Toxicity of contaminants

Reduced volume and toxicity of contaminated groundwater toxicity of soil contamination reduced... 

Reduced volume and toxicity of contaminated groundwater toxicity of soil contamination in Area 2 reduced by 97% mobility of contaminants in Area 1 reduced by 10% while volume increased by 20%... 

Accordingly, the total petroleum hydrocarbons at a gasoline spill site will be comprised of mostly Cs to Cu compounds, while total petroleum hydrocarbons at an older site where the fuel has weathered will likely measure mostly Cg to Cn compounds. Because of this inherent variability in the method and the analyte, it is currently not possible to directly relate potential enviromnental or health risks with concentrations of total petroleum hydrocarbons. The relative mobility or toxicity of contaminants represented by total petroleum hydrocarbons analyses at one site may be completely different from that of another site (e.g., Ce to Cn compared to Cio to C25). There is no easy way to determine if total petroleum hydrocarbons from the former site will represent the same level of risk as an equal measure of the total petroleum hydrocarbons from the latter. For these reasons it is clear that the total petroleum hydrocarbons value offers limited benefits as an indicator measure for cleanup criteria. Its current widespread use as a soil cleanup criterion is a function of a lack of understanding of its proper application and... 

Bowmer, C.T. (1993). Method for the assessment of acute toxicity of contaminated sediment using the burrowing heart vachm Echinocardium cordatum. Test Guideline for OSPAR sediment reworker ring test. Report IMW R93/317. 

This last equation forms the basis for the EPA s sediment quality guidelines that are used to assess the potential toxicity of contaminated sediments. The idea is to simply measure Cs and foe, look up K0w in a table, compute the predicted Cw, and compare this result to established water quality criteria for the protection of aquatic life or human life (e.g., carcinogenicity risk factors). The use of this simple equilibrium partitioning expression for this purpose is currently the subject of much debate among scientists as well as policy makers. 

Benoit, D.A., Sibley, P.K., Juenemann, J.L. and Ankley, G.T. (1997) Chironomus tentans life-cycle test design and evaluation for use in assessing toxicity of contaminated sediments, Environmental Toxicology and Chemistry 16 (6), 1165-1176. 

Nebeker, A.V., Caims, M.A., Gakstatter, J.H., Malueg, K.W., Schuytema, G.S. and Krawczyk, D.F. (1984) Biological methods for determining toxicity of contaminated freshwater sediments to invertebrates, Environmental Toxicology and Chemistry 3 (4), 617-630. 

Temperature is one of the most important variables that determines the distribution and abundance of species (Cossins and Bowler 1987) and imposes critical limits on fitness. As a result of increasing metabolic rate, increasing temperature can increase the uptake and toxicity of contaminants by poikilothermic species, but may also increase rates of detoxification and excretion of toxicants (e.g., pyrethroid insecticides National Research Council of Canada [NRCC] 1987). Temperature extremes in themselves are stressful to organisms, causing induction of various stress proteins, which may be associated with fitness costs (Hoffmann et al. 2003). 

Aqueous geochemical models have become routine tools in the investigation of water-rock interactions (Alpers and Nordstrom, 1999 Drever, 1997 Langmuir, 1997 Nordstrom and Munoz, 1994 Parkhurst and Plummer, 1993), in the study of bioavailability and toxicity of contaminants to organisms (Morrison, 1989 Parker et al., 1995), in the prediction of arsenic behaviour in mining pit lakes in Nevada (Tempel et al., 1999), in the... 

Love Canal also contributed strongly to the development of risk assessment methodologies since the Superfund Act required that determinations of clean-up levels be made based on a scientific assessment of data on the toxicity of contaminants found at the hazardous waste sites and the potential for exposure to those contaminants. In light of the limitations in available knowledge, new approaches had to be devised to answer the question of how clean is clean The methodology that was adopted married scientific data to value judgments about acceptable risk and margins of safety. This approach remains in use. 

The use of models for the prediction of metal toxicity using acid-volatile sulfide (DiTorro et al., 1990, 1992) and equilibrium partitioning for hydrophobic compounds (DiTorro et al., 1991) has been very useful for the prediction of bioavailability and associated toxicity of contaminants in sediments. Recently the Biotic Ligand model has been developed to relate metal bioavailability (and its potential toxicity) using the most recent chemical and physiological effects information on metals in aquatic environments (Paquin et al., 1999 DiTorro et al., 2001 Santore et al., 2001). 

The OECD Daphnia spp acute immobilisation and reproduction tests. A mainstay in aquatic toxicity testing, Daphnia tests have been used also to evaluate the toxicity of contaminated groundwaters and leachates (Kross and Cherryholmes, 1992). As with any of the aquatic tests, the principal problem with the Daphnia test is the need to extract a suitable aqueous sample. This problem is illustrated by Kross and Cherryholmes (1992), who compared D. magna and Microtox assay results in leachates but found a poor correlation between the two methods. 

Observations Speciation models are useful for determining the relative importance of individual aqueous complexes and the toxicity of contaminated waters. They can establish whether a water has the potential to precipitate or dissolve a mineral or gas phase and whether or not various mass transfer processes such as ion exchange have the potential to affect the concentrations of various constituents. They are often used in conjunction with mass-balance models. 

An Expert System for Prediction of Aquatic Toxicity of Contaminants... 

AIWARE, description, 64 Analysis, expert systems to support, 69-80 Aquatic toxicity of contaminants, prediction by expert system, 91-104 Architecture, expert system to diagnose performance limiting factors atPOTWs, 126... 

Word JQ, Hardy JT, Crecelius EA, et al. 1987. A laboratory study of the accumulation and toxicity of contaminants at the sea surface from sediments proposed for dredging. Marine Environmental Research 23 325-338. 

Attenuation occurs as a result of various mechanisms operating in the landfill which serve to minimise the movement and/or reduce the toxicity of contaminants... 

The membrane technoli can be used as an integral part of a remediation system to significantly reduce the volume and toxicity of contaminated wastewater. The technology is particularly suited for the treatment of contaminated groundwater as part of a pump and treat system. The technoli reduces risks to human health and the environment by transferring the cmtaminants to a smaller volume facilitating destruction or detoxification by other technologies. 

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