동해안의 경포호를 비롯한 6개 석호를 조사한 결과 모든 호수가 부영양화가 매우 심한 것으로 나타났다. 투명도는 1.0 m 내외의 낮은 값을 보였으며 청초호를 제외한 모든 호수에서 남조류인 Oscillatoria sp.가 우점종이었다. 염분의 경우 청초호와 화진포호의 북호는 각각 18~30‰와 10~25‰이었으며, 다른 호수는 10‰ 내외 로 호수별로 큰 차이를 보였다. 또한 모든 호수의 Chl. a, TN 및 TP도 각각 11.4~97.3 mg/m3, 0.77~2.36mgN/L 및 0.056~0.292 mgP/m3의 범위로 보여 차이가 큰 것으로 나타났다. 표층의 TN/TP 무게비는 6~14 정 도로 매호가 가장 적었으며, TSI는 56~79의 범위로 영랑호가 가장 컸다.

Trophic state parameters were surveyed in seven lagoons located along the eastern coast of Korea. Salinity, DO, SS, TP, TN, chlorophyll a concentration, Secchi disc transparency (SD) and dominant phytoplankton were measured from May to November 1998. Trophic state indices (TSI) was calculated from TP, Chl. a, and SD data of growing season average. The amount of phosphorus and nitrogen generation within the water shed of each lake was estimated. Strong vertical chemocline was observed in some lakes, which resulted in large difference of DO and salinity between surface and deep water. Salinity of Lake Chungcho and North aera of Lake Hwajinpo were 18~30‰ and 10~25‰, respectively, whereas other lakes were below 10‰. SD, Chl. a, TN and TP of the all lakes were in the range of 0.29~1.02 m, 11.4~97.3 mg/m3, 0.77~2.36 mgN/L, 0.056~0.292 mgP/L, respectively. Epilimnetic TN/TP weight ratios were 6~14. The lowest TN/TP ratio of all lakes was observed in Lake Maeho. TSI was in the range of eutrophy to hypereutrophy, from 56 to 79. The highest TSI of all the lakes was observed in Lake Youngrang. The dominant phytoplankton species were Oscillatoria sp. except for Lake Chungcho, where Microspora sp. was dominant. It seems that the unique phytoplankton community in Lake Chongcho was caused by the difference of salinity and seawater intrusion.

• 허우명(삼척대학교 환경공학과) | Heo Woo-Myung (Dept. of Environmental Engineering, Samchok National University) Corresponding author
• 김범철(강원대학교 환경학과) | Bomchul Kim (Dept of Environmental Science, Kangwon National University)
• 전만식(강원대학교 환경학과) | Man-Sig Jun (Dept of Environmental Science, Kangwon National University)