Vertical changes of POC flux and indicators of early degradation of organic matter in the South China Sea

Time-series sediment trap materials at different water depths and surface s ediments in northern and central South China Sea (SCS) were analyzed for or ganic carbon, amino acids, amino sugars and carbohydrates. Results show tha t particulate organic carbon (POC) is mainly derived from marine plankton, only 1.4%-1.6% of primary production sinks into deep SCS water column and l ess than 0.22% of primary production ultimately reaches the sediments. The remineralization and dissolution of organic matter as well as the compositi onal alterations of organic matter mixtures may mainly take place in the up per few hundred meters of water column, deep carbonate (opal) lysocline zon es, and interface layers between sediments and water column, rather than in mid-waters. The organic geochemical parameters such as (T-AA + T-SUG)OC%, AA/AS, Gluam/Galam, Arom. AA/non-prot. AA, ASP/b-ALA, Glu/g-ABA decrease fr om living marine plankton (or planktonic shells), to settling particulate m atter and to sediments suggesting that they appear to be good early degrade d indicators of organic matter.