Marguerite C. Pelletier

An overview of toxicant identification in sediments and dredged materials

The identification of toxicants affecting aquatic benthic systems is critical to sound assessment and management of our nations waterways. Identification of toxicants can be useful in designing effective sediment remediation plans and reasonable options for sediment disposal. Knowledge of which contaminants affect benthic systems allows managers to link pollution to specific dischargers and prevent further release of toxicant(s). In addition, identification of major causes of toxicity in sediments may guide programs such as those developing environmental sediment guidelines and registering pesticides, while knowledge of the causes of toxicity which drive ecological changes such as shifts in benthic community structure would be useful in performing ecological risk assessments. To this end, the US Environmental Protection Agency has developed tools (toxicity identification and evaluation (TIE) methods) that allow investigators to characterize and identify chemicals causing acute toxicity in sediments and dredged materials. To date, most sediment TIEs have been performed on interstitial waters. Preliminary evidence from the use of interstitial water TIEs reveals certain patterns in causes of sediment toxicity. First, among all sediments tested, there is no one predominant cause of toxicity; metals, organics, and ammonia play approximately equal roles in causing toxicity. Second, within a single sediment there are multiple causes of toxicity detected; not just one chemical class is active. Third, the role of ammonia is very prominent in these interstitial waters. Finally, if sediments are divided into marine or freshwater, TIEs perforMed on interstitial waters from freshwater sediments indicate a variety of toxicants in fairly equal proportions, while TIEs performed on interstitial waters from marine sediments have identified only ammonia and organics as toxicants, with metals playing a minor role. Preliminary evidence from whole sediment TIEs indicates that organic compounds play a major role in the toxicity of marine sediments, with almost no evidence for either metal or ammonia toxicity. However, interpretation of these results may be skewed because only a small number of interstitial water (n = 13) and whole sediment (n = 5) TIEs have been completed. These trends may change as more data are collected.

Effects of benzo[a]pyrene exposure on a fish population resistant to the toxic effects of dioxin-like compounds ☆

Effects of a model polycyclic aromatic hydrocarbon (PAH) were compared in populations of the estuarine fish Fundulus heteroclitus indigenous to a reference site and one highly contaminated with polychlorinated biphenyls (PCBs) and other compounds. The fish population resident to the PCB-contaminated site is genetically resistant to those PCB congeners categorized as dioxin-like compounds (DLCs) that act through the aryl hydrocarbon receptor (AHR). In response to DLC exposures, these DLC-resistant fish showed poor inducibility for enzymes known to be regulated by the AHR pathway and important for the metabolism of xenobiotics including some PAHs that also act as AHR agonists. Therefore, a laboratory study using the model PAH, benzo[a]pyrene (BaP), was conducted to evaluate how PAHs might affect these wild fish populations that differed in their inherent sensitivities to DLCs and in their tissue concentrations of contaminants. Following BaP treatment, the activities of two xenobiotic metabolizing enzymes and the concentrations of BaP-DNA adducts, as measured using the 32P-postlabeling method, were lower in the livers of DLC-resistant than reference fish. These results suggest that DLC-resistance could provide protection following chronic exposures to PAHs from the long-term consequences of DNA adduct formation, such as cancer. Alternatively, reduced metabolism and elimination of toxic or photo-activated PAHs could have acute consequences to the health and reproduction of these DLC-resistant fish and their progeny. These fish populations provide useful models to evaluate the potential costs and benefits of genetic adaptation in wildlife populations subject to anthropogenic stress.

Use of powdered coconut charcoal as a toxicity identification and evaluation manipulation for organic toxicants in marine sediments

We report on a procedure using powdered coconut charcoal to sequester organic contaminants and reduce toxicity in sediments as part of a series of toxicity identification and evaluation (TIE) methods. Powdered coconut charcoal (PCC) was effective in reducing the toxicity of endosulfan-spiked sediments by 100%. Powdered coconut charcoal also was effective in removing almost 100% of the toxicity from two field sediments contaminated with polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). Powdered coconut charcoal did not change the toxicity of ammonia or metal-spiked sediments; however, there was some quantitative reduction in the concentrations of free metals (element specific) in metal-spiked sediments. Powdered coconut charcoal is an effective, relatively specific method to sequester and remove toxicity from sediments contaminated with organic contaminants.

