The particulate amino sugars (PAS), organic carbon (POC) and nitrogen (PN), the chlorophyll a (Chl-a), and the heterotrophic bacterial cell count (HBC) in the Yangtze River Estuary (YRE) were determined to study the biological source, bioavailability and bacterial contribution of particulate organic matter (POM) under the influence of algal bloom during the spring and autumn of 2017. The contents of PAS were 2.6–69.6 nmol/(mg dw) and made up 5.29 ± 2.55% of POC and 5.39 ± 2.77% of PN. The strong positive correlations between Chl-a and POC, PN and PAS and their similar distributions indicated that phytoplankton was a major source of POM and PAS in the YRE. When algal blooms occurred, the high ratios of glucosamine to galactosamine (GlcN/GalN) (~10.9) and the high carbon and nitrogen normalized yields of PAS (%PAS-POC and %PAS-PN, respectively) clearly indicated the planktonic (especially zooplankton) source of POM, although the high muramic acid (Mur) contents implying high contents of fresh bacterial organic matter (OM) were also found. Additionally, the high proportion of fresh plankton- and bacterial-derived OM indicated that the POM was more labile when algal bloom occurred. In contrast, when the primary production was low, the lower %PAS-POC and GlcN/GalN ratios (< 3) in the POM demonstrated the decreased contribution of planktonic OM and the relatively elevated contribution of bacterial OM. In addition, the higher %PAS-PN and the lower DO concentrations in seawater indicated that the POM experienced some degree of degradation but was still at an early stage in the nearshore site in autumn. In spring, the Changjiang diluted water (CDW) carried considerable plankton-derived POM into the estuary and influenced the distribution of POM. In autumn, the terrestrial OM might become more bacterial-derived and had less influence on the bulk POM of the estuary. The bacterial OM estimated by the Mur accounted for an average of 10.8 ± 3.7% and 40.5 ± 19.1% of the POC in spring and autumn, respectively, which was approximately two times higher than the results based on the heterotrophic bacterial cell count (HBC), indicating that most of the bacterial OM in the POM was detritus. In summary, the content, source and bioavailability of POM were significantly affected by algal bloom and the CDW, and the amino sugars represent a reliable tool to indicate the source and bioavailability of POM.

确定了长江口（YRE）中的颗粒氨基糖（PAS），有机碳（POC）和氮（PN），叶绿素a（Chl- a）和异养细菌细胞数（HBC），以研究该病。在2017年春季和秋季的藻华影响下，颗粒有机物（POM）的生物来源，生物利用度和细菌贡献。PAS含量为2.6–69.6 nmol /（mg dw），占5.29±2.55％ POC和PN的5.39±2.77％。Chl-之间的强正相关关系一POC，PN和PAS及其相似分布表明，浮游植物是YRE中POM和PAS的主要来源。发生藻华时，葡糖胺与半乳糖胺的比率高（GlcN / GalN）（〜10.9），PAS的碳和氮标准化产率高（分别为％PAS-POC和％PAS-PN）清楚地表明了浮游生物（尤其是浮游生物）虽然还发现了高的山酸（Mur）含量暗示着高含量的新鲜细菌有机质（OM），但仍是POM的浮游动物来源。另外，新鲜的浮游生物和细菌来源的OM的比例很高，表明当藻华发生时POM更不稳定。相反，当初级生产量较低时，％PAS-POC和GlcN / GalN比率较低（< 3）在POM中显示出浮游性OM的减少和细菌OM的相对升高。此外，海水中较高的％PAS-PN和较低的DO浓度表明，POM经历了一定程度的降解，但在秋季近岸站点仍处于早期阶段。春季，长江稀释水（CDW）将大量浮游生物来源的POM携带到河口，并影响了POM的分布。在秋天，陆地OM可能会更多地来源于细菌，并且对河口大块POM的影响较小。Mur估计的细菌OM分别在春季和秋季分别占POC的10.8±3.7％和40.5±19.1％，比基于异养细菌细胞计数（HBC）的结果高大约两倍。 ，指示POM中的大多数细菌OM是碎屑。总之，藻华和CDW对POM的含量，来源和生物利用度有显着影响，而氨基糖是表明POM来源和生物利用度的可靠工具。