Reducing concentrations of ammonia to nontoxic levels prior to initiating whole-sediment bioassays
- Battelle/Marine Sciences Lab., Sequim, WA (United States)
Determining the suitability of dredged material for ocean disposal requires whole-sediment toxicity tests with marine organisms. In addition to potential contaminants in dredged sediment, factors including grain size, salinity, hydrogen sulfide and ammonia can contribute to observed toxicity, thereby confounding test results. The presence of ammonia, a non-persistent but toxic compound, is particularly interesting because in open-water dredge and disposal situations, ammonia may not be a contaminant of concern. Sediment porewater ammonia concentrations in bioassays can be reduced to nontoxic levels before exposing organisms to permit evaluation of sediment contaminants without the additional toxicity effects of ammonia. Ten-day acute toxicity tests were conducted on sediments with Ampelisca abdita, Rhepoxynius abronius, Eohaustorius estuarius, and Mysidopsis bahia. Two procedures were followed to reduce ammonia prior to test initiation. In one, sediments in test chambers stood for 7 to 1 2 days while natural, nitrogen-reducing processes took place. In the other, sediments were tested in modified, flow-through systems. Ammonia was monitored in sediment porewater during ``purging`` periods, at test initiation and termination, and in overlying water during testing. Results were compared to the measured dose response of each species to ammonia, as determined by water-only reference toxicant tests. The question remains whether other sediment characteristics are affected by these procedures.
- OSTI ID:
- 37404
- Report Number(s):
- CONF-9410273-; TRN: IM9519%%328
- Resource Relation:
- Conference: 15. annual meeting of the Society of Environmental Toxicology and Chemistry (SETAC), Denver, CO (United States), 30 Oct - 3 Nov 1994; Other Information: PBD: 1994; Related Information: Is Part Of Society of Environmental Toxicology and Chemistry 15th annual meeting: Abstract book. Ecological risk: Science, policy, law, and perception; PB: 286 p.
- Country of Publication:
- United States
- Language:
- English
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