东海陆架典型断面颗粒态氨基酸的分布及控制因素分析

采用高效液相色谱法,通过现场调查对东海典型PN断面(文中为C断面)的颗粒态氨基酸(Particulate Amino Acids,PAA)进行了分析,并结合叶绿素a(Chla)、颗粒有机碳(POC)、颗粒有机氮(PON)及颗粒态氨基酸的构型特征(D和L型)等参数探讨了该区颗粒有机氮的来源和降解情况。结果表明,在长江口最大浑浊带,受咸淡水混合和生物现场生产双重作用影响,POC、PON以及PAA的总浓度均达到了极大值,其中,受再悬浮作用影响,底层水体中的有机物呈现高度降解的状态;近岸水华区域的颗粒态氨基酸则更多来源于现场生产,而且POC/Chla质量比值与降解因子DI值的负相关特征表明冲淡水向海洋输送的过程中,现场生产力对颗粒有机碳的贡献比重逐渐增大,悬浮颗粒物也变得越来越新鲜。值得关注的是,一些D型氨基酸如D型天冬氨酸(D-Asp),D型丙氨酸(D-Ala)]与细菌生物量之间存在良好的正相关性,暗示颗粒态氨基酸在受到物理水团和生物现场生产作用控制的同时,还受控于微微型浮游生物以及异养细菌。

DISTRIBUTION OF PARTICULATE AMINO ACIDS AND ITS CONTROLLING FACTORS IN THE PN TRANSECTION OF THE EAST CHINA SEA SHELF

Particulate amino acids (PAA) were analyzed by high performance liquid chromatography (HPLC) after field work in the PN transection (Section C in this paper) of the East China Sea on May 2011, and several parameters were analyzed including chlorophyll a (Chl a), particulate organic carbon (POC), nitrogen (PON) and configuration of amino acids (D- and L-enan?tiomers), to understand the origin and degree of degradation of particulate organic nitrogen (PON) deeply. It turned out that at the Changjiang River estuarine turbidity maximum zone, the total concentrations of POC, PON and PAA reached their maximum influenced by the dynamic mixing of fresh and salt water and in situ production of phytoplankton, with the organic matters in turbid bottom layer presenting high degree of degradation caused by the resuspended sediments. On the shelf of nearshore zone, phytoplankton production and biological detritus became the main origin of PAA in water volume including water bloom. The mass ratio of POC/Chl a display a negative correlation with the degradation index (DI) inferring that field productivity contributes more organic carbon to the SPM in the transporting process of fresh water to the sea, with the SPM becoming fresher. Particularly, some D-enantiomers of amino acids such as aspartic acid and alanine performed a good positive correlation with the cell abundance of picoeukaryotes and heterotrophic bacteria, inferring that additional to the dynamics of water mass and biological field production, PAAs were also controlled by degradation process of bacteria.