Protective effect of biological iron sulfide composites against chromium (Ⅵ)pollution in zebrafish
Chromium pollution has become a worldwide environmental problem.This paper reports our studies of the feasibility and effect of using biological iron sulfide composites (BISC) to protect Cr6+-exposed fish,aimed at Cr6+ polluted water.After determining the median lethal dose (LC50) of Cr6+ in zebrafish,we studied the treatment effect of BISC on soluble Cr6+.Furthermore,we studied the effect of dosing ratio and time of BISC and pH of the water on the protection of zebrafish in Cr6+ polluted water.The results showed that in the 79.30 mg/L (24 h-LC50) Cr6+-polluted water (natural pH =6.98),BISC treatment apparently reduced the concentration of soluble Cr6+.When the dosing ratio of BISC was 3,Cr6+ was removed quickly,and the maximum removal ratios were achieved,which were 81.85％ in 15 min and 99.99％ in 96 h.The survival rate of zebrafish increased in a dosing ratio-dependent manner while it reduced in a dosing time-dependent manner.The optimal dosing ratio of BISC was 0.5 and the optimal dosing time was 0-4 h,which increased the survival ratio of the zebrafish by more than 90％.In addition,BISC dosed at 24 h,increased the survival ratio of zebrafish to three times of the normal ratio after 96 h.In the Cr6+-polluted water with a pH range of 6-9,BISC apparently protected the zebrafish and increased their survival ratio.Moreover,the protective effect of BISC was enhanced with the reduction in pH.Therefore,BISC significantly protected the zebrafish in Cr6+polluted water,suggesting its wide application potential in Cr6+ pollution emergencies.
heavy metal pollutionbiological iron sulfideCr6+zebrafishprotective effect
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