Full text loading...
Abstract
Sodium dodecyltriethoxy sulphate (SDTES), either pure or as a component of commercial surfactant mixtures, underwent rapid primary biodegradation by mixed bacterial cultures in OECD screen and river-water die-away tests. Inoculation of [35S]SDTES-containing solutions with OECD screen test media acclimatized to surfactants or their degradation products led to production of various 35S-labelled glycol sulphates and their oxidation products, all known to occur during degradation of [35S]SDTES by pure bacterial isolates. Triethylene glycol monosulphate was the major catabolite together with smaller amounts of di- and monoethylene glycol monosulphates implying, by analogy with pure cultures, that ether-cleavage was the major primary biodegradation step. The oxidation product (carboxylate derivative) of each glycol sulphate was also detected together with metabolites tentatively identified as Ω-/β-oxidation products of the dodecyl chain. Relatively little SO4 2- was liberated directly from SDTES but mixed cultures derived from sewage could metabolize the sulphated glycols to SO4 2-. The environmental relevance of these degradation routes was established by following metabolite production from [35S]SDTES in full-scale river-water die-away tests. Triethylene glycol sulphate was formed first, then rapidly oxidized to acetic acid 2-(diethoxy sulphate) which persisted as the major metabolite for 2–3 weeks. Small amounts of sulphated derivatives of di- and monoethylene glycols were also detected during the same period. Very little SO4 2- was formed directly from SDTES but large amounts accompanied the eventual disappearance of glycol sulphate derivatives. None of the 35S-labelled organic metabolites was persistent and, whenever [35S]SDTES was a component of a commercial mixture, all ester sulphate was completely mineralized to 35SO4 2- within 28 d.
- Received:
- Revised:
- Published Online: