title: Role of dissolved organic matter in ice photochemistry.
abstract: In this study, we provide evidence that dissolved organic matter (DOM) plays an important role in indirect photolysis processes in ice, producing reactive oxygen species (ROS) and leading to the efficient photodegradation of a probe hydrophobic organic pollutant, aldrin. Rates of DOM-mediated aldrin loss are between 2 and 56 times faster in ice than in liquid water (depending on DOM source and concentration), likely due to a freeze-concentration effect that occurs when the water freezes, providing a mechanism to concentrate reactive components into smaller, liquid-like regions within or on the ice. Rates of DOM-mediated aldrin loss are also temperature dependent, with higher rates of loss as temperature decreases. This also illustrates the importance of the freeze-concentration effect in altering reaction kinetics for processes occurring in environmental ices. All DOM source types studied were able to mediate aldrin loss, including commercially available fulvic and humic acids and an authentic Arctic snow DOM sample isolated by solid phase extraction, indicating the ubiquity of DOM in indirect photochemistry in environmental ices.
authors.affiliation: Department of Chemistry, Villanova University , Villanova, Pennsylvania 19085, United States.
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Grannas
authors.forename: Lisa P
authors.initials: LP
authors.lastname: Pagano
authors.forename: Brittany C
authors.initials: BC
authors.lastname: Pierce
authors.forename: Rachel
authors.initials: R
authors.lastname: Bobby
authors.forename: Alexis
authors.initials: A
authors.lastname: Fede
mesh_terms: D000452:Aldrin / Q000737:chemistry; D004777:Environment; D006812:Humic Substances / Q000032:analysis; D007053:Ice / Q000032:analysis*; D007700:Kinetics; D009930:Organic Chemicals / Q000737:chemistry*; D055668:Photochemical Processes; D010782:Photolysis; D017382:Reactive Oxygen Species / Q000737:chemistry; D012995:Solubility; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D006812:Humic Substances; D007053:Ice; D009930:Organic Chemicals; D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D000452:Aldrin