Benzene- and naphthalenesulfonates in leachates and plumes of landfills

Benzene- and naphthalenesulfonates (BS, NS) are xenobiotic, highly water-soluble chemical compounds that are used for the production of many consumer products such as fluorescent whitening agents, dyes, or concrete plasticizers, and for various applications in industrial processes. They are mainly introduced into ambient waters by industrial or municipal wastewater directly or following municipal sewage treatment. In order to characterize an additional pathway for BS and NS into the environment, leachates and groundwater samples collected from the pollution plumes of four Swiss landfills were investigated. The samples were analyzed using ion-pair liquid chromatography with UV absorption and fluorescence detection. Liquid chromatography coupled to mass spectrometry was performed for the selective identification of aromatic monosulfonates. The results show that landfill sites are point sources for BS and NS in the aquatic environment. BS and NS were measured in the leachates at a wide concentration range from a few μg l−1 up to several mg l−1, depending on the composition of the deposited material. Their contribution to the leachate DOC was from below 1‰ up to around 30%. BS and NS were also found in groundwater samples contaminated by percolating leachates. The concentrations, which contributed less than 1‰ to the groundwater DOC, ranged from a few ng l−1 to several μg l−1.