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采用三步逐级提取方法,对长江口沉积物中痕量金属(Fe、Mn、U、Mo、Cr、Ni、Cu、Pb和Zn)的黄铁矿化程度进行分析。结果表明,痕量金属的化学形式主要以活性态为主,黄铁矿态组份含量较低。Fe、Mn、V、Cr、Ni、Cu、Pb、Zn和Mo的黄铁矿化程度分别介于4.3%～15.9%、0.1%～0.7%、0.7%～4.3%、2.4%～7.3%、3.5%～6.6%、18.4%～47.4%、0.7%～2.6%、2.1%～9.6%和47.2%～82.1%,并且按以下顺序(均值)递减:Mo>Cu>Fe>Pb>Cr>Ni>Zn>Mn>U。U的黄铁矿态组分末被检出。这些差异与每一种痕量金属的地球化学行为有关。在剖面上,DOP随深度增加而增大。河口的水动力条件、总硫及有机碳含量是影响痕量金属黄铁矿化程度的主要因素。细粒、富硫及有机质的沉积物中痕量金属的黄铁矿化程度较高。与其它沉积环境相比,长江河口沉积物中铁及痕量金属的黄铁矿化程度都较低。这可能代表了一种端元模式。高沉积速率、低有机质含量、贫硫的河口沉积物中,黄铁矿并不是痕量金属重要的捕获器及载体。
The pyritization degree of trace metals (Fe, Mn, U, Mo, Cr, Ni, Cu, Pb and Zn) in the sediments of the Yangtze Estuary was analyzed by a three-step stepwise extraction method. The results show that the chemical forms of trace metals mainly dominate the active state, while the content of pyrite components is relatively low. The pyritization degree of Fe, Mn, V, Cr, Ni, Cu, Pb, Zn and Mo ranged from 4.3% to 15.9%, 0.1% to 0.7%, 0.7% to 4.3%, 2.4% to 7.3% 3.5% -6.6%, 18.4% -47.4%, 0.7% -2.6%, 2.1% -9.6% and 47.2% -82.1%, and decreases in the following order (mean value): Mo> Cu> Fe> Pb> Cr> Ni > Zn> Mn> U. U pyrite component was detected at the end. These differences are related to the geochemical behavior of each trace metal. In the section, DOP increases with depth. Hydrodynamic conditions, total sulfur and organic carbon in the estuary are the main factors affecting the degree of pyritization of trace metals. Trace metals in fine-grained, sulfur-rich and organic sediments have a high degree of pyritization. Compared with other depositional environments, the iron and trace metals in the sediments of the Yangtze River estuary are relatively low in pyrite mineralization. This may represent an endmember pattern. Pyrite is not an important trapper and carrier of trace metals in sediments with high deposition rate, low organic matter content and poor sulfur content.