Removal of ammonia toxicity in marine sediment TIEs: a comparison of Ulva lactuca, zeolite and aeration methods

Toxicity Identification Evaluations (TIEs) can be used to determine the specific toxicant(s), including ammonia, causing toxicity observed in marine sediments. Two primary TIE manipulations are available for characterizing and identifying ammonia in marine sediments: Ulva lactuca addition and zeolite addition. In this study, we compared the efficacy of these methods to (1) remove NH(x) and NH(3) from overlying and interstitial waters and (2) reduce toxicity to the amphipod Ampelisca abdita and mysid Americamysis bahia using both spiked and environmentally contaminated sediments. The utility of aeration for removing NH(x) and NH(3) during a marine sediment TIE was also evaluated preliminarily. In general, the U. lactuca and zeolite addition methods performed similarly well at removing spiked NH(x) and NH(3) from overlying and interstitial waters compared to an unmanipulated sediment. Toxicity to the amphipod was reduced approximately the same by both methods. However, toxicity to the mysid was most effectively reduced by the U. lactuca addition indicating this method functions best with epibenthic species exposed to ammonia in the water column. Aeration removed NH(x) and NH(3) from seawater when the pH was adjusted to 10; however, very little ammonia was removed at ambient pHs ( approximately 8.0). This comparison demonstrates both U. lactuca and zeolite addition methods are effective TIE tools for reducing the concentrations and toxicity of ammonia in whole sediment toxicity tests.

The chemistry and toxicity of sediment affected by oil from the North Cape spilled into Rhode Island Sound

Abstract On 19 January 1996, the barge North Cape spilled more than three million liters of No. 2 fuel oil into Rhode Island Sound near Matunuck, Rhode Island. The toxicity and chemistry of this oil in two subtidal sediments were followed for more than 9 months. Maximum concentrations of polycyclic aromatic hydrocarbons (PAHs) in the sediments reached 730 μg / g dry weight (DW). Water samples taken immediately after the spill were phototoxic to embryos of the bivalve Mulinia lateralis. Total PAHs and toxicity to the amphipod Ampelisca abdita were high immediately after the spill, decreasing to background values ( 10 μg / g DW and

pH dependent toxicity of five metals to three marine organisms

The pH of natural marine systems is relatively stable; this may explain why metal toxicity changes with pH have not been well documented. However, changes in metal toxicity with pH in marine waters are of concern in toxicity testing. During porewater toxicity testing pH can change 1–2 units as porewater is transferred from in situ to a test container. These changes in pH may alter metal toxicity. Also, deliberately altering the sample pH is an important toxicity identification and evaluations (TIE) manipulation designed to detect changes in ammonia toxicity. If altering pH also changes metal toxicity, this may confound interpretation of TIE manipulation results. This study demonstrates that alteration of pH can also change the toxicity of Cu, Cd, Ni, Pb, and Zn to Mysidopsis bahia (mysid), Ampelisca abdita (amphipod) and Vibrio fischerii [Microtox solid phase test (MSP)]. Changes in toxicity with respect to pH were metal and organism specific with the following trends. For the MSP assay, as pH decreased there was a decrease in toxicity for Pb, Ni, Cd, and Zn and an increase in toxicity for Cu. For mysids, as pH decreased, there was a decrease in toxicity for Pb and an increase in toxicity for Cu and Ni. For amphipods, Cu was the only metal that showed decreased toxicity with decreasing pH; the toxicity of all other metals for amphipods remained constant. Results of this study indicate changes in metal toxicity with respect to pH must be considered for porewater testing and TIE interpretation. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 235–240, 1999

Effects of triclosan on marine benthic and epibenthic organisms

Triclosan is an antimicrobial compound that has been widely used in consumer products such as toothpaste, deodorant, and shampoo. Because of its widespread use, triclosan has been detected in various environmental media, including wastewater, sewage sludge, surface waters, and sediments. Triclosan is acutely toxic to numerous aquatic organisms, but very few studies have been performed on estuarine and marine benthic organisms. For whole sediment toxicity tests, the sediment-dwelling estuarine amphipod, Ampelisca abdita, and the epibenthic mysid shrimp, Americamysis bahia, are commonly used organisms. In the present study, median lethal concentration values (LC50) were obtained for both of these organisms using water-only and whole sediment exposures. Acute 96-h water-only toxicity tests resulted in LC50 values of 73.4 and 74.3 µg/L for the amphipod and mysid, respectively. For the 7-d whole sediment toxicity test, LC50 values were 303 and 257 mg/kg (dry wt) for the amphipod and mysid, respectively. Using equilibrium partitioning theory, these whole sediment values are equivalent to interstitial water LC50 values of 230 and 190 µg/L for the amphipod and mysid, respectively, which are within a threefold difference of the observed 96-h LC50 water-only values. Triclosan was found to accumulate in polychaete tissue in a 28-d bioaccumulation study with a biota-sediment accumulation factor of 0.23 kg organic carbon/kg lipid. These data provide some of the first toxicity data for triclosan with marine benthic and epibenthic species while also indicating a need to better understand the effects of other forms of sediment carbon, triclosan ionization, and organism metabolism of triclosan on the chemicals behavior and toxicity in the aquatic environment.

