关键词: 王港, 潮滩, 重金属, 污染

Abstract: The vertical distribution law of heavy metals of Pb, Cu and Zn from Wanggang tidal flat and status of its pollution were studied. The background value of Wanggang ²¹⁰Pb is measured, which is 1.116dpm/g. It was suggested by the study that the modern average rate of sedimentation in Wanggang tidal flat is 4.13cm/a. It was found that the vertical changes of heavy metal content of Wanggang tidal flat have the same homoplasy, that it reduces from surface layer to bottom step by step, in accordance with granularity. This argued more obviously the conclusion summarized previously that heavy metals and granule sediment have good relativity. The common rule that the content of heavy metals was in the order of high tide>middle tide>low tide has straight correlation with the process of water dynamics. It was deduced by the relativity of heavy metals that the Fe,Cu,Pb,Zn and Li have better relativity. Thereinto the relation of Fe, Ni and Cr was very marked, exceeding 0.900. It was obvious that the vertical changes of heavy metals were relatively stable and possibility came from rock. Pb,Cu and Al have minus-correlations with Fe,indicating that Pb and Cu of Wanggang tidal flat were impacted by anthropogenic activities to a greater degree. The Cu and Zn normalization value in 15 years is stable in contrast to that of Pb. The undulating scope of Cu is between 0.4 and 2 and Zn is between 1.5 and 2.6. But Pb has a greater scope. Using Hokanson's latency ecological risk index method, it was deduced that the latency ecological risk index of Pb, Cu and Zn was less than 95, an indication of light harmfulness. But it had pollution of Pb and Cu by all means in this area. Pb was the main pollution factor in the estimated area.The application of pesticide and fertilizer was the main reason of heavy metal pollution. It is suggested that the heavy metals in Wanggang tidal flat come from pollution of land-based farming activities.

Key words: Wanggang, tidalflat, heavy metal, pollution