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Use of microcosms to study transport, transformation and fate of organics in aquatic systems
Author(s) -
Rodgers John H.,
Dickson Kenneth L.,
Saleh Farida Y.,
Staples Charles A.
Publication year - 1983
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620020204
Subject(s) - microcosm , lindane , environmental chemistry , environmental science , sediment , aquatic ecosystem , pollutant , persistent organic pollutant , ecotoxicology , ecology , chemistry , pesticide , biology , paleontology
Assessing the hazards of chemicals in aquatic ecosystems requires methods for examining where a potential toxicant is likely to be in place, time, form and concentration. Currently there is considerable interest in the use of microcosms as predictors of transport, transformation and fate of potentially toxic organics in aquatic systems. Generic microcosms of varying complexity can serve as useful tools for studying partitioning and kinetics of organic chemicals. Microcosms facilitate determination of mass balances and recovery of transformation products for further study. In this study, extensively characterized generic microcosms were used to examine the fates of naphthalene and lindane, and to compare observed compartmentalization and processing to predictions by two fate models, the Exposure Analysis Modeling System (EXAMS) and Simplified Lake and Stream Analysis (SLSA). Inputs to the fate models consisted of microcosm characteristics and laboratory‐determined rate coefficients for the two chemicals. Both fate models demonstrated good capabilities for predicting aqueous phase concentrations of naphthalene and lindane. However, EXAMS and SLSA predicted sediment naphthalene and lindane concentrations that exceeded observed concentrations by up to two orders of magnitude. This lack of agreement for sediments may be attributed to model inputs or model constructs. Sediments deserve further attention, since many organic chemicals of environmental concern have relatively large sediment‐water partition coefficients and are not biodegraded at an appreciable rate. Both the questions of depth distribution of chemicals through time and sediment microbial degradation rates need further study, since the understanding of them may enhance model development. Depending upon the question or the hypothesis addressed, microcosm construction may range from simple to complex with one to several compartments. Through careful microcosm design, processes controlling the fate of a particular chemical in nature may be isolated and examined in detail. Fates of a variety of chemicals can be compared and contrasted efficiently in replicate microcosms. As simplified systems, microcosms are accurate predictors only for those processes and equilibrium phenomena that are sufficiently understood to scale to natural systems. Microcosms can provide feedback information for theoretical model testing and validation.