APPENDIX 3. EVAULATION OF ECOLOGICAL EFFECTS DATA

Transcription

1 APPENDIX 3. EVAULATION OF ECOLOGICAL EFFECTS DATA

2 Evaluation of Ecological Effects Data St. Louis River/Interlake/Duluth Tar Superfund Site Minnesota Pollution Control Agency Prepared by: Steven Hennes, Environmental Research Scientist July 29, 2004

3 TABLE OF CONTENTS TABLE OF CONTENTS... ii 1.0 INTRODUCTION METHODS Sampling Sediment Biota Invertebrates Aquatic Plants Sediment and Tissue Chemical Analysis Laboratory Exposure Tests Toxicity Tests Hyalella azteca (amphipod) 28-Day Test Chironomus tentans (midge) Partial Life-Cycle Test Typha latifolia (cattail) 17-Day Test Zizania aquatica (wild rice) 10-Day Test Bioaccumulation Test Lumbriculus variegatus (Oligochaete Worm) 28-Day Test Data Management RESULTS AND DISCUSSION Sediment Chemistry Laboratory Exposure Tests Toxicity Tests Hyalella azteca 28-Day Test Chironomus tentans Partial Life-Cycle Test Typha latifolia 17-Day Test Zizania aquatica 10-Day Test Lumbriculus variegatus Bioaccumulation Test Field-Collected Organism Tissue Residues Benthic Invertebrates Aquatic Plants Weight of Evidence Evaluation to Determine Effects Threshold Ranges REFERENCES revapp3 Text1.doc ii

4 LIST OF TABLES Table 1. Sediment Chemistry Analytes and Methods Table 2. Tissue Chemistry Analytes and Methods Table 3. Analytical Chemistry Data for SLRIDT Site and North Bay Sediment Samples collected in 10/2001 Table 4. Hyalella azteca 28-day toxicity test results. Table 5. Chironomus tentans partial life-cycle test results. Table 6. Typha latifolia 17-day toxicity test results. Table 7. Zizania aquatica 10-day toxicity test results. Table 8. Lumbriculus Tissue Chemistry Data for SLRIDT Site and North Bay Samples Table 9. Lumbriculus Biomass for SLRIDT Site and North Bay Samples Table 10. Field-collected Invertebrate Tissue Chemistry Data for SLRIDT Site and North Bay Samples Table 11. Aquatic Plant Tissue Chemistry Data for the SLRIDT Site and North Bay LIST OF FIGURES Figure 1. Bay West 2001 Sampling Locations Figure 2. Hyalella 28-day Survival Compared to Sediment TPAH Concentration Figure 3. Chironomus 28-day Survival Compared to Sediment TPAH Concentration Figure 4. Lumbriculus Tissue TPAH Concentration Compared to Sediment TPAH Concentration Figure 5. Lumbriculus Biomass Compared to Sediment TPAH Concentrations Figure 6. Lumbriculus Biomass Compared to Tissue TPAH Concentrations Figure 7. Field-collected Invertebrate Tissue TPAH Concentration Compared to Sediment TPAH Concentration Figure 8. Comparison of Field-collected and Laboratory Invertebrate Tissue TPAH Concentration Figure 9. Comparison of Field-collected and Laboratory Invertebrate Tissue TPAH with Sediment TPAH Concentrations Figure 10. Aquatic Plant Tissue TPAH Concentration by Location Figure 11. Aquatic Plant Tissue TPAH Compared to Sediment TPAH Concentrations Figure 12. Multiple Effects Endpoints (normalized to control) Plotted Against Sediment TPAH Concentrations revapp3 Text1.doc iii

5 1.0 INTRODUCTION This report summarizes the Minnesota Pollution Control Agency (MPCA) evaluation of the ecological effects data that were used to determine the Remedial Action Objectives (RAOs) and Cleanup Levels for remediation of contaminated sediments at the St. Louis River/Interlake/Duluth Tar Superfund Site (Site). As a part of the re-opened RI/FS process for the SLRIDT site, reviewers from the U.S. Environmental Protection Agency (EPA), National Oceanic Atmospheric Administration (NOAA), U.S. Fish and Wildlife Service (FWS), Minnesota Department of Natural Resources (DNR), and the Tribal Agencies identified data gaps related to the development of RAOs and Cleanup Levels that would be protective of the environment. To address these data gaps, a Technical Advisory Group (TAG) consisting of technical experts from the above agencies identified ecological effects of concern (assessment endpoints) and recommended specific data collection activities (measurement endpoints). The data collection activities included the following: Collection of sediment samples which span a gradient of sediment PAH concentrations at the Site, as well as samples from a reference area, for chemical analysis and laboratory exposure testing. The sediment concentration gradient should encompass the lower range of PAH concentrations to allow estimation of effects thresholds for the more sensitive endpoints because earlier testing had already established effects at high concentrations. Collection of co-located benthic invertebrate and submergent aquatic plant samples at each sediment location to be analyzed for tissue residues of Contaminants of Concern (COCs). Performance of longer term (e.g. 28 day Hyalella test) laboratory sediment toxicity tests on benthic invertebrates and aquatic plants. Performance of a laboratory bioaccumulation test using a benthic invertebrate. Collection of fish with limited home ranges from the Site and reference area for tissue residue analyses. (This data was collected but is not included in this report because it was not used directly in the development of RAOs and Cleanup Levels. The fish data may be used by the Natural Resource Trustees for injury determination). In 2001, the MPCA hired Bay West Inc. (Bay West) to collect the field data for laboratory analysis. The purpose of this report is to present a summary of the results of that effort and to determine effects threshold concentration ranges to be used in setting the RAOs and Cleanup Levels for the Site.

