Peat cores were collected in 4 remnant marsh islands and 4 drained, farmed islands throughout the Sacramento - San Joaquin Delta of California in order to characterize the peat accretion history of this region. Radiocarbon age determination of marsh macrofossils at both marsh and farmed islands showed that marshes in the central and western Delta started forming between 6030 and 6790 cal yr BP. Age-depth models for three marshes were constructed using cubic smooth spline regression models. The resulting spline fit models were used to estimate peat accretion histories for the marshes. Estimated accretion rates range from 0.03 to 0.49 …
continued below
Publisher Info:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA
Place of Publication:
Livermore, California
Provided By
UNT Libraries Government Documents Department
Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.
Descriptive information to help identify this article.
Follow the links below to find similar items on the Digital Library.
Description
Peat cores were collected in 4 remnant marsh islands and 4 drained, farmed islands throughout the Sacramento - San Joaquin Delta of California in order to characterize the peat accretion history of this region. Radiocarbon age determination of marsh macrofossils at both marsh and farmed islands showed that marshes in the central and western Delta started forming between 6030 and 6790 cal yr BP. Age-depth models for three marshes were constructed using cubic smooth spline regression models. The resulting spline fit models were used to estimate peat accretion histories for the marshes. Estimated accretion rates range from 0.03 to 0.49 cm yr{sup -1} for the marsh sites. The highest accretion rates are at Browns Island, a marsh at the confluence of the Sacramento and San Joaquin rivers. Porosity was examined in the peat core from Franks Wetland, one of the remnant marsh sites. Porosity was greater than 90% and changed little with depth indicating that autocompaction was not an important process in the peat column. The mean contribution of organic matter to soil volume at the marsh sites ranges from 6.15 to 9.25% with little variability. In contrast, the mean contribution of inorganic matter to soil volume ranges from 1.40 to 8.45% with much greater variability, especially in sites situated in main channels. These results suggest that marshes in the Delta can be viewed as largely autochthonous vs. allochthonous in character. Autochthonous sites are largely removed from watershed processes, such as sediment deposition and scour, and are dominated by organic production. Allochthonous sites have greater fluctuations in accretion rates due to the variability of inorganic inputs from the watershed. A comparison of estimated vertical accretion rates with 20th century rates of global sea-level rise shows that currently marshes are maintaining their positions in the tidal frame, yet this offers little assurance of sustainability under scenarios of increased sea-level rise in the future.
This article is part of the following collection of related materials.
Office of Scientific & Technical Information Technical Reports
Reports, articles and other documents harvested from the Office of Scientific and Technical Information.
Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.
Drexler, J Z; de Fontaine, C S & Brown, T A.PEAT ACCRETION HISTORIES DURING THE PAST 6000 YEARS IN MARSHES OF THE SACRAMENTO - SAN JOAQUIN DELTA, CALIFORNIA, USA,
article,
July 20, 2009;
Livermore, California.
(https://digital.library.unt.edu/ark:/67531/metadc931622/:
accessed June 14, 2024),
University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu;
crediting UNT Libraries Government Documents Department.
