苏北废黄河三角洲海域表层沉积物粒度的空间变异和分布特征

Spatial variability characteristics of sediment grain size in sea area of the abandon Yellow River Delta,north of Jiangsu Province

在苏北废黄河三角洲海域采集了266个表层沉积物样品,经粒度分析获得各样品粘土、粉砂和砂3种粒级组分的质量百分数,在此基础上运用地统计学方法和GIS软件分析了粘土、粉砂和砂3种粒级组分的空间变异特征,根据空间变异特征研究结果,用Kriging插值方法绘制了各粒级组分的空间分布图.结果表明:废黄河三角洲表层沉积物中砂组分具有较强的空间自相关性,其自相关距离为30.5 km;粘土和粉砂具有中等的空间自相关性,其自相关距离分别为40.3 km和13.8km.在大于17.0 km的尺度上,3种粒级组分的空间变异性表现出明显的各向异性特征,且以NE55°和SE145°两组相互垂直的方向上差异最为明显,这是由于波浪、潮流等因素作用所引起的沉积物离岸梯度变化造成的.制图结果显示,废黄河三角洲表层沉积物3种粒级组分的空间分布状况,粘土表现为近岸低、远岸高;砂表现为近岸高、远岸低,高值区主要在河口附近;粉砂表现为均匀性特征.

A total of 266 surface sediment samples were collected from sea area of the abandon Yellow River delta,north of Jiangsu province in October,2013,and the quality percentage of different grain size components（sand,silt and clay） for each sample was also obtained in the laboratory.A geostatistics method,combined with the Geographic Information System（GIS）,was used to analyze spatial variability characteristics of the sand,silt and clay,and Kriging interpolation was used to draw the spatial distribution maps of each grain size components.Results show that sand had a relatively high strong spatial autocorrelation with range of autocorrelation extending to about30.5 km.In comparison,clay and silt had a middle strong spatial autocorrelation with ranges of around 40.3 km and 13.8 km,respectively.The spatial variability of different grain size components was apparent in isotropy within the maximum extent of 17.0 km,beyond which their anisotropy was increasing,especially between the perpendicular directions of NE40° and SE130°.The spatial distribution of 3 grain size components interpolated through Kriging based on the fitted theoretical models depicted that clay was low in the near shore,high in the far shore and sand was high in the near shore,low in the far shore,with higher value areas around the estuaries.However,the silt distribution was in an uniformity characteristics.