6 2.0 METHODS 2.1 Sampling Details of the sampling and analysis methods can be found in the Quality Assurance Project Plan (QAPP) (Bay West 2001). In general, samples were analyzed for the following COCs: Polynuclear Aromatic Hydrocarbons (PAHs) Metals (Arsenic, Cadmium, Chromium, Copper, Mercury, Lead, Nickel, Zinc) Sample collection procedures are briefly summarized below Sediment Surficial sediment samples (approximately the upper 6 inches) were collected from locations previously selected based on reconnaissance sampling. Seven locations in Stryker Bay, seven locations in Keene Creek Bay, and five locations in the North Bay reference area were sampled (Figure 1). Approximately gallons of sediment were collected using an Ekman dredge from an anchored barge with a moon pool through which the dredge was lowered. Multiple dredge lifts (necessary to obtain the required sample volume) were taken from an approximately 30 square foot area at each location by rotating the moon pool around the marked sampling point. Sediment was pooled and homogenized in a 50 gallon tub before subsampling for chemical analyses and/or exposure testing Biota Invertebrates Sediment sampling for benthic invertebrate organisms was based on a method described in Thijssen et. al, Benthic invertebrates were collected from each sediment sampling location by sieving a portion of the collected sediment until a sufficient mass of organisms for residue analysis was obtained. The sediment samples were initially screened in the field through a 500- micrometer mesh sieve to separate the organisms from a large portion of the sediments. The organisms and some sediment were retained on the screen and subsequently washed into onegallon plastic jars using water from the river. The targeted sample mass was 3 grams of tissue. Organisms were sent to the University of Wisconsin-Superior where they were sorted, identified, rinsed, allowed to purge gut contents, blotted dry, weighed and frozen in preparation for chemical analyses. Targeted invertebrates were oligochaetes (worms) and chironomids (midge larvae). However, oligochaetes were not found in sufficient size or volume in any of the sample locations. In addition, chironomids were not found in sufficient numbers in some locations. Therefore, amphipods and tricopterans (caddisfly larvae) were also collected to fill the data gap. At a few locations, there were insufficient organisms of any kind present to provide adequate sample volume for tissue analyses. Tissue samples were analyzed for COCs and lipid content.

7 Aquatic Plants Rooted submergent aquatic plants were also collected from each sediment sampling location for plant tissue residue analysis. Whole plants, including roots, were separated from sediments, rinsed free of sediment with river water, separated by species and placed in labeled plastic bags. Species collected in sufficient quantity for analysis at most sites were Myriophyllum exalbescens (northern watermilfoil), Valisneria americana (wild celery) and Potamogeton zosteriformis (flatstemmed pondweed); but all three species were not present at all sites. Plant tissue samples were analyzed for COCs. 2.2 Sediment and Tissue Chemical Analysis Laboratories, analytical methods and analytes are summarized in Tables 1 and 2 and detailed in the QAPP (Bay West 2001). 2.3 Laboratory Exposure Tests All laboratory exposure tests were conducted by ASci Corp. in Duluth, MN. Laboratory Standard Operating Procedures (SOPs) can be found in Appendix 17 of the QAPP (Bay West 2001). Control sediment used for all tests (except the bioaccumulation test) was collected from West Bearskin Lake in the Boundary Waters Canoe Area, Cook County, MN. This sediment has been routinely used as a control because it contains low levels of contaminants and results in acceptable survival of test organisms as required by testing protocols Toxicity Tests Reconnaissance sampling was used to target a range of desired PAH concentrations for laboratory tests. Due to the heterogeneous nature of Site sediments, the final Site samples did not provide the expected range of concentrations. Therefore, two sediment samples with relatively high PAH concentrations were used to prepare sediment dilutions to attempt to cover the range of desired PAH concentrations. To prepare dilutions, samples were blended with West Bearskin control sediment. Several samples with higher than expected PAH concentrations, including the two samples used to prepare dilutions, were not used in toxicity tests because of anticipated high mortality rates Hyalella azteca (Amphipod) 28-Day Test ASci-Environmental Testing Laboratory (ASci-ETL) performed a 28-day Hyalella azteca test with sediment samples from the lower Site and North Bay reference area (ASci 2002a). The 28- day test was performed to measure the effects of the selected sediment samples to Hyalella azteca (freshwater scud). The test was performed to measure both bulk sediment toxicity and the potential toxicity of bioaccumulated polyaromatic hydrocarbons (PAHs) when activated by ultraviolet (UV) light. The Hyalella azteca test endpoints were survival, growth (weight and length), and UV-induced mortality. At the end of the 28 day exposure, three replicates were exposed to UV-A light at an intensity of 65 microwatts per square centimeter (µw/cm 2 ) for four hours and then additional mortality was recorded 20 hours after the end of exposure. This level of UV-A was selected to approximate the midsummer, midday, clear sky UV-A intensity at 30 centimeter water depth in Stryker Bay, based on field measurements of UV attenuation performed by staff of the USEPA Duluth Environmental Research Laboratory.

8 Chironomus tentans (Midge) Partial Life-Cycle Test ASci-ETL performed a modified life-cycle Chironomus tentans test with sediment samples from the Site and North Bay reference area (ASci 2002b). The life-cycle test was performed to measure the effects of the selected sediment samples with a range of contaminant concentrations to Chironomus tentans (midge), and the potential toxicity of bioaccumulated PAHs when activated by ultraviolet radiation. The Chironomus tentans test endpoints were survival, growth, emergence, and UV-induced mortality. At the end of the 20 day exposure, three replicates were exposed to UV-A light at an intensity of 65 µw/cm 2 for four hours and then additional mortality was recorded 20 hours after the end of exposure Typha latifolia (Cattail) 17-Day Test ASci-ETL performed a 17-day Typha latifolia test with sediment samples from the Site and reference area (ASci 2003a). The 17-day test was performed to measure the effects of the selected sediment samples to Typha latifolia (cattail). The Typha latifolia test endpoints were 7 day germination, 17-day germination/survival, and growth (ash-free dried weight) Zizania aquatica (Wild Rice) 10-Day Test ASci-ETL performed a 10-day Zizania aquatica test with sediment samples from the Site and North Bay reference area (ASci 2003b). The 10-day test was performed to measure the effects of the selected sediment samples to Zizania aquatica (wild rice). The Zizania aquatica test endpoints were survival and growth (weight and length) Bioaccumulation Test Undiluted field samples from the Site and North Bay reference area were used for the bioaccumulation tests Lumbriculus variegatus (Oligochaete Worm) 28-Day Test AScI-ETL performed 28-day bulk sediment exposures to determine the potential for bioaccumulation of contaminants by the oligochaete Lumbriculus variegatus (ASci 2002c). At the end of 28 days the organisms were collected and allowed to purge gut contents, blotted dry, weighed and frozen in preparation for COC and lipid analysis. 2.4 Data Management Sediment chemistry, toxicity, and tissue residue data were entered into a NOAA Query Manager database to facilitate analysis. The database as well as the Query Manager program are available at the following web address:

9 3.0 RESULTS AND DISCUSSION 3.1 Sediment Chemistry Sediment chemistry results are presented in Table 3. TPAH concentrations in the 14 samples collected at the Site ranged from 5.1 to 1,899 milligrams per kilogram (), whereas TPAH concentrations in the five North Bay reference area samples ranged from 0.41 to 1.48 (with a mean concentration of 1.1 ). The TPAH Probable Effects Concentration quotient (PEC-Q), the ratio of the sediment concentration of TPAH to the MacDonald et al. (2000) PEC value for TPAH, ranged from 0.2 to 83 for Site samples, compared to a range of 0.02 to 0.06 for North Bay. Mean Probable Effects Concentration Quotients (mean PEC-Qs) for summed individual PAHs ranged from 0.3 to 214, compared to 0.03 to 0.11 for North Bay. Equilibrium partitioning-based sediment benchmark toxic units (without an uncertainty factor; EPA 2002) ranged from 0.3 to 64 for Site samples, while North Bay samples had a range of 0.03 to Although the highest concentration for each non-mercury metal except chromium occurred in Site samples, ranges for all these metals overlapped with and in general were not significantly different from North Bay concentrations. Mean PEC-Qs for metals ranged from 0.1 to 0.55 for Site samples, similar to the range of 0.19 to 0.38 for North Bay. Similar results were observed for mercury: Site concentrations ranged from to 0.5, compared to 0.08 to 0.39 for North Bay. No obvious relationships were observed between sediment metals and PAH concentrations. The Site sediments tended to have a somewhat coarser grain size and higher solids content than North Bay sediments, although the ranges overlapped, and had a broader range of TOC concentrations than North Bay. 3.2 Laboratory Exposure Tests Detailed results of the laboratory exposure tests can be found in the laboratory reports (ASci 2002a, 2002b, 2002c, 2003a, 2003b). Additional statistical analysis of the Hyalella and Chironomus test data was performed by Donald MacDonald of the NOAA Coastal Protection and Restoration Program. Laboratory exposure test results are summarized here Toxicity Tests Hyalella azteca 28-Day Test Sediments were classified as toxic when they were significantly different from the control or reference sediments. Using this criterion, all but four Site samples tested exhibited reduced survival compared to the control or North Bay sediments (Table 4). An additional sample was identified as causing significant effects when the growth as dry weight endpoint is included. Effects generally increased with increasing sediment TPAH concentrations (Figure 2). Stryker Bay sediments appeared to be more toxic than Slip 7 sediments. The No Observed Effect Concentration (NOEC) and Lowest Observed Effect Concentration (LOEC) for reduced survival or growth are estimated to be between and between 5 15, respectively. Exposure to UV light for 4 hours after the 28 day sediment exposure resulted in significantly increased mortality within 24 hours in four Stryker Bay stations. This photoenhanced toxicity

10 indicates that PAHs were likely responsible for the toxicity and that the organisms were accumulating sufficient tissue PAHs from the sediments for this effect to be potentially significant. The threshold for the phototoxic effect under the conditions tested was between 33 and 47 sediment TPAHs Chironomus tentans Partial Life-Cycle Test The same criteria used in the Hyalella azteca test were used to classify sediments as toxic. Seven samples tested caused significant reductions in survival after 20 days of exposure, fewer than for the Hyalella test (Table 5). No additional samples were classified as having significant effects when the growth as dry weight endpoint was included. Four samples with the highest sediment TPAH concentrations resulted in reduced emergence of adults, including one sample (K6C) which did not cause reduced survival. As for Hyalella, Stryker Bay sediments appeared to be more toxic than Slip 7 sediments (Figure 3). The estimated TPAH NOEC and LOEC for reduced survival, growth or emergence are 29 and 33. Exposure to UV-A light for 4 hours after the 28 day sediment exposure resulted in significantly increased mortality within 24 hours in the same four Stryker Bay stations as for Hyalella, plus one station (K7) in Slip 7 (Table 5). This photoenhanced toxicity indicates that sediment PAHs were probably responsible for the toxicity and that the organisms were accumulating sufficient body burdens of PAHs from the sediments for this effect to be potentially significant in the field. The threshold for the phototoxic effect under the conditions tested was between 33 and 47 sediment TPAHs Typha latifolia 17-Day Test Five sediment samples (K1, K12, K13, S6, and S8) tested caused significant reductions in both germination and 17-day survival of cattail seedlings (Table 6). Four of these sediment samples had TPAH concentrations greater than 100 ; the fifth sample (K1) had only 5 TPAH. None of the test sediments significantly reduced the ash-free dry weight of the cattail seedlings harvested at the end of the test. Longer duration of testing may have resulted in a greater incidence of effects Zizania aquatica 10-Day Test None of the sediment samples appeared to affect survival or growth of wild rice seedlings exposed for 10 days (Table 7). Longer duration of testing may have been required for effects to become evident Lumbriculus variegatus Bioaccumulation Test PAHs Lumbriculus exposed to site sediments for 28 days accumulated tissue residues of TPAHs ranging from 0.5 to 62.9 wet weight (Table 8). In comparison, residues in North Bay samples ranged from 0.03 to 0.08 (mean concentration of mg/kg). Lumbriculus from all Site sample locations accumulated significantly more TPAHs than the North Bay reference area, with tissue concentrations ranging from 9 to 1110 fold higher (Table 8). Lumbriculus tissue TPAH concentrations increased in a concentration dependent manner with sediment TPAHs (Figure 4). Lumbriculus exposed to station S8 sediment, with the highest PAH concentration (TPAH = 1899 ) avoided burrowing into the sediment and suffered some mortality, but still accumulated the highest tissue residues (62.9 ). Complete mortality

