An Integrated Case Study for Evaluating the Impacts of an Oil Refinery Effluent on Aquatic Biota in the Delaware River: Introduction, Study Approach, and Objectives

By Hall, Lenwood W Jr; Burton, Dennis T

ABSTRACT

This is the first in a series of article presenting results from a case study designed to assess the impacts of an oil refinery effluent [primarily polynuclear aromatic hydrocarbons (PAHs)] on aquatic biota in the Delaware River. During the course of the study, the oil refinery was owned by Motiva Enterprises LLC. This article provides background information on the study area, the study approach and objectives. The specific objectives of this multiyear study were to: (1) measure water column concentrations of PAHs and other contaminants (i.e., metals) in Motiva’s effluent and intake canal and selected Delaware River sites; (2) assess fate and transport issues associated with the Refinery effluent; (3) characterize sediment PAHs, total organic carbon (TOC), and grain size distributions in the discharge canal, near-field, mid-field and far-field areas of the Refinery to aid in the selection of Triad sample sites (including reference areas); (4) conduct Triad studies (chemical characterizations, sediment toxicity assessments, and benthic community characterizations) at selected study sites during the spring and summer of 2001 and 2002; (5) perform fingerprinting of PAHs in Motiva’s effluent to differentiate Motiva-related PAHs in sediment and biota from other sources; (6) assess bioavailability of PAHs, PCBs, and metals by using resident bivalve studies; (7) conduct long-term coring to determine potential impact of past non- complying discharges; and (8) integrate and analyze all study components to address the research goals. The results from objectives 1, 2, and 3 are briefly summarized in this series of articles whereas the other five objectives are the subject of the various papers presented in this volume.

Key Words: refinery effluent, PAHs, triad studies, Delaware River.

CHARACTERIZATION OF THE STUDY AREA

Motiva Enterprises LLC (formerly Star Enterprises Delaware City Refinery) owned and operated an oil refinery on the Delaware River in Delaware City, Delaware from 1956 to 2004 when it was purchased by The Premcor Refining Group Inc. The Motiva Refinery, one of the largest industrial sites on the eastern seaboard, is located on a 5,000-acre tract. The rated daily capacity of the Motiva Refinery is 140,000 barrels (5,880,000 gallons) of crude oil. The Refinery discharges ~10 million gallons per day of treated effluent, which is mixed with 200 to 400 million gallons of cooling water per day before it is discharged via a discharge canal into the Delaware River. The estuarine cross-sectional area near the Motiva Refinery is approximately 300,000 square feet and the maximum tidal current speed is approximately 3.9 feet per second. This corresponds to a maximum tidal flux of 1.1 million cubic feet per second (i.e., significant dilution). The hydrodynamics of the discharge plume in the Delaware River are well documented (Najarian Associates 2002). The Motiva Refinery is located at River Mile (RM) 61.7 on the Delaware River in Delaware City, Delaware (Figure 1). The Delaware River, which is ~330 miles long, drains a 13,533 square-mile basin located within four states: Pennsylvania, New Jersey, New York, and Delaware (USEPA 1995a). The Delaware Estuary comprises all tidally inundated areas from the falls at Trenton, New Jersey to the mouth of the Delaware Bay. This includes both the main stem of the Estuary, which extends ~133 miles, as well as all tidal tributaries. The Delaware Estuary is connected with the upper Chesapeake Bay via the Chesapeake and Delaware (C&D) Canal at RM 59. The physical features of the Delaware River, such as morphology, surface water hydrology, groundwater hydrology, estuarine hydrodynamics, and transport processes are well documented (Najarian Associates 2002).

Figure 1. Delaware River including the location of the Motiva oil refinery.

