Photochemical Fate of Lampricides in Tributaries of the Great Lakes
Christy Remucal
Civil and Environmental Engineering, University of Wisconsin-Madison
ABSTRACT: Lampricides have been intentionally added to tributaries of the Great Lakes since the 1950’s to kill the invasive parasitic sea lamprey. This direct application of lampricides into the Great Lakes ecosystem is in contrast to legacy contaminants and many chemicals of emerging concern. Despite the widespread and intentional use of lampricides TFM and niclosamide, their fate in the environment is poorly understood. Remucal performed laboratory experiments to assess the susceptibility of both compounds to direct and indirect photochemical degradation. While the direct photodegradation rates of TFM are orders of magnitude faster than those of niclosamide, both compounds eventually undergo dehalogenation during direct photolysis. The presence of dissolved organic matter increases the photodegradation rate of niclosamide through the production of a series of reactive oxidants. In contrast, TFM is not susceptible to indirect photolysis. In addition, Remucal conducted two field campaigns to quantify TFM photolysis during lampricide applications in 2015 and 2016. From these two field campaigns, it is illustrated that TFM in both small and large systems may enter the Great Lakes with minimal photodegradation, which has important implications for Great Lakes ecosystems.
