ISSN:0730-7268    

DOI:10.1002/etc.5620101201

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe hazard assessment of pulp and paper effluents in the aquatic environment is a complex task. Hundreds of individual compounds in pulping effluents and site‐specific differences in processes, effluent treatment, and receiving ecosystems hinder hazard assessment. As a result, it is difficult to relate environmental effects with specific contaminants. Conventional parameters such as organic and nutrient loadings, solids deposition, and color complicate efforts to define chemical toxicants by causing environmental impacts at community and population levels. Reproduction is the most sensitive, consistent, and relevant end point tested to date in the laboratory, in mesocosms and experimental streams, and in field situations near some pulping discharges. Despite the application of a wide range of within‐organism measurements, only the induction of mixed‐function oxidase activities has been associated with exposure to particular effluent compounds in field situations. No complete mechanism of toxic action has been demonstrated that connects contaminant exposure, within‐organism responses, whole‐organism effects, and effects at the population and the community levels. Hazard assessments of pulping effluents require multidisciplinary efforts that integrate chemical, toxicological, and biological data at several organizational levels. Tiered or stepwise assessments are recommended that first clarify what adverse effects have occurred and then attempt to identify the responsible con

ISSN:0730-7268    

DOI:10.1002/etc.5620101202

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe purpose of this review paper is to present the technical basis for establishing sediment quality criteria using equilibrium partitioning (EqP). Equilibrium partitioning is chosen because it addresses the two principal technical issues that must be resolved: the varying bioavailability of chemicals in sediments and the choice of the appropriate biological effects concentration.The data that are used to examine the question of varying bioavailability across sediments are from toxicity and bioaccumulation experiments utilizing the same chemical and test organism but different sediments. It has been found that if the different sediments in each experiment are compared, there is essentially no relationship between sediment chemical concentrations on a dry weight basis and biological effects. However, if the chemical concentrations in the pore water of the sediment are used (for chemicals that are not highly hydrophobic) or if the sediment chemical concentrations on an organic carbon basis are used, then the biological effects occur at similar concentrations (within a factor of two) for the different sediments. In addition, the effects concentrations are the same as, or they can be predicted from, the effects concentration determined in water‐ only exposures.The EqP methodology rationalizes these results by assuming that the partitioning of the chemical between sediment organic carbon and pore water is at equilibrium. In each of these phases, the fugacity or activity of the chemical is the same at equilibrium. As a consequence, it is assumed that the organism receives an equivalent exposure from a water‐only exposure or from any equilibrated phase, either from pore water via respiration, from sediment carbon via ingestion; or from a mixture of the routes. Thus, the pathway of exposure is not significant. The biological effect is produced by the chemical activity of the single phase or the equilibrated system.Sediment quality criteria for nonionic organic chemicals are based on the chemical concentration in sediment organic carbon. For highly hydrophobic chemicals this is necessary because the pore water concentration is, for those chemicals, no longer a good estimate of the chemical activity. The pore water concentration is the sum of the free chemical concentration, which is bioavailable and represents the chemical activity, and the concentration of chemical complexed to dissolved organic carbon, which, as the data presented below illustrate, is not bioavailable. Using the chemical concentration in sediment organic carbon eliminates this ambiguity.Sediment quality criteria also require that a chemical concentration be chosen that is sufficiently protective of benthic organisms. The final chronic value (FCV) from the U.S. Environmental Protection Agency (EPA) water quality criteria is proposed. An analysis of the data compiled in the water quality criteria documents demonstrates that benthic species, defined as either epibenthic or infaunal species, have a similar sensitivity to water column species. This is the case if the most sensitive species are compared and if all species are compared. The results of benthic colonization experiments also support the use of the FCV.Equilibrium partitioning cannot remove all the variation in the experimentally observed sediment‐ effects concentration and the concentration predicted from water‐only exposures. A variation of approximately a factor of two to three remains. Hence, it is recognized that a quantification of this uncertainty should accompany the sediment quality criteria.The derivation of sediment quality criteria requires the octanol/water partition coefficient of the chemical. It should be measured with modern experimental techniques, which appear to remove the large variation in reported values. The derivation of the final chronic value should also be updated to include the most recent toxicological info

ISSN:0730-7268    

DOI:10.1002/etc.5620101203

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe science of sediment toxicology essentially began in the late 1970s. It was largely a product of dredging concerns and recognition of widespread contamination of sediments. During the past few years, sediment toxicity research activity has increased dramatically. Currently, most tests are of an acute nature with fewer available for determining sublethal endpoints of chronic toxicity. Test systems of single and multiple species have included most levels of biological organization in aquatic ecosystems and have been conducted in the laboratory on whole sediments, interstitial waters, elutriates, or other extractable fractions under a wide variety of conditions. Evaluations of methodological effects and comparisons with in situ toxicity using surrogate test species and indigenous communities have, on occasion, shown significant differences in test responses. These differences may be attributed to laboratory‐controlled parameters (e.g., light, species, life stage, exposure conditions, test phase, spiking method); sampling and laboratory‐induced disruption of sediment integrity; alteration of toxicant partitioning due to manipulations and temporal effects; and failure to recognize other influencing ecosystem variables (e.g., organism niche and life cycle, sediment partitioning and gradient dynamics, physicochemical and biological process integration, biotic and abiotic disturbances, micro‐ and macrobiota patches, food‐web interactions). Optimizing and standardizing test methods will require further studies of these variables to improve inter‐laboratory comparisons and ecosystem validity. Despite the many unknowns that exist, a variety of sediment toxicity tests have been effectively used in assessing toxicant contamination by measuring the bioavailable fraction of the in‐place pollutants. The optimal assays vary with the study and its objectives. Intergrative studies using several chemical, community, and toxicity measures are currently the most effective at defining ecosystem pe

ISSN:0730-7268    

DOI:10.1002/etc.5620101204

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY