| Petroleum and its products will cause serious pollution in the process of mining, refining, shipping and using. Planktonic algae as primary producers in marine ecology, its fate directly affects the healthy development of the food web. This article selects four kinds of microalgae, mainly adopts the cell count, MDA content and carbon and nitrogen stable isotope analysis technology, studies the toxic effects of petroleum dispersion and emulsion on four kinds of microalgae. The results are as follows:As for cell count, in the acute experiment, Heterosigam akashiwo is more sensitive; Compared with the sensitivity difference of single alaga, the 96h-EC50 value of Dis-WAF<WAF; In the subacute experiment, in low concentration (≤1mg/L), WAF stimulates the growth of Nitzschia closterium, while in relatively high concentrations(≥5mg/L), the growth of N.closterium is restrained, under the same concentration, effect of Dis-WAF is more stronger.As for MDA concent, in the acute experiment of Gymnodinium aerucyinosum, 96h-EC50 value of Dis-WAF>WAF. In the subacute experiment, the MDA content increased with time and concentration, it shows that both WAF and Dis-WAF could cause the membrane lipid peroxidation.As for carbon and nitrogen stable isotope composition, in the acute experiment, we measure the δ13C、δ15N value of three kinds of microalage, Using T test, We find that under different concentrations and time point, the experimental group make significant difference (P<0.05). In low concentration(<lmg/L), the δ13C、δI5N value of N.closterium is higher, while in high concentrations (≥5mg/L), result is opposite.To sum up, the oil spill pollution stress on the growth of microalgae, after joining chemical dispersants,the toxicity is enhanced; in addition to, oil spill pollution could change the carbon and nitrogen stable isotope composition of microalgae. Therefor the stable isotopic composition of microalgae may be used as an alternative method for oil pollution monitoring. |
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