Abstract
Studying the carbon dynamics of estuarine sediment is crucial to understanding of carbon cycle in the coastal ocean. This study is to evaluate the mechanisms regulating the dynamics of organic (TOC) and inorganic carbon (TIC) in surface sediment of the Yellow River Estuary (YRE). Based on data of 15 surface sediment cores, we found that TIC (6.3–20.1 g kg−1) was much higher than TOC (0.2–4.4 g kg−1). Both TOC and TIC were generally higher to the north than to the south, primarily due to the differences in kinetic energy level (i.e., higher to the south). Our analysis suggested that TOC was mainly from marine sources in the YER, except in the southern shallow bay where approximately 75% of TOC was terrigenous. The overall low levels of TOC were due to profound resuspension that could cause enhanced decomposition. On the other hand, high levels of TIC resulted partly from higher rates of biological production, and partly from decomposition of TOC associated with sediment resuspension. The isotopic signiture in TIC seems to imply that the latter is dominant in forming more TIC in the YRE, and there may be transfer of OC to IC in the water column.
Highlights
The rate of CO2 build-up in the atmosphere depends on the rate of fossil fuel combustion and the rate of CO2 uptake by the ocean and terrestrial biota
Our analyses showed that the change ratio between there might be more inorganic carbon (TIC) and the dynamics of organic (TOC) in the surface sediment of the Yellow River Estuary (YRE) was close to the ratio of 3.6 for IC:OC in particles in the water column by Gu, et al.[15], indicating that the spatial variability of TIC might be driven by variability of POC
To our best of knowledge, this study is the first to evaluate both TOC and TIC in the surface sediment of the YRE, and to explore the underlying processes determining the dynamics of TOC and TIC
Summary
The rate of CO2 build-up in the atmosphere depends on the rate of fossil fuel combustion and the rate of CO2 uptake by the ocean and terrestrial biota. A later analysis demonstrated that rate of CaCO3 precipitation was modestly higher than rate of biological production in the water columns of the estuary[16] These findings suggest that there might be more inorganic carbon (TIC) than TOC accumulated in the sediment of the YRE. Climate change and human activities in the Yellow River basin have decreased fine sediment from the Loess Plateau and increased coarse sediment scouring from the lower river channel[20]. These changes may have profound impacts on the physical, biogeochemical and biological processes in the YRE. The objective of this study is to test the hypothesis of more TIC than TOC accumulated in the sediment, and to explore the underlying mechanisms that regulate the variability of TOC and TIC in the YRE
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
