This study evaluated the contamination levels of inland pollution sources flowing into Taeanhaean National Park. The nutritional status of influents was assessed by analyzing water quality and trophic status index (TRIX) at 52 stations, and the contamination levels of sediments were evaluated by analyzing eutrophication cleanup index (CIET) and heavy metals at 36 stations. The results of the TRIX analysis showed that 26 of the 52 stations had influents with a TRIX value of 6-10 (poor water quality/very high trophic level), indicating atrocious water quality and high eutrophication levels. The results of the CIET analysis showed that 4 out of the 36 stations were highly contaminated with organic matter. Analysis of heavy metals showed that the copper (Cu) and zinc (Zn) levels exceeded the threshold effects level (TEL) and probable effects levels (PEL) at several stations. In addition, the arsenic (As) level exceeded the threshold effects level at one station, and the levels of the other heavy metals (Cd, Cr6+, Ni, Pb, and Hg) were lower. Most inland pollution sources have been identified as small-scale, but long-term and continuous exposure can negatively affect the marine ecosystem; therefore, it necessary to prepare inland pollution source management standards and measures suitable for the characteristics of the coastal area.

The influence of the point source inflow on the water quality variation in the downstream of Hyeongsan River was investigated. As the results of seasonal variation, the pollutant concentrations of dry season were 1.5~4 times higher than those of wet season. The increase rate of BOD5, CODMn, T-N, T-P due to point source were ranged to 8.1~42.6%, 7.3~41.9% and 17.1~207% as the inflow of P1, P2 and P3, respectively. After P1, P2 and P3 inflow, the accumulated increase rate were 64.3%, 32.6%, 93.1% and 258.9% in BOD5, CODMn, T-N, T-P, respectively. It was found that the influence of point source inflow on the water quality in the downstream of Hyeongsan River is severe.