11 occurred in the Site sediment with the next highest TPAH concentration (K12; 209 ), and significant mortality occurred in the third highest concentration sediment (K13; 184 ). Lumbriculus biomass (as wet weight; a measure of the combined effects of mortality and growth inhibition) declined in a concentration dependent manner with increasing sediment TPAHs (Table 9) (Figure 5) and with increasing tissue TPAH concentration (Figure 6). Lowest mass was observed for station S8, the sample with the highest sediment TPAH concentration. Average masses were significantly lower than the mean North Bay mass at all but one site station (S4, 5.1 TPAH). However, because station K1, also with 5.1 TPAH, did have reduced biomass, the sediment PAH NOEC and LOEC concentrations are both 5.1. Reductions in biomass were observed when tissue concentrations of TPAHs were between 0.5 and 1.4. Therefore, the tissue TPAH NOEC and LOEC for biomass reduction are 0.5 and 1.4, respectively. Metals Concentrations of arsenic, cadmium, chromium, lead and nickel were below detection limits in most tissue samples (Table 8). Of metals for which there was more than one detection, chromium was detected only in some replicates in reference area samples, and lead was detected only in some replicates in several Site samples. Mercury was detected in all tissue samples, but concentrations did not differ between reference and Site samples. Copper and zinc concentrations were somewhat higher in Site samples than in reference area samples, but did not exhibit any relationship with sediment concentrations. 3.3 Field-Collected Organism Tissue Residues Benthic Invertebrates Amphipods, chironomids and tricopterans were the most abundant organisms of sufficient size to provide adequate mass for tissue residue analyses across the most stations, so these organisms were selected for analysis. Three stations (S4, S8 and K12) had too few organisms to do any tissue analysis; two of these stations (S8 and K12) also had the highest sediment TPAH concentrations (1899 and 209, respectively). Seven stations had sufficient quantities of all three taxa to analyze tissue residues for all three. The remaining stations had analyses performed for two of the three taxa. PAHs Tissue concentrations of TPAHs ranged from 0.3 to 29 wet weight for Site stations, compared to a range of 0.1 to 0.4 (mean concentration of 0.23 mg/kg) in the North Bay reference area (Table 10). One or more taxa from all of the stations which had sufficient organism mass had TPAH residues which were significantly higher than the mean North Bay concentration for all taxa combined. When individual taxa are examined, it is apparent that tricopterans and chironomids accumulated generally similar residues, but consistently accumulated higher body burdens than amphipods at a given station (Table 10). This would be expected given that amphipods live more at the water column/sediment interface and thus likely have less direct sediment contact than the other two taxa. The three stations at which amphipods were analyzed with the lowest sediment TPAH concentrations (K1-5 ; S2-15 ; and K11-29 ) did not have significantly higher residues in amphipods than the reference area mean for amphipods, while all of the remaining stations did, with concentrations ranging

12 from 4 to 28 fold higher. For chironomids and tricopterans, all stations were significantly higher than their respective reference area means, with concentrations ranging from 5 to 213 fold higher. For all three taxa, tissue TPAH concentrations exhibited a general concentration dependent increase with sediment TPAH concentrations (Figure 7). Metals Arsenic, cadmium, and nickel were below detection limits in all or nearly all samples (Table 10). Chromium was detected only in chironomids in some site and reference samples at similar concentrations. Lead was also detected only in chironomids, but only in three Site samples and at relatively low concentrations. Copper, mercury and zinc were detected in all samples, but there were no significant differences between Site and reference stations. Copper concentrations were highest in amphipods and lowest in chironomids; mercury was highest in chironomids; and zinc was highest in tricopterans and lowest in amphipods. Comparison to laboratory bioaccumulation in Lumbriculus Overall, concentrations of TPAHs in field-collected organisms were roughly similar to concentrations bioaccumulated by laboratory-exposed Lumbriculus after 28 days of exposure (Figure 8), and concentrations generally tracked those in Lumbriculus and sediments (Figure 9). Concentrations in chironomids and tricopterans from the field were more similar to those in Lumbriculus than were amphipod concentrations, which tended to be lower. In Lumbriculus, reductions in biomass were observed when tissue concentrations of TPAHs were between 0.5 and 1.4, i.e., the NOEC and LOEC, respectively for biomass reduction in Lumbriculus. The critical body burden approach predicts that toxic effects in different organisms will occur at similar tissue concentrations of the toxicant (EPA 2002). Therefore, the tissue residue based effects thresholds for Lumbriculus should approximate toxicity thresholds in other benthic invertebrates and can be applied to the field-collected organisms. Making this assumption, it is predicted that growth and/or mortality is occurring to sediment burrowing invertebrates at locations where tissue residues exceed the midpoint between the NOEC and LOEC, 0.95 TPAHs. Chironomid tissue residues exceeded both the NOEC and LOEC at all stations, and tricopteran residues exceeded the NOEC at all stations and the LOEC at all but two stations, indicating that sediment concentrations greater than 5 TPAHs are likely impacting organisms that live in intimate contact with sediment such as these. Anecdotal support for the predictability of effects in field organisms from Lumbriculus comes from the observation that virtually no invertebrates were found in the sediment at station S8, the same sediment which Lumbriculus avoided burrowing into in the lab Aquatic Plants Three species of submerged aquatic plants, Myriophyllum exalbescens (northern watermilfoil), Valisneria americana (wild celery) and Potamogeton zosteriformis (flat-stemmed pondweed) were the plants that provided adequate mass for tissue residue analyses across most stations, so these organisms were selected for analysis. Valisneria and Myriophyllum both occurred in sufficient quantity at all North Bay reference area and Stryker Bay stations. Therefore, they were selected for analysis there, but did not occur at all of the Slip 7 stations, so Potamogeton was chosen as an additional species in Slip 7 to provide complete coverage of the stations. All three species were analyzed at three stations, to allow comparison of tissue residues among the species.