The Delaware Estuary is delineated into three regions based on general patterns of salinity, turbidity, and biological productivity (USEPA 1995a). The uppermost region, the freshwater tidal zone, extends 53 miles from the head-of-tide at Trenton (RM 133) to Marcus Hook, Pennsylvania (RM 80). Over the years, this zone has experienced severe impacts due to industrialization, development, and other anthropogenic influences. The lower-most zone, the Delaware Bay Zone, extends from the mouth of the Delaware Bay (RM O) to Artificial Island, New Jersey (RM 50). The Delaware Bay is characterized by relatively high salinity, low turbidity, and high biological productivity. In contrast, the Transition Zone (i.e., RM 50-RM 80) is a region of relatively high turbidity, variable salinity (0-18%o), and low productivity. The Refinery is located within the Transition Zone. This location separates the Refinery from some of the most productive regions of the Estuary and provides enhanced tidal currents for plume dilution (Najarian Associates 2002).

Delaware Estuary water quality conditions vary both spatially and temporally in response to natural and anthropogenic influences. Physical factors such as tides, wind, and freshwater inflows induce water quality variability at time scales ranging from several minutes to years. Superimposed on this natural continuum are human activities that also influence water quality at both short and long time scales. Short-term events such as oil spills may occur over periods of hours to days, but their effects many linger for months or years. Eong-term water quality trends may be linked to factors such as sewage treatment plant upgrades and coal-mining activities (Albert 1988; Tarr and McCurley 1984).

The Delaware Estuary has a long history of pollutant loadings from both non-point and point sources. Non-point sources of pollution are a function of land use/land cover, which are quite varied in the watershed (Tarr and McCurley 1984). The upper watershed is comprised of Appalachian-mountain plateaus and hilly Piedmont areas; the lower watershed consists of coastal plain sediments and includes four densely populated municipalities: Philadelphia; Trenton and Camden, New Jersey; and Wilmington, Delaware. Agricultural land use is widespread throughout the watershed. Industrial development is concentrated in two watershed areas: the lower Lehigh River Valley and the main stem Estuary from Trenton to Philadelphia, with its extensive production of chemicals, metals, textiles, and papers. The nation’s second largest complex of oil refining/petrochemical plants are located throughout the middle and upper Delaware Estuary (Tarr and McCurley 1984). Non-point sources from various land uses consist of uncontrolled inputs such as urban stormwater and agricultural runoff.

The Delaware watershed has approximately 1,450 industrial and municipal wastewater discharges that are permitted point source discharges (Sutton et al. 1996). Major municipal dischargers are located along the main stem Estuary between RM 90 and 104, which include Philadelphia-Southwest; Camden County MUA; Philadelphia- Southeast, and Philadelphia-Northeast. The largest industrial dischargers are Public Service Electric and Gas Salem Generating Station; Premcor Refinery (formerly Motiva Refinery); BP-Oil and Dupont-Chamber Works, which are located within, or adjacent to, the Estuary’s Transition Zone (RM 53-80). Najarian Associates (2002) have discussed the following water quality trends in detail: dissolved oxygen, nutrients, pH, water temperatures, fecal coliforms, total suspended solids, turbidity, and transparency.

A number of studies have been conducted on the inorganic and organic chemical contaminants in the Delaware Estuary. Both water column and sediment concentrations of heavy metals have been evaluated. Heavy metal concentrations in the water column have been shown to exceed ambient water quality criteria primarily within the heavily urbanized region around Philadelphia, between RM 94 and RM 120 (ANSP 1991). Reidel and Sanders (1998) sampled the tidal freshwater Delaware from Trenton (RM 133) to Marcus Hook (RM 60) and found arsenic, chromium, and copper concentrations that were elevated above natural background but were below relevant water quality criteria. Santoro (1998) found that sediment concentrations of chromium, copper, lead, and zinc all exceeded National Oceanic and Atmospheric Administration freshwater sediment screening levels at Delaware River Basin Commission (DRBC) sampling stations within the stretch of the lower Tidal River Zone between RM 80 and RM 115. At the most downstream DRBC station located at RM 56.3 (~5 miles south of the Refinery), Santoro (1998) found that sediment metal levels were generally lower than those observed farther upstream. Possible sources of the metals include: municipal and industrial discharges, stormwater runoff, atmospheric input, and natural sources (e.g., surficial and groundwater weathering processes).

