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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

Commercially available naphthenic acids can be removed to a major extent by bacterial cultures from wetlands.

Key value for chemical safety assessment

Additional information

The study does not report values for half-life in water and sediment but overall it is concluded that Naphthenic acid is biodegradable.

Sediments from eleven wetlands, both natural and process-affected, and one tailings settling pond were studied.

The extent of degradation of a 14C-labelled monocyclic NA surrogate (14C-cyclohexane carboxylic acid) was relatively uniform in all sediments (approximately 30%) after 14 days. In contrast, degradation of a bicyclic NA surrogate (14C-decahydronaphthoic acid) was significantly lower in non process-affected sediments. Enrichment cultures, obtained from an active tailings settling pond, using commercially available NAs as the sole carbon source, resulted in the isolation of a co-culture containing Pseudomonas putida and Pseudomonas fluorescens. Quantitative analysis showed that the co-culture removed >95% of the commercial NAs, and partially degraded the process NAs from OSPW with a resulting NA profile similar to that from ‘aged wetlands’.