한강기수역에서 조석주기에 따른 지화학적 환경특성 변화연구

초록

Diurnal variability of nutrients, DOC, turbidity and other environmental parameters (salinity, temperature, pH, DO, current) was investigated during the spring tidal cycle at the lower part of Han River Estuary. All the measurements were accomplished on board, in situ, at every second or minute interval using online autoanalyzer, multi-parameter environmental monitoring sensors, DGPS, echo sounder and ADCP to evaluate the short-time scale variability and geochemical behavior of nutrients during the tidal cycle. Tidal cycle was asymmetry and maximum tidal velocity was 1.8m/s with 9.2m of tidal range. During the flood tide, nitrate ranged from 21 to 152 mM and showed a non-conservative property of slightly convex curve along the salinity gradient. Nitrite ranged from 3.7 to 11.9 mM and behaved like the nitrate. Meanwhile, ammonia ranged from 21 to 77 mM but showed a non-conservative property of concave curve along the salinity gradient. This implies that nitrification process balanced source of nitrate and nitrite with ammonia removal during a tidal excursion. Dissolved organic carbon ranged from 1.7 to 2.4 mg C/l and showed a non-conservative property of removal along the salinity gradient. Dissolved oxygen ranged from 8.3 to 10.0 mg/l and saturation level ranged from 83% to 105%. Dissolved oxygen, also showing an apparent non-conservative property of removal along the salinity gradient, was presumably consumed for nitrification and oxidation of dissolved organic carbon during the tidal cycle. On the other hand, phosphate showed very complicate behavior that was quite different from those of inorganic nitrogenous nutrients.