Development and evaluation of reverse polyethylene samplers for marine phase ii whole‐sediment toxicity identification evaluations

Marine and estuarine sediments accumulate contaminants and act as a sink for a wide range of toxic chemicals. As a result, the sediments themselves can become a source of contamination. At sufficient levels, contaminated sediments can cause benthic impairments and toxicity to marine organisms. Among the wide range of contaminants, nonionic organic contaminants (NOCs) are a primary cause of toxicity in marine sediments. Toxicity identification evaluations (TIEs) are used to characterize and identify chemicals causing toxicity in effluents, interstitial waters, and whole sediments using whole-organism endpoints. Phase I whole-sediment TIE methods for NOCs exist, but the development of phase II TIE methods for NOCs is a current research challenge. In the present study, the use of reverse polyethylene samplers (RePES) for phase II methods is examined. Various RePES designs were evaluated in an experimental design study with NOC chemical solutions. Based on equilibration time and proximity of measured NOC water concentrations in the reconstituted system to theoretical concentrations, a nontriolein design with loading of chemical solutions on the inside of the polyethylene tubing was chosen as most effective. A partitioning study demonstrated NOCs partitioned between the RePES and water as well as between the water and air, as expected using this nontriolein RePES design. Finally, a sediment toxicity study comparing the nontriolein RePES to contaminant-spiked sediments was conducted. The nontriolein RePES design was capable of successfully recreating the toxicity and water concentrations observed with the intact sediments.

Evaluation of the effects of coal fly ash amendments on the toxicity of a contaminated marine sediment.

Approaches for cleaning up contaminated sediments range from dredging to in situ treatment. In this study, we discuss the effects of amending reference and contaminated sediments with coal fly ash to reduce the bioavailability and toxicity of a field sediment contaminated with polycyclic aromatic hydrocarbons (PAHs). Six fly ashes and a coconut charcoal were evaluated in 7-d whole sediment toxicity tests with a marine amphipod (Ampelisca abdita) and mysid (Americamysis bahia). Fly ashes with high carbon content and the coconut charcoal showed proficiency at reducing toxicity. Some of the fly ashes demonstrated toxicity in the reference treatments. It is suspected that some of this toxicity is related to the presence of ammonia associated with fly ashes as a result of postoxidation treatment to reduce nitrous oxide emissions. Relatively simple methods exist to remove ammonia from fly ash before use, and fly ashes with low ammonia content are available. Fly ashes were also shown to effectively reduce overlying water concentrations of several PAHs. No evidence was seen of the release of the metals cadmium, copper, nickel, or lead from the fly ashes. A preliminary 28-d polychaete bioaccumulation study with one of the high-carbon fly ashes and a reference sediment was also performed. Although preliminary, no evidence was seen of adverse effects to worm growth or lipid content or of accumulation of PAHs or mercury from exposure to the fly ash. These data show fly ashes with high carbon content could represent viable remedial materials for reducing the bioavailability of organic contaminants in sediments.

Effects of different forms of organic carbon on the partitioning and bioavailability of nonylphenol

Oxygenated nonpolar organic contaminants (NOCs) are underrepresented in studies of the partitioning and bioavailability of NOCs, including nonylphenol. In this investigation, we evaluated the toxicity, partitioning, and bioavailability of nonylphenol as affected by different forms of organic carbon. Along with organic carbon content, the role of organic carbon polarity was assessed. Toxicity of nonylphenol to a mysid and amphipod was comparable to results reported in the literature for marine organisms with median lethal concentrations (LC50s) of 82.3 and 236 microg/L, respectively. The presence of the different forms of organic carbon in every instance altered, often statistically significantly, the toxicity and bioavailability of the nonylphenol and increased the LC50 by approximately a factor of two. Partition coefficients (KPs) for nonylphenol ranged from 21.3 for cellulose to 9,770 for humic acid; log organic carbon-normalized partition coefficients (KOCs) ranged from 1.71 for cellulose to 4.71 for sediment. An exercise to predict nonylphenol effects using our toxicity data and normalized partition coefficients indicated organic carbon content was most protective and also highlighted the need for further research to better understand nonylphenol bioavailability. These data suggested that with regard to partitioning and bioavailability, the oxygenated NOC nonylphenol behaves like conventional NOCs. The data also suggest that, with refinements, polarity may have some advantages in predicting nonylphenol bioavailability.