The bioavailability of the heavy metals in the surface sediment from Pearl River Guangzhou Section

The contents of heavy metals, such as cadmium, chromium, copper, lead and zinc in surface sediments from the Pearl River Guangzhou Section were measured, that were classed as bio-available state, potential bio-available state and bio-unavailable state using Tessier method. Based on this, the absorbed possibility by aquatic organisms and the impacts on the aquatic ecosystems of these five heavy metals were evaluated. The results showed that the bio-available state of cadmium in the sediment samples of Pearl River Guangzhou Section accounts for the ratio of the total range of 14.72-59.52%. The bio-available state of cadmium being in a high level, so it can be easily absorbed by aquatic organisms and it is great harmful to aquatic ecosystems. The results also showed that the other four heavy metals of chromium, copper, lead, zinc are mainly exist in the potential bio-available states, and the potential bio-available state in each sampling point accounts for the ratio of the total range are as follows: chromium being 47.80-88.64%, copper being 70.98-93.78%, lead being 27.72-67.32%, zinc being 72.30-94.79%. These four heavy metals would translate into bio-available states in the appropriate conditions, so their harm to the ecosystem should also be given attention.