13 PAHs Tissue concentrations of TPAHs in whole plants ranged from 0.4 to 25 wet weight for Site stations, compared to a range of 0.01 to 1.2 (with a mean concentration of 0.15 mg/kg) in the North Bay reference area (Table 11). One or more species from all of the stations had TPAH residues which were significantly higher than the mean North Bay concentration for all taxa combined. The three species appeared to accumulate PAHs to approximately the same concentrations (Figure 10), with no consistent pattern of differences among species. All stations were significantly higher than their respective reference area mean concentrations, with concentrations ranging from 2 to 674 fold higher. Tissue TPAH concentrations did not exhibit as strong a relationship with sediment TPAH concentrations as did invertebrates (Figure 11). Metals Two metals, arsenic and cadmium, were detected at low levels in samples from three Site stations, but not in North Bay samples. For several other metals, including chromium, copper, lead, nickel and zinc, maximum concentrations were higher in Site samples than in North Bay samples, but no obvious relationship between plant tissue concentrations and sediment concentrations were observed. Mercury was below or only slightly above detection limits in all samples, with no apparent differences between North Bay and the Site. There were no obvious consistent patterns of differences in metals concentrations among the three plant species. 3.4 Weight of Evidence Evaluation to Determine Effects Threshold Ranges Individual lines of evidence involving biological effects data often show somewhat variable results that can be difficult to interpret in isolation, but when data from multiple measurement endpoints are combined, often patterns become more evident. In an earlier evaluation of ecological effects data, MPCA concluded that acute toxic effects were likely occurring in benthic invertebrates exposed to sediments at the Site (MPCA 1999). However, determination of effects thresholds could not be made due to a lack of data at sediment PAH concentrations below those which resulted in mortality in short-term tests. The purpose of the 2001 data collection effort was to attempt to fill data gaps and obtain information on additional measurement endpoints which could be combined with the earlier data in a weight of evidence approach. In Figure 12, data for all of the measurement endpoints in this study for which effects were observed are presented along with endpoint data from the Site collected by IT Corp. (IT 1997) and the EPA 1995 R-EMAP study (10-day Hyalella and Chironomus survival and growth). All effects data are normalized to control or reference values so that all endpoints are presented on the same scale (i.e., percent of control response with a range of 0 to 100%). Tissue residue data were transformed by taking the inverse so that decreasing values on the y-axis represent increasing effect (i.e., increasing body burden & reduced biomass). Additionally, points representing Effect samples are shaded red, and No Effect samples are shaded green for ease of visually distinguishing patterns in the data. The endpoint data are all plotted against sediment TPAH concentration on the x-axis, because effects appear to be primarily related to this stressor at the site. For reference, the consensus-based sediment quality guideline Threshold Effects Concentration (TEC; 1.6 ) and Probable Effects Concentration (PEC; 23 ) for TPAHs from MacDonald et al. (2000) are indicated on Figure 12 along with the TPAH concentration of 13.7

14 (0.6 x PEC) selected by MPCA as a preliminary remediation goal (PRG) for use in the Feasibility Study (FS). Sample points to the left of the TEC value represent data from the North Bay reference area, i.e., ambient background PAH concentrations. Sample data are limited between the TEC and PEC, but it is clear that effects begin to become evident within that range, and that the incidence of Effect samples rapidly increases in the vicinity of the PEC. Sitespecific data appear to indicate that for this Site, the TPAH TEC and PEC values predict effects ranges relatively well for a variety of endpoints in benthic invertebrates and other organisms, and that the PRG value of 13.7 was a reasonable level to use in identifying areas to be remediated for the FS. Therefore, a final TPAH RAO and Cleanup Level selected within the range between the TEC and the PEC would be supported by the site-specific data. The most protective level would be the TEC, which would be similar to ambient background. Reasonably protective values include 5, the lowest Site concentration for which effects data are available, or a midrange value between the TEC (1.6 ) and the PEC (23 ) such as the 13.7 TPAH concentration selected as a PRG for the FS.

15 4.0 REFERENCES ASci. 2002a. Results of 28-day Hyalella azteca Toxicity Tests with St. Louis River Sediments Samples Received September 25-October 18, ASci Corp. ASci. 2002b. Results of Chironomus tentans Toxicity Tests with St. Louis River Sediments Samples Received September 25-October 18, ASci Corp. ASci. 2002c. Summary of Test Results to Determine Bioaccumulation Potential of Selected Sediment Samples to Lumbriculus variegatus. ASci Corp. ASci. 2003a. Results of 17-day Typha latipholia (Cattail) Toxicity Test with St. Louis River Sediments Samples Received September 25-October 18, ASci Corp. ASci. 2003b. Results of 10-day Zizania aquatica (Wild Rice) Toxicity Test with Baywest Sediments Samples Received September 25-October 18, ASci Corp. Bay West Quality Assurance Project Plan, Saint Louis River/Duluth Tar/Interlake Superfund Site. October, MacDonald, D.D., C.G. Ingersoll, and T.A. Berger Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Archives of Environmental Contamination and Toxicology 39: MPCA 1999b. MPCA Assessment of Sediment Contamination at the SLRIDT Superfund Site Using the Sediment Quality Triad Approach and Sediment Effect Concentrations. Thijssen, M Body burdens of PAHs in benthic invertebrates from the Duluth-Superior Harbor. USEPA Methods for Measuring the Toxicity and Bioaccumulation of Sedimentassociated Contaminants with Freshwater Invertebrates. Second Edition. EPA/600/R-99/064. USEPA Procedures for the derivation of equilibrium partitioning sediment benchmarks (ESBs) for the protection of benthic organisms: PAH mixtures. EPA 600-R

16 Table 1. Sediment Chemistry Analytes and Methods ANALYTE PAH Dioxins/Furans Dioxins/Furan, expressed as 2,3,7,8 - TCDD equivalents VOCs Metals Mercury Methyl-Mercury TOC Total Cyanide Sulfate Semivolatiles Particle Size PCBs FINAL ANALYSIS (SEDIMENT) LAB/ANALYTICAL METHOD Axys SW Axys SW CAS SW EnChem EPA SW MDH 466F List EnChem EPA Method 6020 EnChem SW Frontier Geosciences Frontier SOP EnChem EPA Method 150.1/9060 EnChem SW EnChem SW EnChem SW A CQM ASTM D422 EnChem SW CONTAINER AND PRESERVATIVE 8 oz amber glass with teflonlined lid, cool to 4 degrees C 8 oz. Amber glass, cool to 4 degrees C 8 oz. Amber glass, cool to 4 degrees C 2 oz glass container with teflon-lined lid, methanol cool to 4 degrees C HOLDING TIME 14 days to extract, 40 days from extract to analysis 30 days to extract 30 days 14 days 8 oz glass 6 months Included with other metals 28 days 8 oz. glass, cool to 4 degrees C 7 days Included with metals Included with metals Included with metals 8 oz. Amber glass, cool to 4 degrees C Two 1 L plastic Included with metals 28 days 14 days 28 days 14 days to extract, 40 days from extract to analysis 28 days 14 days to extract, 40 days from extract to analysis

17 Table 2. Tissue Chemistry Analytes and Methods ANALYTE PAH Metals Mercury BENTHIC INVERTEBRATE, FISH AND PLANT ANALYSES (TISSUE) LAB/ANALYTICAL CONTAINER AND METHOD PRESERVATIVE HOLDING TIME 5-gallon bucket, with 14 days to extract, 40 Axys subsequent invertebrate ID days from extract to SW and sampling analysis EnChem EPA Method 6020 Included with PAHs 6 months EnChem EPA Method 6020 Included with PAHs 6 months

