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deep-sea oil deposition and conditions that favor its preservation or degradation in
the context of both Ixtoc 1 and Deepwater Horizon spills.
Keywords Oil spill forensics · Tithonian oil families · Marine sediments · Ixtoc 1 ·
Bay of Campeche · Deepwater Horizon
19.1 Introduction
The 2010 Deepwater Horizon (DWH) blowout was the first major deep-sea oil spill in
history. The lack of precedent hindered prediction of the fate of residues of spilled oil in
seafloor sediments in the northern Gulf of Mexico (GoM). Early reports have found the
half-lives of Macondo well (MW) oil constituents in sediments to be quite short (e.g.,
Bagby et al. 2017), but as impacted horizons are buried by sediment, degradation rates
of residual petrocarbon are likely to decrease due to oxygen depletion. The longer-term
fate and persistence of residues of MW oil in seafloor sediment remain uncertain.
The 1979 Ixtoc 1 oil spill in the southern GoM provides a window for forecasting
the fate of MW oil over multi-decadal time scales. Approximately 500,000 metric
tons of oil were released over a 10-month period following the Ixtoc 1 blowout
(PCEESC 1980; CSLP 1980), creating the second largest marine oil spill to date.
Although the blowout occurred in shallow waters (56 m depth) of the Bay of
Campeche, the oil slick extended to deep waters (Sun et al. 2015), and residues were
transported as far as the Texas coast (Farrington 1983).
This chapter summarizes evidence for the persistence of traces of Ixtoc oil in deepsea sediments of the southern GoM over ~4 decades. Recognizing the complex hydrocarbon background of the region, which is impacted by both natural and anthropogenic
sources of petroleum, we focused on metrics with the greatest potential for assessing
Ixtoc 1 input. Polycyclic aromatic hydrocarbons (PAHs), sulfur heterocycles, and
petroleum biomarkers measured using conventional gas chromatography- mass spectrometry as well as molecular compound classes revealed by Fourier transform ion
cyclotron resonance-mass spectrometry (FTICR-MS) indicated that signatures of
Ixtoc 1 oil can still be detected in Bay of Campeche sediments underlying >500 m of
water (Lincoln et al. 2017, Radović et al. 2017). Finally, we discuss the spatial heterogeneity of deep-sea oil deposition and conditions that may favor its preservation or
degradation in the context of both Ixtoc 1 and Deepwater Horizon spills.
19.2 The Ixtoc 1 Oil Spill
The subsea blowout of the Petróleos Mexicanos (PEMEX) exploratory well Ixtoc 1
released ~500,000 metric tons of oil into the GoM in 1979 (CSLP 1980; Jernelöv
and Lindén 1981). It was the second largest marine oil spill in history, surpassed
only by the 2010 Deepwater Horizon (DWH) spill in the northern GoM.
19 Molecular Legacy of the 1979 Ixtoc 1 Oil Spill in Deep-Sea Sediments…
deep-sea oil deposition and conditions that favor its preservation or degradation in
the context of both Ixtoc 1 and Deepwater Horizon spills.
Keywords Oil spill forensics · Tithonian oil families · Marine sediments · Ixtoc 1 ·
Bay of Campeche · Deepwater Horizon
19.1 Introduction
The 2010 Deepwater Horizon (DWH) blowout was the first major deep-sea oil spill in
history. The lack of precedent hindered prediction of the fate of residues of spilled oil in
seafloor sediments in the northern Gulf of Mexico (GoM). Early reports have found the
half-lives of Macondo well (MW) oil constituents in sediments to be quite short (e.g.,
Bagby et al. 2017), but as impacted horizons are buried by sediment, degradation rates
of residual petrocarbon are likely to decrease due to oxygen depletion. The longer-term
fate and persistence of residues of MW oil in seafloor sediment remain uncertain.
The 1979 Ixtoc 1 oil spill in the southern GoM provides a window for forecasting
the fate of MW oil over multi-decadal time scales. Approximately 500,000 metric
tons of oil were released over a 10-month period following the Ixtoc 1 blowout
(PCEESC 1980; CSLP 1980), creating the second largest marine oil spill to date.
Although the blowout occurred in shallow waters (56 m depth) of the Bay of
Campeche, the oil slick extended to deep waters (Sun et al. 2015), and residues were
transported as far as the Texas coast (Farrington 1983).
This chapter summarizes evidence for the persistence of traces of Ixtoc oil in deepsea sediments of the southern GoM over ~4 decades. Recognizing the complex hydrocarbon background of the region, which is impacted by both natural and anthropogenic
sources of petroleum, we focused on metrics with the greatest potential for assessing
Ixtoc 1 input. Polycyclic aromatic hydrocarbons (PAHs), sulfur heterocycles, and
petroleum biomarkers measured using conventional gas chromatography- mass spectrometry as well as molecular compound classes revealed by Fourier transform ion
cyclotron resonance-mass spectrometry (FTICR-MS) indicated that signatures of
Ixtoc 1 oil can still be detected in Bay of Campeche sediments underlying >500 m of
water (Lincoln et al. 2017, Radović et al. 2017). Finally, we discuss the spatial heterogeneity of deep-sea oil deposition and conditions that may favor its preservation or
degradation in the context of both Ixtoc 1 and Deepwater Horizon spills.
19.2 The Ixtoc 1 Oil Spill
The subsea blowout of the Petróleos Mexicanos (PEMEX) exploratory well Ixtoc 1
released ~500,000 metric tons of oil into the GoM in 1979 (CSLP 1980; Jernelöv
and Lindén 1981). It was the second largest marine oil spill in history, surpassed
only by the 2010 Deepwater Horizon (DWH) spill in the northern GoM.
19 Molecular Legacy of the 1979 Ixtoc 1 Oil Spill in Deep-Sea Sediments…