322
spectra from this horizon, seafloor surface sediment (0–5 mm below seafloor), more
deeply buried sediment (200–210 mm below seafloor), and the Ixtoc 1 reference oil
revealed important differences. Most notably, both the visibly oiled horizon and the
Ixtoc 1 reference oil spectra showed a characteristic pseudo-Gaussian distribution
peaking at m/z 400–500, a feature typical of FTICR-MS spectra of petroleum
(McKenna et al. 2013). Spectra of the 0–5 mm below seafloor horizon, by contrast,
had an irregular distribution indicative of recent organic matter derived from the
water column. Both the oiled horizon (70–72 mm) and the surficial sediment
(0–5 mm) showed distinctive peaks at high molecular weight corresponding to tetraether lipids (glycerol dialkyl glycerol tetraethers, or GDGTS; Radović et al. 2015)
synthesized by water column and sediment archaea and bacteria, indicating that the
petrogenic signal overprinted the background biogenic organic composition.
Molecular formula assignment revealed that the 70–72 mm horizon contained a
higher abundance of hydrocarbon-, nitrogen-, and sulfur-containing compound
classes than either surficial or deeper horizons (Fig. 19.3) and that it had a higher
double bond equivalent (DBE) distribution. Increased DBE values are consistent
with an enrichment in condensed aromatic species, as has been observed during
PP
PP
PP
PP
PP
,;:FRUH
&RPSRXQGFODVV
+&
+&
1
12
2
1
12
12
1
12
12
12
12
12
12
2
2
2
2
2
2
2
2
2
2
2
26
26
26
26
26
26
6
6
16
12
26
26
6
6
6DPSOHV
,[WRFRLO
5HODWLYHDEXQGDQFH
$33,3
Fig. 19.3 Distribution and relative abundance of compound classes in extracts from core IXW500 and the reference Ixtoc 1 oil (black). The sediment horizon 70–72 mm below seafloor (red)
contained pronounced hydrocarbon (HC)-, nitrogen (N)-, and sulfur (S1–S3)-containing compound classes and more closely matched reference oil in these respects than it did sediments from
the core top. (Data from Radović et al. Data are publicly available through the Gulf of Mexico
Research Initiative Information & Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org (https://doi.org/10.7266/n7-dya3-dj37))
S. A. Lincoln et al.
spectra from this horizon, seafloor surface sediment (0–5 mm below seafloor), more
deeply buried sediment (200–210 mm below seafloor), and the Ixtoc 1 reference oil
revealed important differences. Most notably, both the visibly oiled horizon and the
Ixtoc 1 reference oil spectra showed a characteristic pseudo-Gaussian distribution
peaking at m/z 400–500, a feature typical of FTICR-MS spectra of petroleum
(McKenna et al. 2013). Spectra of the 0–5 mm below seafloor horizon, by contrast,
had an irregular distribution indicative of recent organic matter derived from the
water column. Both the oiled horizon (70–72 mm) and the surficial sediment
(0–5 mm) showed distinctive peaks at high molecular weight corresponding to tetraether lipids (glycerol dialkyl glycerol tetraethers, or GDGTS; Radović et al. 2015)
synthesized by water column and sediment archaea and bacteria, indicating that the
petrogenic signal overprinted the background biogenic organic composition.
Molecular formula assignment revealed that the 70–72 mm horizon contained a
higher abundance of hydrocarbon-, nitrogen-, and sulfur-containing compound
classes than either surficial or deeper horizons (Fig. 19.3) and that it had a higher
double bond equivalent (DBE) distribution. Increased DBE values are consistent
with an enrichment in condensed aromatic species, as has been observed during
PP
PP
PP
PP
PP
,;:FRUH
&RPSRXQGFODVV
+&
+&
1
12
2
1
12
12
1
12
12
12
12
12
12
2
2
2
2
2
2
2
2
2
2
2
26
26
26
26
26
26
6
6
16
12
26
26
6
6
6DPSOHV
,[WRFRLO
5HODWLYHDEXQGDQFH
$33,3
Fig. 19.3 Distribution and relative abundance of compound classes in extracts from core IXW500 and the reference Ixtoc 1 oil (black). The sediment horizon 70–72 mm below seafloor (red)
contained pronounced hydrocarbon (HC)-, nitrogen (N)-, and sulfur (S1–S3)-containing compound classes and more closely matched reference oil in these respects than it did sediments from
the core top. (Data from Radović et al. Data are publicly available through the Gulf of Mexico
Research Initiative Information & Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org (https://doi.org/10.7266/n7-dya3-dj37))
S. A. Lincoln et al.