A simple, miniaturized algal assay procedure using microplates has been developed to assess aquatic toxicity with the green alga, Selenastrum capricornutum. Cell count‐generated EC50 data comparisons with the classic assay using flasks have indicated good agreement between the two methods following toxic assessment of various wastewater samples and metal solutions. Parametric comparisons (ATP us cell counts) with the microplate method show equally good correlation. The technique is highly versatile in conducting basic algal bioassays for varying times (4‐hour, 4‐day, 8‐day EC50's) and with differing parameters, depending on set objectives. Other interesting features of the microplate technique include handling rapidity, economy, space‐saving convenience, and automation potential.
An index allowing the assessment and comparison of the toxic potential of industrial effluents is described. Integrating the results of practical small‐scale screening bioassays (Photobacterium phosphoreum Microtox® test. Selenastrum capricornutum growth inhibition microtest, Ceriodaphnia dubia lethality and reproduction inhibition tests, Escherichia coli genotoxicity SOS Chromotest), this index takes into account persistence of toxicity, (multi) specificity of toxic impact, as well as effluent flow. The resulting Potential Ecotoxic Effects Probe (PEEP) index number is reflected by a log10 value that varies from 0 to infinity but normally will not surpass a value of 10. The structure of the mathematical formula generating PEEP values is simple and “user friendly” in that it can accommodate numbers and types of bioassays to fit particular needs. Thirty‐seven effluents from 8 industrial sectors (pulp and paper, petroleum refining, inorganic/organic chemical production, mining, metallurgy, metal plating, textile production) were appraised and compared with the proposed PEEP scale. The pulp and paper sector effluents (n = 15) markedly stood out from the others owing to their greater toxicity and higher discharge volume, with reported PEEP values lying between 4.4 and 7.5. For most of these effluents, toxicity was found to be persistent, multitrophic (i.e., affecting our bacterial, algal, and crustacean bioindicators), and it expressed itself at all levels of assessment (i.e., lethal, acute sublethal, chronic sublethal, and genotoxic levels). The usefulness of the PEEP index in the environmental management of industrial effluent toxicity is discussed herein. © 1993 John Wiley & Sons, Inc.
The purpose of this study was to examine broad-scale correlation between presence of priority substances and whole effluent toxicity (WET) across a range of industry types. Using regression analysis, we examined how chemical-based inferred toxicity predicted measured WET of the effluents. Whole effluent toxicity was determined using a suite of acute and chronic bioassays; chemical-based toxicity was inferred from concentrations of priority chemicals and from published chemical toxicity values. When inferred toxicity was corrected for bioavailable metal and ion concentrations, 43% of the variability in measured toxicity was explained. For many industries, priority contaminants accounted for WET, and their toxic action was generally additive. However, industry-specific analysis of the residuals highlighted effluent types for which there was over one order of magnitude variation in inferred and measured toxicity. In particular, chemical-based assessments tended to overestimate toxicity of effluents containing high concentrations of metals and to underestimate toxicity of pulp mill effluents.
Past and present Canadian experiences with biological testa for controlling the quality of wastewaters are discussed. Test use has evolved from data acquisition on acute toxicities, to physicochemical and biological parameters being regulated and monitored by industrial sector in the 197013, and hazard assessments conducted by the 1980s. At a time when Environment Canada is reviewing its ecotoxicological procedures, new opportunities for waste assessment with "second generation" biotests are emerging. Recent experiences suggest that small-scale, sensitive, biological testa can be employed for environmentally and economically effective control of effluents entering aquatic environments.It is also expected that biotesting activities will increase because of new environmental strategies and regulations. These will stimulate biological research and development, and promote a partnership between ecotoxicology, environmental chemistry, and biotechnology.
This article introduces the Sediment Toxicity (SED‐TOX) Index for the assessment and ranking of toxic hazards in sediment. Major features include expression of toxicity responses on a single scale of measurement (dry weight–based toxic units), consideration of multiple routes of exposure (pore water, organic extract, wet sediment, and whole sediment), application of differential treatments to toxicity data depending on the level of response (acute lethal or chronic sublethal), and use of weighting factors to discriminate sediment exposure phases and effect endpoints on the basis of sensitivity. A battery of seven bioassays with four test species (Vibrio fischeri, Escherichia coli, Lytechinus pictus, and Amphiporeia virginiana) was conducted on 49 marine sediment samples collected from six sites at Anse‐à‐Beaufils and Cap‐aux‐Meules, which are in the Gulf of St. Lawrence. The SED‐TOX scores were calculated for each sampling station and compared with sediment contaminant concentrations. Results indicate that physicochemical characterization is not sufficient to assess contaminated‐sediment hazard for organisms; furthermore, using several exposure phases and test species belonging to various trophic levels increases the possibility of correctly identifying toxic sediments. The results of this study indicate that the SED‐TOX approach is valuable as a toxicity assessment and ranking tool for sediments. It could easily be combined with other measures of ecosystem disturbance to discriminate between polluted and unpolluted sites.
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