厦门西港沉积环境变化及重金属的污染累积

Variation of Depositional Environment and Accumulation of Heavy Metals in West Harbour,Xiamen

通过测定柱状沉积物中的重金属、有机碳和硫化物含量,结合沉积物粒度分析及现代沉积速率,重现了厦门西港近70a的沉积环境变化及重金属的污染历史,探讨了沉积环境对重金属累积过程的影响.结果表明,厦门西港污染指示元素为Cu,Zn,Pb,As,富集程度依次为As>Cu>Zn>Pb,元素Cr,Cd和Hg在研究海域内没有富集现象.综观70a来,厦门西港沉积物组成变化较大,沉积环境变化明显,重金属含量的垂向变化特征与当时的水动力、沉积环境变化紧密相关.研究表明,沉积物来源越稳定,沉积物粒径越小,分选性越好,则沉积物中重金属含量越高;同时,各层位的绝大部分重金属与有机碳和硫化物呈显著正相关关系.

The contamination history of heavy metals and changes of the depositional environment of the West Harbour in Xiamen for the last 70 years were studied by using high resolution records, the measurement of concentrations of heavy metals, organic matters and sulfide in its marine sediment core, grain-size analysis, and recent sedimentation rate of the sediment. The results indicate that Cu, Zn, Pb, and As can be considered as indicators of anthropogenic metal pollution. The degree of enrichment is As〉Cu〉Zn〉Pb, whereas Cr, Cd and Hg are not enriched in the sediment of the area. The variation of the sediment composition and depositional environment in the site has been obvious in the last 70 years. There is direct correlation among the vertical distribution characteristics of the heavy metals, hydrodynamic force and depositional environment of the time. For the sediment, the more stable of the source, and the smaller of the grain size and the better of the separation, the higher the content of heavy metals are in sediment. There is significant positive correlation between the concentrations of the most heavy metals and the concentrations of organic carbon and sulfide in all depth.