18 Table 3 Analytical Chemistry Data for SLRIDT Site and North Bay Sediment Samples Collected in 10/2001 North Bay Stryker Bay N7 N8 N9 N10 N11 S2 S4 S6 S8 S9 S11 S12 S12A S12B 0-6" 0-6" 0-6" 0-6" 0-6" 0-6" 0-6" 0-6" 0-6" 0-6" 0-6" 0-6" Dilution Dilution Analyte units of S12 of S12 METALS Arsenic Cadmium Chromium Copper Lead Nickel Zinc Mean Metals PEC-Q Mercury Methyl mercury ng/kg < Cyanide <1.8 <2.4 <1.2 <1.7 <1.0 <0.69 <0.70 < <0.67 <1.9 <1.1 <1.4 <1.5 Sulfate, soluble 240 < <140 < < Grain size (% fines) % Solids, percent % TOC % PAHS Acenaphthene <46.5 < Acenaphthylene < Anthracene Benz[a]anthracene Benzo[b,j,k]fluoranthene Benzo[g,h,i]perylene Benzo[a]pyrene Chrysene Dibenz[a,h]anthracene Fluoranthene Fluorene Indeno[1,2,3-cd]pyrene Methylnaphthalene < Methylnaphthalene Naphthalene <150 < Phenanthrene Pyrene Total PAHs (TPAH) = sum 17 PAHs Individual PAHs Mean PEC-Q TPAH PEC-Q Metals + Indiv. PAHs Mean PEC-Q Metals + TPAH Mean PEC-Q PAH ESG-TUs (without uncertainty factor) of 2

19 Analyte METALS Arsenic Cadmium Chromium Copper Lead Nickel Zinc Mean Metals PEC-Q units Table 3 Analytical Chemistry Data for SLRIDT Site and North Bay Sediment Samples Collected in 10/2001 Keene Cr. Bay K1 K4 K6 K6A K6B K6C K7 K11 K12 K13 K16A 0-6" 0-6" 0-6" Dilution Dilution Dilution 0-6" 0-6" 0-6" 0-6" Dilution of K6 of K6 of K6 Dup. of K Mercury Methyl mercury ng/kg Cyanide Sulfate, soluble Grain size (% fines) % Solids, percent % TOC % <1.7 < < < < PAHS Acenaphthene Acenaphthylene Anthracene Benz[a]anthracene Benzo[b,j,k]fluoranthene Benzo[g,h,i]perylene Benzo[a]pyrene Chrysene Dibenz[a,h]anthracene Fluoranthene Fluorene Indeno[1,2,3-cd]pyrene 1-Methylnaphthalene 2-Methylnaphthalene Naphthalene Phenanthrene Pyrene Total PAHs (TPAH) = sum 17 PAHs < < < < Individual PAHs Mean PEC-Q TPAH PEC-Q Metals + Indiv. PAHs Mean PEC-Q Metals + TPAH Mean PEC-Q PAH ESG-TUs (without uncertainty factor) of 2

20 Table 4 Hyalella azteca 28-day Toxicity Test Results Survival, No UV Survival, UV Growth, length Growth, weight Control Control Control Dry Control Sample ID Survival Normalized Survival Normalized Length Normalized Weight Normalized (%) (%) (%) (%) (mm) (%) (mg) (%) West Bearskin Control N N N N N11 na na na na Pooled North Bay S * 86.1 * S * 80.6 * * 91.4 * S * 0.0 * S * 87.3 * 0.0 * 0.0 * S * 73.6 * 10.0 * 10.7 * S12A 66.2 * 73.6 * S12B 77.1 * 85.7 * 26.7 * 28.6 * K K * 86.1 * K6A 75.0 * 83.3 * K6B 61.7 * 68.5 * K6C 77.5 * 86.1 * K * 71.4 * K * 76.2 * K16A * = significantly lower than control or pooled reference at p < 0.05 na = not included in analysis, excluded as an outlier due to extreme variability

21 Table 5 Chironomus tentans Partial Life-Cycle Toxicity Test Results Survival, no UV Survival, UV Growth Emergence Control Control Dry Control Control Sample ID Survival normalized Survival normalized Weight Normalized Emergence Normalized (%) (%) (%) (%) (g) (%) (%) (%) West Bearskin Control N N N N N Pooled North Bay S S S * 51.4 * 19.4 * 26.9 * * 37.5 * S * 87.0 * 0.0 * 0.0 * S * 60.7 * 0.0 * 0.0 * * 53.1* S12A 69.4 * 76.9 * * 1.29 * * S12B 52.8 * 58.5 * 30.6 * 42.3 * * 46.9 * K K K6A 48.3 * 53.5 * ** 56.3 ** K6B 45.2 * 50.1 * K6C * * 20.0 * 37.5 * K * 34.6 * K K16A * = significantly lower than control or pooled reference at p < 0.05 ** = significantly lower than control or pooled reference at p < 0.10

22 Table 6 Typha latifolia 17-day Toxicity Test Results Endpoint 7-day 17-day Ash free Sample ID Germination Survival dry weight (%) (%) (mg) West Bearskin Set # West Bearskin Set # N N N N N Pooled North Bay S S S * 70 * 0.25 S * 62.5 * 0.18 S S S12A S12B K * 0.14 K K6A K6B K6C K K K12 80 * 78.8 * 0.17 K * 82.5 * 0.17 K16A * Significantly different from control and reference

23 Table 7 Zizania aquatica 10-day Toxicity Test Results Endpoint 10-day Wet Shoot Sample ID Survival Weight Length (%) (g) (cm) West Bearskin Control N N N N N Pooled North Bay S S S S S S S12A S12B K K K6A K6B K6C K K K K K16A

