辽东湾夏季叶绿素a分布特征与浮游植物溶解有机碳释放率估算

DISTRIBUTION OF CHLOROPHYLL aAND ESTIMATION OF RELEASING RATE OF DOC BY PHYTOPLANKTON DURING SUMMER IN LIAODONG BAY,CHINA

基于2013年夏季现场调查和14 C同位素示踪培养实验结果,对辽东湾水文环境参数、叶绿素a浓度与分布、浮游植物在光合作用过程中的溶解有机碳释放率进行了测试和分析。结果表明,辽东湾夏季叶绿素a表层平均值约为(6.10±0.41)mg/m3,且在局部出现显著的高值区和低值区,其中高值区可能存在藻华现象。叶绿素a低值区出现在双台子河的河口,主要原因是河水中过量泥沙悬浮物降低该区水体透明度,从而导致浮游植物生长受到光限制。6个典型站点的溶解有机碳释放率范围为(1.69±0.06)^(7.59±0.94)mg/(m3·h),平均值为(3.42±0.94)mg/(m3·h),占总有机碳生产率的3.57%~7.30%,平均为4.94%±0.59%。回归分析结果表明,叶绿素a含量对初级生产力的大小具有直接影响,而浮游植物溶解有机碳的释放率也与叶绿素a和光合作用率具有显著的线性相关性,表明在辽东湾水域富营养化所导致的局部高生物量促进了水体藻类光合固碳效率,溶解有机碳的生产率也同步增高。

Based on an in situinvestigation and incubation experiments using 14 C as a tracer during the summer of 2013 in Liaodong Bay,China,we examined the concentrations and distributions of the environmental parameter,chlorophyll a（Chl a）,and the releasing rates of dissolved organic carbon（DOC）by phytoplankton in the process of photosynthesis.Results show that the average concentration of Chl ais（6.10±0.41）mg/m^3 in the surface water.Several high-and low-Chl azones appeared in some places of the bay with possible blooms in the high-Chl aareas,which resulted in the fast consumption of nutrients.An apparent low-Chl azone appeared nearby the mouth of Shuangtaizi River,and the weak light availability caused by sandy suspended particulate matter（SPM）was probably the limiting factor for phytoplankton growth in this region.The estimated total DOC productivities at six selected typical stations range from（1.69±0.06）to（7.59±0.94）mg/（m^3·h）with an average of（3.42±0.94）mg/（m^3·h）,and account for 4.94%±0.59% of the total primary productivities.Regression analyses suggest that the concentration of Chl a,i.e.phytoplankton biomass,was correlated well with the primary productivities.The DOC releasing rate by phytoplankton was correlated well with the Chl aconcentrations and phytoplankton photosynthesis rates,implying that regional high biomass caused by eutrophication promote the high primary productivities and high releasing rates of DOC as well in Liaodong Bay.