Microcosm procedure for determining safe levels of chemical exposure in shallow-water communities
This paper describes a method for determining safe levels of chemical exposure in shallow-water communities, using laboratory microcosms as test subjects. The safe level is considered to be the maximum exposure that causes no persistent, ecologically significant changes in the ecosystem. In experiments completed at Oak Ridge National Laboratory, microcosm-derived estimates of safe exposure levels were confirmed using outdoor artificial ponds, which suggests that the microcosm procedure can be an efficient and economical means of determining safe levels for shallow-water communities. Details of microcosm construction, techniques for monitoring ecological variables in microcosms, and an experimental design for determining safe exposure levels are provided here. The microcosms are assembled by transferring components of natural ecosystems to 80-litre aquaria in a controlled laboratory environment. The communities that develop in these systems are typically dominated by common, cosmopolitan littoral species of macrophytes, algae, and invertebrates. Methods are described for measuring changes in water chemistry, phytoplankton, periphyton, macrophytes, zooplankton, and ecosystem production and respiration. By monitoring these variables over a gradient of pollutant exposure levels, the safe level can be determined accurately and precisely. 16 refs., 2 figs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5523699
- Report Number(s):
- CONF-8505158-1; ON: DE85012421
- Resource Relation:
- Conference: ASTM symposium on community toxicity testing, Colorado Springs, CO, USA, 6 May 1985
- Country of Publication:
- United States
- Language:
- English
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