Other possible sources of zinc in corals from Daya Bay include domestic and industrial sewage discharge, and input from other point sources such as oil terminals and ports. High rates of ICG-001
growth and industrial development have occurred in Daya Bay during the last 30 years (Wang et al., 2008a), with major increases since 1994 (Fig. 6). Locally, industrial sewage (which typically contains heavy metal contamination) is mainly discharged from the industrial area distributed along the north coast of Daya Bay. Contaminants are most likely transported and distributed by currents (north-south currents during rising- and ebb-tides) through the entire region (Fig. 7). The Zn/Ca patterns in corals revealed that the Zn content in seawater has been increasing since 1994, coeval with the timing of rapid growth of population
and industry. The aquatic environment of Daya Bay has been progressively impacted by Zn contamination since that time. Our interpretation is consistent with other studies throughout the world where it has been observed that high levels of Zn in seawater are derived mostly from industrial discharges (Hanna and Muir, 1990, Guzmán and Jiménez, 1992, Esslemont, 2000, Runnalls and Coleman, 2003, Ramos et al., 2004 and Al-Rousan et al., 2007).