Evaluating solid peroxide algaecides for sediment targeted preventative management of harmful algal blooms: Effect of prill size, water column depth and temperature

Solid-peroxide algaecides have been used to preventatively treat overwintering cyanobacteria in sediment prior to a bloom as well as active benthic harmful algal blooms (HABs). However, the effectiveness of these treatments hinges upon achieving appropriate exposures to the lake bottom where cells are located. This experiment evaluated the impacts of algaecide prill radii and an experimental coating as well as the environmental variables (e.g., water temperature and column depth) on settling and dissolution rates to develop predictive exposure models for benthic applications. Increased prill radii enhanced settling rates and decreased dissolution rates, while elevated water temperatures increased both settling and dissolution rates. The experimental coating was ineffective at delaying active ingredient release and resulted in increased settling rates. Predictive exposure models using settling and dissolution rates allow the estimation of lake bottom exposures, inform selection of appropriate benthic algaecides, provide a practical approach to adjust algaecide treatments, and can increase treatment efficacy across different aquatic systems.