Spatial Extent of Contamination , Toxicity and Associated Biological Effects in Puget Sound Sediments

Analyses were performed to quantify chemical concentrations, acute toxicity in laboratory tests, and the structure of benthic infauna communities in sediments from 300 randomly chosen locations in Puget Sound during 1997 to 1999. Samples of surficial sediments were collected from the vicinity of the U.S./Canada border to the inlets of southern Puget Sound and Hood Canal as part of a joint research program of the National Oceanic and Atmospheric Administration and Washington State Department of Ecology. The study was designed to provide information on the severity, spatial patterns, and spatial extent of contamination, toxicity, and degraded benthos and the relationships among these measures of sediment quality. The weight-of-evidence from the three complimentary analyses suggests that degraded conditions (high chemical concentrations, significant toxicity, and adversely altered benthos) occurred in samples that represented about 1% of the total area. These conditions invariably occurred in samples collected within urbanized bays and industrial waterways in which degraded conditions had been reported in previous studies. Sediments with good quality (as indicated by no toxicity, no contamination, and abundant and diverse infauna) occurred in 42% of the total study area. Sediments in which moderate or intermediate degrees of degradation occurred represented 57% of the study area (9% with significant toxicity and high chemical contamination, but abundant infauna; 48% with significant toxicity or high chemical contamination (i.e., not both), but abundant infauna). This large area with intermediate levels of sediment degradation underscores the need for continued surveillance to assess changes in sediment condition over time. Introduction Toxic substances introduced into estuarine ecosystems, such as Puget Sound, can bind to suspended particles, settle to the bottom, and become incorporated into deposited sediments. Toxicants associated with sediments can represent a potential toxicological threat to the resident biota if concentrations become sufficiently elevated. Toxic chemicals are known to occur in a wide range of concentrations in surficial (recently deposited) sediments of Puget Sound. Although contaminant levels in some areas have been well characterized with data from many previous studies, other regions were poorly known. Also, despite source controls initiated in recent decades, some areas remain highly contaminated and thus pose a serious threat to the estuarine ecosystems of the Sound. Despite the availability of historical data on sediment quality from many studies in regions of Puget Sound, none of these historical data were collected with methods that allowed estimates to be made of the surficial or spatial extent of degradation. Often, studies were performed in the vicinity of specific point sources or other focused areas; thus, precluding analyses of the data to determine the actual size and spatial dimensions of the degraded areas on a Sound-wide basis. The Washington State Department of Ecology (Ecology) Marine Sediment Monitoring Team has conducted the Sediment Monitoring Component of the Puget Sound Ambient Monitoring Program (PSAMP) since 1989. This program used the "Sediment Quality Triad" approach of Long and Chapman (1985) to determine relative sediment quality in Puget Sound. Ecology established baseline data for toxicity and chemical contamination of Puget Sound sediments (Llansó and others 1998a) and characterized infaunal invertebrate assemblages (Llansó and others 1998b) at 76 selected monitoring stations throughout Puget Sound. A portion of this baseline work is continuing at a subset of ten stations at the present time. Puget Sound Research 2001 The National Status and Trends (NS&T) Program of NOAA has conducted bioeffects assessment studies in more than 30 embayments and estuaries nationwide since 1990 (Long and others 1996; Long, 2000). All of these studies followed a random-stratified sampling design. Most involved use of the triad approach to estimate the spatial extent, magnitude, and spatial patterns in relative sediment quality and to determine the relationships among measures of toxicity, chemical contamination, and benthic infaunal structure within the study areas. In 1996, Ecology and NOAA entered into a three-year cooperative agreement, combining the sediment monitoring and assessment programs of the two agencies into one large survey to quantify the magnitude and extent of toxicity and chemical contamination of sediments throughout Puget Sound utilizing NOAA’s random-stratified sampling design and the "Sediment Quality Triad" approach. The shared goal of this study for both the PSAMP Sediment Monitoring Component and NOAA’s nationwide bioeffects assessment program was to characterize the ecotoxicological condition of sediments, as well as benthic infaunal assemblage structure, as a measure of adverse biological effects of toxic chemicals in Puget Sound. Specific objectives of the program in Puget Sound were: 1. Determine the incidence and severity of sediment toxicity. 