Duwamish Waterway Research Articles

Allocating Lower Duwamish Waterway Sediment Remediation Cost by Insurance Policy Period

To mitigate risk from contaminated sediment in the Lower Duwamish Waterway, the United States Environmental Protection Agency selected a remedial strategy that will address impacted shallow sediment. Since new sediment is deposited in the waterway each year, remediation of shallow sediment primarily addresses new sediment in many areas, and remediation costs can be time-allocated accordingly. For example, by selecting 1986 as the key year, it can be shown that much of the environmental injury being remediated occurred after the Absolute Pollution Exclusion was incorporated into most General Liability insurance policies. This methodology could be applied to other mega-sediment remediation sites. The author notes, however, that this analysis method may not be directly applicable to allocating CERCLA liability due to the differing emphasis placed on the timing of environmental injury.

Investigating the Effect of Bioirrigation on In Situ Porewater Concentrations and Fluxes of Polychlorinated Biphenyls Using Passive Samplers.

Polychlorinated biphenyl (PCB) fluxes from contaminated sediments can be caused by mechanisms including diffusion, bioirrigation, and resuspension, but it is often unclear which mechanisms are important. In the Lower Duwamish Waterway (Seattle, Washington), the presence of abundant benthic macrofauna suggests that porewater bioirrigation may be an important mechanism for PCB transport from the bed into the overlying water column. In this field study, the fluxes of PCBs due to bioirrigation were quantified by using (a) polyethylene (PE) samplers to quantify in situ and ex situ (i.e., equilibrium) PCB porewater concentration profiles and (b) measurements of the geochemical tracer 222Rn to quantify the rate of porewater exchange with overlying water. The results showed that bioirrigation caused sorptive disequilibrium with the surrounding sediment, which led to lower in situ porewater concentrations than expected from sediment concentrations. The combined fluxes of seven PCB congeners (Σ7PCBs) were 1.6-26 ng/m2/day for the three field sites, similar in magnitude to the upper limit estimates of diffusive fluxes calculated assuming water-side boundary layer control (Σ7PCBs = 1.3-47 ng/m2/day). Moreover, the depleted in situ porewater concentrations imply lower diffusive flux estimates than if the ex situ porewater concentrations had been used to estimate fluxes (Σ7PCBs = 89-670 ng/m2/day). These results suggest that nondiffusive PCB fluxes from the sediment bed are occurring and that quantifying in situ porewater concentrations is crucial for accurately quantifying both diffusive and nondiffusive PCB fluxes.

The atmosphere as a source/sink of polychlorinated biphenyls to/from the Lower Duwamish Waterway Superfund site

Waterbodies polluted with polychlorinated biphenyls (PCBs) may cause the air in the surrounding area to become PCB-contaminated. Conversely, when a waterbody is located in or near an urban area, the deposition of atmospheric PCBs may act as a low-level, ongoing source of PCB contamination to that water. Distinguishing these situations is necessary to be protective of human populations and to guide efforts seeking to cleanup such aquatic ecosystems. To assess the situation at the Lower Duwamish Waterway (LDW) Superfund site, low-density polyethylene passive samplers were deployed in the summer of 2015 to quantify freely dissolved water and gaseous air concentrations of PCBs thereby enabling estimates of the direction and magnitude of air-water exchange of PCB congeners. For the sum of the 27 PCB congeners, average concentrations were 220 pg/m3 (95% C.I.: 80–610) in the air and 320 pg/L (95% C.I.: 110–960) in the water. The sum of air-water exchange fluxes of these PCB congeners was estimated to be 68 ng/m2/day (95% C.I.: 30–148) into the lower atmosphere, contrasting with the reported wet and dry depositional flux of only 5.5 ng/m2/day (95% C.I.: 1–38) from the air into the water. Therefore, the atmosphere was ultimately a sink of PCBs from the LDW Superfund site, at least under 2015 summertime conditions. However, we conclude that air-water exchange of PCBs is likely only a minor sink of PCBs from the LDW and only a minor source of contamination to the region's local atmosphere.

