Levels Of Linear Alkylbenzenesulfonates (LAS) In Sediments Of The Berre Lagoon (FRANCE)

Abstract

A method is described to extract, concentrate and determine trace levels of linear alkylbenzenesulfonates (LAS) (a major anionic surfactant) from sediment samples. It consists of an ultrasonic extraction, followed by clean up and enrichment with C18 mini-columns cartridges and determination by HPLC. Both efficiency and accuracy of the method are high, i.e. mean recovery of 85% and repeatability of 2.8% relative standard deviation for five-replicate LAS analyses. The spatial distribution of LAS and their composition of homologues in sediments of the Berre lagoon, the widest lagoon of the Mediterranean littoral, have been studied. The levels of total LAS in sediments range from 0.21 to 5.00 mg=g (dry weight). Results show that LAS principally associated with solids in suspension, and originating from industrial and urban wastewaters, are principally discharged into the Arc and Cadière Rivers then decant in the mouths of these rivers. The maximum concentrations have been monitored in three zones of the site: the Bolmon lagoon, the Vaine lagoon and the northeast part of the Berre lagoon. The distribution of the LAS homologues in the sediments is not the same as that of the commercial LAS. A great percentage of C13-LAS has been observed (>50%).