Behavior of anionic and nonionic surfactants and their persistent metabolites in the Venice lagoon, Italy

The occurrence and behavior of the aromatic surfactants linear alkylbenzene sulphonates (LAS) and nonylphenol polyethoxylates (NPE) as well as their biotransformation products in the central lagoon of Venice, Italy, were investigated by monitoring deep- and shallow-water lagoon stations, two riverine sites, and one sea station. Additional samplings were conducted at the three inlets connecting the lagoon with the open sea under both ebb and low-tide conditions, and a radiometrically dated sediment core spanning the last century was examined. The spatial distributions of LAS, NPE, and their carboxylic metabolites sulphophenyl carboxylates and nonylphenol carboxylates, respectively, appeared to be rather homogeneous over the entire central lagoon. Remarkable seasonal differences were found, however, primarily because of the increased biodegradation at temperatures greater than 20 degrees C. The estimated primary and ultimate biodegradations of LAS in the lagoon waters were approximately 90 and 72%, respectively. Analysis of the dated sediment core showed similar annual fluxes of both LAS and NPE (48 ng/cm(2) year), which were between previously reported values of polychlorinated biphenyls (4.7 ng/cm(2) year) and polycyclic aromatic hydrocarbons (167 ng/cm(2) year).