Dynamics and mechanisms of bioaccumulation and elimination of Nonylphenol in Zebrafish

Abstract

Nonylphenol (NP) has been widely concerned for its endocrine disrupting effects and bioconcentration in aquatic organisms. However, the knowledge on the dynamic uptake and depuration in model organisms - zebrafish (Danio rerio) were still limited. In this study, we investigated the accumulation and elimination of NP for the whole body and trunk of zebrafish by a modified pretreatment and analysis method with fewer samples. The results of acute toxicity test showed that the LC50 values of NP in zebrafish ranged from 474 µg·L− 1 for a 24-h exposure to lower than 238 µg·L− 1 for a 96-h exposure. Meanwhile, the NP concentrations in zebrafish during the depuration stage fitted the first-order kinetic model well, and the depuration rate constant (K2) was reduced with higher NP concentrations. Both the accumulation and elimination of NP in the trunk were faster than those in the whole fish, indicating the preferential transfer from viscera to muscle and rapidly diffusion in reverse. The bioconcentration factors at a steady state (BCFSS) of NP were 104–112 L·kg− 1 in the whole body and 76–104 L·kg− 1 in the trunk, respectively, suggesting that the muscle was a major position for NP storage. The BCFSS were increased within a certain concentration due to the decreasing depuration capacity inhibited by NP toxicity. To our knowledge, this study was the first to emphasize the correlation between NP exposure concentration and bioconcentration capacity.