Sources of Mercury in Sinclair Inlet Project
The sediments in Sinclair Inlet within Puget Sound, Washington have elevated concentrations of a number of organic compounds and elements including mercury. Following remediation actions under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), it was determined that there is insufficient information to determine whether remedial action taken at OU B Marine with respect to mercury in sediment is protective of ingestion of mercury through rockfish consumption by subsistence fishers. Three pathways were identified as having the capability to transport chemicals from the terrestrial landscape of the Bremerton Naval Complex (BNC) to the marine environment, thus having the potential to re-contaminate recently remediated marine sediment. The pathways included discharges from the dry dock discharge systems, groundwater, and storm water systems.
Recent Research
Metal fluxes to Sinclair Inlet along intertidal unwalled shorelines, Bremerton Naval Complex, Washington (2023-25)
The primary objective of this phase of work is to update the Conceptual Site Model regarding contaminant fluxes along unwalled shorelines of the Bremerton Naval Complex to Sinclair Inlet. This will be done by 1) using geophysical tools to characterize the dynamic shape and extent of the subterranean recirculating seawater cell and freshwater-marine water interface over tidal cycles, 2) measuring temporal and spatial variability of direct discharge (seepage rates) over a complete tidal cycle, and 3) measuring temporal and spatial variability of contaminant concentrations including mercury and other metals in nearshore marine pore water and seeps over a complete tidal cycle.
Metals in terrestrial groundwater and intertidal marine porewater along unwalled shorelines of the Bremerton Naval Complex, WA (2020-22)
The primary objective of this phase of work is to update the Conceptual Site Model at the Bremerton Naval Complex regarding the role of groundwater in transporting terrestrially-derived contaminants to the marine nearshore environment. This will be done by characterizing concentrations of mercury and other metals in nearshore terrestrial groundwater wells, identifying where groundwater discharges to the marine nearshore along unwalled BNC shoreline segments, and characterizing concentrations of mercury and other metals in marine porewater and intertidal sediment at the sediment-water interface along unwalled BNC shoreline segments that may be impacted by direct groundwater discharge.
9722-D6M - Data collection and technical support for the mercury-specific decision framework, Bremerton Naval Complex OU B Terrestrial and Marine (2017-19)
The USGS is providing technical support to the Navy to help identify data gaps for the mercury-specific decision framework. The USGS is conducting tidal studies at Site 1/10C and synoptic sampling at Dry Docks 1-5 and 6 to quantify the levels of mercury in groundwater and the release of mercury-containing groundwater to Sinclair Inlet via direct groundwater versus indirect discharge through the dry dock system. To aid source identification of mercury in Sinclair Inlet sediments and biota, samples from various locations on the base and archived Sinclair Inlet sediment samples will be analyzed for mercury isotope signature identification.
These objectives contribute to the goal of the USGS Washington Water Science Center of conducting basin-wide assessments of the sources and transport of contaminants within Puget Sound. The study serves a local need to develop a better understanding of the relation between sources, processes, and concentrations of mercury in Sinclair Inlet. The data and concepts derived from these activities will facilitate engineered solutions to reduce the loading of mercury from the Bremerton Naval Complex.
Previous Objectives (completed)
The overall objective was to estimate the magnitudes of the different predominant sources of mercury to OU B Marine (Sinclair Inlet) at the BNC, the transformation of Hg to a bioavailable form (methyl-mercury) in OU B, and the impact of the sources and transformation processes on the mercury burden in marine organisms. The individual primary objectives were:
Objective 1 -
Describe the sources of mercury to Sinclair Inlet and their relationship with mercury concentrations in fish tissue using mainly existing data, and new or slightly refined applications of existing models.
Objective 2 -
Describe the occurrence of methyl-mercury in fresh-water sources of mercury in the marine-water column and in the pore water of Sinclair Inlet sediments.
Objective 3 -
Evaluate the submarine discharge of mercury from the ground-water system represented by monitoring well LTMP-3.
