浮游植物。硅藻为两季主要浮游植物,春季浮游植物细胞丰度远大于夏季。春季共发现1种明显的优势种,为柔弱几内亚藻(Guinardia delicatula(Cleve)Hasle)。夏季共发现5种优势种,分别为具槽帕拉藻(Paralia sulcata)、裸甲藻(Gymnodinium sp.)、圆筛藻(Coscinodiscus sp.)、离心列海链藻(Thalassiosira eccentrica)与具齿原甲藻(Prorocentrum dentatum)。影响春季浮游植物分布的最佳解释变量组合为温度(WT)、透明度(SD)、风速(WS)和溶解总碳(DTC)组合,其中,温度影响最显著(极显著负相关);夏季则为盐度(S)、活性磷酸盐(SRP)和N/Si组合,其中活性磷酸盐影响最大(显著负相关)。     

Distribution of Biological Activity in the Lower St Lawrence Estuary as Determined by Multivariate Analysis

Three stations located in the Laurentian Trough were investigated three times during the summer production maximum (in June-July 1990; COUPPB90-1 cruise). A range of multivariate analyses was carried out to extract major physical-biological features in a large data set covering the whole cruise. This study presents the advantages of combining conventional principal component analysis (PCA) with a three-way data analysis. PCA provides the centre of gravity of the different locations for each variable and each sample during the cruise without temporal information. Three-way data analysis produces the trajectory of the different site/time locations for each variable and each sample, and clarifies spatial and temporal relationships between variables. The results reproduce the main patterns of the lower St Lawrence Estuary during the summer plankton bloom and indicate an upstream movement of warm and less saline waters associated with surface production. Apparently these large changes at the surface are not reflected in the deeper layers. Cluster analysis suggests that autotrophic and heterotrophic activities are decoupled when production is low and are correlated only when production increases.     

The influence of bank strength on channel geometry: an integrated analysis of some observations

Bank strength exerts a significant influence on river channel geometry, but quantification of this relationship has been limited to only a few specific circumstances. This is due to both the complex nature of bank strength and the difficulty in incorporating its influence in river channel geometry relations. In order to undertake an integrated analysis of wide-ranging field observations, this study applies a recently developed multivariate model of channel geometry. When the banks of a number of laterally stable streams are categorized on the basis of the bank sediment and vegetation, the multivariate model yields numerical indices of bank strength. Within the range of the data analysed, bank strength can produce a three-fold change in channel width and a two-fold change in depth corresponding to about a 1·6-fold change in cross-sectional area. © 1998 John Wiley & Sons, Ltd.     

Benthic Communities of the lnfralittoral in the N. Sporades (Aegean Sea): a Variety of Biotopes Encountered and Analysed

Abstract. The infralittoral benthos was studied on three islands of the Northern Sporades in the Aegean Sea. Thirteen stations were sampled on both hard and soft substrata and 408 taxa were identified, some of zoogeographical interest. Multivariate statistical methods such as classification, ordination and Similarilies Terms Analysis were combined with existing ecological information to delineate the various communities present and to point to the indicator species characterising them. The communities were then defined using the indicator species and their affinities to typical biocoenoses. The main factor responsible for the observed distribution proved to be the type of substratum (algal cover or sediment type), which reflects the light and hydrodynamic conditions. The observed bathynietric zonation was similar lo that of the Balearic Islands in the western Mediterranean.     

北京东郊722土壤垂向剖面重金属污染的磁学响应及其统计意义

对北京城东附近某苗圃内典型的土壤污染剖面进行了环境磁学和地球化学分析,发现某些重金属(Pb、Zn、Sr、Ba、Cu)和磁性参数呈现相同的垂向变化趋势,都在37cm以上显示高值区,磁化率均值达到192.02×10-8m3/kg,如Pb含量达到67.62mg/kg,而在37cm以下,明显属低值区,磁化率均值只有18.38×10-8m3/kg,Pb含量也只有23.43mg/kg.借助于指标聚类分析和主成分分析方法,揭示出各种指标之间的内在联系,表明磁参数与Pb、Zn、Sr、Ba、Cu等元素显著相关,彼此的相关系数都达到0.90以上,属于同一类别的隶属度在80%以上,说明磁指标可以作为这些重金属污染的一种代用指标.利用模糊C均值聚类分析分辨出了土壤上部污染物堆积层和下部未污染土壤背景2种不同的特征段.     

Universal cokriging under intrinsic coregionalization

Under the intrinsic coregionalization model if both primary and secondary measurements are available at all sample locations, the conventional geostatistical wisdom is that cokriging provides exactly the same solution as univariate kriging on the primary process alone. However, recent eamples have been given where nonzero secondary cokriging weights have accurred under this spatial dependence structure. This note identifies the conditions under which secondary information is useful under the assumption of intrinsic coregionalization. An illustration is given using a dataset of plutonium and americium concentrations collected from a region of the Nevada Test Site.