The influence of sediment particle size on the properties of adsorbed dissolved organic matter in the Yangtze Estuary and its interactions with As/Sb

•The characteristics of DOM extracted from four particle-size sediments were compared.•Particle size obviously influenced the quality and quantity of extracted DOM.•Protein-like material dominated in DOM and processed a stronger complex capacity with As/Sb.•The binding capacity of DOM with As/Sb decreased with the increasing particle size.•A positive correlation between complexation capacity and acidic functional group content.

The characteristics of dissolved organic matter (DOM) extracted from sediments with four particle sizes (< 25, 63–25, 200–63 and > 200 μm) in the Yangtze Estuary were compared. The differences in their binding capacities for individual fluorescent components with As/Sb were studied using fluorescence-quenching titrations combined with excitation–emission matrix (EEM) spectra. The results indicated that the particle size influenced the quality and quantity of extracted DOM. With increasing particle size, the extracted DOM content, value of UV280 and acidic functional group content of the DOM decreased. Three protein-like components (C2, C3 and C4) and one humic-like component (C1) were identified using the parallel factor analysis (PARAFAC) model. Wherein, protein-like material dominated in DOM on different particle-size fractions and possessed a stronger complex capacity with As/Sb. A significant positive correlation between the complexation capacity of extracted DOM from samples, as well as with the acidic functional group content, was observed.