Polychlorinated biphenyls (PCBs) have been found throughout the Estuary in concentrations ranging from <50 ng/g dry weight sediment to over 250 ng/g (Costa and Sauer 1994). The highest concentrations were found in the most urbanized section of the Estuary between Chester, Pennsylvania and Trenton. F\rithsen etal. (1995) calculated area-wide averages of total PCBs using USEPA Environmental Monitoring and Assessment Program (EMAP) and National Oceanic and Atmospheric Administration (NOAA) survey data summarized by NOAA (NOAA 1994). The average concentrations ranged from approximately 140 ng/g near Philadelphia to <8 ng/g in the lower Estuary. DRBC (1996) has indicated that PCBs are a contaminant of concern in all estuarine zone sediments. The PCBs appear to originate mainly from non-point sources, although recent data suggest that point sources may also be important (DRBC 1998).

A number of persistent pesticides have been found in the Delaware River. Sediment concentrations of 4,4′-DDT (parent compound) have been shown to range from <3 ng/g near Trenton to over 100 ng/g near the Walt Whitman Bridge (Philadelphia), with lower concentrations down-estuary (DRBC 1994). DRBC (1994) reported that sediment concentrations of 4,4'-DDD ranged from <0.4 ng/g in two locations in the Estuary to over 200 ng/g between the Tacony-Palmyra and Betsy Ross bridges (Philadelphia), with generally lower concentrations down-estuary near Reedy Island. Costa and Sauer (1994) reported 2,4'- DDD concentrations ranging from 1.1 ng/g near False Egg Island Point (RM 24.2) in the southern Delaware Bay to 21 ng/g near Plum Point above Philadelphia. Higher concentrations were found in the upper portion of the Estuary above RM 80. DRBC (1996) has indicated that DDT is a contaminant of concern due to sediment concentrations throughout the Estuary. Dieldrin concentrations range from <0.3 ng/ g in many areas of the Estuary to over 29 ng/g within the tidal freshwater area upstream of the Ben Franklin Bridge (Philadelphia), with generally lower concentrations down-estuary near Reedy Island (DRBC 1994). Sutton et al. (1996) have indicated that non-point inputs are the major source of the pesticides.

Various studies indicate that the sediments are enriched in PAHs in both the upper and lower Delaware Estuary (e.g., Costa and Sauer 1994; DRBC 1994; NOAA 1994; USEPA 1995b). The data of Costa and Sauer (1994) show that total PAH concentrations range from <2,000 ng/ g near False Egg Island Point to over 40,000 ng/g near Darby Creek (RM 84.5). Concentrations were generally above 10,000 ng/g in the upper Estuary at various locations (Racoon Creek to Philadelphia). These total PAH concentrations can often exceed the Effect Range Low (ERL) of 4,022 ng/g but are generally less than the Effect Range Median (ERM) of 44,792 ng/g (Buchman 1999). DRBC (1996) indicated that sediment total PAHs were contaminants of concern in all estuarine zones. Sources of PAHs in estuarine sediments include the combustion of fossil fuels as well as direct petroleum sources. Frithsen et al. (1995) estimated (to a first approximation) that 35,000 kg/year of total PAHs enter the Delaware Estuary from urban runoff and atmospheric deposition, with urban runoff accounting for 95% of the total input. In summary, the Delaware River estuary below Philadelphia is highly altered by human activity and far from a pristine environment. The normal baseline condition in this aquatic system is one of chronic stress from a variety of sources, as discussed earlier. At the margin between freshwater and saltwater ecosystems, the aquatic environment is populated by plants and animals resistant to stress due to large changes in salinity. Superimposed on this are the chronic stress effects associated with any industrialized river that is part of major shipping and industrial activity. In addition, a major focus of the industrial activity as (discussed earlier) is petrochemicals (including PAHs). This means that permitted and non-permitted discharges for hazardous substances can occur from many sources. Setting the historical context for the Delaware River study area is particularly important for the case study presented in this series of articles as the multiple stressors and various sources are problematic when attempting to determine the ecological impacts from a single source such as the Motiva Refinery versus numerous other point and non- point sources.

