Quantum Yields for the Formation of Reactive Intermediates from Dissolved Organic Matter Samples from the Suwannee River

Photochemical properties of dissolved organic matter (DOM) are of interest due to their effects on natural and engineered systems, including the fate and transport of organic contaminants and pathogen inactivation. DOM absorbs energy and produces different reactive intermediates (RI), including the hydroxyl radical (HO center dot), singlet oxygen (O-1(2)), and excited triplet states ((DOM)-D-3*). Recently, a new set of DOM samples, including natural organic matter (NOM), the hydrophobic organic acid fraction (HPOA), and the transphilic acid fraction (TPIA) from the Suwannee River, were collected. Apparent quantum yields for the formation of HO center dot, O-1(2), and (DOM)-D-3* were measured for DOM samples using a solar simulator. Values were 2.09-4.20x10(-4) for triplet states, 2.74-6.54x10(-2) for singlet oxygen, and 0.95-1.65x10(-5) for hydroxyl radical for the different samples. In addition, fluorescence quantum yields were measured with obtained values between 0.79-1.3x10(-2). In some cases, values obtained were different from older DOM samples, indicating potential changes in properties of DOM in the Suwannee River over time.