Effects of tetracycline on copper and zinc toxicity and accumulation in Chlorella sp.
Livestock wastewater contains pollutants such as heavy metals and antibiotics.To clarify the potential of microalgae to clean up such wastewater with combined pollution,it is necessary to systematically study the joint toxicity of antibiotics and heavy metals on microalgae and the effects of antibiotics on heavy metal accumulation.As such,Chlorella sp.was exposed to 4-day treatments of two heavy metals-copper(Cu)and zinc(Zn),and antibiotics-tetracycline(TC),which are typical pollutants found in livestock wastewater.We measured the algal growth,chlorophyll contents,and fluorescent substances in extracellular polymeric substances(EPS)and the removal,adsorption,and absorption of Cu and Zn by Chlorella sp.The results showed that Cu(0.1,0.5,and 1 mg/L)and Zn(0.5 and 5 mg/L)inhibited the algal growth and chlorophyll synthesis and induced the secretion of EPS fluorescent substances.In contrast,TC(1,5,and 10 mg/L)did not inhibit the growth of the Chlorella sp.,alleviated the toxicity of Cu and Zn to the algae,and reduced the fluorescent intensity of tyrosine protein-like substances in the algal EPS.There are differences in the effects of TC on Cu and Zn removal rates.Under the single Cu treatment,the Cu removal rate by Chlorella sp.was 25.9％.It increased significantly to 43.5％under the combined treatment of TC and Cu for one day.However,the coexistence of TC and Zn did not influence the Zn removal rate by the algal cells.Meanwhile,TC affected the Cu and Zn accumulation pattern by Chlorella sp.Upon the single treatment of Cu and Zn,the adsorption ratio in the accumulation of Cu and Zn was 16.89％and 51.6％,respectively.After adding TC,these values increased to 44.49％and 86.73％.In summary,TC changed the accumulation pattern of Cu and Zn and promoted the removal of Cu by Chlorella sp.by increasing the extracellular adsorption of Cu and Zn,and alleviated the toxicity of Cu and Zn to algal cells by reducing the intracellular absorption of Cu and Zn.
NETL
NSTL
万方数据