In situ passive sampling of sediments in the Lower Duwamish Waterway Superfund site: Replicability, comparison with ex situ measurements, and use of data

Superfund sites with sediments contaminated by hydrophobic organic compounds (HOCs) can be difficult to characterize because of the complex nature of sorption to sediments. Porewater concentrations, which are often used to model transport of HOCs from the sediment bed into overlying water, benthic organisms, and the larger food web, are traditionally estimated using sediment concentrations and sorption coefficients estimated using equilibrium partitioning (EqP) theory. However, researchers have begun using polymeric samplers to determine porewater concentrations since this method does not require knowledge of the sediment's sorption properties. In this work, polyethylene passive samplers were deployed into sediments in the field (in situ passive sampling) and mixed with sediments in the laboratory (ex situ active sampling) that were contaminated with polychlorinated biphenyls (PCBs). The results show that porewater concentrations based on in situ and ex situ sampling generally agreed within a factor of two, but in situ concentrations were consistently lower than ex situ porewater concentrations. Imprecision arising from in situ passive sampling procedures does not explain this bias suggesting that field processes like bioirrigation may cause the differences observed between in situ and ex situ polymeric samplers.

Everything goes somewhere; tracking the movement of contaminated sediments in an industrialised estuary using dual signature sediment tracers

Source control i.e. the reduction of contamination from upstream or diffuse sources, is a critical element in any management plan for contaminated waterways. If source control measures are not successfully implemented, then a situation exists in which contamination will continue through time, and the cleanup of waterway segments becomes increasingly problematic. To provide greater understanding of the issues surrounding source control, it is essential to have some knowledge of contaminant sources and transport pathways of contaminated particulates. In port areas a plethora of factors interact to control contaminant transport pathways. These include: rain and river flow; tidal circulation, surface waves and wind drift, and temporally changing water column stratification. Particle tracking offers a practical means to map the transport pathways of contaminated sediments under these collective influences. This paper introduces a new and novel “dual signature” tracer product, and describes the particle tracking technique on a practical level through a study example in the Lower Duwamish Waterway, Washington, USA.

In situ biomonitoring of caged, juvenile Chinook salmon (Oncorhynchus tshawytscha) in the Lower Duwamish Waterway

Contaminated sediments may have wide-ranging impacts on human and ecological health. A series of in situ caged exposure studies using juvenile Chinook salmon was conducted in the Lower Duwamish Waterway (LDW). Chemical analysis of sediment, water, and fish tissue were completed. Additionally, in 2004, DNA adducts in hepatic and gill tissues were measured. Gills contained significantly higher DNA adducts at stations B2 and B4, prompting further analysis of gills in 2006 and 2007. Fluorescent aromatic compounds (FACs) in bile, and CYP1A1 in hepatic tissue were also measured during 2006 and 2007, respectively. FACs in field-caged fish were comparable or significantly higher than wild-caught fish LDW fish and significantly higher than lab fish after only 8–10days, demonstrating the equivalency of exposure to that of migrating salmon. Furthermore, selected biomarkers appear to be capable of detecting spikes in contamination between sampling years, emphasizing the need for multiple year data collection.

In situ biomonitoring of juvenile Chinook salmon ( Onchorhynchus tshawytscha) using biomarkers of chemical exposures and effects in a partially remediated urbanized waterway of the Puget Sound, WA

In situ biomonitoring has been used to assess the effects of pollution on aquatic species in heavily polluted waterways. In the current study, we used in situ biomonitoring in conjunction with molecular biomarker analysis to determine the effects of pollutant exposure in salmon caged in the Duwamish waterway, a Pacific Northwest Superfund site that has been subject to remediation. The Duwamish waterway is an important migratory route for Pacific salmon and has received historic inputs of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Juvenile pre-smolt Chinook salmon ( Oncorhynchus tshawytscha) caged for 8 days in the three contaminated sites in close proximity within the Duwamish were analyzed for steady state hepatic mRNA expression of 7 exposure biomarker genes encompassing several gene families and known to be responsive to pollutants, including cytochrome P4501A (CYP1A) and CYP2K1, glutathione S-transferase π class (GST-π), microsomal GST (mGST), glutamylcysteine ligase catalytic subunit (GCLC), UDP-glucuronyltransferase family 1 (UDPGT), and type 2 deiodinase (type 2 DI, or D2). Quantitation of gene expression was accomplished by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) in assays developed specifically for Chinook salmon genes. Gill PAH-DNA adducts were assessed as a chemical effects biomarker using 32P-postlabeling. The biomarkers in the field-caged fish were analyzed with respect to caged animals maintained at the hatchery receiving flow-through water. Chemical analysis of sediment samples from three field sampling sites revealed relatively high concentrations of total PAHs in one site (site B2, 6711 ng/g dry weight) and somewhat lower concentrations of PAHs in two adjacent sites (sites B3 and B4, 1482 and 1987 ng/g, respectively). In contrast, waterborne PAHs at all of the sampling sites were relatively low (<1 ng/L). Sediment PCBs at the sites ranged from a low of 421 ng/g at site B3 to 1160 ng/g at site B4, and there were no detectable waterborne PCBs at any of the sites (detection limit=10 ng/L). There were no significant differences ( p<0.05) in biomarker gene expression in the Duwamish-caged fish relative to controls, although there was a pattern of gene expression suppression at site B3, the most heavily PAH-enriched site. The lack of a marked perturbation of mRNA biomarkers was consistent with relatively low levels of gill PAH-DNA adduct levels that did not differ among caged reference and field fish, and which were also consistent with relatively low waterborne concentrations of chemicals. The results of our study suggest a low bioavailability of sediment pollutants in caged juvenile Chinook potentially reflecting low waterborne exposures occurring at contaminated sites within the Duwamish waterway that have undergone partial remediation.

Bioaccumulation of polychlorinated biphenyls in juvenile chinook salmon (Oncorhynchus tshawytscha) outmigrating through a contaminated urban estuary: dynamics and application

A field study was conducted to examine bioaccumulation of polychlorinated biphenyls (PCBs) for hatchery-raised and naturally reared (wild) ocean-type juvenile chinook salmon outmigrating through the Lower Duwamish Waterway (LDW), a contaminated urban estuary in Seattle, WA, USA. These results show differences in bioaccumulation of PCBs over time and space in this estuary, which may also occur for any contaminant that is distributed heterogeneously in this system. Highly mobile, outmigrating salmon accumulated approximately 3-5 times more PCBs on the east side of the LDW than fish on the west side, which is supported by an almost identical difference in mean sediment concentrations. The tPCB concentration data suggest that for most of the spring and early summer, juvenile chinook were likely segregated between the east and west side of the LDW, but may have crossed the channel later in the year as larger fish. Additionally, we used biota-sediment accumulation factors to assess the relative degree of bioaccumulation and explore these factors as potential metrics for predicting adverse sediment concentrations. These results highlight the importance of time and space in sampling design for a highly mobile species in a heterogeneous estuary.

Coupled consolidation and contaminant transport model for simulating migration of contaminants through the sediment and a cap

Capping contaminated sediments in waterways is an alternate remediation technique to dredging and is typically much cheaper than dredging. When cap material is placed on top of contaminated sediment, it has both a short-term and long-term hydraulic impact on the underlying sediment. A numerical model of consolidation, based on a nonlinear finite strain theory for a consolidating fine-grained sediment bed was developed. The nonlinear equation of consolidation was solved in a material (or reduced) coordinate using an explicit finite difference numerical scheme. An one-dimensional advection–diffusion equation with sorption and decay was solved on a convective coordinate using a finite volume total variation diminishing (TVD) scheme for the contaminant concentration within the consolidating sediment. The contaminant transport model was coupled with the consolidation model. The time and space varying porosities, permeabilities, and advective velocities computed by the consolidation model were linked to the transport model at the same time level. A number of benchmark tests that are relevant to the consolidation of a fine-grained sediment were designed and tested. The relative contribution of consolidation-induced transient advective velocities on the migration of a contaminant during consolidation was also investigated. The coupled model performance was validated by simulating the transport of hazardous chemicals under consolidation in a confined aquatic disposal (CAD) site in the Lower Duwamish Waterway, Seattle.

