Environmental Chemistry and Technology Program, University of Wisconsin - Madison, Madison, Wisconsin, USA.
Environ Sci Process Impacts. 2017 Aug 16;19(8):1028-1039. doi: 10.1039/c7em00208d.
3-Trifluromethyl-4-nitrophenol (TFM) and 2',5-dichloro-4'-nitrosalicylanilide (niclosamide) are lampricides used in tributaries of the Great Lakes to kill the invasive parasitic sea lamprey (Petromyzon marinus). Although the lampricides have been applied since the late 1950s, their photochemical behavior in natural environments is still not well understood. This study examines the indirect photodegradation of these two compounds and the resulting yields of organic and inorganic photoproducts in water samples collected from five tributaries of Lake Michigan. The tributaries were selected to span the length of Lake Michigan and its natural carbonate geologic gradient. In the presence of dissolved organic matter (DOM), the niclosamide photodegradation rate triples, while the rate of TFM photodegradation is unchanged. Additionally, the yield of lampricide organic products is influenced by DOM because many of the organic photoproducts themselves are prone to DOM-mediated indirect photodegradation. The indirect photodegradation of niclosamide is primarily mediated by reaction with singlet oxygen, which accounts for more than 50% of the increased photodegradation rate. Additionally, hydroxyl radicals and carbonate radicals (CO˙) influence niclosamide indirect photolysis, and their contribution is dependent on the specific river water chemistry. For example, CO˙ contribution to niclosamide photodegradation, while small, is greater in southern tributaries where there is higher carbonate alkalinity.
3-三氟甲基-4-硝基苯酚（TFM）和 2'，5-二氯-4'-硝基水杨酰苯胺（灭虫脒）是用于大湖支流的灭lampricide，用于杀死入侵的寄生性海lamprey（Petromyzon marinus）。尽管自 20 世纪 50 年代末以来一直在使用这些灭lampricide，但它们在自然环境中的光化学行为仍未得到很好的理解。本研究考察了这两种化合物的间接光降解以及从密歇根湖五个支流采集的水样中有机和无机光产物的生成。选择支流来跨越密歇根湖及其天然碳酸盐地质梯度的长度。在溶解有机物（DOM）存在下，灭虫脒的光降解速率增加了两倍，而 TFM 的光降解速率不变。此外，DOM 还影响lampricide 有机产物的产量，因为许多有机光产物本身容易受到 DOM 介导的间接光降解。灭虫脒的间接光降解主要是通过与单线态氧反应来介导的，单线态氧占增加的光降解速率的 50%以上。此外，羟基自由基和碳酸盐自由基（CO˙）也会影响灭虫脒的间接光解，其贡献取决于特定的河水化学性质。例如，CO˙对灭虫脒光降解的贡献虽然很小，但在碳酸盐碱度较高的南部支流中更大。
