| As the product of human activity and rock weathering, the environmental labile element is less-bound in sediment, which is easily transferred into water and organic bodies. It's useful to remedy the lacks of study to"total"element, and is significant to sedimentary geochemistry and ecological environment. According to the distribution of the environmental labile metal element in surface sediment and two typical cores in mud area of East China Sea, along with datas of marine hydrology, grain size, Cs-137 dating, metal concentration in seawater, this paper analyzes the factors which influence the enrichment of environmental labile element, and discusses the changes of sedimentary environment with time and space. Moreover it discusses the sediment environmental quality valuation by the concentration enrichment ratio (CER) of the environmental labile element.The surface sediments reveal a predominance of clayey silt, except relict sedimentary area in the north. 16 core and 31 core are located in the center of Changjiang Estuary mud area and Min-Zhe Coast mud area separately. The 137Cs dating of the two cores reveals that the mean sedimentation rate of the cores of 16 and 31 were 3.27cm/a and 0.82cm/a, respectively, in corresponding to the sedimentation duration of 49a ( 1954～2003) for core 16 and 181a (1822～2003) for core 31. two cores reveal a predominance of clayey silt, which shows the calm environment in mud area. The grain size is finer in 31 core for mechanical differentiation of Changjiang sediment during transport.The concentration of most element in environmental labile speciation of surface sediment is lower and lower from Min-Zhe Coast mud area, Changjiang Estuary mud area, southwest mud area of Jizhou Island to relict sedimentary area, and it is lower seaward along the coastline in Min-Zhe Coast mud area. The RSD of environmental labile speciation is lower than 20% in two cores, although Cu, V, Ni, Pb, Zn and Co present prominent changes. Cu, V, Ni and Co are enriched in the middle-deep depth of two cores, which reflects element remigration due to early diagenesis. Fe and Mn become much lower since 1960, whereas they are enriched in 31 core at the same time. The increasing trend of Pb and Zn since 1980 in two cores shows more serious human pollution recently.The distribution of environmental labile element in surface sediment indicates stronger human influence in mud area along the shore and stronger biogeochemical activity in the Southwest mud area of Jizhou Island. Mn is obviously lower in 16 core since 1960, and shows redox sensitive character, which reflects hypoxia in 16 core since 1960. Mn and Zn in 31 core after 1960 show close association with sediment transport at Datong Station, which shows no redox changes in 31 core. The distribution of element indicates close association with material source, finer fraction, early diagenesis and human activity, while grain size's influence to 31 core is diluted for long time diagenesis.According CER of environmental labile Ni, Cu, Zn, Pb and Co in surface sediment and two typical cores, the article indicates severe pollution of Cu, lower pollution of Pb and almost no pollution of Zn, Co, Ni in the study area. In spatial scale the most severe quality of metals in sediment appears at Min-Zhe Coast mud area and Changjiang Estuary mud area. In two cores CER of Co and Ni show few changes, whereas Cu is much more enriched in the deep depth due to early diagenesis. The CER of Pb and Zn increased since 1980 for enhanced human pollution.
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