한국심해연구해역에서 수온약층 변화에 따른 무기영양염(질소, 인)의 연변화 특성

Abstract

Annual variations of inorganic nitrogen (nitrate+nitrite) and phosphorus (phosphate) in association with thermocline were investigated in the upper 200 m of the water column at Korea Deep Ocean Study (KODOS) area from 1995 to 2001 in the northeast equatorial Pacific. Global climatic disturbances such as El Ni o and La Ni a, should have affected KODOS area during the study period. In 1995∼97 and 2000∼2001, a thermocline where temperatures rapidly decrease with depth, was formed at 50∼70 m water depth. Nutrient depleting areas, specially for nitrate+nitrite and phosphate, or oligotrophic regions were extended down to approximately 50 m depth, which coincided with the surface mixed layer depth. However, in 1998 and 1999, a very fluctuating thermocline was observed at 30∼100 m water depth. In the photic zone (up to 100m depth), depth integrated nitrogen and phosphorus values ranged from 1.04 to 20.27 gN/m2 and from 0.71 to 3.69 gP/m2, respectively. As a result of changes in the water column structures, nutrient concentrations also showed fluctuation parallel to the changes of thermocline in the study area.