Relationship between dissolved organic matter and heavy metals in surface water of typical metal mining areas in southern china

Mining activities have significantly impacted the water ecological environment, but few studies have shown the relationship between dissolved organic matter (DOM) and heavy metals. We were selected the surface water and shallow groundwater around metal mines in southern Anhui Province (China) as the research objects and explored the content characteristics of hydrochemical parameters and heavy metals and the optical characteristics of DOM. The results showed that both surface water and groundwater were weakly alkaline, and the chemical types of surface water and groundwater are CaHCO3 and Mg-HCO3, respectively. The total fluorescence intensity of the five fluorescence peaks (Peak A, B, C, M, and T) in groundwater was significantly lower than that in surface water and mine drainage. Fluorescence excitation-emission (EEM) spectrophotometry coupled with parallel factor analysis (PARAFAC) revealed humic-like components (C1, C2, and C3) and protein-like components (C4). The content of seven heavy metals (Cr, Cu, Ni, Zn, As, Cd, and Pb) in surface water and groundwater did not exceed China's drinking water hygiene quality standards. The co-occurrence network analysis showed a relationship between the humification of DOM, protein-like component (C4), and heavy metals.