Historical changes in organic matter input to the muddy sediments along the Zhejiang-Fujian Coast, China over the past 160 years

Li-lei Chen; Jia Liu; Lei Xing; Ken W. Krauss; Jia-sheng Wang; Gang Xu; Li Li

doi:10.1016/j.orggeochem.2017.06.003

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Historical changes in organic matter input to the muddy sediments along the Zhejiang-Fujian Coast, China over the past 160 years

Li-lei Chen·Jia Liu·Lei Xing·Ken W. Krauss·Jia-sheng Wang·Gang Xu·Li Li

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Abstract

The burial of sedimentary organic matter (SOM) in the large river-influenced estuarine-coastal regions is affected by hydrodynamic sorting, diagenesis and human activities. Typically, the inner shelf region of the East China Sea is a major carbon sink of the Yangtze River-derived fine-grained sediments. Most of the previous work concentrated on the studies of surface sediments or used a single-proxy in this region. In this study, two cores from the Zhejiang-Fujian Coast were analyzed using bulk (TOC, TN and δ 13 C TOC ) and molecular biomarker ( n -alkane, brassicasterol, dinosterol and glycerol dialkyl glycerol tetraether lipids) techniques to clarify the sources, spatiotemporal distribution and fate of SOM in the Yangtze River Estuary and adjacent shelf. Results from this study indicated that the effects of diagenesis and diffusion on different sedimentary biomarkers resulted in overestimation of the relative contribution of terrestrial organic matter (%OM terr ), compared with those based on δ 13 C TOC . The amounts of terrestrial plant organic matter (OM plant ) and%OM terr in sediments decreased offshore. In contrast, the amounts of marine organic matter (OM marine ) increased offshore, but closer to the Yangtze River mouth, the amounts of soil organic matter (OM soil ) increased. Moreover, the amounts of TOC, OM plant and OM marine biomarkers increased, but OM soil and%OM terr decreased over time in recent decades. Our study suggests that spatial organic matter distribution patterns in marine shelf sediments were controlled primarily by hydrodynamic sorting and nutrient concentrations, and temporally diverse patterns were controlled predominantly by anthropogenic influence (e.g., dam construction and soil conservation, reclamation and agricultural plantations, anthropogenic nutrient input, dust storms, eutrophication, etc) and climate events (e.g., interdecadal climatic jump and heavy rain events) in the geological period.

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Organic Geochemistry Article

Source-reported bounding extent: 25° to 35° latitude; 118° to 128° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Li-lei Chen, Jia Liu, Lei Xing, Ken W. Krauss, Jia-sheng Wang, Gang Xu, Li Li. 2017. Historical changes in organic matter input to the muddy sediments along the Zhejiang-Fujian Coast, China over the past 160 years. https://doi.org/10.1016/j.orggeochem.2017.06.003

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