Environmental Dynamics and Anthropogenic Impacts in the Seomjin River Es tuary and Gwangyang Bay: A Comprehensive Review of Hydrology, Nutrient Fluxes, and Benthic Ecosystems
Abstract:
This study reviews academic research on the lower Seomjin River and the northern part of Gwangyang Bay to assess the environmental conditions of the Seomjin River estuary and propose directions for improvement. A density front forms where freshwater from the Seomjin River meets seawater from Gwangyang Bay; however, the hydrological estuary does not align precisely with its geographical counterpart. Phytoplankton production plays a critical role in regulating particulate organic matter (POM), with nitrate and silicate primarily sup plied by the river and phosphate by the bay. Nutrient distribution is largely governed by biological processes, while primary production significantly alters nutrient fluxes entering Gwangyang Bay. These fluxes are influ enced by freshwater discharge and the concentration of dissolved inorganic nutrients. Sediment distribution, previously dominated by fine particles west of the river delta, shifted following industrial development, includ ing delta degradation. High concentrations of di-butyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) were detected in seawater and surface sediments, suggesting riverine transport of these pollutants into the bay. Salinity was found to be a major factor shaping the spatial distribution of zooplankton, fish, and polychaete communities. To restore and protect the estuarine environment, it is essential to improve the upstream water quality, install monitoring stations with water quality management systems in the estuary, and implement a comprehensive pollutant discharge monitoring system in Gwangyang Bay.
