제주도 연안 환경에서의 용존유기물질의 계절적 특성 변화

Abstract

In order to understand seasonal variation of dissolved organic matter (DOM) in coastal environment, dissolved organic carbon (DOC), dissolved organic nitrate (DON), chlorophyll-a (Chl.a), and fluorescent dissolved organic matter (FDOM) were analyzed in Jeju Island, Korea, from January to December 2017. The concentration of DOC, DON, and Chl.a ranged from 53.71 to 135.73 μM, 0.17 to 33.08 μM, and 0.04 to 4.16 mg/m3, respectively. Seasonally, high concentrations of DOM (DOC: 80±12 µM, DON: 9±2 µM) were observed in summer. Spatially, those (DOC: 72±11 µM, DON: 6±2 µM) were found in the northern area. The DOM concentrations were negatively correlated with salinity in summer. In addition, the correlation between DOM concentrations and Chl.a showed no significant correlation. In order to identify the DOM, FDOM was characterized by three components using excitation-emission matrix spectroscopy (EEMs). C1 indicates DOM of marine origin with characteristics of humic-acid and fulvic-acid during decomposition by microorganism, C2 indicates terrestrial origin and allochthonous origin, and C3 indicates protein-like by plankton. The correlation between FDOM and DOC showed no correlation in spring, but the positive correlation between C2 and DOC (r2= 0.63) showed in all area in summer. The DOM was mainly originated from terrestrial and allochthonous in all area during summer. However, the correlation between DOC and C1, C2, and C3 showed significant correlation in western area during summer. The DOM was originated from the microbial activity and terrestrial sources such as Changjiang Diluted Water (CDW) in western area. There was a correlation between DOC and C1 in the northern area during fall, and there was no correlation between C1 and C2. The DOC in northern area seems to be originated from the marine microbial activity. In order to understand behavior of DOM, extensive studies are necessary in the future over greater time-scaling using various chemical tracers.