Weathering patterns of polycyclic aromatic hydrocarbons contained in submerged Deepwater Horizon oil spill residues when re-exposed to sunlight
Weathering patterns of polycyclic aromatic hydrocarbons contained in submerged Deepwater Horizon oil spill residues when re-exposed to sunlight
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DOI：
10.1016/j.scitotenv.2016.08.059
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发表时间：
2016-12-15
影响因子：
9.8
通讯作者：
Clement, T. Prabhakar
中科院分区：
文献类型：
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作者：
John, Gerald F.;Han, Yuling;Clement, T. Prabhakar
深水地平线（DWH）漏油事件向墨西哥湾（GOM）释放了大量的低硫原油。这些石油中的一个未知部分沿着亚拉巴马海岸线到达，与近岸沉积物相互作用并下沉，形成水下油席（SOM）。大量的碳氢化合物，包括多环芳烃（PAHs），被困在这些埋藏的SOM。最近利用沿着亚拉巴马海岸线收集的溢油残留物完成的研究表明，几种多环芳烃，特别是较高分子量的多环芳烃（四个或更多个芳环），与漂浮在墨西哥湾上空的石油所经历的风化程度相比，正在缓慢风化。在这项研究中，我们假设，在SOMs的多环芳烃的风化速率已经放缓，因为被掩埋的石油被隔离，从直接暴露在阳光下，从而阻碍了光降解途径。我们进一步假设，重新暴露SOM的日晒可以重新激活各种风化反应。此外，SOM含有75-95%的砂（按重量计），并且截留的砂可以阻挡阳光直射或形成具有非常小的暴露表面积的大的油聚集体;这些过程可能会干扰风化反应。为了验证这些假设，我们完成了控制实验，研究多环芳烃的风化模式在现场恢复SOM样品后，重新暴露于阳光下。我们的实验结果表明，风化水平的几个较高的分子量的多环芳烃已经放缓，主要是由于没有阳光诱导的光降解反应。这些数据还表明，SOM材料中的沙粒可能会干扰光降解反应。(C)© 2016 Elsevier B. V.版权所有。
The Deepwater Horizon (DWH) oil spill event released a large amount of sweet crude oil into the Gulf of Mexico (GOM). An unknown portion of this oil that arrived along the Alabama shoreline interacted with nearshore sediments and sank forming submerged oil mats (SOMs). A considerable amount of hydrocarbons, including poly cyclic aromatic hydrocarbons (PAHs), were trapped within these buried SOMs. Recent studies completed using the oil spill residues collected along the Alabama shoreline have shown that several PAHs, especially higher molecular weight PAHs (four or more aromatic rings), are slowly weathering compared to the weathering levels experienced by the oil when it was floating over the GOM. In this study we have hypothesized that the weathering rates of PAHs in SOMs have slowed down because the buried oil was isolated from direct exposure to sunlight, thus hindering the photodegradation pathway. We further hypothesized that re-exposing SOMs to sunfight can reactivate various weathering reactions. Also, SOMs contain 75-95% sand (by weight) and the entrapped sand could either block direct sunlight or form large oil agglomerates with very little exposed surface area; these processes could possibly interfere with weathering reactions. To test these hypotheses, we completed controlled experiments to study the weathering patterns of PAHs in a field recovered SOM sample after re-exposing it to sunlight. Our experimental results show that the weathering levels of several higher molecular weight PAHs have slowed down primarily due to the absence of sunlight-induced photodegradation reactions. The data-also show that sand particles in SOM material could potentially interfere with photodegradation reactions. (C) 2016 Elsevier B.V. All rights reserved.