STUDY APPROACH AND OBJECTIVES

This multiyear investigation was conducted to meet a Court- ordered study designed to determine the impacts of PAHs present in Motiva’s (currently Premcor) effluent that could impact aquatic resources in the Delaware River. PAHs were identified as the primary constituent of concern in the Court order. However, other contaminants such as metals, pesticides, and PCBs were also measured in this study in order to tease out possible ecological effects from these known contaminants versus PAHs.

The first step in our study approach was to characterize PAHs present in Motiva’s effluent that may be impacting aquatic life in the Delaware River (results presented in detail in Hall et al. 2004). To address this issue, characterization of PAHs in Motiva’s effluent was initiated in March of 1999 during a pilot study. These characterizations continued throughout the four-year investigation.

A detailed characterization of the various interactions that influence the fate and transport of PAHs in the receiving waters, sediments, and biota of the Delaware River was conducted and presented in detail in Hall et al. (2004). PAH transport and deposition studies were conducted; however, a mass balance chemical fate study was not. The fate and transport studies included a dye- tracer study, development of a hydrodynamic plume and transport model, and a three-phase (estimate of dissolved, particulate, and colloidal phases) study. These studies plus additional mid-field sampling for PAHs, grain size distributions, and TOC in sediment near the Refinery were used to select study sites for the Triad studies described in detail in a later article in this series (Hall et al. 2005). Study sites were located both within Motiva’s physical mixing zone (or area of influence) and outside of Motiva’s influence (reference areas) . Potential impact to the aquatic ecosystem was quantified by directly measuring the potential toxicity of ambient river sediments in concert with benthic community assessments both within and outside the Refinery’s physical mixing zone. A sediment quality Triad approach described in detail in Hall et al. (2005) was used to address potential biological impact.

In using the Triad approach, the working assumption was that exceedences of Motiva’s NPDES permit (i.e., oil and grease exceedences) may result in potential adverse effects on aquatic biota in the Delaware River. If adverse effects were found from the Triad approach (sediment toxicity or impaired benthic communities) in the vicinity of the Refinery and Motiva-associated contaminants (PAHs) are implicated by using fingerprinting methods described by Uhler et al. (2005), then effects could be related to exceedences. The Triad approach was also used to provide an overall spatial assessment of the Refinery’s potential impact to the Delaware River ecosystem.

The Triad approach to environmental assessment is a widely accepted approach that integrates environmental chemistry, instream sediment toxicity, and assessments of resident biological communities to determine pollution-induced degradation (Chapman et al. 1987; Chapman 1996; Chapman et al. 1997; Long 1989). The Triad approach has been used in a long-term ambient toxicity testing program in the Chesapeake Bay watershed (Alden 1992; Hall et al 1998; Hall et al. 2000). The USEPA and NOAA have also used this approach in evaluating long term status and trends of ecological condition in estuarine environments (Strobel et al. 1995). Leppanen et al. (1998) used this approach for assessing impacts of a hazardous waste site on instream biological communities.

Interpretation of the integrated Triad components is a “weight of evidence” (WOE) approach that can be defined as drawing conclusions based on all available information, including the interrelationships of the various types of data. This determination incorporates judgments concerning the quality, extent, and congruence of data contained in different lines of evidence (Chapman et al. 2002). It also includes both observational (i.e., ecology) and investigative (i.e., toxicology used to determine cause and effect) components. This WOE approach involved collecting three types of data to determine potential impacts of Motiva’s effluent on aquatic life in the Delaware River: (1) chemical characterization of PAHs, other contaminants possibly related to Motiva and contaminants not related to Motiva both within and outside the Refinery’s physical mixing zone; (2) concurrent chronic toxicological effects characterization of representative benthic species exposed to river sediment; and (3) assessment of resident benthic biological communities in the study area (preferred in this study design because they are sessile biological assemblages that can integrate potential effects over time from both aqueous phase and sediment bound contaminants such as PAHs).

