Study On The Toxicity And Mechanisms Of Several Dyes To Aquatic Organisms

Dyes, which have been widely used in food, pharmaceutical, cosmetic, textile, leather and many other industries. Lots of dyes were emitted into the aquatic environment during use. Printing and dyeing wastewater affect the aquatic organisms directly or indirectly and the entire aquatic environment account for its complex composition, no good biochemical quality and full of harmful substance. In order to investigate the effects and mechanism of dyes on the aquatic ecosystems and accurately assess the ecological risks caused by dyes, this research chose some dyes as target compounds, used Daphnia magna, Chlorella pyrenoidosa(green algae) and Microcystis flos-aquae(cyanobacteria) as tested subjects, investigated the mechanism of Daphnia magna and freshwater microalgae in response to dyes stress by determining the growth, physiological and biochemical characteristic, photosynthetic activity of Daphnia magna and two microalgaes. The results indicated:(1) The results obtained that Disperse Violet HFRL 48 h-LC50 values for Daphnia magna in the experimental conditions were 177.93 mg/L(95% CI is 133.23~279.60 mg/L), not acutely toxic,Disperse Orange S-4RL 24 h-LC50 and 48 h-LC50 were 0.05 mg/L and 0.03 mg/L(95% CI is 0.04~0.07 and 0.02~0.03 mg/L), very acutely toxic. Same results concerning evaluation of the joint toxicities were obtained through TU, AI, MTI and TEI: with the expansion of the concentration of Disperse Orange S-4RL, the joint toxic effects turn to antagonistic from weak synergistic.(2) There will have an impact on the influence of growth and reproduction to Daphnia magna with the concentration of Disperse Orange S-4RL increasing as the 14 days chronic toxicity test. Different indexes have different sensitivities:breed> time of first child= embryo number>body length>intrinsic rate of increase. In the experimental composition range, Disperse Orange S-4RL can induce oxidative injury of Daphnia magna. It turns out that SOD increased when Daphnia magna exposed to low concentration and SOD reduce at higher concentration of dye. CAT activity of Daphnia magna was unchanged at all test concentrations(p>0.05) and all test concentrations alter lipid oxidation. We can see that gills and abdomen are the main sources of ROS induced by oxidative stress in Daphnia magna cells from confocal fluorescence images of DCF in Daphnia magna and ROS increase as the increase of exposing concentrations.(3) Disperse Orange S-4RL had shown a "low concentrations promotion and high concentrations inhibition" phenomenon on the growth of Chlorella pyrenoidosa and Microcystis flos-aquae. Enzyme activity and MDA responses varied across different kinds of microalgae. It turns out that SOD level increased as the increase of Disperse Orange S-4RL concentration on Chlorella pyrenoidosa, but no impact on Microcystis flos-aquae under the given concentrations. CAT level of two kinds of microalgae increases and later decreases as the increase of Disperse Orange S-4RL concentration and all test concentrations alter lipid oxidation.(4) After exposure to Disperse Orange S-4RL, the chlorophyll a content of Chlorella pyrenoidosa was increased and later decreased while Microcystis flos-aquae was decreased as the increase of Disperse Orange S-4RL concentration. Fv/Fm, Fv/F0 and ? remained unchanged(p>0.05). This illustrates that Disperse Orange S-4RL has little effect upon the PSII transformation efficiency of the original light, PSII potential activation and efficiency of light energy utilization. ETRmax and Ik increase with the increase of Disperse Orange S-4RL and this illustrates that Disperse Orange S-4RL has a effect upon photosynthesis and the tolerance of light.