진해만 빈산소 수괴의 통계적 특성분석

Abstract

Oxygen deficient water or hypoxia refers to a state in which DO (Dissolved Oxygen) concentration in seawater is lowered to 3 mg/L or less. This phenomenon occurs mainly in the eutrophic semi-closed inner bay waters. The reasons for this are known as stratification of density, decomposition of organic matter, pollutant loads from the land, and elution from seabed sediments. Jinhae Bay is an enclosed inner bay, and as the eutrophication and red tide occur due to the industrial complex, industrialization, and urbanization in the 1970s, oxygen deficient water mass have been observed. As a result, Jinhae Bay's farms are suffering a great deal of damage, and in order to prevent the damage, it is necessary to predict the timing of occurrence of oxygen deficient water mass in Jinhae Bay or to take complex countermeasures. Among the independent variables affecting dissolved oxygen in Jinhae Bay, pH, Chlorophyll-a(Chl-a), NO2, water temperature, salinity and temperature were the most sensitive independent variables. In the lower layer, the sensitivity decreased in order of SiO2, temperature, pH, TN, NO3, Chl-a, and so on. When the stepwise regression analysis was performed after normalization the data of each independent variable, the regression equation of the surface layer was DO = 0.4678 + 0.563 pH + 0.165 Chl-a – 0.238 NO2 –0.285 water temperature - 0.257 salinity + 0.153 temperature (r2 = 68.98), the bottom layer regression equation was found to be DO = 0.471 - 0.36 SiO2 - 0.27 air temperature + 0.274 pH - 0.435 TN + 0.275 NO3 + 0.246 Chl-a (r2 = 68.38). As a result of the weakening of the stratification phenomenon due to the typhoon NORU that occurred in July 2017 and the typhoon TALIM that occurred in September, it was confirmed that the area of occurrence of oxygen deficient water mass is reduced.