Risk Assessment, Monitoring, and Management of Contaminated Marine Sediments
Presentation Abstract
Sediments are a sink and a source for contaminants discharged directly or indirectly (e.g., via rivers, estuaries) into marine waters such as the Salish Sea. Contaminants in sediments, although less bioavailable than in the water column, can adversely affect benthic infauna and epifauna and, if released to overlying waters (e.g., by extreme events such as storms in shallow waters), can affect water column fauna. Determining the risk posed by contaminated sediments requires more than simply measuring total concentrations of contaminants in sediments, although such can serve for subsequent monitoring. Such measurements provide no information on bioavailability, provide simple binary decision-points related to hazard not risk, and ignore uncertainty. Biological assessments are also necessary, for instance determining sediment toxicity and the status of resident benthic communities. The latter assessments are the most realistic, but are confounded by increasing human-related natural variability (e.g., due to climate change, invasive species). Thus, risk assessment of contaminated sediments requires both chemical and biological measurements, which should be interpreted in the context of ecosystem services (i.e., the benefits people obtain from ecosystems), not in the context of protection of individual or even all species. They should also be interpreted relative to other, non-chemical stressors. Management of contaminated sediments requires not doing more harm than good; in general, when appropriate, monitored natural recovery is the preferred option. Other management options include capping, in situ treatment, dredging and disposal. All management options have constraints; none is useful without effective source control, and none should be undertaken based solely on perception, political, and/or bureaucratic reasons. Such decisions require a rational, technically defensible basis.
Session Title
Sediments as a sink: Tracking pollutants over space and time in the Salish Sea
Conference Track
Fate and Effects of Pollutants
Conference Name
Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)
Document Type
Event
Start Date
2016 12:00 AM
End Date
2016 12:00 AM
Location
2016SSEC
Type of Presentation
Oral
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Contaminated sediments--Toxicity testing--Salish Sea (B.C. and Wash.); Benthic animals--Effect of contaminated sediments on--Salish Sea (B.C. and Wash.); Marine ecosystem management--Salish Sea (B.C. and Wash.)
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
Risk Assessment, Monitoring, and Management of Contaminated Marine Sediments
2016SSEC
Sediments are a sink and a source for contaminants discharged directly or indirectly (e.g., via rivers, estuaries) into marine waters such as the Salish Sea. Contaminants in sediments, although less bioavailable than in the water column, can adversely affect benthic infauna and epifauna and, if released to overlying waters (e.g., by extreme events such as storms in shallow waters), can affect water column fauna. Determining the risk posed by contaminated sediments requires more than simply measuring total concentrations of contaminants in sediments, although such can serve for subsequent monitoring. Such measurements provide no information on bioavailability, provide simple binary decision-points related to hazard not risk, and ignore uncertainty. Biological assessments are also necessary, for instance determining sediment toxicity and the status of resident benthic communities. The latter assessments are the most realistic, but are confounded by increasing human-related natural variability (e.g., due to climate change, invasive species). Thus, risk assessment of contaminated sediments requires both chemical and biological measurements, which should be interpreted in the context of ecosystem services (i.e., the benefits people obtain from ecosystems), not in the context of protection of individual or even all species. They should also be interpreted relative to other, non-chemical stressors. Management of contaminated sediments requires not doing more harm than good; in general, when appropriate, monitored natural recovery is the preferred option. Other management options include capping, in situ treatment, dredging and disposal. All management options have constraints; none is useful without effective source control, and none should be undertaken based solely on perception, political, and/or bureaucratic reasons. Such decisions require a rational, technically defensible basis.
