title: Influence of ionic strength on triplet-state natural organic matter loss by energy transfer and electron transfer pathways.
abstract: Triplet state excited natural organic matter chromophores ((3)NOM*) are important reactive intermediates in indirect photochemical processes, yet the impact of salt concentrations relevant to estuarine and marine environments on (3)NOM* is poorly understood. The formation rates, pseudo-first-order loss rate constants, and steady-state concentration of (3)NOM* were monitored using the sorbate probe method in synthetic matrices with increasing ionic strength (IS) to seawater values using seawater halides or other salts. The steady-state concentration of (3)NOM* approximately doubled at seawater IS, regardless of the salt used, due to a decrease in the (3)NOM* decay rate constant. The electron transfer-mediated degradation of 2,4,6-trimethylphenol (TMP) by (3)NOM* was significantly slowed at higher IS. A model is proposed wherein high IS slows intra-organic matter electron transfer pathways, an important (3)NOM* loss pathway, leading to longer (3)NOM* lifetimes. Although IS did not appear to impact energy transfer pathways directly, the higher (3)NOM* steady-state concentrations promote energy transfer interactions. The observed decrease in decay rate constant, increase in steady-state concentration of (3)NOM* at high IS, and the inhibition of electron transfer pathways should be considered when determining the fate of organic pollutants in estuarine and marine environments.
authors: Department of Chemical, Environmental Engineering, Yale University , Mason Lab 313b, 9 Hillhouse Avenue, New Haven, Connecticut 06520, United States.
authors: Kimberly M
authors: KM
authors: Parker
authors: Joseph J
authors: JJ
authors: Pignatello
authors: William A
authors: WA
authors: Mitch
mesh_terms: D001577:Benzophenones / Q000737:chemistry; D003408:Cresols / Q000737:chemistry; D004735:Energy Transfer; D005618:Fresh Water / Q000737:chemistry; D005663:Furans / Q000737:chemistry; D006812:Humic Substances; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D017319:Photosensitizing Agents / Q000737:chemistry; D012492:Salts / Q000737:chemistry*; D012623:Seawater / Q000737:chemistry*; D013011:Sorbic Acid / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: C530484:4-carboxybenzophenone; D001577:Benzophenones; D003408:Cresols; D005663:Furans; D006812:Humic Substances; D017319:Photosensitizing Agents; D012492:Salts; C012986:furfuryl alcohol; C505148:2,4,6-trimethylphenol; D013011:Sorbic Acid