Event Title

Factors influencing Puget Sound nearshore sediment chemistry: results from the Stormwater Action Monitoring (SAM) program

Presentation Abstract

In an effort to assess the status of current nearshore sediment chemical concentrations and the effectiveness of stormwater management overtime, the Stormwater Action Monitoring (SAM) program initiated a spatially balanced randomized sediment sampling study design in the Puget Sound. Forty one randomly selected sites were chosen in the nearshore adjacent to Urban Growth Areas (UGA). During summer 2016, sediment was collected at the sites six feet below the mean low low water (MLLW) line and was sieved to 2mm and less. All samples were analyzed for organic carbon, metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and polybrominated diphenyl ethers (PBDEs). Concentrations were generally low and typically below sediment criteria, but exhibited a wide range often exceeding 2 orders of magnitude. Only two sites exhibited substantially elevated levels of PAH and/or total PCBs. These two sites were located adjacent to a rail line and industrial area. A number of statistical tests were performed, but we were unable to discover any significant relationships between land cover attributes in the watersheds adjacent to the sampling sites and sediment chemical concentrations. However, sediment chemical concentrations were significantly related to the type of drift cell in which the sampling site was located. Puget Sound drift cell types are characterized by the direction and amount of sediment movement along a shoreline. For this study, sediment chemical concentrations were significantly lower in sites located in actively moving drift cells. These results suggest a resorting and dilution of nearshore sediment chemical concentrations is occurring, but is dependent on the type of drift cell the site is located in. Future efforts designed to assess how changes in watershed stormwater management may influence nearshore sediment chemistry will need to consider the role drift cells play in nearshore sediment dynamics.

Session Title

Monitoring Stormwater Impacts on Contaminants in Receiving Waters

Conference Track

SSE3: Fate, Transport, and Toxicity of Chemicals

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE3-183

Start Date

6-4-2018 2:15 PM

End Date

6-4-2018 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

This document is currently not available here.

Share

COinS
 
Apr 6th, 2:15 PM Apr 6th, 2:30 PM

Factors influencing Puget Sound nearshore sediment chemistry: results from the Stormwater Action Monitoring (SAM) program

In an effort to assess the status of current nearshore sediment chemical concentrations and the effectiveness of stormwater management overtime, the Stormwater Action Monitoring (SAM) program initiated a spatially balanced randomized sediment sampling study design in the Puget Sound. Forty one randomly selected sites were chosen in the nearshore adjacent to Urban Growth Areas (UGA). During summer 2016, sediment was collected at the sites six feet below the mean low low water (MLLW) line and was sieved to 2mm and less. All samples were analyzed for organic carbon, metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and polybrominated diphenyl ethers (PBDEs). Concentrations were generally low and typically below sediment criteria, but exhibited a wide range often exceeding 2 orders of magnitude. Only two sites exhibited substantially elevated levels of PAH and/or total PCBs. These two sites were located adjacent to a rail line and industrial area. A number of statistical tests were performed, but we were unable to discover any significant relationships between land cover attributes in the watersheds adjacent to the sampling sites and sediment chemical concentrations. However, sediment chemical concentrations were significantly related to the type of drift cell in which the sampling site was located. Puget Sound drift cell types are characterized by the direction and amount of sediment movement along a shoreline. For this study, sediment chemical concentrations were significantly lower in sites located in actively moving drift cells. These results suggest a resorting and dilution of nearshore sediment chemical concentrations is occurring, but is dependent on the type of drift cell the site is located in. Future efforts designed to assess how changes in watershed stormwater management may influence nearshore sediment chemistry will need to consider the role drift cells play in nearshore sediment dynamics.