Presentation Abstract

Inputs of sediment and sediment-bound contaminants from urbanized watersheds to the nearshore region are a growing concern as coastal populations increase around the Salish Sea and worldwide. Geochemical sourcing and aging of nearshore sediment is one potential way to: a) distinguish land-derived sediment in nearshore environments, b) gain insights about how sediment and contaminants are redistributed, and c) determine how recently they were deposited. Sediments from Cascade volcanoes have distinct geochemical compositions that allow discrimination between land-derived (volcanic) and marine (lowland) sediment. As sediment is transported by rivers to the nearshore, it adsorbs particle-reactive contaminants and short-lived radionuclides, and the latter (7Be, 137Cs, and 210Pb) show time elapsed since deposition of <1 >year, ~30 years, and ~100 years, respectively. Geochemical sourcing and aging of nearshore fine sediment in Commencement Bay showed that sediment from Mount Rainier that discharged from the Puyallup River during the wet season was primarily deposited along the north shore of Commencement Bay (CB). Along the south shore of CB, which is backed by glacial bluffs, inputs from local drainages played a larger role. At two sites where contaminants and age were determined, fecal sterols, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) occurred in sediment that predated the current wet season. Geochemical sourcing without aging was explored in Bellingham Bay, which receives sediment from Mount Baker via the Nooksack River, as a way to determine how land-derived sediment is distributed in the bay. Geochemical sourcing of nearshore sediment collected in conjunction with the Washington State Department of Ecology’s Puget Sound Assessment and Monitoring Program can complement contaminant studies by the Urban Bays focus by showing areas at risk from land-derived inputs. Geochemical sourcing and aging provide unique insights about sedimentation patterns and current versus earlier contaminant inputs to nearshore environments.

Session Title

Transcending the Land-Ocean Boundary. Responses of Ecosystem Process to Climate and Human Impacts Across a Wide Spectrum of Processes, Habitats and Space

Keywords

Sediment, Geochemistry, Sourcing, Aging

Conference Track

SSE16: Long-Term Monitoring of Salish Sea Ecosystems

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE16-229

Start Date

5-4-2018 2:15 PM

End Date

5-4-2018 2:30 PM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

Share

COinS
 
Apr 5th, 2:15 PM Apr 5th, 2:30 PM

Source, transport, and age of sediment from Cascade volcano watersheds to the nearshore: insights for contaminant and ecological studies

Inputs of sediment and sediment-bound contaminants from urbanized watersheds to the nearshore region are a growing concern as coastal populations increase around the Salish Sea and worldwide. Geochemical sourcing and aging of nearshore sediment is one potential way to: a) distinguish land-derived sediment in nearshore environments, b) gain insights about how sediment and contaminants are redistributed, and c) determine how recently they were deposited. Sediments from Cascade volcanoes have distinct geochemical compositions that allow discrimination between land-derived (volcanic) and marine (lowland) sediment. As sediment is transported by rivers to the nearshore, it adsorbs particle-reactive contaminants and short-lived radionuclides, and the latter (7Be, 137Cs, and 210Pb) show time elapsed since deposition of <1>year, ~30 years, and ~100 years, respectively. Geochemical sourcing and aging of nearshore fine sediment in Commencement Bay showed that sediment from Mount Rainier that discharged from the Puyallup River during the wet season was primarily deposited along the north shore of Commencement Bay (CB). Along the south shore of CB, which is backed by glacial bluffs, inputs from local drainages played a larger role. At two sites where contaminants and age were determined, fecal sterols, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) occurred in sediment that predated the current wet season. Geochemical sourcing without aging was explored in Bellingham Bay, which receives sediment from Mount Baker via the Nooksack River, as a way to determine how land-derived sediment is distributed in the bay. Geochemical sourcing of nearshore sediment collected in conjunction with the Washington State Department of Ecology’s Puget Sound Assessment and Monitoring Program can complement contaminant studies by the Urban Bays focus by showing areas at risk from land-derived inputs. Geochemical sourcing and aging provide unique insights about sedimentation patterns and current versus earlier contaminant inputs to nearshore environments.