Toxicity in semiarid sediments influenced by tailings of an abandoned gold mine.

The mining district of El Triunfo (ET-MD) has an estimated 800,000 t of mine wastes scattered in the environment, contaminating the sediment with potentially toxic elements such as As, Cd, Pb, and Zn. In order to estimate the toxicity of the sediment to the adjacent biota, the aims of our study are to calculate the mortality and inhibition through bioassays, using sediment, and test organisms such as Daphnia magna and Selenastrum capricornutum (Pseudokirchneriella subcapitata), respectively. The D. magna mortality was 31 ± 12% and the S. capricornutum growth inhibition was 53 ± 24%. The contamination of the sediment determines the high mortality of D. magna and the high inhibition of S. capricornutum in the system, indicating risk for the biota in the contaminated system.