The three components of the Triad results were used in a WOE- type analysis described in Hall et al. (2005). Itwas anticipated that all three lines of evidence (chemical characterization, sediment toxicity, and benthic community status) would not always agree at all study sites. However, in order for Motiva’s effluent to be implicated in possible sediment toxicity or impaired benthic communities, concurrent PAH exposure must be documented (potentially toxic concentrations measured in sediment). The Triad approach was used to combine all three lines of evidence in a retrospective evaluation of the effect of Motiva’s effluent on the Delaware River ecosystem.

PAHs and other contaminants were measured in resident bivalves to determine the bioavailability of these constituents as described in Salazar et al. (2005). The use of long core sampling as described by Alexander et al. (2005) was also used to determine pote\ntial ecological impacts of the oil and grease exceedences from March 1993 through 2002. These data were integrated with the other components of this study in the final analysis of all the data (Alden et al. 2005).

The specific objectives of this multiyear study were to: (1) measure water column concentrations of PAHs and other contaminants (i.e., metals) in Motiva’s effluent and intake canal and selected Delaware River sites; (2) assess fate and transport issues associated with the Refinery effluent; (3) characterize sediment PAHs, total organic carbon (TOC), and grain size distributions in the discharge canal, near-field, mid-field, and far-field areas of the Refinery in a reconnaissance study to aid in the selection of Triad sample sites (including reference areas); (4) conduct Triad studies (chemical characterizations, sediment toxicity assessments, and benthic community characterizations) at selected study sites during the spring and summer of 2001 and 2002 (Hall et al. 2005); (5) perform fingerprinting of PAHs in Motiva’s effluent to differentiate Motiva-related PAHs in sediment and biota from other sources (Uhler et al. 2005); (6) assess bioavailability of PAHs, PCBs, and metals by using resident bivalve studies (Salazar et al. 2005); (7) conduct long-term coring to determine potential impact of past non-complying discharges (Alexander et al. 2005); and (8) integrate and analyze all study components to address the research goals (Alden et al. 2005). Results from objectives 1, 2, and 3 are briefly summarized in the series of articles but presented in detail in Hall et al. (2004). Detailed results from the other 5 objectives are the subject of the series of article presented in this special volume. For objective #8, the following basic questions were addressed by integrating all components of the study: (1) Are there sediment contaminant concentrations of potential ecological concern found anywhere in the Delaware River study area?; (2) Are historical or current (surficial layer) patterns of sediment contaminations (i.e., PAHs) inferentially related to Motiva’s effluent?; (3) Are contaminant-associated biological impacts (i.e., sediment toxicity or benthic community impairment) indicated?; and (4) Are biological effects correlated with sediment contamination related to Motiva’s effluent?

ACKNOWLEDGMENTS

The authors thank Motiva Enterprises LLC for providing financial support for this study. We received full cooperation from Motiva and were provided complete freedom to inspect, analyze and interpret all data based on sound scientific principles and new perspectives in aquatic toxicology. We are particularly grateful to Mr. Hank Lloyd for providing all the necessary information and assistance needed to conduct this study. Drs. Phil Dorn and Ileana Rhodes are acknowledged for providing constructive comments on study design and review of data. The following staff of Wye Research and Education Center are acknowledged for their dedicated efforts in conducting this study: Ron Anderson, Bill Killen, Steve Turley, and Michelle Osborn. We are grateful to the following subcontractors for their valuable contributions to the study: Battelle Duxbury for chemical analysis and PAH fingerprinting (Mrs. Julie Frederickson); Najarian Associates for overseeing the dye-tracer studies and development of a hydrodynamic plume and transport model; Old Dominion University for benthic community analysis (Mr. Bud Rody and Dr. Mike Lane); and Dr. Elgin Perry for statistical analysis of the effluent monitoring data. We also acknowledge Dr. David Page and Dr. Jerry Neff for their thorough review and constructive comments on this series of articles.

