Brünjes Jonas, Seidel Michael, Dittmar Thorsten, Niggemann Jutta, Schubotz Florence
MARUM Center for Marine Environmental Sciences, University of Bremen, Bremen 28359, Germany.
Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University of Oldenburg, Oldenburg 26129, Germany.
Environ Sci Technol. 2022 Jun 21;56(12):9092-9102. doi: 10.1021/acs.est.2c01123. Epub 2022 May 18.
Natural oil seepages contribute about one-half of the annual petroleum input to marine systems. Yet, environmental implications and the persistence of water-soluble hydrocarbons from these seeps are vastly unknown. We investigated the release of oil-derived dissolved organic matter (DOM) from natural deep sea asphalt seeps using laboratory incubation experiments. Fresh asphalt samples collected at the Chapopote asphalt volcano in the Southern Gulf of Mexico were incubated aerobically in artificial seawater over 4 weeks. The compositional changes in the water-soluble fraction of asphalt-derived DOM were determined with ultrahigh-resolution mass spectrometry (Fourier-transform ion cyclotron resonance mass spectrometry, FT-ICR-MS) and by excitation-emission matrix spectroscopy to characterize fluorescent DOM (FDOM) applying parallel factor (PARAFAC) analysis. Highly reduced aliphatic asphalt-derived DOM was readily biodegraded, while aromatic and sulfur-enriched DOM appeared to be less bioavailable and accumulated in the aqueous phase. A quantitative molecular tracer approach revealed the abundance of highly condensed aromatic molecules of thermogenic origin. Our results indicate that natural asphalt and potentially other petroleum seepages can be sources of recalcitrant dissolved organic sulfur and dissolved black carbon to the ocean.
天然油渗漏对海洋系统的年石油输入贡献约占一半。然而，这些渗漏产生的水溶性碳氢化合物对环境的影响以及其持久性却鲜为人知。我们通过实验室培养实验研究了天然深海沥青渗漏中油衍生溶解有机物（DOM）的释放情况。在墨西哥湾南部的查波波特沥青火山采集的新鲜沥青样品，在人工海水中进行了为期4周的好氧培养。利用超高分辨率质谱（傅里叶变换离子回旋共振质谱，FT-ICR-MS）以及通过激发-发射矩阵光谱法并应用平行因子（PARAFAC）分析来表征荧光DOM（FDOM），从而确定沥青衍生DOM水溶性部分的成分变化。高度还原的脂肪族沥青衍生DOM很容易被生物降解，而芳香族和富含硫的DOM似乎生物可利用性较低，并在水相中积累。一种定量分子示踪方法揭示了热成因高度缩合芳香分子的丰度。我们的结果表明，天然沥青以及潜在的其他石油渗漏可能是海洋中难降解溶解有机硫和溶解黑碳的来源。
