Responses of aquatic invertebrates to three homologous nonionic surfactants in model stream mesocosm exposures
- Univ. of Mississippi, University, MS (United States). Dept. of Biology
- Shell Development Co., Houston, TX (United States)
The effects of three homologous nonionic surfactants were evaluated in outdoor stream mesocosms. No observed effects concentrations and effect concentrations of three nonionic linear alcohol ethoxylate (LAE) surfactants with average carbon chain lengths of 10, 12.8, and 14.5 and average ethylene oxide units/mole of 6, 7, and 7, respectively were determined for aquatic invertebrate communities colonizing the stream mesocosms. Changes in benthic invertebrate densities and changes in invertebrate drift were monitored for 30 days. Mean measured concentrations of LAE in replicate streams ranged from 0.73 to 11.24 mg/L, 0.32 to 5.2 mg/L and 0.08 to 0.55 mg/L for C{sub 10}, C{sub 12.8}, and C{sub 14.5} AEs, respectively. In each experiment, over 30 taxa were identified in the stream mesocosms and included relatively sensitive taxa such as Ephemeroptera and Trichoptera. Based upon responses of Simuliidae, Copepoda, and Cladocera densities, the estimated NOECs for each experiment compared to replicate controls were 2.04 mg/L (C{sub 10}), < 0.32 mg/L (C{sub 12.8}), and 0.08 mg/L (C{sub 14.5}). The estimated LOECs for invertebrate densities were 4.35 mg/L (C{sub 10}), 0.32 mg/L (C{sub 12.8}), and 0.16 mg/L (C{sub 14.5}). No statistically significant effects on drifting invertebrates were observed in any of the stream mesocosm experiments, however, trends were observed with increased numbers of drifting organisms in streams treated with high concentrations as compared to controls. Observed toxicity of these surfactants to aquatic invertebrates is directly related to carbon chain length with greater toxicity associated with longer chain lengths.
- OSTI ID:
- 390187
- Report Number(s):
- CONF-9511137--; ISBN 1-880611-03-1
- Country of Publication:
- United States
- Language:
- English
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