去吸附法测定珠江口颗粒附着细菌的丰度特征及其环境因子耦合研究

Using detaching method to determine the abundance of particle-attached bacteria from the Pearl River Estuary and its coupling relationship with environmental factors

海洋颗粒有机碳(POC)的输出通量决定了生物泵的运作效率,海洋颗粒上附着细菌的丰度和活性影响POC向海洋内部的传输,对全球碳封存起关键作用。为了更准确地评估珠江口近岸浊度较大水域中颗粒附着细菌的丰度特征,本文在国内首次报道运用去吸附法对颗粒附着细菌进行直接测定,避免了间接测定中因总细菌计数不准确而可能产生的偏差,同时将该丰度特征与相关环境因子进行耦合研究。结果显示,珠江口3个站位均是2~20μm粒级颗粒上面的附着细菌丰度占优势,其中珠海香洲港码头水域的丰度最大(4.21×10^9 cells/L),接下来是中大码头(1.13×10^9 cells/L)和万山岛水域(0.27×10^9 cells/L)。颗粒附着细菌丰度最大的香洲港码头对应的Chl a含量相对较低,可能是由于河口再悬浮颗粒有机质支撑了细菌的生长。此外,珠江口水体营养盐的浓度和比例也影响着颗粒附着细菌的生长。

Export fluxes of sinking particulate organic carbon(POC) are important for the function of biological carbon pump. Vertical transportation of POC into the ocean interior can be affected by particle-attached bacteria(PAB) via the change of their abundance and activities, which may eventually affect the carbon sequestration into the ocean. In order to better understand the characteristics of PAB in the turbid nearshore waters along the Pearl River Estuary(PRE), we applied and modified an existing analytical procedure to effectively detach PAB from sinking particles for more direct and accurate estimation of PAB. The coupling relationship between environmental factors and the abundance of PAB were further analyzed and discussed. our results suggested that PAB from the fraction 2~20 μm particles was the dominant component of PAB in all stations. Moreover,there was a spatial change of PAB along the PRE with the highest abundance at Xiangzhou port(4.21×10^9 cells/L), following by Zhongda port(1.13×10^9 cells/L) and Wanshan island(0.27×10^9 cells/L). We also found that suspended organic particles might have supported PAB growth at Xiangzhou port where there was high PAB but low chlorophyll a. In addition, the growth of PAB might also subject to influences by varying concentrations and species compositions of inorganic nutrients in coastal waters. These results may be important for further understanding of PAB associated biogeochemical processes in coastal ecosystem.