Natural and anthropogenic geochemical signatures of floodplain and deltaic sedimentary strata, Sacramento Delta, CA

TitleNatural and anthropogenic geochemical signatures of floodplain and deltaic sedimentary strata, Sacramento Delta, CA
Publication TypeJournal Article
Year of Publication2005
AuthorsBrown, K., & Pasternack G.
JournalEnvironmental Pollution
Volume141
Issue2
Date Published08/05
AbstractThe geochemical history of an upper deltaic plain pending tidal wetland restoration was reconstructed to assess remobilization of redoxsensitive constituents in sediment, identify depositional processes promoting geochemical retention, and determine the extent of contamination with Hg, As, Pb, Cu, and Zn. Three 12—14-m sediment cores were analyzed for bulk sediment geochemistry using ICP-AES. Rather than showing similar stratigraphic and geochemical down-core trends, cores had a unique record indicative of strong spatial gradients in deposition processes. Each strata type (e.g. basal clay, sand channel, distal floodplain, and agriculturally impacted surficial horizon) had a unique geochemical ‘‘fingerprint’’. The agriculturally impacted surficial layer showed high [Hg], [As], and [Pb]. The significance is that a restored upper delta will have a complex geomorphology defying conventional criteria of ‘‘success’’ in a restoration framework. Also, there is a significant risk of generating toxic, bio-available CH3Hg+ that would be hazardous to fish
URLhttp://watershed.ucdavis.edu/pdf/Brown-Pasternack-2006.pdf