鸭绿江河口西岸潮间带柱状沉积物中重金属的分布特征及其对流域变化的响应

2010年和2011年在鸭绿江西水道和西岸潮间带共采集4根柱状样，通过对2mPb测年、粒度、总有机碳、重金属元素等多指标综合分析，探讨了：（1）鸭绿江河口西水道和西岸潮间带柱状沉积物中重金属的垂向分布及其来源：（2）重金属分布的粒度控制作用：（3）不同时期的粒度和重金属分布变化及其对流域变化的响应。结果表明：f1）Cu和zn可能来源于有机质降解的内源释放：Cr和Ni表征了岩石风化剥蚀形成陆源碎屑的自然来源：Cd和Pb反映了人类活动的影响。（2）除西岸潮间带的Cd和Pb含量可能部分受来源影响外，研究区的粒度效应是控制鸭绿江地区重金属含量分布的最主要因素。（3）粒度变化与流域演变密切相关，重金属含量对流域变化和人类活动响应明显，大致以1940年、1970年、1995年为界分为四个沉积阶段：1940年以前，自然演变对鸭绿江河口西岸潮间带的重金属分布控制明显，而1940年来至今，人类活动的控制作用日益凸显。

Distribution characteristics of intertidal sediment heavy metal of the western bank of the Yalu River,and its responses to catchment changes

Four sediment cores were collected at the western channel and the intertidal flats of the western Yalu River estuary in 2010 and 2011. We analyzed the 21~pb dating, grain size, total organic carbon （TOC）, and heavy metal contents through the core to investigate the spatial distribution patterns and the sources of heavy metals in the west of intertidal flats of the Yalu River estuary. Furthermore, we analyzed the effect of grain size on the distribution of heavy metal contents and discussed the responses of variation of grain size and heavy metal contents to catchment flow dynamic changes in different periods. Also, the principal component analysis （PCA） and cluster analysis were applied to analyze the origin of heavy metal. Our observations show that the heavy metal Cu and Zn may originate from organic matter degradation. On the other hand, the sources of Cr and Ni are dominated by the rock erosion while Cd and Pb reflect the impacts of human activities. Further analysis indicate that, the distribution of heavy metal in the entire study area is mainly dominated by grain size effect, except that the contents of Cd and Pb are partly influenced by sources in the western intertidal flat of Yalu River Estuary.Moreover, the grain size variations are highly correlated to the catchment revolution, and the variations of heavy metal contents displayed remarkable response to anthropogenic activities and catchment fluid dynamic changes. Overall, the vertical distribution of heavy metal within the core sediments can be divided into four phases： before 1940, 1941-1970, 1971-1995, and 1996-2010. Before 1940s, the distribution of heavy metal was mainly subjected to a natural evolution; however, from 1940s to 2010s, human activities played a more important role in the distributions of heavy metals.