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

Abstract

Sediments represent the major sink of antibiotics in aquatic systems. However, few studies have proposed effective models that can predict the adsorption capacity of sediments through their physicochemical parameters. Here, 49 sediment samples were collected from different locations in the Yangtze Estuary and its adjacent coastal areas. The sediments were characterized, and their adsorption behavior towards tetracycline (TC) was investigated. It was found that both the Langmuir and Freundlich models fit the TC adsorption data well, and the sediments in the mud area showed the highest adsorption capacity. Subsequently, through correlation analysis for the adsorption coefficients and physicochemical parameters of sediments, 11 models were established to predict the adsorption coefficients (Kd), in which clay and cation exchange capacity played significant roles. When the salinity was increased from 0 to 32.79‰, the Freundlich adsorption coefficient (Kf) of TC for most sediments was reduced by more than75% (except sediment C6). Therefore, the methods provided herein can be helpful in predicting the sorption behavior of antibiotics with similar structures toward TC by sediments in this region.