【Title】Distribution of dissolved organic carbon in and near the Prydz Bay ,Antarctica
Prydz Bay , Antarctic;
dissolved organic carbon;
【摘要】中国南极科学考察第16航次期间(1999年11月～2000年4月) ,在南极普里兹湾及邻近海域的不同站位与水深采集海水样品用于溶解有机碳测定,通过高温催化氧化法完成样品的分析.结果表明,在调查期间,南极普里兹湾及其邻近海域各测站上层水体(0～100 m) 溶解有机碳浓度的变化范围为1413～18111μmol/ dm3 ,平均为5215μmol/ dm3 ,该变化幅度比Ross海、太平洋等海域的相应值略大. 溶解有机碳垂直分布的特征是0大于25大于50大于100 m ,即随深度的增加溶解有机碳浓度逐渐减小,与生物活动在垂直方向上的强弱变化相关. 根据200 m以深水柱溶解有机碳的垂直分布,可确定研究海域难降解溶解有机碳的浓度为4014μmol/dm3 ,与其他研究所报道的数值(～42μmol/dm3) 相近.上层水体(0～100m)过剩溶解有机碳的空间分布显示,64°S 以北海域溶解有机碳过剩较多,而64°S以南海域则过剩溶解有机碳较少. 溶解有机碳浓度与分布特征显示,普里兹湾及其邻近海域溶解有机碳浓度与南大洋其他海域相当,具有低溶解有机碳的一般特征. 溶解有机碳浓度的空间分布呈现由西南向东北方向逐渐增加的趋势,这可能与南极陆架夏季上层水的北向扩展有关. 生物活动及水体运动是研究海域溶解有机碳分布的主要影响因素.
【Abstract】Marine carbon cycling is a hotspot in international marine research due to its close link to global change.Dissolved organic carbon (DOC) , the most important carbon pool in the ocean , play an important role in marine car
bon cycling. One particular interest pertaining to the Southern Ocean relates to its important role as a region for CO2
sequestration through biological processes of carbon uptake , which can counteract greenhouse gas accumulation in the atmosphere. During the 16th Chinese National Antarctic Research Expedition (CHINARE) (from November 1999 to April 2000) ,seawater samples were collected for DOC determination in the Prydz Bay and its nearby sea areas.All of samples were filtered through the pre2combusted GF/F membranes and drained into the pre2combusted brown glass bottles. After acidification with high grade phosphoric acid , samples were stored in a freezer till DOC determination in laboratory. DOC concentration was determined by high temperature catalytic oxidation (HTCO) method(TOC - 5000A , Shimadzu Corp.) . The results show that the average DOC concentration in the upper water column (0～100 m) ranges from 23.3 to 110.3μmol/ dm3 , with averaging 52.5μmol/ dm3 (n = 55) . These values
are slightly higher than those reported for the Ross Sea , the Pacific Ocean and others. Profiles of the DOC concentration in the study areas show a decreasing concentration with increasing depth in the upper 100 m , which is related to biological activities in the water column. The DOC concentrations below 200 m are relatively constant with a mean of 40.4 μmol/ dm3. These DOC are unactive for physical and biological activities and are called refractory
DOC. The concentration of the refractory DOC in the study area is consistent with previous reported values for the Southern Ocean , which are about 41μmol/ dm3 . Based on the difference between the DOC concentration and refractory concentration , the excess DOC concentration in the upper column can be calculated at every station. The excess
DOC shows a spatial change with a higher excess in the north of 64° and little excess in the south of 64°. In conclusion , the DOC concentrations in the Prydz Bay and its nearby sea areas are consistent with previous reported values in the Southern Ocean. All of them show a low DOC concentration with respect to the other ocean. The distribution of surface DOC concentrations in the study areas shows an increase from the south2western to the northeastern,which is ascribe to the northern spread of continental shelf water from the Prydz Bay in summer. The concentration
and distribution of DOC in the Prydz Bay and its nearby sea areas are mainly controlled by physical and biological processes.