[Three-dimensional excitation emission matrix fluorescence spectroscopic characterization of dissolved organic...

Three-dimensional excitation emission matrix fluorescence spectroscopy (3DEEM) was applied to characterize the fluorescence properties of dissolved organic matter (DOM) in lakes, rivers, streams, and ground waters. The results showed that the 3DEEM of DOM in aquatic environments mainly have four fluorescence peaks: peak A and C was referred to as fulvic-like fluorescence, and peak B and D was referred to as protein-like fluorescence. Results of river water DOM typically showed strong fulvic-like fluorescence. Polluted river waters often showed strong protein-like fluorescence. Four peaks were also found in the 3DEEM of lake DOM, which can origin from terrestrial runoff or from sources within the lakes. In Lake Baihua, strong protein-like fluorescence was found owing to the pollution by municipal wastewaters. Groundwater DOM has relatively lower DOC concentrations at 0.56-0.85 mg x L(-1) and is characterized by fulvic-like fluorescence only if it was polluted by municipal wastewaters, and then it has strong protein-like fluorescence. The authors demonstrate that for all DOM samples, fluorescence intensity at peak C and absorption at 254 nm both showed a strong correlation with DOC concentrations (r2 = 0.82 and 0.95, respectively). Also a strong linear correlation between UV-fulvic-like fluorescence and visible fulvic-like fluorescence was found (r2 = 0.96). The fulvic-like fluorescence at peak A and C varied in accordance to each other with the pH of the DOM samples, and the maximum fluorescence occurred at pH 10, while the maximum value of protein-like fluorescence (peak B) occurred at pH around 8.5.