TY - JOUR
T1 - Natural and anthropogenic geochemical signatures of floodplain and deltaic sedimentary strata, Sacramento-San Joaquin Delta, California, USA
AU - Pasternack, G.B.
AU - Brown, K.J.
N1 - Funding Information:
The authors kindly thank The Seaver Institute, University of California, and CALFED (Ecosystem Restoration Program Co-op Agreement no. 114200J095) for providing funding for this research. We would like to thank Jeff Mount, Ken Verosub, Robert Zierenberg, Mike Singer, and Gary Weissmann for their discussions, comments, and resources. We thank The Nature Conservancy for access to their land, help in field logistics, and partnership in research, outreach, and education. We are grateful to Ellen Mantalica, Kaylene Keller, Derek Sappington, Mike Bezemek, Laurel Aroner, Wendy Trowbridge, Jim MacIntyre, Jose Constantine, and other volunteers for their assistance. Anonymous reviewers provided detailed comments that improved the manuscript.
PY - 2006/5
Y1 - 2006/5
N2 - The geochemical history of an upper deltaic plain pending tidal wetland restoration was reconstructed to assess remobilization of redox-sensitive 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 CH
3Hg
+ that would be hazardous to fish.
AB - The geochemical history of an upper deltaic plain pending tidal wetland restoration was reconstructed to assess remobilization of redox-sensitive 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 CH
3Hg
+ that would be hazardous to fish.
KW - Deltas
KW - Metal accumulation
KW - Sedimentation
KW - Trace metals
KW - Wetland restoration
UR - http://www.scopus.com/inward/record.url?scp=33645137166&partnerID=8YFLogxK
U2 - 10.1016/j.envpol.2005.08.044
DO - 10.1016/j.envpol.2005.08.044
M3 - Article
SN - 0269-7491
VL - 141
SP - 295
EP - 309
JO - Environmental Pollution
JF - Environmental Pollution
IS - 2
ER -