Immunocompetence of juvenile Chinook salmon against Listonella anguillarum following dietary exposure to Aroclor® 1254

Controlled laboratory challenges with pathogenic Listonella (formerly Vibrio) anguillarum bacteria were used to examine potential effects of dietary exposure to polychlorinated biphenyls (PCBs) on the growth and immunocompetence of juvenile Puget Sound (WA, USA) Chinook salmon (Oncorhynchus tschawytscha). Salmon were fed four levels of the PCB congener mixture Aroclor 1254 for 28 d to bracket likely exposure to PCBs in the lower Duwamish waterway near Seattle, Washington, USA. Fish were transferred to five replicate tanks per dose, exposed to L. anguillarum, and monitored for 14 d. Half the PCB-dosed fish were vaccinated against L. anguillarum, and specific immunity was allowed to develop in this group for three weeks prior to challenge. All mortalities following challenge were individually sampled for bacteria to identify the cause of death. The data indicate that dietary PCB exposure, even at relatively high levels, did not have a significant effect on growth, innate disease resistance, or acquired immunity to L anguillarum. The controlled laboratory experiments in this study suggest that the immune system of Chinook salmon is not sensitive to orally delivered PCBs at environmentally relevant concentrations.

Ecological Risk Assessment Paradigm for Salmon: Analyzing Immune Function to Evaluate Risk

Wild Pacific salmon populations are in serious decline, and as a result, a number of salmon stocks are listed as threatened or endangered under the Endangered Species Act. Our research identifies and supports the possibility that certain environmental contaminants can alter salmon survival, and as a result may contribute to these species being at risk. We have shown that juvenile chinook salmon (Oncorhynchus tshawytscha) are exposed to polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) as they migrate through a contaminated urban estuary in Puget Sound WA (the Duwamish Waterway estuary). Immune function was analyzed in these fish by examining the ability of their anterior kidney and splenic leukocytes to produce a primary and secondary in vitro plaque-forming cell (PFC) response to the hapten, trinitrophenyl (TNP), and by determining their susceptibility to a marine pathogen, Vibrio anguillarum. We found that fish outmigrating from the urban estuary produced a significantly lower PFC response to TNP and were more susceptible to the pathogen, compared to juvenile salmon collected from a rural estuary during their outmigration. In the laboratory, we exposed juvenile chinook salmon collected from a hatchery to either a PCB technical mixture or a PAH compound to determine if these contaminants have the potential to alter immune function in salmon. Indeed, we found that salmon exposed in the laboratory to either the PCB mixture or the PAH also produced lower PFC responses and were more susceptible to disease compared to animals treated with the solvent vehicle. In summary, contaminants such as PAHs and PCBs are demonstrated to influence salmon health, and thus have the potential to adversely impact salmon populations.

GIS-Supported Collaborative Decision Making: Results of an Experiment

This article addresses research questions about the sociobehavioral dynamics of geographic information system (GIS) use during collaborative decision making in small interorganizational groups. Using an experimental design of a conference room setting, a study of human-computer-human interaction was conducted with 109 volunteer participants formed into 22 groups, each group representing multiple organizational stakeholder perspectives. The experiment involved the use of GIS integrated with multiple criteria decision models to support group-based decision making concerned with the selection of habitat restoration sites in the Duwamish Waterway of Seattle, Washington. Findings representative of four categories of investigation are presented. In the first category, the experiment demonstrated that groups used maps predominantly to visualize the evaluation results and much less to structure/design the decision problem. Maps played only a limited support role in various decision stages of the experiment. In the second category, while the use of multiple criteria decision models by groups remained steady throughout different phases of the decision process, the use of maps was much lower during the initial exploratory-structuring phase than during the later analytic-integrating phase. In category three, the amount of prior and acquired group member experience with computer tools had no influence on the appropriation of decision aids. In category four, different phases of the decision process had two different levels of conflict: the exploratory-structuring phase was characterized by a lower level of conflict, and the analytic-integrating phase was characterized by high conflict level. The higher level of conflict during the analytic-integrating phase tells us that analytical decision aids aimed at conflict management are likely to help work through conflict, such conflict now being recognized as a necessary part of making progress in public decision problems.

