Doctor of Philosophy (PhD)
Current regulatory assessments of organic chemicals, including pesticides and polycyclic aromatic hydrocarbons, often exclude the effects of variables important to their environmental fate. While evaluating the potential of a chemical to degrade photochemically and hydrolytically is commonly required by these assessments (e.g., pesticide registration), the effects of salinity on these processes are often not considered. Similarly, the impacts of salinity on the partitioning of aqueous organic contaminants to adjacent environmental compartments (e.g., biota and soil) are poorly understood. These knowledge gaps make it difficult to predict the behavior and potential toxic effects of organic chemicals released into estuarine/marine ecosystems. The purpose of this dissertation was to better understand the influence of salinity on the degradation and partitioning behavior of organic chemicals in aquatic systems to account for differences in their overall fate in marine vs freshwater environments. Salinity appeared to play a significant role in both the degradation and partitioning behavior of the majority of the compounds included in this dissertation. Many of the effects of salinity on chemical behavior observed in this dissertation may cause a chemical to become more toxic to aquatic organisms. For instance, salinity enhanced the persistence of multiple organic chemicals, which could result in increased chemical exposure times to aquatic organisms and subsequently impact their potential toxic effects to these organisms. Moreover, salinity significantly enhanced the partitioning of five toxic pesticides to capelin egg tissues, suggesting that it can also increase the partitioning propensity of aqueous organic contaminants to adjacent organic compartments (e.g., tissues of aquatic organisms). This dissertation emphasizes the importance of considering salinity effects in regulatory environmental fate assessments of organic contaminants and highlights the need to account for these effects when evaluating chemical risk to estuarine/marine organisms.
St Romain, Scott, "Impacts of Salinity on the Environmental Fate of Hydrophobic Organic Contaminants in Water" (2023). LSU Doctoral Dissertations. 6157.
Available for download on Wednesday, May 15, 2030