Degree of pollution for marine sediments

In order to keep marine products safe, it is necessary to remediate or remove contaminated marine sediments. A first step is to evaluate the level of pollution with hazardous and toxic substances. For the evaluation of sediment contamination, "degree of pollution", Pd, was defined previously as: Pd =(concentration of an element-background)/(background value of the element). In this study, the concentrations of various elements, such as iron, aluminum, manganese, titanium, copper, zinc, vanadium and phosphorus, were measured from sediment samples obtained from different sites in various bays of Japan, using the inductively coupled plasma emission spectroscopy method. The evaluation of the background values followed the previous studies. The results showed that the sediments were more or less polluted with various species of elements. The polluted thickness of marine sediments ranges approximately from 10 to 70 cm. In some cases, the degree of pollution for copper was >7. In this paper, the history of pollution is also discussed in terms of the age of the sediment. The age of sediments was estimated from the sedimentation rate predicted using the calcium carbonate content of sediments. The results showed that the pollution due to human activities started ca 1975. (C) 1999 Elsevier Science B.V. All rights reserved.