PH06 Agrochemicals, Pesticides, Pharmaceuticals
Exhibit Hall
8:00 AM - Thursday
(PH061) Comparative Toxicity of Two Copper Containing Algaecides to Three Algal Species.
Duke, B.1, Rodgers, J.1, 1 Clemson University, Clemson, SC, U.S.A.
ABSTRACT- The toxicity of copper to vascular and nonvascular aquatic plants is affected by various physiochemical attributes of site water, including hardness, alkalinity, pH, and ionic strength as well as the initial form of copper. For this study, responses of algal species (Synura sp., Cosmarium sp., Anabaena circinalis) to exposures of two chelated copper algaecides (Cutrine®-Plus and Cutrine®-Ultra) were observed. Specific objectives of this study were: 1) to compare the toxicities of two copper-containing algaecides to three different species of algae, and 2) to compare the performance of these algaecides in waters with different characteristics. The characteristics of interest for this study included pH, alkalinity, hardness and algal density. Alkalinity and hardness ranged from 48 to 86 mg / L as CaCO3, and 94 to 122 mg / L as CaCO3, respectively. The pH of these waters ranged from 7.81 to 8.89 SU. Algal densities in each water sample were 1.9 x 105, 7.8 x 104, and 1.38 x 106 cells / ml, and the dominant algal taxa were Synura sp., Cosmarium sp. and Anabaena circinalis, respectively. Algal control (loss of algae from the water column) was obtained at 0.4 mg Cu / L of Cutrine®-Plus for two species. Control of Synura sp. was obtained at 1.0 mg Cu/ L of Cutrine®-Plus. For Cutrine®-Ultra, algal control was obtained at 0.4 mg Cu / L for all algae, except for Synura sp. Control of Synura sp. was not obtained using 1.0 mg Cu / L of Cutrine®-Ultra (the label permitted limit). These algal species illustrated differing responses to forms or species of copper in site waters. Risk-based decisions to use copper-containing algaecides are facilitated when the target algal species (e.g. Anabaena circinalis) produce a potent toxin.
Key words: copper, Toxicity, algaecide, Comparative