Objective 4 -
Collect six stormwater samples and prepare a report on Objectives 1-3.
Objective 5 -
Describe and quantify the biogeochemical processes that lead to methylation of mercury in sediments, the release of methylmercury and ionic mercury from sediments, and the bioaccumulation of methylmercury into the base of the pelagic food web.
Objective 6 -
Prepare Report on methylation processes in Sinclair Inlet (Objective 5)
Objective 7 -
Define if there is a source of mercury for well LTMP-5, similar to what has been defined for LTMP-3 under objective 3. (combined with Objective 8 to form objective 12)
Objective 8 -
Estimate the loading of dissolved and particulate mercury from the largest storm drain on the BNC in a manner that includes the release of mercury to Sinclair Inlet by tidal pumping of seawater through the storm drain. (combined with objective 7 to form objective 12)
Objective 9 -
Measure the loadings of mercury from the storm drain PSNS015 during two ebbing tides from a tidal height of greater than 12 ft mean lower low water (MLLW) during a dry period.
Objective 10 -
Revise Report on Sources and Sink of Total Mercury in Sinclair Inlet in the absence of total suspended loadings data by quantifying sources and sinks of filtered total mercury and qualitatively comparing concentration of total mercury of solids from sources, in sediment and in solids suspended in the water column
Objective 11 -
Update loadings due to changes in operations of the steam plant and reduce the uncertainty of loadings of dry dock discharges and streams.
Objective 12 -
Examine the facilitation of total mercury release to Sinclair Inlet by tidally influenced storm drains.
- Task A (previous objective 7). Examine the releases of total mercury by flushing of seawater landward through storm drains into groundwater from two filled areas of the Bremerton naval complex that have elevated concentrations of total mercury in soil, and have not been previously investigated.
- Task B (previous objective 8). Identify the geographical location, the temporal variability and the geochemical mechanism that leads to release of total mercury to freshwater transported by the most extensive stormwater drainage basin on the Bremerton naval complex.
Below are other science projects associated with this project.
Navy Investigations and Technical Oversight
The sediments in Sinclair Inlet within Puget Sound, Washington have elevated concentrations of a number of organic compounds and elements including mercury. Following remediation actions under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), it was determined that there is insufficient information to determine whether remedial action taken at OU B Marine with respect to mercury in sediment is protective of ingestion of mercury through rockfish consumption by subsistence fishers. Three pathways were identified as having the capability to transport chemicals from the terrestrial landscape of the Bremerton Naval Complex (BNC) to the marine environment, thus having the potential to re-contaminate recently remediated marine sediment. The pathways included discharges from the dry dock discharge systems, groundwater, and storm water systems.
Recent Research
Metal fluxes to Sinclair Inlet along intertidal unwalled shorelines, Bremerton Naval Complex, Washington (2023-25)
The primary objective of this phase of work is to update the Conceptual Site Model regarding contaminant fluxes along unwalled shorelines of the Bremerton Naval Complex to Sinclair Inlet. This will be done by 1) using geophysical tools to characterize the dynamic shape and extent of the subterranean recirculating seawater cell and freshwater-marine water interface over tidal cycles, 2) measuring temporal and spatial variability of direct discharge (seepage rates) over a complete tidal cycle, and 3) measuring temporal and spatial variability of contaminant concentrations including mercury and other metals in nearshore marine pore water and seeps over a complete tidal cycle.
Metals in terrestrial groundwater and intertidal marine porewater along unwalled shorelines of the Bremerton Naval Complex, WA (2020-22)
The primary objective of this phase of work is to update the Conceptual Site Model at the Bremerton Naval Complex regarding the role of groundwater in transporting terrestrially-derived contaminants to the marine nearshore environment. This will be done by characterizing concentrations of mercury and other metals in nearshore terrestrial groundwater wells, identifying where groundwater discharges to the marine nearshore along unwalled BNC shoreline segments, and characterizing concentrations of mercury and other metals in marine porewater and intertidal sediment at the sediment-water interface along unwalled BNC shoreline segments that may be impacted by direct groundwater discharge.
