330
the DWH formed surface oil slicks that eventually impacted nGoM shores (Ryerson
et al. 2012). Weathering of beached DWH oil and coastal residues was driven by
photooxidation, in particular shortly after the spill (Radović et al. 2014; Ward et al.
2018), and in later stages also by biodegradation (Aeppli et al. 2012, 2014). These
weathering processes transformed the parent oil compounds to oxygen-containing
derivatives (Aeppli et al. 2012; Radović et al. 2014; Ruddy et al. 2014), which seem
to be continually produced and preserved/accumulated over periods of several years
after the spill (White et al. 2016; Romero et al. 2017; Stout and Payne 2016).
Due to the post-spill fate similarities of the two GoM spills, Ixtoc 1 can serve as
a good analog to help develop a predictive model of future long-term weathering
effects and the ultimate fate of the DWH oil residues currently found along the
nGoM coastline. However, at the time of the Ixtoc 1 spill, and in the following
years, only limited research efforts were invested into monitoring of the post-spill
fate and impacts of coastal residues (Lizarraga et al. 1984; Lizárraga-Partida et al.
1982; Soto et al. 1981, 2014). In order to fill in this research gap, in 2016, a group
of researchers from the Gulf of Mexico Research Initiative (GoMRI)-funded
C-IMAGE II consortium revisited the sites in the sGoM, which were affected by the
Ixtoc 1 spill, according to the previous data and field observations by J.W. Tunnell
in Sun et al. (2015) (Fig. 20.1), and collected and characterized oil residues found
in these areas. Using an illustrative selection of those residue samples, this chapter
will provide a general overview of the most important initial results and observations related to multi-decadal oil weathering processes.
20.2 Affected Areas and Sampling Sites
Sun et al. (2015) used available historic satellite data collected during the Ixtoc 1
spill (June 1979 to March 1980), namely, Coastal Zone Color Scanner (CZCS,
1978–1986 on Nimbus-7 satellite) and Landsat Multispectral Scanner (MSS, 1972–
1999 on Landsat 1–5 satellites) datasets, to identify and quantify surface oil slicks
from the Ixtoc 1 spill (Fig. 20.1). Their results suggest that the Ixtoc 1 sourced oil
slicks most frequently occurred within 200 km north and west of the spill site. Most
of them moved along the northwestern trajectory, reaching as far north as Corpus
Christi, Texas. Later in the spill event (after mid-September 1979), oil was also
detected in the southern and southeastern portion of the GoM, arriving all the way
up to the offshore areas north of the Yucatan Peninsula. Satellite-derived reconstructions were corroborated by numerous field observations, both from the literature
(Gundlach et al. 1981) and as recorded during the field trips conducted by John
W. Tunnel in the aftermath of the spill. At many of these locations which were revisited in 2016, weathered oil residues could be found (Fig. 20.2).
Oil residues found at these locations were quite diverse, ranging from extremely
weathered oil adhered to the exposed supratidal rocky shores, e.g., at Punta Delgado
and Montepio sampling sites, to relatively preserved oil which was found buried in
low-energy mangrove environments along the western coast of the Yucatan Peninsula
(e.g., at the Isla Arenas site) (Fig. 20.2).
J. R. Radović et al.
the DWH formed surface oil slicks that eventually impacted nGoM shores (Ryerson
et al. 2012). Weathering of beached DWH oil and coastal residues was driven by
photooxidation, in particular shortly after the spill (Radović et al. 2014; Ward et al.
2018), and in later stages also by biodegradation (Aeppli et al. 2012, 2014). These
weathering processes transformed the parent oil compounds to oxygen-containing
derivatives (Aeppli et al. 2012; Radović et al. 2014; Ruddy et al. 2014), which seem
to be continually produced and preserved/accumulated over periods of several years
after the spill (White et al. 2016; Romero et al. 2017; Stout and Payne 2016).
Due to the post-spill fate similarities of the two GoM spills, Ixtoc 1 can serve as
a good analog to help develop a predictive model of future long-term weathering
effects and the ultimate fate of the DWH oil residues currently found along the
nGoM coastline. However, at the time of the Ixtoc 1 spill, and in the following
years, only limited research efforts were invested into monitoring of the post-spill
fate and impacts of coastal residues (Lizarraga et al. 1984; Lizárraga-Partida et al.
1982; Soto et al. 1981, 2014). In order to fill in this research gap, in 2016, a group
of researchers from the Gulf of Mexico Research Initiative (GoMRI)-funded
C-IMAGE II consortium revisited the sites in the sGoM, which were affected by the
Ixtoc 1 spill, according to the previous data and field observations by J.W. Tunnell
in Sun et al. (2015) (Fig. 20.1), and collected and characterized oil residues found
in these areas. Using an illustrative selection of those residue samples, this chapter
will provide a general overview of the most important initial results and observations related to multi-decadal oil weathering processes.
20.2 Affected Areas and Sampling Sites
Sun et al. (2015) used available historic satellite data collected during the Ixtoc 1
spill (June 1979 to March 1980), namely, Coastal Zone Color Scanner (CZCS,
1978–1986 on Nimbus-7 satellite) and Landsat Multispectral Scanner (MSS, 1972–
1999 on Landsat 1–5 satellites) datasets, to identify and quantify surface oil slicks
from the Ixtoc 1 spill (Fig. 20.1). Their results suggest that the Ixtoc 1 sourced oil
slicks most frequently occurred within 200 km north and west of the spill site. Most
of them moved along the northwestern trajectory, reaching as far north as Corpus
Christi, Texas. Later in the spill event (after mid-September 1979), oil was also
detected in the southern and southeastern portion of the GoM, arriving all the way
up to the offshore areas north of the Yucatan Peninsula. Satellite-derived reconstructions were corroborated by numerous field observations, both from the literature
(Gundlach et al. 1981) and as recorded during the field trips conducted by John
W. Tunnel in the aftermath of the spill. At many of these locations which were revisited in 2016, weathered oil residues could be found (Fig. 20.2).
Oil residues found at these locations were quite diverse, ranging from extremely
weathered oil adhered to the exposed supratidal rocky shores, e.g., at Punta Delgado
and Montepio sampling sites, to relatively preserved oil which was found buried in
low-energy mangrove environments along the western coast of the Yucatan Peninsula
(e.g., at the Isla Arenas site) (Fig. 20.2).
J. R. Radović et al.