Robert A. Hoke

Freshwater Sediment Toxicity Bioassessment: Rationale for Species Selection and Test Design

The rationale and conceptual basis for the use of sediment toxicity assays are discussed in relationship to their use in sediment evaluations employing faunal surveys, toxicity assays, and chemical analyses. The disadvantages and advantages of various species from the major classes of aquatic organisms for use as sediment toxicity assay organisms are presented. Relative sensitivities of selected species and their ease of laboratory culture and utility as assay organisms are used to rank assays and propose a battery of assays for the rapid screening evaluation of sediment toxicity. The usefulness of a battery of assays for the screening evaluation of sediment toxicity and statistical considerations which are important in the development of study designs and the analysis of results from the battery of proposed assays are discussed. The assays recommended for inclusion in the screening battery for evaluation of sediment toxicity are Microtox®, an algal assay, the Chironomus tentans 10-d growth assay, and the 48-h Daphnia magna acute assay.

Integrated assessment of contaminated sediments in the lower Fox River and Green Bay, Wisconsin.

Samples of sediment and biota were collected from sites in the lower Fox River and southern Green Bay to determine existing or potential impacts of sediment-associated contaminants on different ecosystem components of this Great Lakes area of concern. Evaluation of benthos revealed a relatively depauperate community, particularly at the lower Fox River sites. Sediment pore water and bulk sediments from several lower Fox River sites were toxic to a number of test species including Pimephales promelas, Ceriodaphnia dubia, Hexagenia limbata, Selenastrum capricornutum, and Photobacterium phosphorum. An important component of the observed toxicity appeared to be due to ammonia. Evaluation of three bullhead (Ictalurus) species from the lower Fox River revealed an absence of preneoplastic or neoplastic liver lesions, and the Salmonella typhimurium bioassay indicated relatively little mutagenicity in sediment extracts. Apparent adverse reproductive effects were noted in two species of birds nesting along the lower Fox River and on a confined disposal facility for sediments near the mouth of the river, and there were measurable concentrations of potentially toxic 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), and planar polychlorinated biphenyls (PCBs) both in the birds and in sediments from several of the study sites. Based on toxic equivalency factors and the results of an in vitro bioassay with H4IIE rat hepatoma cells, it appeared that the majority of potential toxicity of the PCB/PCDF/PCDD mixture in biota from the lower Fox River/Green Bay system was due to the planar PCBs. The results of these studies are discussed in terms of an integrated assessment focused on providing data for remedial action planning.

Use of toxicity identification evaluation techniques to identify dredged material disposal options: A proposed approach

It is common to use the results of various solid-phase and aqueous-fraction toxicity tests as part of the decision-making process for selecting disposal options for dredged sediments. The mere presence of toxicity, however, does not provide a logical basis for selecting economical, environmentally protective disposal techniques. To achieve this, it is necessary to be able to identify specific compounds responsible for sediment toxicity. Toxicity identification evaluation (TIE) procedures, originally developed for complex effluents, represent a useful approach for identifying acutely toxic compounds in dredged materials. Herein we present a conceptual overview for TIE use in part of the decision-making framework for selecting dredged material disposal options; included are discussions concerning appropriate test fractions and species for TIE analyses, and specific TIE manipulations useful for ascertaining whether toxicity is due to any of a number of common sediment contaminants including ammonia, hydrogen sulfide, metals, or nonpolar organics.

Evaluation of the toxicity of marine sediments and dredge spoils with the Microtox bioassay

The MicrotoxR bioassay was used to evaluate the toxicity of sediment and dredge spoil elutriates from several potentially-contaminated sites in Mobile and Pascagoula Bays. Elutriates were prepared using either local seawater or distilled deionized water (osmotically adjusted with NaCl prior to testing), and MicrotoxR assays were performed with the elutriates and three reference toxicants. There were marked differences in the toxicity of several elutriates and reference toxicants in the two different waters, with the seawater generally resulting in the same or lesser toxicity than the osmotically-adjusted distilled deionized water.