Reductions in CYP1A expression and hydrophobic DNA adducts in liver neoplasms of English sole ( Pleuronectes vetulus): Further support for the ‘resistant hepatocyte’ model of hepatocarcinogenesis

Our recent studies have investigated the applicability of the ‘resistance to cytotoxicity’ paradigm for chemically induced hepatocarcinogenesis in rats and mice to liver neoplasia in wild English sole ( Pleuronectes vetulus). Sole resident at polycyclic aromatic hydrocarbon (PAH)-contaminated sites, such as the Duwamish Waterway in Puget Sound, Washington, exhibit high prevalences of hepatic neoplasms and precursor lesions related to the histogenesis of neoplasms. Previous immunohistochemical studies in English sole show a consistent reduction of CYP1A expression, localized with a polyclonal antibody to Atlantic cod CYP1A, in hepatic neoplasms and most preneoplastic foci of cellular alteration. The present study utilized immunohistochemical localization and quantitation of CYP1A expression by image analysis, linked with quantitation of hydrophobic DNA adducts by the 32P-postlabeling method, in hepatocellular neoplasms as compared to matched samples of adjacent non-neoplastic liver tissue from the same fish. All fish were from the Duwamish Waterway in Seattle, Washington. In the eight neoplasms assessed (four hepatocellular adenomas, four hepatocellular carcinomas), there was a significant and nearly parallel reduction in DNA adduct concentrations (56–90%) and levels of CYP1A expression (3–99%) as compared to the adjacent non-neoplastic liver tissue. These findings are consistent with the hypothesis that neoplastic hepatocytes in English sole possess a ‘resistant’ phenotype in which there is a reduced capacity for CYP1A-mediated activation of genotoxic PAHs to their toxic and carcinogenic intermediates, and a consequent reduction in the formation of covalent, hydrophobic DNA adducts from these reactive intermediates.

Quantitation of CYP1A expression in two flatfish species showing different prevalences of contaminant-induced hepatic disease

English sole ( Pleuronectes vetulus) and starry flounder ( Platichthys stellatus) are two sympatric flatfish species which show markedly different responses to chemical contaminant exposure. Whereas English sole develop hepatic neoplasms, the prevalences of which are strongly linked to exposure to polycyclic aromatic hydrocarbons (PAHs), evidence of neoplasia is virtually nonexistent in starry flounder, even those residing in areas with very high levels of PAH in the sediments. Because PAHs are activated to genotoxic forms by the action of cytochrome P450 1A (CYP1A) in teleosts, we are examining the hypothesis that variation in the hepatic expression of this major inducible cytochrome P450 isozyme may contribute to the differential contaminant response. These two species were captured in the Duwamish Waterway, a contaminated area of Puget Sound, Washington. Catalytic activity of CYP1A [determined as aryl hydrocarbon hydroxylase (AHH) activity] was measured in the liver to quantitatively assess the relative induction of CYP1A in these two species, and AHH activity was significantly higher in English sole than in starry flounder ( p = 0.015). Cellular expression of CYP1A was determined by immunohistochemical localization of tissues, using an avidin-biotin peroxidase complex method, with polyclonal rabbit anti-cod CYP1A. The results showed a markedly reduced expression of CYP1A in hepatocytes of starry flounder, which is consistent with the apparent resistance of this species to the development of hepatocellular neoplasia. This reduced expression of CYP1A in hepatocytes of contaminant-exposed fish was previously seen in oyster toadfish from the Elizabeth River, Virginia, and this species is also apparently resistant to hepatocellular neoplasia.

Approaches for Determining Effects of Pollution on Fish Populations of Puget Sound

