The role of dissolved organic matter in marine carbon cycle elucidation by production and turnover rates

1994年8月和1996年10月，日本海洋科学技术中心“海洋”号巡洋舰和东京大学海洋研究所“白虎丸”号巡洋舰分别在东海和北太平洋（1995年11月）进行了<13 bb0 C示踪试验。孵育24h后，用玻璃纤维过滤器（Whatman GF/F）过滤，将溶解有机物与颗粒有机成分分离。过滤压力控制在150mmHg以下。初级生产力变化范围从副热带环流的200mgC m^<-2>d^<-1>到长涧口的1500mgc m^<-2>d^<-1>。采用^<13>C/GC/MA法测定颗粒脂肪酸产率。14:0、16:0和16:1等脂肪酸是构成颗粒物产物的主要脂肪酸，16:1的贡献存在空间差异。为了测定溶解有机碳的^<13>C原子%，溶解有机碳首先用湿氧化法转化为二氧化碳。溶解有机碳中^<13>C原子%在各测点均略有增加，说明在培养实验过程中产生了溶解有机碳。估计溶解脂肪酸的C原子% <13>，并且在高产站发现一些脂肪酸的C原子%有所增加。另一方面，在低生产力站，没有脂肪酸显示出^<13>C原子%的增加，表明浮游植物通过光合作用产生的溶解脂肪酸很少。

^<13>C tracer experiments were carried out in the East China Sea (Aug.1994 and Oct.1996) and North pacific (Nov.1995) during the cruises of R/V "Kaiyo", Japan Marine Science and Technology Center and R/V "Hakuho-maru", Ocean Research Institute, University of Tokyo, respectively. Incubation experiments were continued for 24h and dissolved organic matter was separated from particulate organic constituents by filtration using glass fiber filter (Whatman GF/F). The pressure for the filtration was controlled less than 150mmHg.Primary productivity varied form 200mgC m^<-2>d^<-1> at subtropical gyre to 1,500mgC m^<-2>d^<-1> at the Changjian estuary. Particulate fatty acid production rate was determined by ^<13>C/GC/MA method. Fatty acids such as 14 : 0,16 : 0 and 16 : 1 were major acids constituting particulate products and the contribution of 16 : 1 showed a spatial variation.For the determination of ^<13>C atom % of dissolved organic carbon, dissolved organic carbon was firstly converted to carbon dioxide by wet oxidation method. A little increase in the ^<13>C atom % in dissolve organic carbon was found at every station, indicating the production of dissolved organic carbon during the incubation experiments. ^<13>C atom % of dissolved fatty acid estimated and increase in the atom % was noted in some fatty acids at the high productivity stations. At low productivity stations, on the other hand, no fatty acid showed the increase in the ^<13>C atom %, showing little dissolved fatty acid was produced through photosynthesis of phytoplankton.