Toxicity of Sediments from Western Lake Erie and the Maumee River at Toledo, Ohio, 1987: Implications for Current Dredged Material Disposal Practices

The toxicity of sediments in the Maumee River, the Maumee River-western Lake Erie federal navigation channel, and selected areas of western Lake Erie was measured using four assays: Photobacterium phosphoreum 15-minute bioluminescence inhibition (Microtox®) in sediment pore-waters and elutriates; Ceriodaphnia dubia 7-day survival and reproduction; Pimephales promelas 7-day larval survival and growth in sediment elutriates; and Chironomus tentans 10-day growth inhibition in whole sediments. The Microtox® assay generally was the most sensitive of the four assays used in this investigation. Sediment elutriates were always equally or more toxic than porewaters from the same location when tested using the Microtox® assay. The greatest toxicity in the Microtox® and C. tentans assays was observed with porewaters or elutriates and sediments collected near point sources of contaminants to the Maumee River. Very little toxicity was observed in any assay using open-lake navigation channel or disposal site sediments or sediment extracts. Previous investigations also have reported little acute toxicity and little or no bioaccumulation of any measured sediment contaminants from study area sediments during laboratory toxicity or bioaccumulation assays. Sediments from the Lake Erie portion of the navigation channel evaluated during this investigation were suitable for open-lake disposal based on the lack of observed effects in the four assays. Toxicity of sediment from the open lake disposal site was similar to that of sediments from other locations in the western basin of Lake Erie which have not been impacted by dredged material disposal events. Sediments from near point sources such as industrial discharges, liquid unloading facilities, or sewage treatment plant outfalls on the Maumee River represent potential sources of toxicity for downstream resuspension and distribution. Further studies will be necessary to delineate the exact distribution of contaminated sediments near the point source discharges to the Maumee River.

CONCENTRATIONS OF INORGANIC AND ORGANIC CONTAMINANTS IN SEDIMENTS OF SIX HARBORS ON THE NORTH AMERICAN GREAT LAKES

Abstract Samples of surficial sediments were collected from six different harbors on the North American Great Lakes in May of 1989. Concentrations of 12 metals, 17 pesticides, total PCBs, chlorinated naphthalenes, cyanide and total and unionized ammonia were determined. The sediments were also characterized for moisture content, particle size, total organic carbon content, pH, COD, total solids, total volatile solids.

Sediment pore water toxicity identification in the lower fox river and Green Bay, Wisconsin, using the microtox assay

Microtox assays with two different methods of osmotic adjustment were used to assess the toxicity of pore waters from 13 sediment samples collected from the Fox River watershed in Wisconsin. No toxicity was observed in Microtox assays osmotically adjusted with NaCl; however, 15-min EC50 values for assays osmotically adjusted with sucrose ranged from 52 to 63% pore water. Un-ionized ammonia accounted for a large part of the observed toxicity, but, based on a toxic units approach, did not account for all observed toxicity. Metals (Cu, Zn) and an unidentified compound(s) may potentially contribute to the observed effects in Microtox assays osmotically adjusted with sucrose. The use of alternative osmotic adjustment techniques in the Microtox assay is one potentially useful tool for elucidating several classes of compounds responsible for effects observed in toxicity assays.

Use of in vitro microbial assays of sediment extracts to detect and quantify contaminants with similar modes of action

Abstract Mutagenicity of organic solvent extracts of contaminated sediments from a Great Lakes Area of Concern (AOC) was evaluated with Ames and Mutatox® assays. Extract mutagenicity was evaluated with and without S9 metabolic activation in both assays. H4IIE rat cell hepatoma assays also were conducted on the organic solvent extracts of the sediments. Little direct mutagenicity was observed in either the Ames or Mutatox® assays, however, a greater number of extracts were observed to be mutagenic after S9 metabolic activation. Although numerous potentially mutagenic compounds exist in sediments from this AOC, polycyclic aromatic hydrocarbons (PAHs) appear to be the likely cause of a major fraction of the observed mutagenicity in the Ames and Mutatox® assays. PAHs, as opposed to compounds with a mode of action similar to 2,3,7,8-TCDD, also appear responsible for the majority of the enzyme induction observed in the H4IIE assay.