REFERENCES

Albert RC. 1988. The historical context of water quality management for the Delaware Estuary. Estuaries 11:99-107

Alden RW. 1992. Uncertainty and sediment quality assessments: Confidence limits for the triad. Environ Toxicol Chem 11:645-51

Alden RW III, Hall LWJr., Dauer DM, et al. 2005. An integrated case study for evaluating the impacts of an oil refinery effluent on aquatic biota in the Delaware River: Integration and Analysis of study components. Hum Ecol Risk Assess 11:879-936

Alexander CR, Lee RF, Burton DT, et al. 2005. An integrated case study for evaluating the impacts of an oil refinery effluent on aquatic biota in the Delaware River: Sediment core studies. Hum Ecol Risk Assess 11:861-77

ANSP (Academy of Natural Sciences of Philadelphia). 1991. Status and Trends of Toxic Pollutants in the Delaware Estuary. Delaware Estuary Program Report No. 91-14. Academy of Natural Sciences of Philadelphia, Philadelphia, PA, USA

Buchman MF. 1999. NOAA Screening Reference Tables. NOAA HAZMAT Report 99-1. Coastal Protection and Restoration Division, National Oceanic and Atmospheric Administration, Seattle WA, USA

Chapman PM. 1996. Presentation and interpretation of sediment quality triad data. Ecotoxicol 5:327-39

Chapman PM, Anderson B, Carr S, et al. 1997. General guidelines for using the sediment quality triad. Marine Pollution Bull 34:368- 72

Chapman PM, Dexter RN, and Long ER. 1987. Synoptic measures of sediment contamination, toxicity and infaunal community structure (the sediment quality triad). Marine Ecol Program Series 37:75-96

Chapman PM, McDonald BG, and Lawrence GS. 2002. Weight-of- evidence issues and frameworks for sediment quality (and other) assessments. Hum Ecol Risk Assess 8:1489-515

Costa HJ and Sauer TC. 1994. Distributions of Chemical Contaminants and Acute Toxicity in Delaware Estuary Sediments. Delaware Estuary Program Report No. 94-08. US EPA Region III, Philadelphia, PA, USA

DRBC (Delaware River Basin Commission). 1994. Sediment Contaminants of the Delaware Estuary. Estuary Toxics Management Program Report, West Trenton, NJ, USA

DRBC (Delaware River Basin Commission). 1996. Delaware River and Bay water quality assessment: 1994-1995 305 (b). Report. West Trenton, NJ, USA

DRBC (Delaware River Basin Commission). 1998. Study of the Loadings of Polychlorinated Biphenyls from Tributaries and Point Sources Discharging to the Tidal Delaware River. Estuary. Toxics Management Program Report. West Trenton, NJ, USA

FrithsenJB, Strebel DE, Schreiner S, et al. 1995. Estimates of Contaminant Inputs to the Delaware Estuary. Report prepared for the Delaware Estuary Program, Delaware River Basin Commission. US Environmental Protection Agency Region III, Philadelphia, PA, USA

Hall LWJr, Anderson RD, Alden RW III, et al. 1998. Ambient Toxicity Testing in Chesapeake Bay: Year 6 Report. EPA 903/R/98/017 and CBP/TRS 210/98. US Environmental Protection Agency, Chesapeake Bay Program Office, Annapolis, MD, USA

Hall LWJr, Anderson RD, Messing A, et al. 2000. Ambient Toxicity Testing in Chesapeake Bay: Year 8. Draft report. US Environmental Protection Agency, Chesapeake Bay Program Office, Annapolis, MD, USA

Hall LW Jr, Burton DT, Alden RW III, et al. 2004. A Baseline Study for Assessing the Potential Aquatic Ecological Effects from Motiva Enterprises LLC Delaware City Refinery Effluent Using the Sediment Triad Approach. Final Report. University of Maryland, Wye Research and Education Center, Queenstown, MD, USA

Hall LWJr, Dauer DM, Alden RW III, et al. 2005. An integrated case study for evaluating the impacts of an oil refinery effluent on aquatic biota in the Delaware River: Sediment quality triad studies. Human Ecol Risk Assess 11:657-770