24 Table 8 Lumbriculus Tissue Chemistry Data for SLRIDT Site and North Bay Samples Sample number N7 N8 N9 N10 N11 S2 S4 S6 S8 Analyte units METALS Arsenic <1 <1 <1 < <1 <1 <1 <1 Cadmium <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Chromium < <0.3 <0.3 <0.3 <0.3 Copper Lead <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 Mercury Nickel < <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 Zinc Lipid % na PAHs Acenaphthene < Acenaphthylene < Anthracene Benz[a]anthracene Benzo[a]pyrene Benzo[b,j,k]fluoranthenes Benzo[g,h,i]perylene Chrysene Dibenz[a,h]anthracene < Fluoranthene Fluorene Indeno[1,2,3-cd]pyrene Methylnaphthalene Methylnaphthalene Naphthalene Phenanthrene Pyrene Total PAHs * Each value represents the mean of 5 replicate concentrations 1 of 2

25 Table 8 Lumbriculus Tissue Chemistry Data for SLRIDT Site and North Bay Samples Arsenic Cadmium Chromium Copper Lead Mercury Nickel Zinc Analyte METALS Sample number units S9 S11 S12 K1 K4 K6 K7 K11 K <1 <1 <1 <1 <1 <1 <1 <1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.3 <0.3 <0.3 <0.3 <0.3 <0.3 <0.3 <0.3 < < < < <0.5 < <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 < Lipid % na PAHs Acenaphthene Acenaphthylene Anthracene Benz[a]anthracene Benzo[a]pyrene Benzo[b,j,k]fluoranthenes Benzo[g,h,i]perylene Chrysene Dibenz[a,h]anthracene Fluoranthene Fluorene Indeno[1,2,3-cd]pyrene 1-Methylnaphthalene 2-Methylnaphthalene Naphthalene Phenanthrene Pyrene Total PAHs * Each value represents the mean of 5 replicate concentrations 2 of 2

26 Table 9 Lumbriculus Biomass for SLRIDT Site and North Bay Samples Significant Sediment Tissue difference Sample TPAH TPAH Mean from Station () () Biomass reference? N N N N N S yes S no S yes S yes S yes S yes S yes K yes K yes K yes K yes K yes K na na na K yes na = not analyzed due to 100% mortality of organisms

27 Table 10 Field-collected Invertebrate Tissue Chemistry Data for SLRIDT Site and North Bay Samples N7 N8 N9 N10 N11 Analyte units Amphipod Tricopteran Amphipod Chironomid Amphipod Tricopteran Chironomid Tricopteran Chironomid Amphipod Tricopteran Chironomid METALS Arsenic <0.98 <0.96 na <1 <1 <1 <1 <1 <0.98 <1 <0.91 <1 Cadmium <0.098 <0.096 na <0.1 <0.1 <0.1 <0.1 <0.1 <0.098 <0.1 <0.091 <0.1 Chromium <0.29 <0.29 na <0.31 <0.3 < < <0.3 < Copper na Lead <0.49 <0.48 na <0.5 <0.5 <0.5 <0.5 <0.5 <0.49 <0.5 <0.45 <0.5 Mercury na < Nickel <0.49 <0.48 na <0.5 <0.5 <0.5 <0.5 <0.5 <0.29 <0.5 <0.45 <0.5 Zinc na Lipid % PAHs Naphthalene Acenaphthylene < Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benz[a]anthracene Chrysene Benzo[b/j/k]fluoranthenes Benzo[a]pyrene 2.83 < < < < Dibenz[ah]anthracene < < < Indeno[1,2,3-cd]pyrene < <0.365 <0.929 Benzo[ghi]perylene < < Methylnaphthalene Methylnaphthalene Total PAHs na = not analyzed 1 of 4

28 Table 10 Field-collected Invertebrate Tissue Chemistry Data for SLRIDT Site and North Bay Samples Arsenic Cadmium Chromium Copper Lead Mercury Nickel Zinc Analyte METALS units S2 S4 S6 S8 S9 S11 Amphipod Tricopteran Amphipod Tricopteran Chironomid Amphipod Tricopteran Tricopteran Chironomid <1 na na <1 <1 <0.94 na <1 <1 <1 <1 <0.1 na na <0.1 <0.1 <0.094 na <0.1 <0.17 <0.1 <0.1 <0.3 na na <0.3 <0.3 <0.28 na <0.3 <1.1 <0.61 < na na na <0.5 na na <0.5 <0.5 <0.47 na <0.5 <0.5 <0.5 < na na na <0.031 < <0.5 na na <0.5 <0.5 <0.47 na < <0.5 < na na na Lipid % 0.98 PAHs Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benz[a]anthracene Chrysene Benzo[b/j/k]fluoranthenes Benzo[a]pyrene Dibenz[ah]anthracene Indeno[1,2,3-cd]pyrene Benzo[ghi]perylene 2-Methylnaphthalene 1-Methylnaphthalene Total PAHs na = not analyzed na na na na na na na na na na na na na na na na na na na na na na na na na na na na na < na na na na na of 4

29 Table 10 Field-collected Invertebrate Tissue Chemistry Data for SLRIDT Site and North Bay Samples Arsenic Cadmium Chromium Copper Lead Mercury Nickel Zinc Analyte METALS units S12 K1 K4 K6 K7 Amphipod Chironomid Amphipod Tricopteran Chironomid Tricopteran Chironomid Amphipod Tricopteran Chironomid Amphipod Tricopteran <0.98 <1 <1 <1 na na na <1 <0.98 <1 <1 <1 <0.098 <0.1 <0.1 <0.1 na na na <0.1 <0.098 <0.1 <0.1 <0.1 < <0.3 <0.32 na na na <0.3 < <0.46 < na na na < <0.5 <0.5 na na na <0.5 < <0.5 < <0.01 <0.014 na na na < <0.49 <0.5 <0.5 <0.5 na na na <0.5 <0.49 <0.5 <0.5 < na na na Lipid % PAHs Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benz[a]anthracene Chrysene Benzo[b/j/k]fluoranthenes Benzo[a]pyrene Dibenz[ah]anthracene Indeno[1,2,3-cd]pyrene Benzo[ghi]perylene 2-Methylnaphthalene 1-Methylnaphthalene Total PAHs na = not analyzed of 4

