Linear alkylbenzene sulfonates (LAS) in the terrestrial environment

The occurrence of linear alkylbenzene sulfonates (LAS) in a series of soil samples originating from the municipality of Roskilde has been studied. The study includes soil samples from eight different locations with different histories: a preserved natural area that has not been cultured for 50-100 years, a soil that has been ecologically cultured for 40 years, a soil sustainably manured in ecologically culture for 5 years (formerly conventionally cultured) and a soil that has been conventionally cultured using artificial fertilizer. In addition, a soil was studied that had been sludge amended by applying medium amounts of sludge as well as a soil that has been amended with high amounts of sludge for a 25-year period. In the latter case, the sludge amendment was abandoned 6 years before the first sampling, followed by the application of artificial fertilizers. Finally, a meadow in the run-off zone from a sludge storage area was included in the investigations. In addition to the soil samples, selected samples of the applied sludge and other fertilizers were analyzed for their possible content of LAS. Apart from the location where the soil had been heavily sludge-amended and the location situated in the run-off zone of the sludge storage, concentrations of LAS in all soil samples were found to be below approximately 1 mg/kg, which is well below the proposed preliminary soil quality criteria for LAS of 5 mg/kg. On the other hand, the study unambiguously disclosed that in the case of heavy sludge amendment, the proposed soil quality criteria might well be exceeded.