Toxicity Evaluation Using Fish And Other Aquatic Organisms

The toxic effect of single chemical substance, i.e. tetrabromobisphenol A (TBBPA), Cd2+and Sodium dodecyl benzene sulfonate (SDBS), on fish swimming behavior was investigated, using three selected small fresh water fishes via3D-biosensor. Subsequently, a battery of toxicity test was conducted to evaluate the toxicity profile of coking wastewater and the toxicity reduction by vertical tubular biological reactor (VTBR) treatment process.Firstly, the bio-toxicity of Cd2+, as well as SDBS, was investigated using three selected small fresh water fishes (Zebra fish, Japanese medaka and Red carp) to study whether the local fish can be used as test organism for behavior toxicity test. The results showed that the sensitivity order of three fishes to Cd2+was Japanese medaka>Zebra fish>Red carp, and to SDBS was Zebra fish>Red carp>Japanese medaka. It can be concluded that, to different substances, the sensitivity of three kinds of fishes may be different; the Red carp, one of the native fish species in China, was found to be suitable to indicate the water quality changes as the other two fish reference species.Secondly, the biotoxicity effect of TBBPA on swimming behaviors of Zebra fish (Danio rerio) was investigated, to study the emerging contaminant toxicity using the selected model fish. The results showed that, there were no significant changes of swimming behaviors when the Zebra fish was exposed to low concentration (2mg/L) of TBBPA; however, when exposed to the middle concentrations (5to10mg/L), the swimming speed increased first and then decreased, and the fish trended to swim in the upper layer. Furthermore, when exposed to a high concentration (100mg/L), the swimming speed of Zebra fish decreased immediately and the fish trended to stay in the bottom layer. Swimming behaviors (swimming speed and vertical position) were illustrated to be more sensitive than the traditional acute toxicity test.Lastly, the whole effluent toxicity (WET) profile and the toxicity reduction of coking wastewater by VTBR treatment process were evaluated using a battery of toxicity test. The results showed that, VTBR reduced the acute toxicity of coking wastewater significantly: toxicity unit (TUa) for Lux bacteria (Photobacterium phosphoreum) decreased from21.2to0.4, TUa for Alga (Isochrysis galbana) from9.5to0.6, TUa for Daphnia (Daphnia magna)from31.9to1.3, and TUa for Zebra fish (Danio rerio)from30.0to nearly0; the sensitivity of the organisms was Daphnia>Zebra fish>Lux bacteria>Alga. This suggested that the monitoring of fish behavior will have a good application prospect in water ecotoxicity test; Daphnia magna seemed to be the most sensitive organism to coking wastewater according to the result of a battery of toxicity test, and the sensitivity of the organisms was Daphnia>Zebra fish>Lux bacteria>Alga; VTBR can reduce chemical pollutants and acute bio-toxicity effectively and it was proved to be a promising alternative treatment process for the refractory industrial wastewater. Our results can provide basic data and test basis to toxicity evaluation of wastewater or polluted water.