Environmental risk assessment of heavy metals in Bohai Sea, North China

A risk assessment method recommended by PEMSEA was introduced to assess environmental risk of heavy metals (Copper, Lead, Mercury and Cadmium) in Bohai seawater, North China. Risk quotient was calculated upon measured data of 2002 and sea water quality criteria. Monte Carlo technique was used to estimate the uncertainty of risk. The priority risk agents were Hg and Pb, the localized risk agent was Cu while risk from Cd was at acceptable level. The coastal waters near estuaries and big cities have higher potential risks; especially Bohai Bay located in the west Bohai Sea had the highest risk where the heavy metal pollution was most serious. Data of the next year verifies the uncertainty analysis result that with a confidence of more than 75% the risk quotients for Hg and Pb exceed the critical value. The sources, background concentration and biota assessment of heavy metals of Bohai Sea were discussed too.