Puget Sound is a large marine and estuarine ecosystem in Washington State that serves as the habitat for a number of recreationally and commercially important species of groundfish and Pacific salmon Onchorhynchus spp. Over the past several decades, the human population of the Puget Sound drainage basin has increased substantially, resulting in increased habitat degradation and chemical pollution. There is now a body of evidence showing that groundfish and salmon in Puget Sound are experiencing a range of biological effects from chemical contaminant exposure, including impairment of several stages in the reproductive process, increased susceptibility to pathogens resulting from altered immune competence, and development of toxicopathic diseases. Preliminary studies suggest the potential for reduced survival of fish from urban areas of Puget Sound resulting from increased infectious and idiopathic diseases. The question that now must be addressed is whether contaminant-related reductions in reproductive and survival rates are sufficient to affect fish abundance in Puget Sound. In the current study, the potential impact of contaminant-related mortality and reproductive impairment on the population growth rate of English sole Pleuronectes vetulus was examined by simulation modeling. An initial Leslie matrix population model was constructed for investigation of contaminant effects. The adult mortality rate for English sole in Puget Sound was estimated from recent historical data. Age-specific fecundity was determined from previously collected English sole ovary samples. Existing data on the effects of contaminants on reproduction, including impaired gonadal development, reduced spawning ability, and decreased egg and larval viability, were incorporated into the fecundity component of the model. The influence of density-dependent population regulation on model results was also examined. Results suggest that declines in the fecundity component of the model, like those observed in field studies of fish from contaminated sites such as the Duwamish Waterway and Eagle Harbor, could substantially decrease the population growth rate (r) if density dependence is weak or moderate, Estimated declines in r are comparable in magnitude to those associated with typical levels of commercial fishing pressure, However, a compensation for loss of recruits due to contaminant effects is observed if strong density-dependent population regulation is assumed.

Effects of a complex mixture of chemical contaminants on hepatic glutathione, L‐cysteine and γ‐glutamylcysteine synthetase in english sole (Pleuronectes vetulus)

AbstractThe effects of chemical contaminants on concentrations of hepatic glutathione (GSH), cysteine (L‐Cys), and the activity of γ‐glutamylcysteine synthetase (γ‐GCS) were assessed in English sole (Pleuronectes vetulus) in the laboratory and in fish from the Duwamish Waterway, a contaminated urban site in Puget Sound, Washington. In the laboratory studies, fish from a nonurban (reference) site were exposed to an organic‐solvent extract of sediment from the Duwamish Waterway. Hepatic GSH concentrations significantly increased at 3 d after exposure to the extract at 1,000 g sediment extracted/kg fish. At this time point, hepatic GSH showed a dose‐dependent increase at dosages ranging from 300 to 1,600 g sediment extracted/kg fish, whereas fish exposed to a reference sediment extract showed no increase. Moreover, the increases in GSH in fish exposed to the contaminated sediment extract were not accompanied by changes in either L‐Cys concentrations or γ‐GCS activity. Similarly, fish sampled directly from the Duwamish Waterway showed increased GSH concentrations but showed no significant differences in L‐Cys levels or γ‐GCS activity compared to fish from a reference site. These results substantiate that hepatic GSH in fish is responsive to chemical contaminant exposure and further support its use as a biomarker in environmental monitoring studies. The findings also indicate that L‐Cys availability and induction of γ‐GCS were not major factors in the increase of hepatic GSH in contaminant‐exposed English sole.

Immunohistochemical localization of cytochrome P4501A in multiple types of contaminant-associated hepatic lesions in English sole ( Pleuronectes vetulus)

Variations in the expression of cytochrome P450 (CYP) isozymes in cells may affect the response of and consequent toxic effects in those cells during xenobiotic exposure. The expression of cytochrome P4501A (CYP1A), a major inducible CYP in teleosts, was examined immunohistochemically in multiple toxicopathic hepatic lesion types, including neoplasms and several types of preneoplastic foci of cellular alteration (FCA), in English sole ( Pleuronectes vetulus) captured from the Duwamish Waterway, a highly contaminated estuary of Puget Sound, WA. Formalin or Bouin's-fixed, paraffin-embedded tissue sections were stained with polyclonal rabbit anticod CYP1A IgG by the avidin-biotin peroxidase complex method; this antibody binds to both Atlantic cod ( Gadus morhua) and English sole CYP1A in Western blotting and ELISA, and immunohistochemically-localizes CYP1A in hepatic and other tissues of cod exposed to β-naphthoflavone. CYP1A-associated staining intensity was lower in hepatocellular and cholangiocellular neoplasms, areas of biliary hyperplasia, and normal intrahepatic exocrine pancreas and bile ducts, as compared to histologically normal hepatocellular parenchyma. FCA of basophilic, eosinophilic and clear cell types showed variable staining intensities in comparison to background parenchymal staining, but generally showed reduced CYP1A-associated staining. Staining intensity for a single hemangiopericytic sarcoma showed highly reduced staining for CYP1A. These results, in fish naturally exposed to environmental toxicants, suggest a parallel response between teleosts and mammals with respect to CYP1A expression and resistance to cytotoxicity in cells composing several types of hepatic neoplasms and foci of cellular alteration.

