Sorption Behavior and Prediction of Tetracycline on Sediments from the Yangtze Estuary and its Coastal Areas

SSediments represent the major sink of antibiotics in aquatic systems. So it is important to study the adsorption capacity of sediments to antibiotics. However, few studies have proposed models that predict the sorption capacity of sediments by their physicochemical parameters. In this research, 49 sediment samples were collected from different locations in Yangtze Estuary and adjacent coastal areas. Sediments were characterized, and their adsorption behavior towards tetracycline (TC) in water-sediment systems was evaluated. Subsequently, through correlation analysis for adsorption coefficients and physicochemical parameters of sediments, 10 models were established to predict the adsorption parameter Kd . According to our model, the clay content and cation exchange capacity (CEC) played the most significant roles on TC adsorption by sediments. Langmuir model was best fitted to TC adsorption data (R2 = 0.829-0.996), followed by Freundlich model (R2 = 0.839-0.988). For most sediments, the adsorption efficiency for TC decreased from about 70% to less than 30% when salinity increased from 0 to 32.79‰.Therefore, the methods provided herein will be helpful in predicting the sorption behavior of antibiotics similar in structures to TC by sediments in this region, as well as to improve our understanding of the fate of antibiotics in aquatic systems