期刊
CHEMICAL GEOLOGY
卷 495, 期 -, 页码 104-117出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.chemgeo.2018.08.012
关键词
Marginal seas; Sedimentary regimes; Pore waters; Sedimentary organic carbon; Remineralization; Yellow and East China Seas
资金
- National Natural Science Foundation of China [41676063, 41620104001]
- National Natural Science Foundation for Creative Research Groups [41521064]
- 111 project [B13030]
We investigated the remineralization of sedimentary organic carbon (SOC) at 12 sites in East China Sea mobile-muds (ECSMMs) and South Yellow Sea central mud deposits (SYSMDs) - using a time-sequence sediment incubation experiment. We examined pore-water dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), fluorescent dissolved organic matter (FDOM), dissolved inorganic nitrogen (DIN) nutrients (NH4+, NO3-, and NO2-), redox sensitive elements (Fe2+ and Mn2+), and major anions (SO42- and Cl-) in incubated sediments, to better constrain controlling mechanisms of SOC remineralization under different sedimentary regimes. Lower DIC production rates in SYSMDs (2.36-3.13 mmol m(-2)d(-1)) than those in ECSMMs (2.94-13.5 mmol m(-2)d(-1)), were mainly attributed to cold bottom water masses and a relatively stable sedimentary environment in SYS. Higher DIC production rates were observed mostly at offshore sites of ECSMMs that had relatively enriched C-13 of SOC - which indicated preferential degradation of labile SOC of marine origin. When compared with tropical mobile-muds, higher bottom-water temperatures, thicker mobile-muds, and large inputs of reactive terrestrial OC resulted in more intense remineralization of SOC in Amazon mobile-muds than in ECSMMs. Lower ratios of DOC/DIC production rates in ECSMMs (0.11-0.72) were likely indicative of efficient transformation of OC, and largely due to sulfate reduction. A rapid increase in marine protein-like FDOM components during the incubation indicated that less stable marine SOC was preferentially converted to DOC and then to DIC. Our SOC budget indicates that 16.8% of SOC was decomposed in sediments of ECSMMs, but only about 5.4% of SOC was decomposed in SYSMDs, suggesting lower SOC preservation efficiency in mobile-muds than distal muds.
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