Distribution and potential ecological risk of Cu, Cd, Pb and Zn in surface water and sediment from Tianjin coastal areas of Bohai Bay, China

Owing to the wide pollution of heavy metals in Bohai Sea, China, and their associated ecological risk, the presence of heavy metals in water source has aroused much concern to public. The present study aimed to evaluate selected heavy metals spatial distribution i.e. copper (Cu), cadmium (Cd), lead (Pb) and zinc (Zn) and their potential ecological risk in the Tianjin coastal area of Bohai Bay. The water and sediment samples in each station were collected simultaneously. The results showed that overall concentrations of four concerned metals in the study area met the Seawater Quality (GB3097-1997) and Marine Sediment quality of China (GB18668-2002). Compared the HC5 values (hazardous concentration for 5% of species) with their corresponding pollution levels of four heavy metals, the species diversities were expected to be reduced by more than 5% because of the Cu and Zn pollution. Meanwhile, the Cu and Zn in water might pose high risk to the local aquatic organisms by using RQ (Risk Quotient) to assess the site-specific ecological risk. Therefore, the Cu and Zn pollution in water should be paid more attentions. The assessment results using Sediment Quality Guidelines (SQGs) showed that only 2.94% of sites for Cu, 14.71% of sites for Cd and 8.82% of sites for Zn in sediment exceeded the TEL (Threshold Effect Level) values, indicating that adverse biological effects rarely occur in sediments.