The interaction between chromophoric dissolved organic matter and xenobiotics (bisphenols and perfluoroalkyl substances) identified by UV-vis absorption and FT-IR spectroscopy

Abstract

Chromophoric dissolved organic matter (CDOM) pool is a key component in biogeochemical processes and carbon cycles in aquatic environments. However, less attention has been paid to how CDOM pool is affected by xenobiotics. Herein, we investigate bisphenols (BPs) and perfluoroalkylated substances (PFAS) interaction with pure purchased humic substances (HS; i.e., humic acid (HA), fulvic acid (FA)) and amino acid (AA; i.e., tyrosine (TYR), tryptophan (TRY)) and the riverine CDOM pool using UV–vis absorption and Fourier-transform infrared spectroscopy (FT-IR). Notably, low and high (2.5 × 10−3 and 1 mg/L) concentrations of BPs and PFAS increase dissolved organic carbon to more than 100 and 200 %, respectively. However, CDOM abundance decreased by ∼95 and ∼60 % in treatments of HA with BPs and PFAS, respectively. Furthermore, controls FA and HA, TRY and TYR had higher aromaticity values (> 2, > 8, > 0.7 and > 0.8, respectively) compared to their corresponding treatments with BPs and PFAS (< 0.5, < 1, < 0.3, and < 0.5, respectively). BPs and PFAS significantly decrease (average of -45.34 and -65.53 %, respectively) riverine CDOM abundance and aromaticity. These findings demonstrate that BPs and PFAS are important carbon sources to aquatic ecosystems. They significantly reduce CDOM abundance which will enhance UV-light penetration into the water column, and also reduce CDOM aromaticity thus, increase its degradability and hydrophilicity, but decrease its disinfection byproduct formation potential. The findings of this study provide new and useful information about the impacts of BPs and PFAS on the CDOM pool.