Chloramination is being used increasingly in water treatment to lower the formation of regulated disinfection byproducts (DBPs). How monochloramine nitrogen becomes incorporated into aquatic natural organic matter (NOM) and potentially affects the formation of nitrogenous DBPs is an unresolved question in the chemistry of humic substances. To address the problem, Suwannee River NOM and Suwannee River fulvic acid were reacted with preformed 15NH2Cl and analyzed by solid and liquid state 15N NMR spectrometry. Both samples were also reacted with 15NH4Cl as a control. A majority of the monochloramine nitrogen incorporated into the samples matched the structural forms resulting from the control reaction with ammonia, indicating that condensation reactions of ammonia with the carbonyl functionality can partly explain the transformation of the 15NH2Cl nitrogen into the NOM. These structural forms include aminohydroquinone, 1° amide, indole, and pyridine-like nitrogens. Spectra of the samples reacted with 15NH2Cl also showed possible evidence for nitrosophenol nitrogens, which would arise from the reaction of hydroxylamine or nitrite, intermediates in the chemical oxidation of the inorganic nitrogen to nitrate.
|Title||Nitrogen-15 NMR study on the incorporation of nitrogen into aquatic NOM upon chloramination|
|Authors||Kevin A. Thorn|
|Publication Subtype||Journal Article|
|Series Title||Aquatic Sciences|
|Record Source||USGS Publications Warehouse|
|USGS Organization||WMA - Earth System Processes Division|