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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

Data are available for the read-across substance TAME. In anaerobic, static sediment/water microcosms, TAME does not biodegrade. 

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Additional information

Based on the considerations described in the document “Read-across substantiation C5-6 branched alkylmethyl-ethers” (incl. the supporting references Tuppurainen et al., 2007 and Niska et al., 2008), it can be concluded that the available information of TAME can be used to predict the biodegradation in water and sediment of the substance ‘C5-6 branched alkylmethyl-ethers’ with sufficient certainty.

In an anaerobic, static sediment/water microcosm study TAME was not degraded in 180 days (6 months) under all conditions tested; sulfate and/or nitrate reducing conditions and/or methanogenic conditions (Mormile et al. 1994). Sediments were collected from sites chronically contaminated with petroleum hydrocarbons. Inoculum was indigenous sedimentary micro-organisms occurring under anoxic/anaerobic subsurface conditions.

After 182 days of incubation TAME did not biodegrade under the test conditions in anaerobic sediment/water test system (Suflita and Mormile, 1993). Samples were collected from sites of contaminated chronically with municipal landfill leachate.

The anaerobic biotransformation of TAME in sediments was evaluated under different anoxic electron-accepting conditions over 3 years by Somsamak et. al. (2001). Enrichments were established with a polluted estuarine sediment inoculum under conditions promoting denitrification, sulfate reduction, Fe(III) reduction, or methanogenesis. Complete primary degradation of TAME was observed under sulfate-reducing conditions, concomitant with the reduction of sulfate. The primary degradation product of TAME was tert-amyl alcohol (TAA) indicating that O-demethylation was the initial step in TAME biodegradation under sulfate-reducing conditions. Further degradation of TAA did not occur. No transformation of TAME was observed under the other electron-accepting conditions over 3 years (Somsmak et al. 2001).