RESUMEN
Microtox solid phase test is an acute toxicity test for solid matrices based on inhibition of natural bioluminescence of the marine bacterium Vibrio fischeri. Protocols developed to overcome the effects of confounding factors are proposed in the literature that differs by important practical and methodological issues. This work focused on diluents used for sediment resuspension and dilution. Two artificial seawaters, one natural seawater and two phosphate buffer solutions, were compared. The results showed that toxicity data obtained using different diluents were not comparable and that test sensitivity is highest using 0.1M phosphate buffer solution. The effects of medium on test organism were also investigated, in order to verify the capacity of media to maintain bioluminescence. The results underlined the importance of pH and Eh to explain the observed differences in toxicity.
Asunto(s)
Aliivibrio fischeri/efectos de los fármacos , Medios de Cultivo/toxicidad , Contaminantes Químicos del Agua/toxicidad , Aliivibrio fischeri/fisiología , Bioensayo , Medios de Cultivo/química , Sedimentos Geológicos/química , Concentración de Iones de Hidrógeno , Concentración 50 Inhibidora , Luminiscencia , Mediciones Luminiscentes , Salinidad , Agua de Mar/química , Sensibilidad y Especificidad , Extracción en Fase Sólida , Factores de Tiempo , Pruebas de Toxicidad Aguda/métodos , Contaminantes Químicos del Agua/químicaRESUMEN
This work reports some considerations on the possible contribution of sulfide and ammonia to the toxicity of elutriate samples of sediments from the Venice lagoon, tested with a battery of bioassays using early life stages of the sea urchin Paracentrotus lividus and the oyster Crassostrea gigas. A comparison of ammonia or sulfide concentration in the test matrix, matrix toxicity, and the sensitivity limit of bioassays for ammonia or sulfide were used in evaluating toxicity data. Results highlighted that sperm cell and embryo toxicity of elutriates were not affected by sulfides. Neither was any direct relationship shown between elutriate toxicity and ammonia concentration. Most elutriates had ammonia concentrations below the sensitivity limit of acute test methods, while the more sensitive subchronic toxicity tests were affected by ammonia interference in some samples.