30 Table 10 Field-collected Invertebrate Tissue Chemistry Data for SLRIDT Site and North Bay Samples Arsenic Cadmium Chromium Copper Lead Mercury Nickel Zinc Analyte METALS units K11 K12 K13 Chironomid Amphipod Tricopteran Chironomid Amphipod Tricopteran <0.88 <1 <1 <1 na <0.96 <1 <0.088 <0.1 <0.1 <0.1 na <0.096 < <0.3 < na <0.29 < na <0.44 <0.5 < na <0.48 < na <0.44 <0.5 <0.51 <0.52 na <0.48 < na Lipid % PAHs Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benz[a]anthracene Chrysene Benzo[b/j/k]fluoranthenes Benzo[a]pyrene Dibenz[ah]anthracene Indeno[1,2,3-cd]pyrene Benzo[ghi]perylene 2-Methylnaphthalene 1-Methylnaphthalene Total PAHs na = not analyzed na na na na na na na na na na na na na na na na na of 4

31 Table 11 Aquatic Plant Tissue Chemistry Data for the SLRIDT Site and North Bay Sample number N7 N8 N9 N10 SLR-PL-N1 SLR-PL-N14 SLR-PL-N5 SLR-PL-N7 SLR-PL-N9 SLR-PL-N16 SLR-PL-N12 SLR-PL-N17 Analyte units Vallisneria Myriophyllum Vallisneria Myriophyllum Vallisneria Myriophyllum Vallisneria Myriophyllum METALS Arsenic <0.98 <0.98 <0.88 <0.94 <1.0 <0.98 <0.94 <0.98 Cadmium <0.098 <0.098 <0.088 <0.094 <0.10 <0.098 <0.094 <0.098 Chromium 0.9 < Copper Lead 0.89 < <0.49 < Mercury 0.01 < < < < Nickel 0.96 < < Zinc PAHs Naphthalene Acenaphthene Acenaphthylene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benz[a]anthracene Chrysene Benzo[b,j,k]fluoranthene Benzo[a]pyrene Dibenz[a,h]anthracene < Indeno[1,2,3-cd]pyrene Benzo[g,h,i]perylene Methylnaphthalene Methylnaphthalene Total PAHs of 5

32 Table 11 Aquatic Plant Tissue Chemistry Data for the SLRIDT Site and North Bay Analyte METALS Arsenic Cadmium Chromium Copper Lead Mercury Nickel Zinc Sample number units N11 S2 S4 S6 SLR-PL-N13 SLR-PL-N18 SLR-PL-S5 SLR-PL-S6 SLR-PL-S1 SLR-PL-S3 SLR-PL-S13 SLR-PL-S15 Vallisneria Myriophyllum Vallisneria Myriophyllum Vallisneria Myriophyllum Vallisneria Myriophyllum <0.89 <0.88 < <0.91 <0.96 <0.089 <0.088 <0.086 <0.088 <0.088 <0.10 <0.091 < <0.45 < < < < < PAHs Naphthalene Acenaphthene Acenaphthylene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benz[a]anthracene Chrysene Benzo[b,j,k]fluoranthene Benzo[a]pyrene Dibenz[a,h]anthracene Indeno[1,2,3-cd]pyrene Benzo[g,h,i]perylene 2-Methylnaphthalene 1-Methylnaphthalene Total PAHs < of 5

33 Table 11 Aquatic Plant Tissue Chemistry Data for the SLRIDT Site and North Bay Analyte METALS Arsenic Cadmium Chromium Copper Lead Mercury Nickel Zinc Sample number units S8 S9 S11 S12 SLR-PL-S18 SLR-PL-S20 SLR-PL-S16 SLR-PL-S17 SLR-PL-S7 SLR-PL-S8 SLR-PL-S9 SLR-PL-S10 Vallisneria Myriophyllum Vallisneria Myriophyllum Vallisneria Myriophyllum Vallisneria Myriophyllum <0.93 <2.4 <0.98 <0.93 <0.98 <0.86 <0.94 <0.91 <0.093 <0.24 < <0.098 <0.086 <0.094 <0.091 <0.28 <0.71 <0.29 <0.28 <0.29 < < <0.46 <1.2 < < < <0.01 < <0.005 < < <1.2 < < PAHs Naphthalene Acenaphthene Acenaphthylene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benz[a]anthracene Chrysene Benzo[b,j,k]fluoranthene Benzo[a]pyrene Dibenz[a,h]anthracene Indeno[1,2,3-cd]pyrene Benzo[g,h,i]perylene 2-Methylnaphthalene 1-Methylnaphthalene Total PAHs of 5

34 Table 11 Aquatic Plant Tissue Chemistry Data for the SLRIDT Site and North Bay Analyte METALS Arsenic Cadmium Chromium Copper Lead Mercury Nickel Zinc Sample number units K1 K4 K6 K7 SLR-PL-K6 SLR-PL-K8 SLR-PL-K9 SLR-PL-K1 SLR-PL-K2 SLR-PL-K17 SLR-PL-K4 SLR-PL-K19 SLR-PL-K5 Vallisneria Myriophyllum Potamageton Myriophyllum Potamageton Vallisneria Vallisneria Myriophyllum Potamageton <0.93 <0.96 <1 <0.88 <0.88 <1.0 <0.94 <1.0 <0.93 <0.093 <0.096 <0.1 <0.088 <0.088 <0.1 <0.094 <0.1 < <0.26 < < <0.44 < <0.005 <0.005 <0.005 <0.005 < <0.005 < < <0.44 < PAHs Naphthalene Acenaphthene Acenaphthylene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benz[a]anthracene Chrysene Benzo[b,j,k]fluoranthene Benzo[a]pyrene Dibenz[a,h]anthracene Indeno[1,2,3-cd]pyrene Benzo[g,h,i]perylene 2-Methylnaphthalene 1-Methylnaphthalene Total PAHs of 5

35 Table 11 Aquatic Plant Tissue Chemistry Data for the SLRIDT Site and North Bay Analyte METALS Arsenic Cadmium Chromium Copper Lead Mercury Nickel Zinc Sample number units K11 K12 K13 SLR-PL-K10 SLR-PL-K12 SLR-PL-K13 SLR-PL-K3 SLR-PL-K14 SLR-PL-K15 Vallisneria Myriophyllum Potamageton Potamageton Vallisneria Potamageton < <1.0 <0.86 <0.96 <1.0 <0.1 < <0.086 < <0.005 < PAHs Naphthalene Acenaphthene Acenaphthylene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benz[a]anthracene Chrysene Benzo[b,j,k]fluoranthene Benzo[a]pyrene Dibenz[a,h]anthracene Indeno[1,2,3-cd]pyrene Benzo[g,h,i]perylene 2-Methylnaphthalene 1-Methylnaphthalene Total PAHs of 5

36