九龙江口厦门港沉积物中镉、铜、铅的分布和行为

THE DISTRIBUTION AND BEHAVIOUR OF Cd, Cu, Pb, IN THE SURFACE SEDIMENTS OF THE JIULONG RIVER MOUTH AND XIAMEN HARBOUR

一、前言河口区是江河所携带的泥砂、悬浮物和各种化学物质的主要沉积场所。河流悬浮物是重金属元素很好的清除剂。在河口水质条件急剧变化和复杂的化学、生物等过程中,它们能从水体中吸附大部分的重金属元素一起进入沉积物。Hely指出:Back河口海水中有些痕量金属的浓度要比排入该河废水中低10—100倍,这种减少既有海水的稀释作用,也有流出物中所含有颗粒的沉积作用,而更重要的是悬浮物的吸附和聚沉作用。因此测定河口沉积物中痕量重金属含量(总含量和各种可能迁移相),通常能预示该地区的污染情况。如果再指出它们与沉积物的某些重要组份及所处环境条件,就有可能进一步了解河流物质进入海洋的过程和机制。

The average contents of Cd,Cu,Pb in the surface sediments of the Jiulong River Mouth and Xiamen Harbour are 0.18,26.84,43.37(μg/g)respectively.Most of Cd,Pb and a small part of Cu exist in the diluted acid-soluble fraction,implying most of Cu exist in the crystalline phase and most of Cd or Pb in the sediments are in the hydrogenous fraction.The higher content of Pb in the sediments is worth of further investigation.There is a seaward decrease for the content of each of the three elements in the surface sediments,the diluted acid-soluble fraction and the interstitial water from river mouth,which is related to the hydrologic and geographic conditions in the area.The organic matter in the sediments plays a significant role in controlling Cd,Cu,Pb.The chemical behaviour of Cd,Pb in the sediments are rather similar.There may exist a quasi-equilibrium between the various speciations of each element in the sediments.The contents of some stations between the Haimen Island and the Jiyu Islet are rather high,which is due to the convergence zone there.