The toxicity of brass dust to the microalgae Ankistrodesmus falcatus and Selenastrum capricornutum

Abstract

The toxicity of brass dust was examined by conducting 96 h growth inhibition tests. Two species of algae were used, Ankistrodesmus falcatus (EC50 = 0.316 mg brass/l) and Selenastrum capricornutum (EC50 = 0.056 mg brass/l). Brass dissociates into two components, Cu (68.5%) and Zn (27.5%). Enhanced algal growth was exhibited at concentrations of 0.01 and 0.001 mg brass/l. Available literature on the toxicity of copper to S. capricornutum (EC50 = 0.047 mg Cu/l), indicate that the toxicity of brass dust is due to the ionized copper. Reported toxicities of zinc are orders of magnitude lower than copper. The ionization of the brass is dependent on pH and hardness. The literature cites cases in which copper toxicity varies with pH, clay content and dissolved organics. At present little is known of the fate and distribution of brass dust upon the release into the environment. However, the presence of heavy metals has consistently been shown to impact aquatic systems.