Impacts of compound properties and sediment characteristics on the sorption behaviour of pharmaceuticals in aquatic systems

• Published in: Journal of hazardous materials Vol. 317; pp. 198 - 209
• Main Authors: Al-Khazrajy, Omar S.A., Boxall, Alistair B.A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05-11-2016
• Subjects: Distribution coefficient (Kd); Modelling; Pharmaceuticals; Sediment characteristics; Sorption isotherms; Modelling; Sediment characteristics; Pharmaceuticals; Sorption isotherms; Distribution coefficient (Kd)
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2016.05.065

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•Sorption behaviour of five pharmaceuticals in ten sediment types was assessed.•Existing sorption models were unable to predict actual sorption behaviour in sediments.•Pharmaceuticals sorption behaviour was found to be correlated to sediment properties.•New approaches to model sorption are needed for environmental risk assessments.
Sorption is a key factor in determining the persistence, attenuation and bioavailability of sediment-associated contaminants. However, our understanding of the sorption behaviour of pharmaceuticals in sediments is poor. In this study, we investigated the sorption behaviour of a diverse set of pharmaceuticals in a range sediment types. Sorption affinity of pharmaceuticals for all sediments was found to increase in the order mefenamic acid<cimetidine<atenolol<amitriptyline<diltiazem. Comparison of the experimental observations with predictions from an existing model for estimating sorption revealed the model worked poorly for the study pharmaceuticals. Multiple linear regression analysis was therefore used to develop new models for estimating sorption of individual pharmaceuticals based on sediment properties. The analyses indicated that sorption is related to properties such as Log Dow of a compound in the sediment (lipophilicity corrected for the sediment pH), cation exchange capacity, clay%, organic carbon content and exchangeable Ca2+, although, with the exception of atenolol, robust relationships between sediment properties and sorption were not obtained. Overall, the results demonstrate how complex the processes are that drive the sorption of pharmaceuticals in sediments and highlight the need for generation of further experimental data and further model development work.