Leppanen CH, Blanner PM, Allan RA, et al. 1998. Using a triad approach in the assessment of hazardous waste sites leaching from a superfund site to an adjacent stream. Environ Toxicol Chem 17:2106- 113

Long ER. 1989. The use of the sediment quality triad in classification of sediment contamination. In: Marine Board, National Research Council Symposium/Workshop on Contaminated Marine Sediments. US Nuclear Regulatory Commission, Washington, DC, USA

Najarian Associates. 2002. A Hydrodynamic and Sediment Transport Model to Support the Motiva Refinery Baseline Ecological Study. Final Report. Najarian Associates, Eatontown, NJ, USA

NOAA (National Oceanic and Atmospheric Administration). 1994. Inventory of Chemical Concentrations in Coastal and Estuarine Sediments. National Status and Trends Program Report No. NOS ORCA 76. Rockville, MD, USA

Reidel GF and Sanders JG. 1998. Trace element speciation and behavior in the tidal Delaware River. Estuaries 21:78-90

Salazar MH, Salazar SM, Burton DT, et al. 2005. An integrated case study for evaluating the impacts of an oil refinery effluent on aquatic biota in the Delaware River: Bivalve bioavailability studies. Hum and Ecol Risk Assess 11:837-59

Santoro ED. 1998. Delaware Estuary Monitoring Report. Monitoring Implementation Team of the Delaware Estuary Program Report. Delaware River Basin Commission, West Trenton, NJ, USA

Strobel CJ, Buffum HW, Benyi SJ, et al. 1995. Statistical Summary: EMAP Estuaries Virginian Province-1990 to 1993. EPA/620/R- 94/026. US Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Narragansett, RI, USA

Sutton CC, O’HerronJC, and Zappalorti, RT. 1996. The Scientific Characterization of the Delaware Estuary. Delaware Estuary Program Project No. 321; HAFile No. 93.21. Delaware River Basin Commission, West Trenton, NJ, USA

Tarr JA and McCurley J. 1984. Pollution Trends in Five Estuaries, 1880-1980. The Potomac, the Delaware, the Hudson-Raritan, the Connecticut, the Narragansett. Report. CarnegieMelon University, Pittsburgh, PA, USA

Uhler AD, Embso-Mattingly S, Liu B, Hall LW Jr, et al 2005. An integrated case study for evaluating the impacts of an oil refinery effluent on aquatic biota in the Delaware River: Advanced chemical fingerprinting. Hum Ecol Risk Assess 11:771-836

USEPA (United States Environmental Protection Agency). 1995a. The Delaware Estuary. Discover its Secrets. A Management Plan for the Delaware Estuary. Delaware Estuary Program Policy Committee Comprehensive Conservation and Management Plan. Draf\t Report, January 1995.Washington, DC, USA

USEPA (United States Environmental Protection Agency). 1995b. EMAP- Estuaries Virginian Province 1990-1993. Statistical Summary. June 1995. Washington, DC, USA

Lenwood W. Hall, Jr. and Dennis T. Burton

University of Maryland, Wye Research and Education Center, Queenstown, Maryland, USA

Received 10 September 2004; revised manuscript accepted 16 April 2005.

Note from HERA’s Editors-in-Chief: This article and the ones that follow in this special issue of HERA were prepared in accord with HERA’s author-directed peer review system. The following peer reviewers reviewed all six manuscripts and have given their approval for their publication: Dr. Jerry Neff, Senior Research Leader, Battelle Memorial Institute, Duxbury, Massachusetts; Dr. David Page, Bowdin College, Department of Chemistry, Brunswick, Maine. The six manuscripts were also reviewed by HERA Managing Editor and edited for compliance with the journal’s formats and style.

Address correspondence to Lenwood W. Hall, Jr., University of Maryland, Wye Research and Education Center, P.O. Box 169, Queenstown, MD 21658, USA. E-mail: lwhall@umd.edu

Copyright CRC Press Aug 2005