Suppression of immunological memory in juvenile chinook salmon ( Oncorhynchus tshawytscha) from an urban estuary

In this present study, juvenile chinook salmon were collected from a contaminated urban estuary, the Duwamish Waterway, as well as from a non-urban estuary, the Nisqually River estuary, to determine if exposure to toxic chemicals affects immunocompetency. Juvenile chinook salmon were also sampled from the two hatcheries that release salmon into these estuaries. The ability of anterior kidney (AK) and splenic (SP) leucocytes from primed and unprimed juvenile salmon from the Duwamish Waterway, Nisqually River estuary, and their respective hatcheries to produce a primary and secondary in vitro plaque-forming cell (PFC) response to the hapten, trinitrophenyl (TNP) was examined. Trinitrophenyl-keyhole limpet haemocyanin (TNP-KLH) was added in vitro to AK leucocytes or as TNP-lipopolysaccharide (TNP-LPS) to both AK and SP leucocytes. The primary AK and SP plaque-forming cell response to TNP in salmon from the estuaries or hatcheries was not significantly different. Primed AK leucocytes from salmon collected from the hatcheries and the non-urban estuary were able to produce a heightened secondary response to TNP-KLH; in contrast, primed AK leucocytes from salmon collected from the urban estuary were unable to produce a secondary PFC response to TNP-KLH. Anterior kidney leucocytes from salmon collected from all four areas were able to produce a heightened secondary PFC response to TNP-LPS. However, the AKs plaque-forming cell response generated in primed chinook salmon collected from the urban estuary to TNP-LPS was significantly lower than that produced in salmon from the hatchery. This suppressed PFC response in primed AK cells to TNP-LPS was not observed in primed AK leucocytes from salmon collected from the non-urban estuary and its hatchery. These results suggest that the cells involved in generating immunological memory to TNP-KLH and TNP-LPS were affected in salmon exposed to contaminants in the urban estuary, with cells which generate memory to TNP-KLH being more affected. The PFC responses of primed SP leucocytes from salmon collected from the Duwamish Waterway and Nisqually River estuaries, stimulated in vitro with TNP-LPS were not significantly different. The consequence of suppressed immunological memory in disease resistance of juvenile salmon is currently unknown.

Consolidation and contaminant migration in a capped dredged material deposit

The effectiveness of capping contaminated dredged material was investigated in a subaqueous depression in the Duwamish Waterway in Seattle, Washington, U.S.A. Field studies were conducted to evaluate the consolidation of the capped material as well as the movement of contaminants from the dredged material into the uncontaminated cap material. Results showed that most of the dredged material consolidation at this site occurred during the first 2 weeks following capping. Monitoring of contaminant concentrations in the capped deposit for 18 months showed no movement of contaminants from the dredged material into the capping material.

Uptake of aromatic and chlorinated hydrocarbons by juvenile chinook salmon (Oncorhynchus tshawytscha) in an urban estuary

A study was conducted to assess the potential for uptake of toxic chemicals by down-stream migrant salmon in an urban estuary. Juvenile chinook salmon (Oncorhynchus tshawytscha) were collected from the Duwamish Waterway (located in Seattle, Washington) and from the Nisqually River (a reference site). The mean concentrations of aromatic hydrocarbons and polychlorinated biphenyls (PCBs) in the stomach contents (food organisms) of salmon from the Duwamish Waterway were approximately 650 times and 4 times, respectively, higher than those in salmon from the Nisqually River. Similarly, the mean concentration of bile metabolites of aromatic compounds which fluoresce at benzo[a]pyrene wavelengths was 24 times higher in the urban salmon compared to the reference salmon, whereas the mean concentration of PCBs in liver of urban salmon was 3 times higher than that in reference salmon. The study clearly demonstrated that, during their residency in this urban estuary, juvenile chinook salmon bioaccumulate substantial levels of toxic chemicals. The possible effects of these chemical exposures on the health and survival of this species are not presently known.