基于长江口泥质沉积区ZK6孔沉积物的沉积地球化学分析和汇总文献数据,综合评估长江口沉积物中4种重金属(Cu、Pb、Zn、Cr)年代际到千年尺度上的累积特征及影响因素.结果显示,富集因子(enrichment factor,EF)和地累积指数法评价结果表明全孔的重金属危害系数较低;千年尺度上(1500aBP至今),重金属含量主要受控于流域自然背景值变化,其中Cu和Pb含量自底部至顶部先降后升,Zn、Cr则持续降低;1899年前,主要识别出唐、宋两个历史时期,这段时期内社会经济繁荣,人类活动较强,重金属的富集程度受到一定影响而波动变化;1899年后,受工业化发展的影响,重金属富集程度大幅上升;百年尺度上,重金属富集程度与我国经济发展阶段显著相关,1950年前累积程度较低,1950——1990年随工业化快速发展而重金属累积加剧,1990年后因环保政策部分元素含量下降;年代际尺度上(2003——2019年),受国家相关政策调控,2010年后长江口沉积物中Pb和Cr元素累积趋于平稳,Cu排放得到有效控制,但Zn的持续升高仍需引起重视.本研究揭示了长江口重金属时空演变的自然与人为驱动机制,为河口环境管理和治理提供了科学依据.
Based on the sedimentary geochemical analysis of sediments from core ZK6 in the muddy sedimentary area of the Changjiang River Estuary and the collection of literature data, this study comprehensively evaluated the accumulation characteristics and influencing factors of four heavy metals (Cu, Pb, Zn, and Cr) in the sediments of the Changjiang River Estuary from interdecadal to millennial scales. The results of the enrichment factor (EF) and the index of geoaccumulation method indicate that the hazard quotient of heavy metals with the whole core is overall low. On the millennial scale (from ca. 1500 aBP to the present), the heavy metal contents were primarily determined by the changes of natural background values in the catchment, while Cu and Pb contents decreased and then increased from the bottom to the top, and Zn and Cr contents displayed decreasing trends. Before 1899, two historical periods, Tang and Song Dynasties, were mainly identified. Due to the social and economic prosperity and strong human activities during these periods, the degree of heavy metal enrichment fluctuated under certain influences. After 1899, the degree of heavy metal enrichment increased significantly due to the influence of global industrial development. On the centennial scale, the degree of heavy metal enrichment was significantly correlated with the stage of economic development in China. The accumulation degree of heavy metals was low before 1950 and intensified with the rapid industrial development from 1950 to 1990. The content of some elements declined due to the environmental protection policy after 1990. On the interdecadal scale (from 2003 to 2019), Pb and Cr element accumulation in sediments of the Changjiang River Estuary showed small variations after 2010, and Cu emission was controlled effectively, but the continuous Zn enrichment deserved more attention. This study revealed the natural and anthropogenic driving mechanisms of the spatial and temporal changes of heavy metals in the Changjiang River Estuary and provided scientific evidence for estuarine environmental management and governance.
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