珠江口沉积物主元素的组成分布特征及其地化意义

Characteristics of major elements' constitutions and distributions in sediments of the Lingdingyang in the Pearl River Estuary and their geochemical implication

根据1999年夏季采集的沉积物样品,采用X射线荧光法对珠江口沉积物中10种主元素质量分数进行了分析.与长江口和黄河口相比,珠江口沉积物Al、Fe等元素质量分数高,Ca、P等元素质量分数低,反映了"气候控制效应"、区域地质背景和河口类型对沉积物主元素质量分数的影响.Al、Fe、Ti、P、Mn和K等主要在伶仃洋西部和最大混浊带附近富集.Si的分布趋势与Al、Fe、Ti等基本相反.Ca、Sr、Na和Mg等在口外近海质量分数高.物质来源的差异、水动力环境的不同是造成主元素平面分布方式的主要原因.与重金属相比,大部分主元素在珠江口的垂直分布形式较简单.相关分析和因子分析结果均显示出Si、Al、Fe、Ti、P、Mn、K的陆源特征和Na、Mg、Ca、Sr的海源特征.聚类分析结果表明,研究区站位可分为4类,这种元素地球化学分区反映了珠江口不同区域沉积环境和主元素分布的特点.

According to the sediments collected in summer of 1999,ten major elements of sediments in the Pearl River Estuary were analyzed by using XRF method. Comparing with the Yangtse Estuary and the Huanghe Estuary, the contents of Al and Fe are higher, but the contents of Ca and P are lower in the Pearl River Estuary, indicating that climates, geologic backgrounds and types of estuaries influence the contents of major elements in estuarine sediments. Al, Fe, Ti, P, Mn and K are mainly enriched in the west part of Lingdingyang and in the Turbidity Maximum Zone. The distribution of Si is contrary to Al, Fe and Ti. The contents of Ca, Sr, Na, Mg are higher in the outside of the estuary. The difference of element sources and hydrodynamic conditions are the main reasons causing this distribution of major elements. Correlation analysis and factor analysis show that Si, Al, Fe, Ti, P, Mn, K are originated from terrestrial source and Na, Mg, Ca, Sr are mainly derived from marine source. Clustering analysis indicates that the sampling stations may classified into four groups which basically reflected the characteristics of sedimentation environments and distributions of major elements in Pearl River Estuary.