9722-D6M - Data collection and technical support for the mercury-specific decision framework, Bremerton Naval Complex OU B Terrestrial and Marine (2017-19)
The USGS is providing technical support to the Navy to help identify data gaps for the mercury-specific decision framework. The USGS is conducting tidal studies at Site 1/10C and synoptic sampling at Dry Docks 1-5 and 6 to quantify the levels of mercury in groundwater and the release of mercury-containing groundwater to Sinclair Inlet via direct groundwater versus indirect discharge through the dry dock system. To aid source identification of mercury in Sinclair Inlet sediments and biota, samples from various locations on the base and archived Sinclair Inlet sediment samples will be analyzed for mercury isotope signature identification.
These objectives contribute to the goal of the USGS Washington Water Science Center of conducting basin-wide assessments of the sources and transport of contaminants within Puget Sound. The study serves a local need to develop a better understanding of the relation between sources, processes, and concentrations of mercury in Sinclair Inlet. The data and concepts derived from these activities will facilitate engineered solutions to reduce the loading of mercury from the Bremerton Naval Complex.
Previous Objectives (completed)
The overall objective was to estimate the magnitudes of the different predominant sources of mercury to OU B Marine (Sinclair Inlet) at the BNC, the transformation of Hg to a bioavailable form (methyl-mercury) in OU B, and the impact of the sources and transformation processes on the mercury burden in marine organisms. The individual primary objectives were:
Objective 1 -
Describe the sources of mercury to Sinclair Inlet and their relationship with mercury concentrations in fish tissue using mainly existing data, and new or slightly refined applications of existing models.
Objective 2 -
Describe the occurrence of methyl-mercury in fresh-water sources of mercury in the marine-water column and in the pore water of Sinclair Inlet sediments.
Objective 3 -
Evaluate the submarine discharge of mercury from the ground-water system represented by monitoring well LTMP-3.
Objective 4 -
Collect six stormwater samples and prepare a report on Objectives 1-3.
Objective 5 -
Describe and quantify the biogeochemical processes that lead to methylation of mercury in sediments, the release of methylmercury and ionic mercury from sediments, and the bioaccumulation of methylmercury into the base of the pelagic food web.
Objective 6 -
Prepare Report on methylation processes in Sinclair Inlet (Objective 5)
Objective 7 -
Define if there is a source of mercury for well LTMP-5, similar to what has been defined for LTMP-3 under objective 3. (combined with Objective 8 to form objective 12)
Objective 8 -
Estimate the loading of dissolved and particulate mercury from the largest storm drain on the BNC in a manner that includes the release of mercury to Sinclair Inlet by tidal pumping of seawater through the storm drain. (combined with objective 7 to form objective 12)
Objective 9 -
Measure the loadings of mercury from the storm drain PSNS015 during two ebbing tides from a tidal height of greater than 12 ft mean lower low water (MLLW) during a dry period.
Objective 10 -
Revise Report on Sources and Sink of Total Mercury in Sinclair Inlet in the absence of total suspended loadings data by quantifying sources and sinks of filtered total mercury and qualitatively comparing concentration of total mercury of solids from sources, in sediment and in solids suspended in the water column
Objective 11 -
Update loadings due to changes in operations of the steam plant and reduce the uncertainty of loadings of dry dock discharges and streams.
Objective 12 -
Examine the facilitation of total mercury release to Sinclair Inlet by tidally influenced storm drains.
- Task A (previous objective 7). Examine the releases of total mercury by flushing of seawater landward through storm drains into groundwater from two filled areas of the Bremerton naval complex that have elevated concentrations of total mercury in soil, and have not been previously investigated.
- Task B (previous objective 8). Identify the geographical location, the temporal variability and the geochemical mechanism that leads to release of total mercury to freshwater transported by the most extensive stormwater drainage basin on the Bremerton naval complex.
Below are other science projects associated with this project.