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Spatial variability in the abundance, composition, and age of organic matter in surficial sediments of the East China Sea
Author(s) -
Wu Ying,
Eglinton Timothy,
Yang Liyang,
Deng Bing,
Montluçon Daniel,
Zhang Jing
Publication year - 2013
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2013jg002286
Subject(s) - terrigenous sediment , organic matter , total organic carbon , environmental chemistry , lignin , geology , sedimentary rock , sedimentary depositional environment , sediment , geochemistry , chemistry , geomorphology , organic chemistry , structural basin
Abstract Understanding the sources and fate of organic matter (OM) sequestered in continental margin sediments is of importance because the mode and efficiency of OM burial impact the carbon cycle and the regulation of atmospheric CO 2 over long time scales. We carried out molecular (lignin‐derived phenols from CuO oxidation), elemental, isotopic (δ 13 C, Δ 14 C), and sedimentological (grain size and mineral surface area) analyses in order to examine spatial variability in the abundance, source, age of surface sediments of the East China Sea. Higher terrigenous organic matter values were found in the main accumulating areas of fluvial sediments, including the Changjiang (Yangtze) Estuary and Zhejiang‐Fujian coastal zone. Isotopic and biomarker data suggest that the sedimentary OM in the inner shelf region was dominated by aged (Δ 14 C = −423 ± 42‰) but relatively lignin‐rich OM (Λ = 0.94 ± 0.57 mg/100 mg OC) associated with fine‐grained sediments, suggesting important contributions from soils. In contrast, samples from the outer shelf, while of similar age (Δ 14 C = −450 ± 99‰), are lignin poor (Λ = 0.25 ± 0.14 mg/100 mg OC) and associated with coarse‐grained material. Regional variation of lignin phenols and OM ages indicates that OM content is fundamentally controlled by hydrodynamic sorting (especially, sediment redistribution and winnowing) and in situ primary production. Selective sorption of acid to aldehyde in clay fraction also modified the ratios of lignin phenols. The burial of lignin in East China Sea is estimated to be relatively efficient, possibly as a consequence of terrigenous OM recalcitrance and/or relatively high sedimentation rates in the Changjiang Estuary and the adjacent Zhejing‐Fujian mud belt.