| The sediments that accumulate in Jiaozhou Bay of the Shandong Peninsularecorded the information about the history of changes in the source of the material, therate of deposition and the influence of man. Man's influences on the Jiaozhou Baywere significant. Six cores were collected from the Jiaozhou Bay by the Cruise workon Gold Star boat on Sep.6th, 2003. The 210~Pb radioactivities of the sediments weredetermined by 210~Pb geochronology method and ICP-MS was employed for thedetermination of Zn, Cu, Cr, Ni, Pb, Cd and Co concentrations. The modernsedimentary environment, the contamination history of heavy metals and the metalaccumulation process were issued by data analyses and the references. The profiles of 210~Pb radioactivity at the cores J39, B6 and D6 appeared in athree-segment model (i.e. the mixing segment, the decay segment and the backgroundsegment). It may be inferred that the mixing layer in the upper core results in therelatively active hydrodynamic condition and biological distribution. In the centralregion of the bay, the profiles of 210~Pb radioactivity at the cores B3, J37, C2 and C4appeared in two-segment model (i.e. the decay segment and the background segment).It can indicate that the modern sedimentary environment of this region was very stable.In the region off the inner-bay mouth, 210~Pb radioactivity at core D4 decayed with thedepth appeared non-order distribution where the decay segment was composed of twodifferent decay layers. It can be inferred that the modern sedimentary environment ofthis region was unstable and the deposition process of the sediments had changed a lotin the past times. The spatial distributions of 210~Pb radioactivity in the surficial samples were alsoexamined. Higher values were found in the central area of the Jiaozhou Bay where thesediments were mostly composed of fine-grained materials. However, 210~Pbradioactivities were lower in the east region of the bay. The enrichment of 210~Pb andthe characteristic of the 210Pb spatial distribution were largely accounted forhydrodynamic conditions and the grain size of sediments in the Jiaozhou Bay. Based on the 210Pb geochronology, sedimentation rates and sedimentation fluxwere measured in the Jiaozhou Bay. The results showed that sedimentation rates werefound to be somewhat higher in margin areas of the bay, especially in the dumpingareas, where the rates were about 0.77cm/a～3.96cm/a(Station J39: 0.77cm/a, StationB6: 1.62cm/a, Station D6: 2.27cm/a, Station D4: 1.63cm/a and 3.96cm/a). While inthe central region of the bay, there was a patch of fine-grained mud, with thesedimentation rates being lower (Station B3: 0.85cm/a, Station J37: 0.64cm/a, StationC2: 0.56cm/a, Station C4: 0.19cm/a). The concentrations of the heavy metals in marine sediment cores of JiaozhouBay were measured, and the profile distribution characteristic of heavy metals wasdiscussed. Combined with 210Pb dating results, the contamination history of heavymetals was studied and the metal accumulation processes were also analyzed. Themain heavy metals in the sediments of Jiaozhou Bay were Zn, Cu, Cr, Ni and Pb,while the concentrations of the elements Cd and Co were much lower. Theconcentrations of the main heavy metals of the sediments in Jiaozhou Bay were higherthan that in the China Shelf Sea, which showed that the area had been contaminated toa certain extent. But these concentrations were low in comparison with the highestbackground level in former global modern industrialization times and that in otherindustrialized areas. The heavy metal profiles Zn, Cr, Ni, Co and Pb from the sixcores showed a high variability, but also a decreasing trend since 1980s, while theelement Cu presented an increasing trend and the element Cd presented a morechaotic profile than the other elements.
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