Abstract: This study analyzes the heavy metals in the sediments, including Zn, Pb, Cu, Cr, and sediment grain size. It evaluates the degree of pollution and ecological risks of the four heavy metals in the Pearl River Delta and the Beibu Gulf using sediment accumulation coefficient method and HÀKANSON L potential ecological hazard index method. We compare the results between the Pearl River Delta and the Beibu Gulf. The comparison shows that the clay and silt enrichment of heavy metals in sediment is large; Cu in the two regions reached the serious level of pollution, Zn, Pb and Cr reached the middle level of pollution in the Pearl River estuary and in part of the Beibu Gulf. The potential ecological risks in the Pearl River estuary range from lower to higher level, and those in the Beibu Gulf are lower. The Pearl River estuary has been severely damaged due to human activities, and the Beibu Gulf, as a national development site, should receive priority to prevent pollutions, and adapt policies to develop and protect the natural environment.

Key words: Pearl River estuary, Beibu Gulf, sediments, heavy metals, degree of pollution, ecological risk