2006年12月至2007年1月(冬季)期间,对北部湾海区的生物固氮作用进行了初步研究,结果表明:当培养时间为2 H时,水体浮游生物固氮速率最高,且固氮速率随着培养时间的延长而逐渐降低。北部湾冬季固氮速率存在周日变化,8∶10~11∶10时段内固氮速率达到最高值。10 M和30 M水深在夜间仍能检测到固氮活性,这可能是浮游生物昼夜垂直移动引起的。北部湾冬季固氮速率的范围为447.5~1447.2 PMOl/(l.H),固氮速率呈现出从湾内往湾外不断增加的趋势,湾口海区(b06站)的积分固氮速率为319.5μMOl/(M2.d)。b06站fE加富实验表明,添加100 nMOl/l fE能够明显促进生物固氮作用,北部湾冬季湾口海区生物固氮作用可能受到fE限制。The biological nitrogen fixation rates were investigated in Tokin Gulf waters in winter from Dec.2006 to Jan.2007.The nitrogen fixation rates were decreased as extension of culture time,the optimal culture time was 2 h.The nitrogen fixation rates showed diurnal variations,the highest nitrogen fixation rate appeared at 8∶ 10--11∶ 10,the diazotrophs still have the nitrogen fixation activity during the night at the depths of 10 m and 30 m,which may result from the diurnal migration of planktons.The nitrogen fixation rates ranged from 447.5 pmol/(L·h) to 1 447.2 pmol/(L·h) of Tokin Gulf waters in winter.Which showed a longitudinally increasing trend,the integral nitrogen fixation rate at station B06 was 319.5 μmol/(m2·d).The iron enrichment experiment at the mouth of the bay(B06) showed that the biological nitrogen fixation significantly promoted by adding iron concentration of 100 nmol/L.The biological nitrogen fixation rates at the bay mouth might be iron limited.国家自然科学基金重大研究计划重点项目资助(90411016);国家教育部高等学校骨干教师计划基金资助项
