Wang Jian, Zhang Xu, Li Guang-He
School of Environment, Tsinghua University, Beijing 100084, China.
Huan Jing Ke Xue. 2012 Apr;33(4):1352-60.
The aims of this study were to determine the rate of degradation of crude oil in soil, to reveal the fingerprints of residual oil after long-term biodegradation, and to screen parameters for evaluation of the biodegradability residual oil. A total of 18 contaminated soil samples containing heavily degraded crude oil residuals from Daqing, Shengli and Baise oilfields were analyzed. More than 100 individual target compounds including straight-and branched-chain alkanes (n-alkanes, pristane and phytane), polycyclic aromatic hydrocarbons (PAHs), terpanes, steranes and triaromatic steranes (TAS) in residual oil were determined by gas chromatography-mass spectrometry (GC-MS). For all the soil samples, less than 10% and 30% of alkanes and PAHs remained in the residual oils relative to crude oils. Terpanes, steranes and TAS were found to be less biodegradable. Depletions decreased with increasing carbon number of n-alkanes. However, average depletions > 80% were found in n-alkanes with carbon numbers < 37. Average depletions were > 70% for 2-4 ring PAHs, while 5-6 ring PAHs were more resistant. Increase in alkylation level decreased depletion within homologues of naphthalene, phenanthrene, chrysene and Benzo[e] pyrene. GC-MS could only reveal less than 3% of the compounds of residual oils, which were mainly comprised of n-alkanes with carbon number > 20, alkylated naphthalenes and phenanthrenes, terpanes, steranes and TAS. Based on compositional characteristics of alkanes and PAHs in residual oils, 6 diagnostic ratios, which were ratios of susceptible compounds to resistant compounds or to the amounts residual oil, were proposed as the parameters for characterization of residual oils and determining the biodegradability of oils contaminated soils.
本研究的目的是确定土壤中原油的降解速率，揭示长期生物降解后残留油的指纹特征，并筛选评估残留油生物降解性的参数。共分析了18个受污染土壤样品，这些样品含有来自大庆、胜利和百色油田的严重降解的原油残留物。通过气相色谱-质谱联用仪（GC-MS）测定了残留油中100多种单个目标化合物，包括直链和支链烷烃（正构烷烃、姥鲛烷和植烷）、多环芳烃（PAHs）、萜烷、甾烷和三芳甾烷（TAS）。对于所有土壤样品，相对于原油，残留油中烷烃和PAHs的残留量分别不到10%和30%。发现萜烷、甾烷和TAS的生物降解性较差。随着正构烷烃碳数的增加，损耗率降低。然而，碳数<37的正构烷烃平均损耗率>80%。2-4环PAHs的平均损耗率>70%，而5-6环PAHs更具抗性。萘、菲、芘和苯并[e]芘同系物中烷基化水平的增加降低了损耗率。GC-MS只能揭示残留油中不到3%的化合物，这些化合物主要由碳数>20的正构烷烃、烷基化萘和菲、萜烷、甾烷和TAS组成。基于残留油中烷烃和PAHs的组成特征，提出了6个诊断比值，即敏感化合物与抗性化合物的比值或与残留油含量的比值，作为表征残留油和确定受油污染土壤生物降解性的参数。
