During the study of toxicity in Great Lakes sediments, various components of assessment were investigated. They included the evaluation of simple relationships between sediment contaminants and toxic ...impact, validation of the use of a suite of aquatic organisms in assessing the toxic impact, and utilization of a bioassay-driven fractionation protocol to identify dominant toxic chemical agents in sediment. Test organisms comprised natural assemblages of phytoplankton and algal cultures including Selenastrum capricornutum and Scenedesmus quadricauda, the zooplankter Daphnia magna, the amphipod Hyalella azteca, and the fathead minnow Pimephales promelas. Sediment collection sites were from various Areas of Concern in the Great Lakes and included the Cornwall/Massena portion of the St. Lawrence River, Toronto and Hamilton Harbours, the Cuyahoga, Maumee, Raisin, Detroit, and Manistique Rivers, and Saginaw and Green Bays. Contaminants under investigation included heavy metals, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). Fractionation protocol utilized dichloromethane in Soxhlet-extractors and silica-gel chromatography for separation. Although several endpoints were measured, the Cornwall/Massena sediment was not toxic to phytoplankton or Daphnia magna. Bioassays using sediment from Hamilton Harbour and Rouge River indicated extreme toxicity to Daphnia magna and Hyalella azteca, with moderate toxicity noted when these organisms were assayed with sediment from specific sites on the Cuyahoga River and Trenton Channel of the Detroit River. Extraction and separation of the Hamilton Harbour sediment narrowed a causative agent of toxicity to a non-polar organic fraction and chemical analysis identified the dominant compounds as being PAHs. Simple cause-effect relationships between contaminated sediment and toxic impact were not evident. Obviously, factors other than bulk chemical concentration of compounds play a major role in the bioavailability of sediment pollutants. Although there are many species and endpoints that can be utilized in toxicity bioassays, the choice of organisms used in this investigation are highly recommended. Not only was the biota sensitive, discriminatory, and represented a wide range of species in the aquatic food chain, but they were all readily cultured. Since bulk chemical characterization is inadequate in predicting potential toxicity of contaminated sediment, protocols such as the fractionation scheme used in this study should be implemented in future assessments of sediment.
Algal assay procedure with one or five species. Minitest Claesson, A; sberg, A
Mitteilungen. Internationale Vereinigung fuer theoretische und angewandte Limnologie/Communications. International Association of Theoretical and Applied Limnology/Communications. Association internationale de Limnologie theorique et appliquee. 1978,
01/1978
Book Chapter
Two algal assay methods (batch), one with Selenastrum capricornutum and one with this species together with Ankistrodesmus falcatus, Chlorella homosphaera, Euglena gracilis , and Scenedesmus ...quadricauda mixed on equal cell volume basis, are described and compared. Selenastrum capricornutum is routinely used for determining the maximum algal growth potential (AGP) and the limiting nutrients by enrichment experiments in lake water. The mixed algal assay method is used to estimate AGP-values and to indicate toxic effects of wastewater. Different ways to prepare the algae before the assays are described and discussed. Examples of results from some treatment plants and some different lakes using the two algal assay procedures are given, together with a comparison of the two methods.
Removal of 2-14C 2,4-D (2,4-dichlorophenoxy)-acetic acid from water was pronounced with Scenedesmus quadricauda (Turp.) Breb. and most effective uptake occurred at pH 4.7. Three other algae were ...relatively ineffective in removal of 2,4-D. Increasing Scenedesmus cell density increased 2,4-D removal, but the amount absorbed was not a linear function of cell density. Similarly, with a range of herbicide concentrations (0.01 to 1.0 ppmw) the amount removed was greatest at the highest concentration; however, a higher percentage of chemical was removed at lower concentrations. An equilibrium of 14C removal from water and 14C released to the water was reached by 4 hr. More herbicide was removed from water by Scenedesmus in darkness than in light and low temperature (2 C) reduced uptake slightly. Relatively high 2,4-D concentrations were required to reduce growth in any of the four algae and Scenedesmus was most sensitive. Scenedesmus metabolized ring
−14C in 24 hr to several products which were found in suspension fluid and cells. Quantitatively, 3-OH-2,4-D 3-hydroxy-2,4-dichlorophenoxy)acetic acid was the major metabolite, comprising 26% of the radioactivity extracted from cells compared to 15% from suspension fluid. A smaller amount of 5-OH-2,4-D (5-hydroxy-2,4-dichlorophenoxy)acetic acid was isolated from the suspension fluid and none from the cells.
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