Maki H, Sasaki T, Harayama S
Marine Biotechnology Institute, Kamaishi Laboratories, Iwate, Japan.
Chemosphere. 2001 Aug;44(5):1145-51. doi: 10.1016/s0045-6535(00)00292-7.
We investigated the physicochemical changes resulting from irradiation by sunlight of biodegraded crude oil. An Arabian light crude oil sample was first subjected to microbial degradation. n-Alkanes and aromatic compounds such as naphthalenes, fluorenes, dibenzothiophenes and phenanthrenes possessing short, alkyl side chain(s) were almost completely degraded, while the contents of the saturated and aromatic fractions were reduced by 70% and 40%, respectively. This biodegraded oil was then suspended in seawater and exposed to sunlight irradiation for several weeks. The most remarkable change caused by the irradiation was a substantial decline in the aromatic fraction with a concomitant increase in the resin and asphaltene fractions. A 13C-nuclear magnetic resonance (NMR) spectroscopic analysis showed that the aromaticity of the biodegraded oil was significantly lower in the irradiated sample. A field desorption-mass spectrometric (FD-MS) analysis showed that sunlight irradiation reduced the average molecular weight of the oil components and formed oxygenated compounds. Consistent with this observation is that the oxygen content in the oil increased as the irradiation was prolonged. The bioavailability of the biodegraded oil was increased by the photo-oxidation: the growth of seawater microbes was minimal when the non-irradiated biodegraded oil was used as the source of carbon and energy; however, growth was significant when irradiated biodegraded oil was used. The concentration of dissolved organic carbon (DOC) increased linearly during the sunlight irradiation of the biodegraded oil, and this increase was matched by an increase in ultraviolet-absorptive materials in the seawater. The photochemically formed, water-soluble fraction (WSF) showed acute toxicity against the halophilic crustacean, Artemia.
我们研究了生物降解原油经阳光照射后产生的物理化学变化。首先对一份阿拉伯轻质原油样品进行微生物降解。具有短烷基侧链的正构烷烃和芳香族化合物，如萘、芴、二苯并噻吩和菲，几乎完全被降解，而饱和馏分和芳香馏分的含量分别降低了70%和40%。然后将这种生物降解油悬浮在海水中，并暴露于阳光照射下数周。照射引起的最显著变化是芳香馏分大幅下降，同时树脂和沥青质馏分增加。13C核磁共振（NMR）光谱分析表明，经照射的样品中生物降解油的芳香性显著降低。场解吸质谱（FD-MS）分析表明，阳光照射降低了油成分的平均分子量并形成了含氧化合物。与这一观察结果一致的是，随着照射时间延长，油中的氧含量增加。光氧化提高了生物降解油的生物可利用性：当使用未照射的生物降解油作为碳源和能源时，海水微生物的生长极少；然而，当使用经照射的生物降解油时，生长显著。在对生物降解油进行阳光照射期间，溶解有机碳（DOC）的浓度呈线性增加，并且这种增加与海水中紫外线吸收物质的增加相匹配。光化学形成的水溶性部分（WSF）对嗜盐甲壳类动物卤虫表现出急性毒性。
