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Occurrence and fate of selected surfactants in seawater at the outfall of the Marseille urban sewerage system
Robert-Peillard, F.; Syakti, A.D.; Coulomb, B.; Doumenq, P.; Malleret, L.; Asia, L. & Boudenne, J.-L.
Abstract
This paper describes an investigation of linear
alkylbenzene sulfonates (LAS) and nonylphenol ethoxylates
(NPEO) and their metabolites in the vicinity of the Marseille
sewage outfall (wastewater treatment plant with a capacity of
1.860 million inhabitant equivalents, Northwestern Mediterranean,
southeast of France). This analytical survey
describes their occurrence in the subsurface and sea surface
layers and investigates their possible fates in this marine
environment. The results indicated the presence of LAS in
both layers and up to 3 kmfrom the discharge point, whereas
the concentration of sulfophenyl carboxylic acids, which are
the main metabolites of LAS, was only significant near the
sewer outfall and in the surface layer. The NPEO were
present only in minor quantities, especially near the discharge
point, and no other selected metabolites were detected.
The fate of the surfactants in question was then assessed
by two types of experiments according to their potential
means of degradation under natural conditions. Biodegradation
assays were conducted according to a protocol defined
by the United States Environmental Protection Agency
(‘Biodegradability in sea water, 835.3160’), with variations
in the substrate input frequencies. Photodegradation experiments
were carried out in a solar simulator reactor. These
results demonstrated the low photodegradability and rapid
primary biodegradation ofLAS (with half-life times between
10.3 and 11.5 days) in the coastal area under study, although
some LAS metabolites were more recalcitrant to biodegradation
in this specific environment, which was also validated
by linear alkylbenzene analysis in the two selected sediment
stations.
Keywords
Surfactants; LAS; NPEO; LAB; Seawater; Sediment; Biodegradation; Photodegradation
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