Presentation Abstract

The temporal and spatial distribution of dissolved PBDE concentration in the Strait of Georgia (SoG) is combined with concentrations predicted from a time-dependent box model of the Salish Sea to investigate the sources, sinks, dispersion and cycling of PBDE congeners. Prominent sub-surface concentration maxima (up to ca. 400 pg/L for total PBDE) occasionally measured in the southern SoG point to the Iona Island Waste Water Treatment Plant diffusers, discharging primary-treated effluent at 72 - 106 m depth, as an important proximal point source of dissolved PBDE. The decreasing depth of concentration maximum with increasing congener bromination suggests that dissolved PBDEs are desorbed from sewage particles, at rates decreasing with their level of bromination, as the effluent plume rises to its depth of neutral buoyancy (ca. 50 m). The much lower dissolved PBDE concentrations measured in the northern SoG, Haro Strait and Juan de Fuca Strait reflects dilution of the effluent plume by mixing and removal of dissolved PBDE by adsorption on settling marine particles. The large temporal variability of dissolved PBDE concentration in the southern SoG is related to hydrography and the time of residence of the sampled water in the SoG. The lower concentrations of dissolved PBDE predicted by the Salish Sea box model by adding PBDE in the SoG at a rate equivalent to effluent discharge from waste water treatment plants measured in 2003 indicate a higher effluent PBDE concentration in recent years or another dissolved PBDE subsurface source yet to be identified.

Session Title

Session 1.2B: Contaminants in the Salish Sea: Sources, Movement, and Fate

Conference Track

Contaminants, Plastics, Microplastics, Toxicology & Stormwater

Conference Name

Salish Sea Ecosystem Conference (2020 : Online)

Document Type

Event

SSEC Identifier

2020_abstractID_4012

Start Date

21-4-2020 12:30 PM

End Date

21-4-2020 2:00 PM

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

Language

English

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Apr 21st, 12:30 PM Apr 21st, 2:00 PM

Sources, sinks, dispersion and cycling of dissolved polybrominated diphenyl ethers (PBDEs) discharged in the Strait of Georgia

The temporal and spatial distribution of dissolved PBDE concentration in the Strait of Georgia (SoG) is combined with concentrations predicted from a time-dependent box model of the Salish Sea to investigate the sources, sinks, dispersion and cycling of PBDE congeners. Prominent sub-surface concentration maxima (up to ca. 400 pg/L for total PBDE) occasionally measured in the southern SoG point to the Iona Island Waste Water Treatment Plant diffusers, discharging primary-treated effluent at 72 - 106 m depth, as an important proximal point source of dissolved PBDE. The decreasing depth of concentration maximum with increasing congener bromination suggests that dissolved PBDEs are desorbed from sewage particles, at rates decreasing with their level of bromination, as the effluent plume rises to its depth of neutral buoyancy (ca. 50 m). The much lower dissolved PBDE concentrations measured in the northern SoG, Haro Strait and Juan de Fuca Strait reflects dilution of the effluent plume by mixing and removal of dissolved PBDE by adsorption on settling marine particles. The large temporal variability of dissolved PBDE concentration in the southern SoG is related to hydrography and the time of residence of the sampled water in the SoG. The lower concentrations of dissolved PBDE predicted by the Salish Sea box model by adding PBDE in the SoG at a rate equivalent to effluent discharge from waste water treatment plants measured in 2003 indicate a higher effluent PBDE concentration in recent years or another dissolved PBDE subsurface source yet to be identified.