Distribution characteristics of intertidal sediment heavy metal of the western bank of the Yalu River, and its responses to catchment changes
WANG Ying-fei;GAO Jian-hua;SHI Yong;YANG Yang;LI Fu-xiang;LIU Yue;CHENG Yan;The Key Laboratory of Coast and Island Development, Ministry of Education, Nanjing University;School of Urban Construction, East Liaoning University;
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 the210Pb 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.