The concentrations of dissolved chromium in seawater of the Bohai Gulf vary from trace to 1.6 μg/l while those of particulate chromium from trace to 8.66 μg/l, indicating that the concentration of chromium in seawater of nearshore and estuary in the Bohai Gulf is higher than that of offshore, and reflecting the effects of estuarine and terrestrial pollutions. Observation data indicate that there is a positive correlation between particulate chromium and COD. The result shows that organic matter in seawater has a strong ability to combine chromium. When particulate chromium meets with seawater in estuary, it gradually settles down to sea-bottom sediments. Ratio of particulate chromium to total chromium in the Bohai Gulf yields a higher value, exceeding 90% in estuarine area, i.e. particulate chromium is a predominant form in seawater of the Bohai Gulf.
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