Assessment of the environmental fate of linear alkylbenzenesulphonates

Fugacity models, as developed previously, are applied to the chemical linear alkylbenzenesulphonate (LAS) to predict its ultimate fate in the environment. The behaviour of LAS is illustrated using unit worlds or evaluative environments at three successive levels of complexity (Levels I, II, and III). LAS is shown to have a short environmental life of two days attributable to rapid biodegradation in water. Reported concentration data for LAS in Rapid Creek, South Dakota, downstream from a municipal sewage treatment plant, are compared to expected concentrations as generated by the QWASI (Quantitative Water Air Sediment Interaction) fugacity model; the model being based solely on the physical, chemical, reactivity and transport properties of LAS and the emission rate of the chemical into the river. The data are found to fit the model when a sediment-water mass transfer coefficient of 7.80 × 10⁻³ m/h and an effective sediment bed depth of 3 mm are used. The generally satisfying agreement between environmental observations and the QWASI fugacity models lends credibility to the use of evaluative models.