2. Identify spatial patterns and gradients in sediment toxicity and chemical concentrations. 3. Estimate the spatial extent of toxicity and chemical contamination in surficial sediments as percentages of the total survey area. 4. Describe the composition, abundance and diversity of benthic infaunal assemblages at each sampling location. 5. Estimate the apparent relationships between measures of sediment toxicity, toxicant concentrations, and benthic infaunal assemblage indices. 6. Compare the quality of sediment from northern, central, and southern Puget Sound measured in the three phases of this study. In this presentation, estimates of the spatial extent of toxicity and chemical contamination of Puget Sound sediments are displayed separately, and compared with sediment data collected nationally. These data are then combined with benthic infaunal results to display a spatial characterization of the 2363 km Puget Sound study area based on a “weight-of-evidence” characterization of the "Sediment Quality Triad" parameters. Methods All details of the methods used in the program are described in technical reports (Long and others 1999, 2000, in prep.) and summarized in the 1998 Puget Sound Research Conference Proceedings (Long and Dzinbal, 1999). Therefore, only a brief summary is provided in this report. During a three-year period, samples were collected for analyses throughout most of the Puget Sound region (Figure 1). Briefly, the area sampled during 1997 extended from the U.S./Canada border south to Port Gardner Bay. In 1998, samples were collected within a region extending from the Port Gardner area to Des Moines, including the central basin and the inlets west of Bainbridge Island. In 1999, the area sampled extended from the Des Moines area to the southern limits of the Sound and included Hood Canal. Sediments were collected with a double 0.1m van-Veen grab. Sufficient amounts of surficial material (upper 2-3 cm) were removed from multiple deployments of the grab at each station to form a composite sample for chemical analyses and four toxicity tests. Benthic infauna were collected with a single deployment of the 0.1 m sampler at each station. Sorting of taxonomic groups retained on 1.0 mm sieves, identification to species level (when possible), and enumeration of organisms were done with standard protocols developed for Puget Sound (PSEP, 1987). Indices of the diversity and abundance of the macrobenthic infauna were calculated. Chemical analyses were performed for many trace elements (including potentially toxic metals), polynuclear aromatic hydrocarbons (PAHs), pesticides, phenols, phthalate esters, polychlorinated biphenyls (PCBs), other organic toxicants, total organic carbon, and grain size. Protocols were used that satisfied Long and others: Contamination, Toxicity and Associated Biological Effects in Sediment requirements of both NOAA (Lauenstein and Cantillo, 1993) and Ecology (PSEP, 1986, 1987, 1995, 1996a,b,c,d). Chemical concentrations were compared against Washington State Sediment Management Standards (Chapter 173-204 WAC) and effects-based, informal guidelines developed by NOAA (Long and others 1995). Toxicity tests were performed with widely accepted protocols. Amphipod survival tests followed protocols of the ASTM (1993), using the species Ampelisca abdita. Sea urchin fertilization tests of pore waters followed protocols of the U. S. Geological Survey (Carr and Chapman, 1992), using gametes of the purple urchin Strongylocentrotus purpuratus. Cytochrome P-450 assays of the light produced by luciferase in a reporter gene system (RGS) of cultured human liver cells was conducted on organic solvent extracts, following standard protocols (Anderson and others 1995, 1996; APHA, 1996; ASTM, 1997). Microbial bioluminescence (Microtox) tests were performed with protocols initially developed for Puget Sound (PSEP, 1995; Schiewe and others 1985) to determine inhibition of light production. These tests were run on a portion of the extracts prepared for the cytochrome P-450 assays. Results of the toxicity tests were compared to those from negative (non-toxic) controls to assign statistical significance (Long and others 1996).