Dissolved Sugar in the South China Sea：A Preliminary Study

• Main Authors: I-TING CHIANG, 江逸婷
• Other Authors: 溫良碩
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/32173784192599416979

碩士 === 國立臺灣大學 === 海洋研究所 === 92 === Carbohydrates are important components of marine organisms. They are contained in cell walls of plants, bacteria, and fungi, providing structural support. They are also involved in energy reserve, such as D-glucose is stored in the form of polysaccharides, starch in plants and glycogen in animals. Carbohydrates usually comprise 20 to 40％ of dry biomass of phytoplankton（Persons et al., 1961）. Recent studies had indicated that the concentration of carbohydrates in seawater could vary daily and seasonally. In general, total dissolved carbohydrate（monosaccharides and polysaccharides）is about 1 to 10 times greater in concentration than monosaccharides found in seawaters（Thurman, 1985）. In this study, as the world first, concentration of dissolved monosaccharides and polysaccharides in the surface euphotic zone were measured in South China Sea at 21oN 30’ along 119oE 59’. A modified highly sensitive spectrophotometric method based on the alkaline ferricyanide reaction was adapted and employed, which uses 2,4,6-tripyridyl-s-triazine（TPTZ）as reagent instead, together with reduced iron giving a strongly colored complex. This method together with acid hydrolysis procedure was used to determine dissolved mono- and polysaccharides in seawater. In spring of 2004 (Cruise : ORI 710), concentration of total dissolved carbohydrates in the water column decreased as increasing depth during day time, and strong diurnal variation were observed, with a maximal value of 270μg/L between 60 and 70m depth at midnight. The concentration of total dissolved carbohydrates ranged from 180 to 380 μg/L while the concentration of monosaccharides ranged from 0 to 50 μg/L. In sum, total dissolved carbohydrate is about 8 times greater in concentration than monosaccharides found in South China Sea. These changes corresponded to that of Chlorophyll-a, bacterial production and transparent exopolymer particles（TEP） in the water column. The strong correlation found between total dissolved carbohydrates and bacterial production suggested that bacterial metabolism is fueled by availability of carbohydrates in seawater.