Implications of radiocarbon ages of organic and inorganic carbon in coastal lakes in Florida for establishing a reliable chronology for sediment-based paleoclimate reconstruction

Coastal lake sediments are valuable paleoclimate archives provided that they can be accurately dated. Here, we report radiocarbon ages of bulk sediment organic matter (OM), plants, shells, particulate OM, and dissolved OM from coastal lakes in Florida. Bulk sediment OM yielded ages that are consiste...

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Bibliographic Details
Published in:Quaternary research 2019-03, Vol.91 (2), p.638-649
Main Authors: Wang, Yang, Das, Oindrila, Xu, Xiaomei, Liu, Jin, Jahan, Shakura, Means, Guy H., Donoghue, Joseph, Jiang, Shijun
Format: Article
Language:English
Subjects:
Age
Carbon dating
Coasts
Cores
Field study
Inorganic carbon
Laboratories
Lake sediments
Lakes
Magnetic fields
Organic matter
Organisms
Paleoclimate
Parks & recreation areas
Radiocarbon dating
Research Article
Sedimentation
Sedimentation & deposition
Sediments
Water depth
Watersheds
Wildlife sanctuaries
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Summary:Coastal lake sediments are valuable paleoclimate archives provided that they can be accurately dated. Here, we report radiocarbon ages of bulk sediment organic matter (OM), plants, shells, particulate OM, and dissolved OM from coastal lakes in Florida. Bulk sediment OM yielded ages that are consistently older than contemporaneous plants and shells, indicating significant radiocarbon deficiencies in sedimentary OM in these lakes. The data show that the OM radiocarbon deficiency varies over time and with location, making it impossible to determine a proper correction factor for radiocarbon ages of bulk sediments from these lakes. As a result, we consider ages obtained from bulk sediment OM from these lakes unreliable. The age reversals in bulk sediment OM observed in the sediment cores are likely caused by rapid increases in erosion and sedimentation resulting from large storm events. The data also show that sedimentation rate can vary considerably within a given lake, implying that an age-depth model established for one core cannot be directly applied to other cores despite their close proximity. Analyses of shells from one of the lakes suggest that fresh/brackish-water shells may serve as a good substrate for radiocarbon dating owing to a small reservoir effect on inorganic carbon.
ISSN:0033-5894
1096-0287
DOI:10.1017/qua.2018.96