title: Vertical distribution profiles and diagenetic fate of synthetic surfactants in marine and freshwater sediments.
abstract: This manuscript deals with the presence and degradation of the most commonly-used surfactants, including anionic (linear alkylbenzene sulfonates, LAS, and alkyl ethoxysulfates, AES) and non-ionic (alcohol polyethoxylates, AEOs, and nonylphenol polyethoxylates, NPEOs) compounds, in sediments and pore water from several aquatic environments (Southwest, Spain). Different vertical distributions were observed according to the respective sources, uses, production volumes and physicochemical properties of each surfactant. Levels of nonionics (up to 10 mg kg(-1)) were twice as high as anionics in industrial areas and harbors, whereas the opposite was found near urban wastewater discharge outlets. Sulfophenyl carboxylic acids (SPCs), LAS degradation products, were identified at anoxic depths at some sampling stations. Their presence was related to in situ anaerobic degradation of LAS in marine sediments, whereas the occurrence of these metabolites in freshwater sediments was attributed to the existence of wastewater sources nearby. No significant changes in the average length of AEO and NPEO ethoxylated chains were observed along the sediment cores, suggesting that their biodegradation was very limited in the sampling area. This may be directly related to their lower bioavailability, as their calculated sediment-pore water distribution coefficients (log K(sw)), which showed that non-ionic surfactants examined in this study had greater sorption affinity than the anionic surfactants (e.g., 2.3±0.3 for NPEOs).
authors.affiliation: Department of Physical-Chemistry, Faculty of Marine and Environmental Sciences, University of Cadiz, Campus of International Excellence of the Sea (CEI.MAR), Río San Pedro, Puerto Real, 11510, Cadiz, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Corada-Fernández
authors.forename: Pablo A
authors.initials: PA
authors.lastname: Lara-Martín
authors.forename: Lucila
authors.initials: L
authors.lastname: Candela
authors.forename: Eduardo
authors.initials: E
authors.lastname: González-Mazo
mesh_terms: D017738:Alkanesulfonic Acids / Q000737:chemistry; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D002851:Chromatography, High Pressure Liquid; D005026:Ethylene Glycols / Q000737:chemistry; D019015:Geologic Sediments / Q000032:analysis*; D060587:Groundwater / Q000032:analysis*; D013058:Mass Spectrometry; D013030:Spain; D013501:Surface-Active Agents / Q000032:analysis / Q000737:chemistry*
chemical_list: D017738:Alkanesulfonic Acids; D005026:Ethylene Glycols; D013501:Surface-Active Agents; C030641:alkylbenzyl sulfonic acid; C021754:terics
keywords: Degradation; Estuaries; Pore water; Sediment; Sorption; Surfactants