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

Organic Geochemistry
By: , and 

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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 δ13CTOC) 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 (%OMterr), compared with those based on δ13CTOC. The amounts of terrestrial plant organic matter (OMplant) and%OMterr in sediments decreased offshore. In contrast, the amounts of marine organic matter (OMmarine) increased offshore, but closer to the Yangtze River mouth, the amounts of soil organic matter (OMsoil) increased. Moreover, the amounts of TOC, OMplant and OMmarine biomarkers increased, but OMsoil and%OMterrdecreased 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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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Historical changes in organic matter input to the muddy sediments along the Zhejiang-Fujian Coast, China over the past 160 years
Series title Organic Geochemistry
DOI 10.1016/j.orggeochem.2017.06.003
Volume 111
Year Published 2017
Language English
Publisher Elsevier
Contributing office(s) Wetland and Aquatic Research Center
Description 13 p.
First page 13
Last page 25
Country China
Other Geospatial Zhejiang-Fujian Coast