Dissolved organic matter(DOM)plays a pivotal role in coordinating with metal ions,thereby affecting their toxicity,migration,transformation,and bioavailability of metal ions,factors that significantly impact the eco-logical environment of nearshore aquaculture areas.This study delves into the composition and molecular structure of DOM in the coastal waters of Zhoushan through the use of three-dimensional fluorescence spectroscopy com-bined with parallel factor analysis and fluorescence quenching titration.The coordination mechanisms between various fluorescence components of DOM and typical transition metal ions Cu2+,Fe3+,and Pb2+were examined using a modified Stern-Volmer model.Furthermore,the study explored how dissolved oxygen in seawater affects the coordination of DOM with these metal ions.The results identified two humic-like components(Cl and C2)and two protein-like components(C3 and C4)within the DOM of Zhoushan's coastal waters.It was observed that the humic-like components(Cl and C2)exhibited a higher propensity for coordinating with metal ions compared to the two protein-like components(C3 and C4).The stability of the coordination followed the order:Cu-DOM＞Fe-DOM＞Pb-DOM.In addition,an anoxic environment significantly inhibited the coordination ability of DOM with Fe3+,while the coordination ability of Cu2+ions was almost unaffected by dissolved oxygen concentration.These findings provide a scientific foundation for regulating and restoring seawater aquaculture systems.
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