Side-effects of Intertidal Reclamation:Water and Sediment Pollution in the Artificial Lake Shihwa

초록

Lake Shihwa, which was born by the reclamation of an intertidal flat western coast of Korea in February 1994, has been infamous to the public for its malign water qualities. The qualities in the lake are represented by hypoxic to anoxic conditions, perennial eutrophication, and high metal concentrations both in the water and sediments. Key factors affecting the pollution of the lake are the lack of mixing within the water column, the high particulate flux, and the discharge of polluted waters from the industrial complexes and heavily populated cities in the hinterlands. The pollution is more intense in the shallow upper-reach of the lake where the inland-born polluted water enters and stays intact without much mixing. In the western end of the lake where the Yellow Sea water recharges in through the watergate, the pollution is considerably mitigated. Suboxic to anoxic condition frequently develops in the deepest portion of the lake. Stoichiometric mass balance on nutrients suggests the nitrate reduction in suboxic condition and the release of phosphate in anoxic condition. Since the pollution of the lake would only be chronic without a massive, frequent discharge/recharge through the watergate, the original plan for transforming the lake to a freshwater lake is now abandoned, generating serious queston about the rationale for the reclamation project.