Historical Reconstruction of Anthropogenic Mercury Input from Sedimentary Records: Yeongsan Estuary, South Korea

초록

The rapid economic growth of the Republic of Korea (S. Korea) within the last half-century has resulted in a pronounced increase in anthropogenic Hg emission from coal combustion, oil refining, cement production, and waste incineration. The impacts of increasing atmospheric sources have been investigated with a historical reconstruction of Hg input from 30 sediment cores collected from the Yeongsan Estuary. Within the last several decades, this region has undergone severe anthropogenic alteration, including the construction of an estuarine dam forming the Yeongsan Lake, and installation of numerous seawalls that eliminated vast tidal flats and restricted estuarine circulation. Total mercury concentrations (T-Hg) from pre-industrial sediments (i.e. background values) have been determined to be significantly lower than sediments deposited after 1980, with an average increase from 8.6  2.7 (n = 274) to 23.2  9.6 (n = 273) ng g-1, respectively. Surface sample T-Hg results reveal the highest concentrations above the dam, with a gradient to lower values further offshore. The concomitant timing of enrichment of T-Hg within the sedimentary record and increased emissions suggests that regional sources dominate the input to the Yeongsan Estuary. This indicates that with sufficient regional historic emission data, T-Hg may be utilized as a geochronologic tool to corroborate traditional radioisotopic methods.