Abstract: Three sediment cores were collected in November 2003 from Dagu
estuary to Qikou estuary. The main polluted heavy metals in the sediment of
tidal zones for the Bohai Bay have been found by analyzing the relationship
among the contents of heavy metals, the contents of geochemical elements (Fe,
Al and Mn) and the size of grain. The dominating contaminative elements in
tidal sediments of Bohai Bay are Pb, Zn and Cd. Their contents are higher than
the corresponding upper limit of environmental background values and they have
very faint correlation with the corresponding contents of geochemical elements
and the size of grain, indicating the anthropogenic enrichment. Especially, the
preliminary study on the pollution sources and the history of heavy metals in
the Dagu estuary has been done using the dated results. The contamination by Zn
and Cd also started in the middle 1950s, while the contamination by Pb appeared
in the early 1940s. The pollution by Zn and Cd mainly originate from sewage
discharge, while the pollution by Pb has many sources, like atmosphere
deposition and industrial discharge.
Keywords: Bohai Bay, tidal zone, the dated sediment core, heavy metal, pollution