Single And Joint Toxicity Effects Of Heavy Metals, TPT And PCP On Brachydanio Rerio (Zebrafish)

In this study, zebrafish was test organisms, and TPT, PCP, Cu²⁺, Cd²⁺ and Cr⁶⁺ were poisoning substances. The single and joint toxic effects of TPT, PCP, Cu²⁺, Cd²⁺ and Cr⁶⁺ on zebrafish were studied, including the BCF, physiological and biochemical and single and joint effects parameters. The results of experiments were summarized as follow:Firstly, the results showed that the 96 h-LC50 of TPT, PCP, Cu²⁺, Cd²⁺ and Cr⁶⁺ were 1.2313×10-2, 6.1195×10-2, 0.296, 17.719 and 64.636 mg/L, respectively. The safe concentration were 1.231×10-3, 6.120×10-3, 0.030, 1.772 and 6.463 mg/L, respectively. TPT and PCP were virulent substance, Cu²⁺ was high toxic substance, Cd²⁺ and Cr⁶⁺ were low toxic substances, the toxicity order of them was TPT>PCP>Cu²⁺>Cd²⁺>Cr⁶⁺. The types of joint effects of Cu-Cd, Cu-Cr, Cd-Cr and TPT-PCP to zebrafish were synergistic effect, antagonistic effect, synergistic effect and synergistic effect, respectively.Secondly, In poisoning substances exposure 7 days, the BCFs of zebrafish to TPT at 4.18, 6.27 and 8.36μg/L were 251±23.81, 291±30.35 and 321±19.27, respectively; to PCP at 20.00μg/L was 382.7±8.31; to Cu²⁺ at 0.01, 0.20 and 0.50 mg/L were 426.8±56.27, 316.9±39.42 and 214.9±41.33, respectively; to Cd²⁺ at 0.50, 4.00 and 5.00 mg/L were 1668.7±109.21, 720.5±31.64 and 697.1±69.51, respectively; to Cr⁶⁺ at 30.00 and 50.00 mg/L were 36.5±8.90 and 27.6±5.21, respectively. TPT, PCP, Cu²⁺ and Cd²⁺ were mild accumulation, and Cr⁶⁺ was no accumulation to zebrafish. The accumulation order of them was Cd²⁺>Cu²⁺≈PCP≈TPT>Cr⁶⁺.And thirdly, the SOD activity were induced under the TPT, PCP, Cu²⁺, Cd²⁺ and Cr⁶⁺ exposure 1days and 7 days; the POD activity were inhibited under the TPT, PCP, Cu²⁺, Cd²⁺ and Cr⁶⁺ exposure 1days and 7 days; the CAT activity were changed from inductive effects to inhibitive effects with the extended exposure time; the AChE activity were induced under the TPT, PCP, Cu²⁺and Cr⁶⁺ exposure 1days and 7 days, but the AChE activity were inhibited under the Cd²⁺ exposure 1days and 7 days. The inhibition order of enzyme were POD>CAT>SOD>AChE in TPT exposure 1 days; POD>AChE>CAT>SOD in medium-high concentration of PCP exposure 1days; CAT>AChE>POD>SOD in Cu²⁺ exposure 1days; POD>AChE>CAT>SOD in Cd²⁺ exposure 1days; CAT>POD>AChE>SOD in medium-high concentration of Cr⁶⁺ exposure 1days;The inhibition order of enzyme were POD>CAT>AChE>SOD in TPT exposure 7days; POD>SOD >CAT>AChE in PCP exposure 7days; POD>CAT>AChE>SOD in medium-high concentration of Cu²⁺ exposure 7days; POD>AChE>CAT>SOD in Cd²⁺ exposure 7days; POD>CAT>AChE>SOD in medium-high concentration of Cr⁶⁺ exposure 7days. TPT, PCP, Cu²⁺, Cd²⁺ and Cr⁶⁺ single stress on SOD, POD, CAT and AChE activities in zebrafish were changed markedly significantly. So SOD, POD, CAT and AChE can be used as the sensitive environmental toxicology parameter to monitor TPT, PCP, Cu²⁺, Cd²⁺ and Cr⁶⁺ in aquatic environment.Last but not least, TPT, PCP, Cu²⁺, Cd²⁺ and Cr⁶⁺ have significantly affects on CAT activity. Expose the longer and the effects more significantly. The exposure dose and CAT activity have parabolic linear correlation, and have significant dose-effect relationship. So zebrafish can be used as a biological indicator and CAT as physiological and biochemical indexes for water quality monitoring of TPT, PCP, Cu²⁺, Cd²⁺ and Cr⁶⁺ pollution.The study could provide the reference for the heavy metal and organic pollution on the aquatic organism's toxicity mechanism.