Remediation And Response Of Screened Marine Organisms To Petroleum Hydrocarbons

Oil spill accidents occur frequently in the process of oil exploitation and transportation around the world,which showing negative effects on marine ecological environment,social economy and human health,thus oil pollution has become one of the most serious marine environmental problems.Bioremediation of contaminated environment has been popularly applied due to its effective,environment friendly and low cost.In the present study,the removal characteristics of petroleum hydrocarbons by three microalgaes,four macroalgaes and three shellfish were investigated,meanwhile,the effects of petroleum hydrocarbons on these organisms were also measured for screening valuable marine organisms to remove petroleum hydrocarbons in seawater.The results can be beneficial to provide a novel method for the management of offshore oil pollution.The main contents of the dissertation are as follows:1?Removal capacity and response of three microalgaes to petroleum hydrocarbons(1)The removal rates of petroleum hydrocarbons in seawater by Nannochloris oculata,Skeletonema costatum,Alexandrium tamarense decreased with increasing the concentrations(2?4?6mg/L)petroleum hydrocarbons,and the removal rates could be achieved to 98.58%~99.95%.(2)When the concentration of petroleum hydrocarbons was lower than 2 mg/L,the growths,chlorophyll a content and activity of SOD of the three microalgae were no differences from those of the control group.(3)Growths of the three microalgaes were inhibited when the exposure concentration of petroleum hydrocarbons were higher than 4 mg/L,especially the growth of N.oculata,A.tamarense were completely inhibited when the concentration of petroleum hydrocarbons reached to 6 mg/L.The chlorophyll a contents and activity of SOD for higher exposure concentrations were lower than those for the control group and the 2 mg/L group,indicating that the three microalgaes were damaged at higher concentrations of petroleum hydrocarbons.(4)No inhibitory effect of petroleum hydrocarbons(lower than 2mg/L)on the growths of N.oculata,S.costatum,A.tamarense in seawater.Moreover,the three microalgaes show strong ability to remove petroleum hydrocarbons,which can be employed as a valuable tool for bioremediation applications.2?Removal capacity and response of four macroalgaes to petroleum hydrocarbons(1)The petroleum hydrocarbons(0.8,1.7,2.6,3.6,4.5 mg/L)could be removed by Saccharina japonica,Undaria pinnatifida,Grateloupia turuturu and Ulva pertusa in seawater.Moreover,the removal rates declined with rising the concentrations of petroleum hydrocarbons except for the groups that S.japonica and U.pinnatifida exposed to 2.6 mg/L.(2)The various effects of petroleum hydrocarbons on the SOD activity of S.japonica and U.pinnatifida have been observed at different concentrations.The SOD activity of S.japonica and U.pinnatifida could be significantly promoted during the first 4 days under the stress of low concentration(?1.7mg/L)and medium concentration(2.6mg/L).After 5 days,the SOD activity of the groups at low concentration recovered to the level of the control group,while the SOD activity of the groups at medium concentration were higher than that of the control group.In addition,the SOD activity of S.japonica and U.pinnatifida under the stress of high concentration(?3.6mg/L)was obviously lower than that of the control group during the experiment(4~5 days).(3)The influences of petroleum hydrocarbons on the growths of S.japonica and U.pinnatifida were insignificant when the concentration lower 1.7 mg/L.The ramoval rates of petroleum hydrocarbons for S.japonica and U.pinnatifida were 76.3~81.3% and 82.2~87.5%,respectively.The removal capacity of petroleum hydrocarbons for S.japonica and U.pinnatifida was much better than that for G.turuturu and U.pertusa,suggesting that Saccharina japonica and Undaria pinnatifida could be used to remove petroleum hydrocarbons in a certain concentration range in seawater.3?Accumulation and elimination of petroleum hydrocarbons in three shellfish(1)The petroleum hydrocarbons(0.8,1.6,2.4,3.2,4.0 mg/L)could be significantly accumulated by three shellfish,and the bioaccumulation factors(BCF)for Meretrix petechialis,Ruditapes philippinarum and Mytilus coruscus were 17.38~35.75,25.58~65.38,34.47~88.13,respectively.Furthermore,the BCF for R.philippinarum and M.coruscus declined with the increase of concentration of petroleum hydrocarbons in seawater.The bioaccumulation ability of petroleum hydrocarbons was in the order of M.coruscus > R.philippinarum > M.petechialis.(2)The results of elimination experiment showed that the concentration of petroleum hydrocarbons in M.petechialis,R.philippinarum and M.coruscus could not be restored to normal levels under the stress of higher concentrations(?2.4 mg/L).The elimination rates of petroleum hydrocarbons for M.petechialis,R.philippinarum and M.coruscus were 48.68~58.97%,40.66~62.85%,and 60.38~68.87%,respectively.(3)The accumulation rates of petroleum hydrocarbons for M.petechialis,R.philippinarum and M.coruscus were 2.86~7.86 mg/kg/d,5.23~10.23 mg/kg/d and 7.05~14.68 mg/kg/d,while the elimination rates were 1.97~4.66 mg/kg/d,2.91~8.67 mg/kg/d and 3.81~6.53 mg/kg/d,respectively.The accumulation rates and elimination rates increased with increasing the concentration of petroleum hydrocarbons in seawater,and the accumulation rate of petroleum hydrocarbons was higher than the elimination rate.(4)After the accumulation experiment,when the petroleum hydrocarbons oncentration was lower than 2.4 mg/L,the content of petroleum hydrocarbons in M.petechialis meets the second class standard of ‘Marine Biomass Quality'(GB18421-2001),while the content of petroleum hydrocarbons in R.philippinarum meets the third class.The content of petroleum hydrocarbons in M.petechialis meets the third class standard of ‘Marine Biomass Quality'(GB18421-2001)for the stress of petroleum hydrocarbons concentration was lower than 4 mg/L.The content of petroleum hydrocarbons in M.coruscus meets the third standard of Marine Biological Quality(GB18421-2001)which exposed to the petroleum hydrocarbons concentration was lower than 0.8 mg/L.Thus,M.petechialis,R.philippinarum,M.coruscus could be used to remove petroleum hydrocarbons in a certain concentration range in seawater.In conclusion,N.oculata,S.costatum and A.tamarense could excellently remove petroleum hydrocarbons when its concentration was lower than 2 mg/L.Meanwhile,the results of this study showed that S.japonica and U.pinnatifida have good efficiencies in removing petroleum hydrocarbons when its concentration was lower than 1.7 mg/L.Furthermore,M.coruscus could considerably remove petroleum hydrocarbons in seawater.