珠江口及海南岛东南海域海水中氨基酸的分布及其对有机物降解指示的研究OA北大核心CSTPCD

The concentrations and distributions of total dissolved amino acids(THAA),dissolved or-ganic carbon(DOC),organic nitrogen(TN)and chlorophyll a(Chl a)in the seawater of the Pearl Riv-er Estuary and Hainan Island Southeast Sea were systematically investigated in August 2021.The re-sults showed that the concentrations of THAA in the study area ranged from 0.68 to 4.22 μmol/L,with an average of(1.69±0.98)μmol/L.In the vertical distribution,the amino acid concentrations all showed a gradual decrease with increasing depth.Concentrations of THAA positively correlated with aspartic acid(Asp)/β-alanine(β-Ala)and glutamic acid(Glu)/γ-aminobutyric acid(γ-Aba)ratios,in-dicating that bacterial activity had an important influence on the distribution and degradation of THAA.The contribution of bacterial organic carbon to DOC was about(13.04%±4.50%),showing a lower value inshore than offshore and a higher value in surface layer than in bottom layer.It was found that the distribution trend of contribution of carbon in amino acid to organic carbon(THAA-C%)was lower inshore than offshore,indicating a greater degradation of organic matter at the inshore station.Degrada-tion Index(DI)and Reactivity Index(RI)showed similar distribution trends with THAA-C%,and high value areas were observed in the eastern part of the study area and the inshore waters of the Pearl River Estuary.In the vertical profile,lower values of degradation factor were found at the bottom layer of the Pearl River Estuary in transect S8—S14,indicating that the degradation degree of organic matters in the bottom layer was greater,whereas contrast distribution patterns were found near the Southeast Sea of Hainan Island.