| The East China Sea is an important oil exploration and development area in china.Pinghu,Chunxiao and other production platforms have been completed and put into operation for many years.Oil transportation between the platform and the landing point depend on the submarine pipeline.As the submarine pipeline of Pinghu oil drilling platform were damaged by typhoon and sheared off at about 26 km from the Daishan landing point.In order to evaluate the damage of marine organisms after the oil spill caused by the light crude oil produced in the East China Sea,the differences between the chemical components between the Donghai light crude oil and the water accommodated fraction(WAF)were analyzed and compared.The toxic effects of one-off oil spill,persistent oil spill and WAF on marine organisms were simulated under laboratory conditions and the 96 h semi-lethal concentration and safety threshold of four marine organisms were obtained.Tried to provide some reference data for quantitative assessment of damage to marine ecological environment caused by Donghai light crude oil.The main contents are as follows:1、The total petroleum hydrocarbon concentration change of Donghai light crude oil and WAF was determined by UV Spectrophotometry in order to understand the change of the concentration of Donghai light crude oil spill in sea and the change of WAF concentration.The results show that the concentration of total petroleum hydrocarbons of Donghai light crude oil in the seawater will decrease significantly in a short time,it decreased 80% in the 24 h.Each time the WAF solution prepared by mechanical agitation,the initial total petroleum hydrocarbon concentration is different,generally about 20mg/L.The total petroleum hydrocarbon concentration in the WAF will decrease significantly at 48 h,and then stabilized.The changes of n-alkanes in the Donghai light crude oil and WAF components were determined by gas chromatography-mass spectrometry(GC-MS).The results show that the types and concentrations of n-alkanes in WAF solution after mechanical stirring are lower than those in crude oil.But the proportion of polycyclic aromatic hydrocarbons in the WAF increases.2、The 96 h acute toxicity test were conducted on Mugil.cephalus,Ealaemon.carinicauda,Sinonovacula constrzcta,Ruditapes.philippinarum with one-time delivery,continuously dropping crude oil and WAF respectively.The experimental results are as follows:1)The 96 h LC50(95% confidence interval)of the Donghai light crude oil to M.cephalus,E.carinicauda,R.philippinarum,S.constrzcta respectively was: 865mg/L(527~1221 mg/L)、343mg/L(263~421 mg/L)、5221mg/L(881~8386 mg/L)和 2441mg/L(446~3736 mg/L).The safety thresholds were: 86.5 mg/L、34.3 mg/L、522.1 mg/L、244.1 mg/L.2)The 96 h LC50(95%confidence interval)of the WAF to M.cephalus,E.carinicauda,R.philippinarum,S.constrzcta,respectively was: 1.697mg/L(1.155~2.493 mg/L)、0.645mg/L(0.401~0.980 mg/L)、5.783mg/L(2.038~6.824 mg/L)、4.535mg/L(2.821~8.879 mg/L).The safety thresholds were 0.1484mg/L、0.0645 mg/L、0.5783 mg/L 、0.4535mg/L.3)Using 96 h LC50 as the criterion,the tolerance order of M.cephalus,E.carinicauda,S.constrzcta,R.philippinarum in Donghai light crude oil and WAF were,R.philippinarum > S.constrzcta > M.cephalus t> E.carinicauda.For the same marine organism,the 96 h LC50 value of WAF is significantly smaller than the 96 h LC50 value of Donghai light crude oil,that is,the toxicity of WAF is greater than crude oil.4)Through the continuously dropping Donghai light crude oil,sea surface will have obvious oil film exists,even if the Donghai light crude oil has strong volatility.There was a correlation between the thickness of the oil film and the mortality of R.philippinarum,S.constrzcta.3、The changes of superoxide dismutase activity and lipid peroxidation in muscle tissue of E.carinicauda under acute toxicity were investigated.The changes of SOD activity and MDA content in muscle tissues of E.carinicauda were studied in 96 hours under the condition of acute toxicity of Donghai light crude oil and WAF.The experimental results are as follows:1)The activity of SOD in E.carinicauda was significantly increased with the increase of the concentration of Donghai light crude oil.Under the stress of the Donghai light crude oil(0.077 g/L,0.153 g/L,0.230 g/L,0.306 g/L),SOD activity increased with time,but at the highest concentration(0.383g/L),SOD activity increased with time and then increased,the highest value was appeared at 48 h.Under WAF stress,the activity of SOD was gradually increased with the increase of WAF concentration.Under the stress of WAF(0.21 mg/L,0.44 mg/L),the change of SOD activity was similar to the change that under the crude oil stress,the SOD activity were rising over the time.Under the concentration of 0.89 mg/L and 1.77 mg/L,SOD activity declined gradually after reaching the highest value at 24 h.2)With the increase of the concentration of Donghai light crude oil and WAF,the MDA content increased.And the MDA content under all concentration of Donghai light crude oil and WAF were rising over the time. |
