Spatial distribution and accumulation of heavy metals in tidal flat sediments of Shanghai coastal zone

Surface and core sediments from the high, middle and low tidal flats of Shanghai coastal zone were analyzed for heavy metal (e.g. Cu, Pb, Zn, Cr, Cd, Fe, Mn) concentrations. Besides Cd, the concentrations of Cu, Zn, Cr and Pb are 2-5 times higher than their background values and show serious pollution trend due to the direct discharge of industrial and municipal sewage along the Shanghai tidal flat, as well as the wet and dry depositions of industrial dusts. It seems that heavy metals prefer to accumulate and be enriched in the sediments near large sewage outlets, high flats, and the subsurface layer at the depth of 10-30 cm. Several main factors, which include the direct sewage discharge along the tidal flat, tidal hydrodynamic action, large engineering activity, early diagenesis and windstorm tide, are considered to be responsible for influencing spatial distribution patterns of heavy metals in the Shanghai tidal flat.

上海滨岸潮滩沉积物重金属元素的空间分布与累积

对上海滨岸潮滩沉积物重金属元素空间分布格局的系统分析表明 ,由于受多年来城市工业废水和生活污水沿岸直排、以及城市汽车尾气和工业粉尘干湿沉降的影响 ,本区潮滩表层沉积物中 Cu、Zn、Cr、Pb等重金属元素的污染程度已相当严重。大型排污口附近滩地、水动力条件较弱的高潮滩部位、以及沉积物亚表层 1 0～ 30 cm深度是重金属累积并形成富集的主要部位 ,沿岸排污、水动力作用、大型工程活动、早期成岩作用。